AS FILED WITH THE SECURITIES AND EXCHANGE COMMISSION ON DECEMBER 4, 2001 REGISTRATION NO. 333- - -------------------------------------------------------------------------------- - -------------------------------------------------------------------------------- SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 --------------------- FORM S-3 REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933 --------------------- REGENERON PHARMACEUTICALS, INC. (Exact name of registrant as specified in its charter) ---------------------

NEW YORK 13-3444607 (State or other jurisdiction of (I.R.S. Employer incorporation or organization) Identification No.) 777 OLD SAW MILL RIVER ROAD TARRYTOWN, NEW YORK 10591 (914) 347-7000 (Address, including zip code and telephone number, including area code, of registrant's principal executive offices)
--------------------- STUART A. KOLINSKI, ESQ. GENERAL COUNSEL REGENERON PHARMACEUTICALS, INC. 777 OLD SAW MILL RIVER ROAD TARRYTOWN, NEW YORK 10591-6707 (914) 347-7000 (Name, address, including zip code and telephone number, including area code, of agent for service) COPIES TO: DAVID J. GOLDSCHMIDT, ESQ. JI HOON HONG, ESQ. SKADDEN, ARPS, SLATE, MEAGHER & FLOM LLP SHEARMAN & STERLING FOUR TIMES SQUARE 599 LEXINGTON AVENUE NEW YORK, NEW YORK 10036-6522 NEW YORK, NEW YORK 10022 (212) 735-3000 (212) 848-4000
--------------------- APPROXIMATE DATE OF COMMENCEMENT OF PROPOSED SALE TO THE PUBLIC: From time to time after this Registration Statement becomes effective. If the only securities being registered on this form are being offered pursuant to dividend or interest reinvestment plans, please check the following box. [ ] If any of the securities being registered on this Form are to be offered on a delayed or continuous basis pursuant to Rule 415 under the Securities Act of 1933, other than securities offered only in connection with dividend or interest reinvestment plans, check the following box. [X] If this form is filed to register additional securities for an offering pursuant to Rule 462(b) under the Securities Act, please check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering. [ ] - --------------- If this form is a post-effective amendment filed pursuant to Rule 462(c) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering. [ ] - --------------- If delivery of the prospectus is expected to be made pursuant to Rule 434, please check the following box. [ ] CALCULATION OF REGISTRATION FEE
- --------------------------------------------------------------------------------------------------------------------------------- - --------------------------------------------------------------------------------------------------------------------------------- TITLE OF EACH CLASS OF AMOUNT TO BE PROPOSED MAXIMUM OFFERING AMOUNT OF SECURITIES TO BE REGISTERED REGISTERED PRICE PER NOTE REGISTRATION FEE - --------------------------------------------------------------------------------------------------------------------------------- 5 1/2% Convertible Senior Subordinated Notes due 2008............................................... $200,000,000(1) 100%(2) $47,800 - --------------------------------------------------------------------------------------------------------------------------------- Common stock, $0.001 par value (including the associated Rights to purchase Series A Participating Preferred Stock)(3).................. 6,611,300(4) $ $ (5) - --------------------------------------------------------------------------------------------------------------------------------- - ---------------------------------------------------------------------------------------------------------------------------------
(1) Represents the aggregate principal amount at maturity of the notes that were originally issued by the Registrant in October 2001. (2) Equals the aggregate principal amount of the notes being registered. Estimated solely for the purposes of calculating the registration fee pursuant to Rule 457(o) under the Securities Act. (3) The Rights to purchase shares of our Series A Junior Participating Preferred Stock initially are attached to and trade with the shares of our common stock being registered hereby. Value attributed to such Rights, if any, is reflected in the market price of our common stock. (4) Represents the number of shares of common stock that are currently issuable upon conversion of the notes registered hereby. The number of shares of common stock that may be issued upon conversion in the future is indeterminate, and the Registrant is also registering this indeterminate amount pursuant to Rule 416 of the Securities Act. (5) No separate consideration will be received for the shares of common stock issuable upon conversion of the notes and, therefore, no registration fee is required pursuant to Rule 457(i) under the Securities Act. THE REGISTRANT HEREBY AMENDS THIS REGISTRATION STATEMENT ON SUCH DATE OR DATES AS MAY BE NECESSARY TO DELAY ITS EFFECTIVE DATE UNTIL THE REGISTRANT SHALL FILE A FURTHER AMENDMENT SPECIFICALLY STATING THAT THIS REGISTRATION STATEMENT SHALL THEREAFTER BECOME EFFECTIVE IN ACCORDANCE WITH SECTION 8(a) OF THE SECURITIES ACT OF 1933, AS AMENDED, OR UNTIL THIS REGISTRATION STATEMENT SHALL BECOME EFFECTIVE ON SUCH DATE AS THE COMMISSION, ACTING PURSUANT TO SAID SECTION 8(a), MAY DETERMINE. - -------------------------------------------------------------------------------- - --------------------------------------------------------------------------------

THE INFORMATION IN THIS PROSPECTUS IS NOT COMPLETE AND MAY BE CHANGED. THE SELLING SECURITYHOLDERS MAY NOT SELL THESE SECURITIES UNTIL THE REGISTRATION STATEMENT FILED WITH THE SECURITIES AND EXCHANGE COMMISSION IS EFFECTIVE. THIS PROSPECTUS IS NOT AN OFFER TO SELL THESE SECURITIES AND IT IS NOT SOLICITING OFFERS TO BUY THESE SECURITIES IN ANY STATE WHERE THE OFFER OR SALE IS NOT PERMITTED. SUBJECT TO COMPLETION PRELIMINARY PROSPECTUS DATED DECEMBER 4, 2001 $200,000,000 REGENERON PHARMACEUTICALS, INC. 5 1/2% CONVERTIBLE SENIOR SUBORDINATED NOTES DUE 2008 AND SHARES OF COMMON STOCK ISSUABLE UPON CONVERSION OF THE NOTES On October 17, 2001, we issued and sold $200,000,000 aggregate principal amount of our 5 1/2% Convertible Senior Subordinated Notes due 2008 in a private placement. This prospectus will be used by selling securityholders to resell the notes and register the common stock issuable upon conversion of the notes. The notes are convertible, at the option of the holder, at any time on or prior to maturity into shares of our common stock. Holders of our common stock and holders of our Class A stock have identical rights, except for voting and conversion rights and restrictions on transferability. Holders of our Class A stock are entitled to ten votes per share and the holders of our common stock are entitled to one vote per share. The notes are convertible at a conversion price of approximately $30.25 per share, which is equal to a conversion rate of 33.0565 shares per $1,000 principal amount of notes, subject to adjustment. Our common stock is quoted on the Nasdaq National Market under the symbol "REGN." On November 29, 2001, the closing bid price of our common stock as reported on the Nasdaq National Market was $27.67 per share. We will pay interest on the notes on April 17 and October 17 of each year, beginning April 17, 2002. The notes will mature on October 17, 2008. We may provisionally redeem some or all of the notes at any time before October 17, 2004 at a redemption price of $1,000 per $1,000 principal amount of notes, plus accrued and unpaid interest, if any, to the redemption date, if the closing price of our common stock has exceeded 150% of the conversion price then in effect for at least 20 trading days within a period of 30 consecutive trading days ending on the trading day before the date on which we mail the provisional redemption notice, and subject to certain other conditions. Upon any such provisional redemption, we will make an additional payment in cash equal to $165 per $1,000 principal amount of notes, less the amount of any interest actually paid on the notes before the provisional redemption date. We may also optionally redeem some or all of the notes at any time on or after October 17, 2004, at a redemption price of $1,000 per $1,000 principal amount of notes, plus accrued and unpaid interest, if any, if the closing price of our common stock has exceeded 140% of the conversion price then in effect for at least 20 trading days within a period of 30 consecutive trading days ending on the trading day before the date on which we mail the optional redemption notice. The notes are unsecured (except to the extent described in this prospectus) and subordinated to our existing and future senior indebtedness. The notes will rank equally with our existing and future senior subordinated indebtedness. We have pledged a portfolio of U.S. government securities as security for the notes, in an amount sufficient to pay the first six scheduled interest payments on the notes. INVESTING IN THE NOTES INVOLVES RISKS THAT ARE DESCRIBED IN THE "RISK FACTORS" SECTION BEGINNING ON PAGE 5 OF THIS PROSPECTUS. We will not receive any of the proceeds from the sale of the notes or the shares of common stock by any of the selling securityholders. The notes and the shares of common stock may be offered in negotiated transactions or otherwise, at market prices prevailing at the time of sale or at negotiated prices. The timing and amount of any sale are within the sole discretion of the selling securityholders. In addition, the shares of common stock may be offered from time to time through ordinary brokerage transactions on the Nasdaq National Market. See "Plan of Distribution." The selling securityholders may be deemed to be "underwriters" as defined in the Securities Act of 1933, as amended. Any profits realized by the selling securityholders may be deemed to be underwriting commissions. If the selling securityholders use any broker-dealers, any commission paid to broker-dealers and, if broker-dealers purchase any notes or shares of common stock as principals, any profits received by such broker-dealers on the resale of the notes or shares of common stock may be deemed to be underwriting discounts or commissions under the Securities Act. NEITHER THE SECURITIES AND EXCHANGE COMMISSION NOR ANY STATE SECURITIES COMMISSION HAS APPROVED OR DISAPPROVED OF THESE SECURITIES OR DETERMINED IF THIS PROSPECTUS OR THE ACCOMPANYING PROSPECTUS SUPPLEMENT IS TRUTHFUL OR COMPLETE. ANY REPRESENTATION TO THE CONTRARY IS A CRIMINAL OFFENSE. The date of this prospectus is December 4, 2001.

TABLE OF CONTENTS

PAGE ---- Summary..................................................... 1 Risk Factors................................................ 5 Ratio of Earnings to Fixed Charges.......................... 14 Use of Proceeds............................................. 14 Dividend Policy............................................. 14 Description of the Notes.................................... 15 Description of Capital Stock................................ 30 Selling Securityholders..................................... 32 Plan of Distribution........................................ 34 Legal Matters............................................... 36 Experts..................................................... 36
------------------------ In this prospectus, "Regeneron," "our company," "we," "us," "the issuer," "the registrant," and "our" refer to Regeneron Pharmaceuticals, Inc., references to our "common stock" shall include the rights attached to such common stock in accordance with our shareholder rights plan and references to our "common shares" shall mean, collectively, our shares of common stock and Class A stock. WHERE YOU CAN FIND MORE INFORMATION We are subject to the information and reporting requirements of the Securities Exchange Act of 1934, as amended (the "Exchange Act"), under which we file periodic reports, proxy statements and other information with the SEC. Copies of the reports, proxy statements and other information may be examined without charge at the Public Reference Section of the SEC, 450 Fifth Street, N.W. Room 1024, Washington, D.C. 20549, and the SEC's regional office located at 233 Broadway, New York, NY 10279 or 500 West Madison Street, Suite 1400, Chicago, IL 60600 or on the Internet at http://www.sec.gov. Copies of all or a portion of such materials can be obtained from the Public Reference Section of the SEC upon payment of prescribed fees. Please call the SEC at 800-SEC-0330 for further information about the Public Reference Room. The SEC allows us to "incorporate by reference" the information we file with them, which means that we can disclose important information to you by referring you to those documents. The information incorporated by reference is considered to be part of this prospectus and information that we file later with the SEC will automatically update and supersede this information. We incorporate by reference the documents listed below and all future filings we make with the SEC after the date of the initial registration statement and prior to effectiveness of the registration statement and any filings thereafter and prior to the termination of this offering with the SEC under Section 13(a), 13(c), 14, or 15(d) of the Securities Exchange Act of 1934: (1) our definitive Proxy Statements filed on April 30, 2001 and November 21, 2001; (2) our Annual Report on Form 10-K for the year ended December 31, 2000; (3) our Quarterly Reports on Form 10-Q for the quarters ended March 31, 2001, June 30, 2001 and September 30, 2001; (4) our Current Reports on Form 8-K filed on October 12, 2001; and (5) the description of our common stock contained in Item 1 of our Registration Statement on Form 8-A filed on February 20, 1991, as amended by a Form 8 filed on March 27, 1991. i

You may request a copy of these filings, at no cost, by writing or telephoning us at the following address: Regeneron Pharmaceuticals, Inc. 777 Old Saw Mill River Road Tarrytown, New York 10591-6707 (917) 347-7000 Attention: Murray A. Goldberg Chief Financial Officer Exhibits to the filings will not be sent, however, unless those exhibits have specifically been incorporated by reference in this document. ii

FORWARD-LOOKING STATEMENTS This prospectus and the documents incorporated by reference herein include forward-looking statements. We have based these forward-looking statements on our current expectations and projections about future events. These forward-looking statements include, among other things, statements relating to: - our anticipated business strategies; - our anticipated clinical trials; - our intention to introduce new product candidates; - our relationships with collaborators; - anticipated trends in our businesses; - future capital expenditures; and - our ability to conduct clinical trials and obtain regulatory approval. The forward-looking statements included in this prospectus or in the documents incorporated by reference herein are subject to risks, uncertainties and assumptions about us. Our actual results of operations may differ materially from the forward-looking statements as a result of, among other things, the success or failure of our clinical trials, the speed at which our clinical trials progress, the success of our competitors in developing products equal or superior to ours, the success of our collaborative relationships and the other reasons described under "Risk Factors." We undertake no obligation to publicly update or revise any forward-looking statement, whether as a result of new information, future events or otherwise, except as required by law. In light of these risks, uncertainties and assumptions, the forward-looking events discussed in this prospectus might not occur. For these statements, we claim the protection of the safe harbor for forward-looking statements contained in Section 21E of the Exchange Act. iii

SUMMARY The following summary highlights information contained in other parts of this prospectus or incorporated by reference in this prospectus. You should read this summary together with the more detailed information elsewhere in this prospectus and in our financial statements and accompanying notes and other information incorporated by reference in this prospectus. REGENERON PHARMACEUTICALS, INC. We are a biopharmaceutical company that discovers, develops and intends to commercialize therapeutic drugs for the treatment of serious medical conditions. Our product pipeline includes product candidates for the treatment of obesity, rheumatoid arthritis and other inflammatory conditions, cancer and related disorders, allergies, asthma, and other diseases and disorders. Since inception, we have not generated sales or any profits from the commercialization of any of our product candidates. Our core business strategy is to combine our strong foundation in science and technology with state-of-the-art manufacturing and clinical development capabilities to build a successful, integrated biopharmaceutical company. Our efforts have yielded a diverse and growing pipeline of product candidates that have the potential to address a variety of unmet medical needs. Our ability to develop product candidates results from the application of our technology platforms. In contrast to basic genomics approaches which attempt to identify every gene in a cell or genome, our technology platforms are designed to discover specific genes of therapeutic interest for a particular disease or cell type. We will continue to invest in the development of enabling technologies to assist in our efforts to identify, develop, and commercialize new product candidates. ------------------------ We are a New York corporation organized on January 8, 1988. Our executive offices are at 777 Old Saw Mill River Road, Tarrytown, New York 10591-6707 and our telephone number is (914) 347-7000. 1

THE OFFERING The following is a brief summary of the terms of the notes. For a more complete description of the notes, see "Description of the Notes" in this prospectus. Issuer........................ Regeneron Pharmaceuticals, Inc. Notes offered................. $200,000,000 aggregate principal amount of 5 1/2% Convertible Senior Subordinated Notes due 2008. Maturity...................... October 17, 2008. Interest...................... 5 1/2% per annum on the principal amount, payable semi-annually on April 17 and October 17 of each year, beginning April 17, 2002. Conversion rights............. The notes are convertible at the option of the holder at any time on or prior to maturity into shares of our common stock at a conversion price of approximately $30.25 per share, which is equal to a conversion rate of 33.0565 shares per $1,000 principal amount of notes. The conversion price is subject to adjustment. Security...................... We have purchased and pledged to the trustee under the indenture, as security for the notes and for the exclusive benefit of the holders of the notes, $31.6 million of U.S. government securities, which will be sufficient upon receipt of scheduled principal and interest payments thereon, to provide for the payment in full of the first six scheduled interest payments on the notes when due. The notes will not otherwise be secured. Provisional Redemption........ We may redeem the notes, in whole or in part, at any time before October 17, 2004 at a redemption price equal to $1,000 per $1,000 principal amount of notes to be redeemed, plus accrued and unpaid interest, if any, to the date of the provisional redemption if (i) the closing price of our common stock has exceeded 150% of the conversion price then in effect for at least 20 trading days within a period of 30 consecutive trading days ending on the trading day before the date on which we mail the provisional redemption notice and (ii) during the period that we are obligated under the registration rights agreement to keep this shelf registration statement effective, such shelf registration statement covering resales of the notes and the common stock issuable upon conversion of the notes is effective and available for use as of, and including, the date on which we mail the provisional redemption notice through and including the provisional redemption date. Upon any provisional redemption, we will make an additional "make-whole" payment in cash with respect to the notes called for redemption in an amount equal to $165 per $1,000 principal amount of notes, less the amount of any interest actually paid on the notes before the provisional redemption date. We will be obligated to make this additional payment on all notes called for provisional redemption, including any notes converted after the provisional redemption notice date and before the provisional redemption date. 2

Optional redemption........... We may redeem all or a portion of the notes on or after October 17, 2004 at $1,000 per $1,000 principal amount of the notes, plus accrued and unpaid interest, if any, if the closing price of our common stock has exceeded 140% of the conversion price then in effect for at least 20 trading days within a period of 30 consecutive trading days ending on the trading day before the date on which we mail the optional redemption notice. Repurchase Upon Change of Control....................... Holders of the notes may require us to repurchase all or part of the holder's notes at 100% of their principal amount, plus accrued and unpaid interest, if any, in certain circumstances involving a change of control. The repurchase price is payable: - in cash; or - at our option, subject to the satisfaction of certain conditions, in shares of our common stock. The number of shares of common stock will equal the repurchase price divided by 95% of the average closing sales prices of our common stock for the five-trading-day period ending on the third business day prior to the repurchase date. Ranking....................... The notes are our unsecured (except to the extent described under "Description of the Notes -- Security") senior subordinated obligations. They rank junior in right of payment to all of our existing and future Senior Indebtedness (as defined herein), and rank equally with all of our existing and future senior subordinated indebtedness. We had approximately $23.6 million of Senior Indebtedness outstanding as of September 30, 2001, of which approximately $1.5 million was repaid on October 11, 2001. Form and denomination......... The notes were issued in fully registered form. The notes are represented by one or more global notes, deposited with the trustee as a custodian for the Depository Trust Company ("DTC") and registered in the name of Cede & Co., DTC's nominee. Beneficial interests in the global notes are shown on, and any transfers are effected only through, records maintained by DTC and its participants. Use of proceeds............... We will not receive any of the proceeds from the sale by any selling securityholder of the notes or shares of common stock offered under this prospectus. Trading....................... The notes sold to qualified institutional buyers are eligible for trading in the PORTAL market; however, the notes resold pursuant to this prospectus will no longer trade on the PORTAL market. We do not intend to list the notes on any national securities exchange or the Nasdaq National Market. Nasdaq symbol for our common stock......................... Our common stock is quoted on the Nasdaq National Market under the symbol "REGN." Common Shares................. As of October 31, 2001, there were 41,163,133 shares of common stock and 2,570,789 shares of Class A stock issued and outstanding, our Class A stock together with our common stock 3

are our common shares. Holders of our Class A stock are entitled to ten votes per share and the holders of our common stock are entitled to one vote per share. The outstanding shares of Class A stock represented approximately 38.4% of the combined voting power of our outstanding common shares, on that date. The holders of our Class A stock and the holders of our common stock have identical rights, except with respect to voting and conversion rights and restrictions on transferability. Risk Factors.................. See "Risk Factors" and other information in this prospectus for a discussion of factors you should carefully consider before deciding to invest in the notes. 4

RISK FACTORS You should carefully consider the following risk factors together with the other information contained in or incorporated into this prospectus before you decide to buy our notes. If any of these risks actually occurs, our business, financial condition, operating results or cash flows could be materially adversely affected. This could cause the trading price of the notes or our common stock to decline and you may lose part or all of your investment. RISKS RELATED TO OUR BUSINESS, INDUSTRY AND STRATEGY Our research and development programs may be unsuccessful and may not lead to the development of any commercially successful products. Only a small minority of all research and development programs ultimately result in commercially successful drugs. We are attempting to develop drugs for human therapeutic uses. In order to begin the development process, we need to identify potential product candidates. Although we currently have several product candidates, our research and development activities may not successfully identify new product candidates. Our ability to commercialize the product candidates we do identify depends on completing clinical trials which demonstrate their safety and efficacy to the satisfaction of the United States Food and Drug Administration (FDA) and applicable foreign regulatory authorities. Clinical trials are a multi-step process as the product candidate is tested in larger populations, and a product candidate could fail at any step. Each stage of clinical development is more costly than the prior stage and we may expend substantial resources on a product candidate and then determine it cannot be successfully commercialized. For example, following a review of the clinical trial data, we and Amgen discontinued the development of Brain-Derived Neurotrophic Factor (BDNF) for the treatment of amyotrophic lateral sclerosis in January 2001. We may never obtain regulatory approval for any of our product candidates. Even if the safety and efficacy of our product candidates are demonstrated in clinical trials and the necessary regulatory approvals are obtained, the commercial success of any of our product candidates will depend on our ability to successfully develop, manufacture, and market our product candidates and upon their acceptance by patients, the medical community, and third-party payors. If our products are not successfully commercialized, we will not be able to recover the significant investment we have made in developing such products and our business would be severely harmed. We may be required to suspend, repeat, or terminate our clinical trials, which could have a material adverse effect on our business. In order to obtain regulatory approval for the commercialization of our product candidates, we will be required to complete extensive clinical trials in humans to demonstrate safety and efficacy of the product candidates. We have limited experience in conducting clinical trials. A clinical trial may be suspended or terminated by us or the FDA, or otherwise fail, for a number of reasons, including: - the product candidate may cause unforeseen adverse sides effects, including immune reactions; - the time required to determine whether the product candidate is effective may be longer than expected; - the product candidate may not appear to be more effective than current available therapies; - the failure to enroll a sufficient number of patients meeting eligibility requirements; - the clinical investigators, trial monitors, or trial subjects may fail to comply with the trial plan or protocol; or - the failure to be able to supply sufficient quantities of the product candidate to complete the trial. 5

Success in preclinical and early clinical trials may not be predictive of the results in large-scale trials. Any failure or substantial delay in successfully completing clinical trials and obtaining regulatory approval for our product candidates could severely harm our business. We may not be successful in our attempt to broaden our product pipeline as it will require expertise and resources we do not currently have. We have expanded from our initial focus on degenerative neurologic diseases and broadened our product pipeline to include drug candidates for the treatment of other diseases. As our scientific efforts lead us in new directions into conditions or diseases outside of our areas of experience and expertise, we will require additional internal expertise or external collaborations in areas in which we currently do not have substantial resources and personnel. As we develop drug candidates independently, we will require additional resources that may be difficult to obtain. If we have to enter into collaboration arrangements with others, we may be required to relinquish rights to some of our technologies, product candidates, or products that we would otherwise pursue independently. We may not be able to acquire the necessary expertise internally or be able to enter into collaboration arrangements on acceptable terms to develop additional drug candidates. We have never generated sales or profits and expect to incur losses over the next several years. We have not received revenue from the commercialization of our product candidates. We do not expect to receive any revenue from the commercialization of our product candidates for at least the next several years. We intend to continue to invest significantly in our product candidates. We have incurred losses in each year since inception of operations in 1988. As of September 30, 2001, we had an accumulated deficit of $271.3 million. We may never have an approved or commercially successful product or achieve significant revenues or profitable operations. If we fail to gain approval from the FDA to commercialize a product candidate, we may not be able to earn sufficient revenue to continue as a going concern. We currently receive revenue from third parties; if we do not receive these revenues, we may need to find alternative sources of funding for our research and development activities. To date, we have received revenues from (1) our licensees and collaborators for research and development efforts, (2) Merck & Co. Inc. and Sumitomo Pharmaceuticals Co., Ltd. for contract manufacturing, and (3) investment income. We may not continue to receive these revenues or the amount of these revenues may be dramatically reduced. In the absence of these revenues, we will have to obtain other sources of funding to continue to conduct our research and development activities. For example, in January 2001, Amgen-Regeneron Partners discontinued all clinical development of BDNF, which is licensed to Sumitomo Pharmaceuticals for development in Japan. As a result, we do not expect to receive further payments from Sumitomo Pharmaceuticals in connection with the licensing of BDNF. We recognized revenue from Sumitomo Pharmaceuticals of $0.2 million in the nine months ended September 30, 2001, $7.6 million in 2000, $0.1 million in 1999, and $8.8 million in 1998. We may require additional financing, which may be difficult to obtain and may dilute the ownership interest of shareholders. We have had negative cash flow from operations in each year since our inception. We expect that the funding requirements for our activities will remain substantial and could increase significantly if our development or clinical trial programs are successful or our research is expanded. For example, the costs of conducting our Phase III clinical program for AXOKINE, if successful, would likely exceed $75 million or more. We anticipate that the net proceeds from our sale on October 17, 2001 of $200 million aggregate principal amount of our 5 1/2% Convertible Senior Subordinated Notes due 2008, together with our cash, cash equivalents, and marketable securities of $268.0 million as of September 30, 2001, will be 6

sufficient for our working capital needs until 2003. However, we may need additional funding sooner due to a number of factors, including: - the speed with which some of our earlier stage developmental products move into later stage clinical development; - the identification of additional product candidates; - the identification of new indications for a potential product in later stage clinical trials; - the termination of any of our collaboration agreements; - the acquisition of technologies or product candidates; - the pursuit of new business opportunities; - the cost of developing a marketing or sales force; and - the cost of developing or defending our patents, patent applications, and other intellectual property rights. We have no established banking arrangements through which we can obtain short-term financing or a line of credit. We may seek additional funding through collaborative arrangements and public or private financing. Additional financing may not be available to us on acceptable terms or at all. If we are unable to obtain additional funding when needed, we may have to delay or scale back some of our programs or grant to third parties rights to development or other product rights. If we raise additional funds by issuing equity securities or equity-related securities, further dilution to our then existing shareholders may result. Undesirable and unintended side effects of AXOKINE may terminate, interrupt or delay clinical studies and could ultimately prevent or limit its commercial use. Various side-effects have been reported during the clinical trials of AXOKINE, our only product candidate that has completed Phase II trials. During the Phase I study that was conducted in 1999, incidents of nausea, vomiting, and recurrence of herpes simplex virus, or HSV, were reported by patients taking AXOKINE. Recurrence of HSV was also reported in previous clinical studies of CNTF, AXOKINE's parent molecule. In addition, in the Phase I study, one patient who was HSV positive prior to treatment and had been previously diagnosed with Bell's palsy, had a recurrence of Bell's palsy approximately two weeks after the patient's last administration of AXOKINE. In the recently completed Phase II study of AXOKINE, reported side effects included injection site reactions, nausea, cough, and vomiting. Although AXOKINE was generally well tolerated in the recently completed Phase II trial, it is possible that as we test AXOKINE in a large and extended Phase III trial, these side effects, as well as side effects that did not occur or went undetected in smaller clinical trials, will become apparent. We face substantial competition which may result in others discovering, developing or commercializing products before or more successfully than we do. There is substantial competition in the biotechnology and pharmaceutical industries from pharmaceutical, biotechnology, and chemical companies. Our competition includes Hoffmann-La Roche, Inc., Merck, Abbott Laboratories, Inc., Immunex Corporation, Amgen Inc. and others. Each have products under development or currently available for sale that address the same or similar medical conditions as some of our product candidates. Many of our competitors have substantially greater research, preclinical, and clinical product development and manufacturing capabilities, and financial, marketing and human resources than we do. Our smaller competitors may also obtain a significant competitive advantage if they acquire or discover patentable inventions, form collaborative arrangements, or merge with large pharmaceutical companies. Even if we achieve product commercialization, one or more of our competitors may achieve product commercialization earlier than we do or obtain patent protection that can exclude us from the market or adversely affect our activities. Our ability to compete will depend on how fast we can develop 7

safe and effective product candidates, obtain patent protection, complete clinical testing, obtain regulatory approval to commercialize our product candidates, and supply commercial quantities of the product to the market. If a competitor announces a successful clinical study involving a product that may be competitive with one of our product candidates or an approval by a regulatory agency to market a competing product, such announcement may have a material adverse effect on our operations, or future prospects, the price of our common stock and the notes. We also compete with academic institutions, governmental agencies, and other public or private research organizations, which conduct research, seek patent protection and establish collaborative arrangements for the development and marketing of products that would provide royalties for use of their technology. These institutions are becoming more active in seeking patent protection and licensing arrangements to collect royalties for use of the technology that they have developed. Products developed in this manner may compete directly with products we develop. We also compete with others in acquiring technology from such institutions, agencies, and organizations. Collaborative efforts with our academic and corporate partners may fail or be terminated, resulting in significant delays and substantial increases in our costs for research, development, and commercialization of some of our product candidates. We are party to various arrangements with academic and corporate partners and others. Our collaborators may also be our competitors, such as Amgen. The successful development of product candidates covered by these arrangements depends upon these outside parties fully performing their contractual responsibilities. If any of our collaborators breaches, or terminates its agreement with us or otherwise fails to conduct its collaborative activities in a timely manner consistent with the applicable contractual terms, the development or commercialization of the product candidate or research program under such collaborative arrangement may be delayed. If that is the case, we may be required to undertake unforeseen additional responsibilities or to devote unforeseen additional funds or other resources to such development or commercialization, or such development or commercialization could be terminated. For example, our collaboration agreement with Procter & Gamble has an "opt-out" provision whereby a party may decline to participate further in a research or product development program. In such cases, the opting-out party will generally not have any further funding obligation and will not have any rights to the product or program in question (but may be entitled to a royalty on any product sales). If Procter & Gamble were to opt out of a product development program, and we were not to find a new partner, we would bear the full cost of the program which may be substantial. In addition, disagreements between collaborators and us could lead to delays in the collaborative research, development, or commercialization of certain products or could require or result in formal legal process or arbitration for resolution. These consequences could be time-consuming and expensive and could have material adverse effects on us. We may seek additional collaborative arrangements to develop and commercialize our products in the future. We may not be able to negotiate collaborative arrangements on favorable terms and these collaborative arrangements may not be successful. In addition, our collaborative partners may pursue alternative technologies or develop alternative compounds independently or in collaboration with others as a means of developing treatments for the diseases targeted by their collaborative programs with us. If we cannot successfully manufacture our product candidates in an efficient manner, our ability to conduct clinical trials and commercialize our product candidates would be impaired. Our ability to conduct timely preclinical and clinical research and development programs, obtain regulatory approval, commercialize our product candidates and fulfill our contract manufacturing obligations to others will depend, in part, upon our ability to manufacture our products, either directly or through third parties, in accordance with FDA and other regulatory requirements. 8

We may not be able to manufacture products successfully or in a cost-effective manner at our facilities. We may also have difficulties obtaining the raw materials and supplies necessary to manufacture our product candidates or the products we manufacture for others. If we are unable to use our own manufacturing facilities or to contract with a third-party to manufacture our products on acceptable terms, we may not be able to conduct certain future preclinical and clinical testing or to supply commercial quantities of our product candidates. Our dependence upon third parties for the manufacture of some of our products and related therapies may adversely affect our profit margins and our ability to develop and deliver products on a timely and competitive basis. For example, we are aware of only one supplier of the reagent necessary to produce a pegylated formulation of AXOKINE, which is substantially longer acting than unmodified AXOKINE in preclinical studies. Any problems with the supply of reagent from this vendor could result in the delay or interruption in the development of any pegylated form of AXOKINE. In addition, if our manufacturing facilities fail to comply with FDA and other regulatory requirements, we will be required to suspend manufacturing. This will have a material adverse effect on our financial condition, results of operations, and cash flow. Since we have no sales and marketing experience or infrastructure, we may have to engage third parties to market our products or develop this experience and infrastructure internally which would be time consuming and expensive. We have no internal sales, marketing, and distribution experience or infrastructure and may have to rely significantly on arrangements with third parties in order to perform these functions. If we choose to depend on third parties for the marketing and sale of our products, the cost of using such third parties may adversely affect our profit margins. If we decide to perform sales, marketing, and distribution functions ourselves we would face a number of additional risks, including: - we may not be able to attract and build a significant marketing or sales force; - the significant cost of establishing a marketing or sales force may not be justifiable in light of any product revenues; and - our direct sales and marketing efforts may not be successful. We may not be able to attract or retain qualified scientific and management personnel, including our key personnel, on acceptable terms. We may not be able to retain our key personnel, in particular (1) our Chairman, P. Roy Vagelos, M.D., (2) our President and Chief Executive Officer, Leonard S. Schleifer, M.D., Ph.D., and (3) our Chief Scientific Officer, George D. Yancopoulos, M.D., Ph.D., on terms that are acceptable to us. In addition, our anticipated growth and expansion into new areas requiring additional expertise will place increased demands on our resources and require additional management personnel and the development of additional expertise by existing management personnel. Attracting and retaining qualified personnel is critical to our success. Many of our competitors are established pharmaceutical and biotechnology companies that may have greater success in recruiting skilled scientific workers from the limited pool of available talent. The failure to attract and retain management and scientific personnel could have a material adverse effect on our research and development work and on the operation of our business. We could be exposed to significant liability claims and our insurance coverage may not be adequate to cover these claims. The testing, manufacturing, and marketing of human pharmaceutical products entails significant inherent risks. Their use in clinical trials and their sale may expose us to substantial liability claims. These claims might be made directly by patients, consumers, pharmaceutical companies, or others selling the products. We are insured by product liability insurance policies, the purpose of which is to cover certain claims that could arise during the clinical trials of our product candidates. We may not be able to 9

maintain or renew the insurance we have or obtain additional coverage. If our insurance coverage is insufficient, a significant product liability claim or recall would have a material adverse effect on us. If we were required to register as an investment company we would become subject to substantial regulation and our business adversely affected. The Investment Company Act of 1940, as amended (the "1940 Act"), requires the registration of, and imposes various substantive restrictions on, certain companies that engage primarily, or propose to engage primarily, in the business of investing, reinvesting or trading in securities, or fail certain statistical tests regarding the composition of assets and sources of income and are not primarily engaged in businesses other than investing, holding, owning, or trading securities. We presently satisfy these statistical tests and intend to remain primarily engaged in businesses other than investing, reinvesting, owning, holding, or trading securities. In addition, we are relying on an SEC position that biotechnology companies such as our company are not investment companies required to register under the 1940 Act. We expect to continue to be able to avoid registration requirements of the 1940 Act. If we were required to register as an investment company under the 1940 Act, we would become subject to substantial regulations with respect to our capital structure, management, operations, transactions with affiliates described in the 1940 Act and other matters. Application of the provisions of the 1940 Act would have a material adverse effect on our business. RISKS RELATED TO INTELLECTUAL PROPERTY We may not be able to obtain and adequately protect our intellectual property rights or avoid infringing the rights of others. Our success depends to a large part upon our own, our licensors' and our collaborators' ability to obtain and defend patent rights and other intellectual property rights that are important to the commercialization of our product candidates. We or our licensors or collaborators have filed patent applications on products and processes relating to AXOKINE, Cytokine Traps, VEGF Trap, Angiopoietins, and NT-3, as well as other technologies and inventions in the United States and in certain foreign countries. Although we have obtained a number of U.S. patents, patent applications owned or licensed by us may not result in patents being issued. Moreover, these patents may not afford us protection against competitors with similar technology or products. Parts of our technology, techniques, and product candidates may conflict with patents owned by or granted to others. Any patent holders could sue us for damages and seek to prevent us from selling or developing our product candidates. In September 2000, Immunex Corporation filed a request with the European Patent Office seeking the declaration of an Opposition regarding the scope of our European patent relating to Cytokine Traps. This is a legal challenge to the validity and scope of our patent. Although we plan to defend the patent diligently, the scope of the patent may be adversely affected following the outcome of the Opposition. Uncertainties resulting from the litigation and continuation of patent litigation or other proceedings could have a material adverse effect on our ability to compete in the marketplace. Any patent litigation or other proceeding even if resolved in our favor, absorbs significant financial resources and management time. Some of our competitors may be able to sustain these costs more effectively than we can because of their substantially greater financial and managerial resources. If a patent litigation or other intellectual property proceeding is resolved unfavorably to us, we may be enjoined from manufacturing or selling our products and services without a license from the other party and be held liable for significant damages. We may not be able to obtain any required license on commercially acceptable terms, if at all. 10

If we are not able to keep our trade secrets confidential, our technology and information may be used by others to compete against us. In addition to our reliance on patents, we attempt to protect our proprietary products and processes by relying on trade secret laws, nondisclosure and confidentiality agreements, and exclusive licensing arrangements with our employees and certain other persons who have access to our proprietary products or processes or have licensing or research arrangements exclusive to us. These agreements or arrangements may not provide meaningful protection for our proprietary products and processes in the event of unauthorized use or disclosure of such information. Others may independently develop substantially equivalent proprietary information and techniques or otherwise gain access to our trade secrets or technology which will adversely affect our competitive position. If we breach any of the agreements under which we license technology from others, we could lose license rights that are important to our business. We are a party to technology licenses that are important to our business and expect to enter into additional licenses in the future. These licenses impose commercialization, sublicensing, royalty, insurance and other obligations on us. If we fail to comply with these requirements, our licensors may have the right to terminate our licenses which would have a negative impact on our business. RISKS RELATING TO OUR COMMON STOCK Our stock price could be volatile. Since the notes are convertible into shares of our common stock, fluctuations in the trading price of our common stock may affect the price of the notes. There has been a history of significant volatility in the market price of shares of biotechnology companies, including our shares, and it is likely that the market price of our common stock will continue to be highly volatile. The following factors may have a significant effect on the market price of our common stock: - fluctuations in our operating results; - clinical trial results; - announcements of technological innovations or new commercial therapeutic products introduced by us or our competitors; - governmental regulation; - regulatory delays; - litigation; - developments in patent or other proprietary rights; - public concern as to the safety or other implications of the drugs sought to be developed by us or the genetic engineering involved in their production; and - general market conditions. Any clinical trial results that are below the expectations of financial analysts or investors would most likely cause our stock price to drop dramatically. Our existing shareholders may be able to exert significant influence over matters requiring shareholder approval. Holders of Class A stock, who are the shareholders who purchased their stock from us before our initial public offering, are entitled to ten votes per share and holders of common stock are entitled to one vote per share. As of October 31, 2001, holders of Class A stock held 5.9% of the total of our outstanding shares of common stock and Class A stock, or collectively, our common shares, and had 38.4% of the 11

combined voting power of the common shares. These shareholders, if acting together, will be in position to significantly influence the election of our directors and to effect or prevent certain corporate transactions that require majority or supermajority approval of the combined classes, including mergers and other business combinations. This may result in the company taking corporate actions that you may not consider to be in your best interest and may affect the price of our common stock. As of October 31, 2001: - our current officers and directors held 8.9% of our outstanding common shares and 36.9% of the combined voting power of our common shares; - Procter & Gamble held 12.9% of our outstanding common shares and 8.5% of the combined voting power of our common shares; and - Amgen held 10.1% of our outstanding common shares and 6.6% of the combined voting power of our common shares. We have anti-takeover defenses that could delay or prevent an acquisition and could adversely affect the price of our common stock. New York corporate law and our amended and restated certificate of incorporation and by-laws contain provisions that could have the effect of delaying or preventing a change in control of our company or our management that shareholders may consider favorable or beneficial. These provisions could discourage proxy contests and make it more difficult for you and other shareholders to elect directors and take other corporate actions. These provisions could also limit the price that investors might be willing to pay in the future for shares of our common stock. These provisions include: - authorization to issue "blank check" preferred stock, which is preferred stock that can be created and issued by the board of directors without prior shareholder approval, with rights senior to our common stockholders; and - a staggered board of directors, so that it would take three successive annual meetings to replace all of our directors. In addition, we have a shareholders rights plan which will make it more difficult for a third party to acquire us without the support of our board of directors and principal shareholders. A significant number of our shares are eligible for resale. This could reduce our share price and impair our ability to raise funds in new share offerings. As of October 31, 2001, Procter & Gamble and Amgen owned 12.9% (or 5,662,505 shares) and 10.1% (or 4,416,808 shares), respectively, of our outstanding common shares. Our agreements with both Procter & Gamble and Amgen grant them demand and piggyback registration rights with respect to their shares of common stock. Both Procter & Gamble and Amgen have agreed to separate lock-up arrangements with us. Procter & Gamble has agreed not to sell or transfer any of our common stock until March 31, 2002. Amgen has agreed with us not to sell or transfer more than 500,000 shares of our common stock until March 31, 2002. After these lock-up periods expire, either one of these companies could cause a significant number of shares of our common stock to be registered and sold in the public market, particularly in light of the discontinuation of certain of our collaborative efforts with Procter & Gamble and Amgen, which could cause our stock price to decline. As of October 31, 2001, we had 43,733,922 common shares outstanding. In addition, we had 7,487,669 outstanding stock options held by our directors, officers and employees as of October 31, 2001. Sales of substantial amounts of shares of our common stock in the public market after this offering, or the perception that those sales may occur, could cause the market price of our common stock to decline. Those sales also might make it more difficult for us to sell equity and equity-related securities in the future at a time and at a price that we consider appropriate. 12

RISKS RELATED TO THE NOTES The notes are subordinated to any existing and future Senior Indebtedness. The notes are contractually subordinated in right of payment to our existing and future Senior Indebtedness (as the term is defined in the indenture). This means that the payment of the principal and interest on the notes is subordinated to the prior payment in full of all of our existing and future Senior Indebtedness. However, payment from the money or the proceeds from the U.S. government securities pledged to the trustee as security for the exclusive benefit of the holders of the notes, as described under "Description of the Notes -- Security" or amounts deposited with the trustee to pay and discharge all outstanding notes, as described under "Description of the Notes -- Satisfaction and Discharge," will not be subordinated to any Senior Indebtedness or subject to the subordination restrictions described in this offering memorandum. As of September 30, 2001, we had approximately $23.6 million of Senior Indebtedness, of which approximately $1.5 million was repaid on October 11, 2001. Our Senior Indebtedness ranks prior in right of payment to the notes. The indenture does not limit the creation of additional indebtedness. Any significant additional indebtedness incurred may adversely affect our ability to service our debt, including the notes. Due to the subordination provisions, in the event of our insolvency, funds which we would otherwise use to pay the holders of the notes will be used to pay the holders of Senior Indebtedness to the extent necessary to pay the Senior Indebtedness in full. As a result of these payments, our general creditors may recover more, ratably, than the holders of the notes. In addition, the holders of Senior Indebtedness may restrict or prohibit us from making payments on the notes. We may not be able to repurchase the notes, if required. In some circumstances involving a Change of Control (as defined below), the holders of the notes may require us to repurchase some or all of the notes. We may not have sufficient financial resources at such time, or the ability to arrange financing to pay the repurchase price of the notes. Our ability to repurchase the notes in such event may be limited by law, the indenture, by the terms of other agreements relating to our Senior Indebtedness and as such indebtedness and agreements may be entered into, replaced, supplemented or amended from time to time. We may be required to refinance our Senior Indebtedness in order to make such payments. Our outstanding indebtedness will increase substantially with the issuance of the notes and we may not be able to pay our debt and other obligations. As of October 31, 2001, we had approximately $200.6 million in long-term debt which includes $200 million incurred in connection with the sale of the notes. This increased indebtedness will: - make it more difficult for us to obtain any necessary financing in the future for working capital, capital expenditures, debt service requirements or other purposes; - significantly increase our interest expense and related debt service costs; and - make us more vulnerable in the event of a downturn in our business. Currently, we do not have any product sales and we are not generating sufficient cash flow to satisfy the annual debt service payments that will be required as a result of the consummation of the sale of the notes. This may require us to use a portion of the proceeds from the sale of the notes to pay interest or borrow additional funds or sell additional equity to meet our debt service obligations after the first three years when the notes are no longer secured. If we are unable to satisfy our debt service requirements, we will default on the notes. An active trading market for the notes may not develop. The notes are a new issue of securities for which there is currently no trading market. Although the notes that were sold to qualified institutional buyers pursuant to Rule 144 A are eligible for trading in the 13

PORTAL market, the notes resold pursuant to this prospectus will no longer trade on the PORTAL market. As a result, there may be a limited market for the notes. Accordingly, we cannot predict whether an active trading market for the notes will develop or be sustained. If an active trading market for the notes fails to develop or be sustained, the notes could trade at prices that may be lower than the initial offering price of the notes. Whether or not the notes will trade at lower prices depends on many factors, including: - prevailing interest rates and the markets for similar securities; - the market price of our common stock; - general economic conditions; and - our financial condition, financial performance and future prospects. RATIO OF EARNINGS TO FIXED CHARGES The ratios of earnings to fixed charges for the fiscal years indicated are stated below. For purposes of computing the ratios, earnings represent income (loss) from continuing operations before fixed charges and taxes, and fixed charges represent gross interest expense and a portion of rental expense, which is deemed to be representative of the interest factor.

FISCAL YEAR RATIO ------ ----- 2000 * 1999 * 1998 * 1997 * 1996 *
For the nine months ended September 30, 2001, the ratio of earnings to fixed charges was *. * Due to the registrant's losses in the years ended December 31, 2000, 1999, 1998, 1997 and 1996 and the nine-months ended September 30, 2001, the ratio coverage was less than 1:1. The registrant must generate additional earnings of $17.1 million, $18.9 million, $6.1 million, $8.2 million, $18.2 million and $46.7 million for the years ended December 31, 2000, 1999, 1998, 1997 and 1996 and for the nine-months ended September 30, 2001, respectively, to achieve a coverage of 1:1. USE OF PROCEEDS We will not receive any of the proceeds from the sale by any selling securityholder of the notes or shares of common stock offered under this prospectus. DIVIDEND POLICY We have never paid cash dividends and do not anticipate paying any in the foreseeable future. 14

DESCRIPTION OF THE NOTES The notes were issued under an indenture between us and American Stock Transfer & Trust Company, as trustee, to be dated October 17, 2001. The terms of the notes include those provided in the indenture and those provided in the pledge agreement and the registration rights agreement, which we entered into with the initial purchasers. As used in this description, the words "we," "us," "our" or "Regeneron" do not include any current or future subsidiary of Regeneron Pharmaceuticals, Inc. The following description of provisions of the notes is not complete and is subject to, and qualified in its entirety by reference to, the notes, the indenture, the pledge agreement and the registration rights agreement. GENERAL The notes represent general unsecured (except to the extent described under "-- Security") obligations of Regeneron and will rank junior in right of payment to all of our existing and future senior debt. This means that the payment of the principal, premium, if any, and interest on the notes is subordinated to the prior payment in full of all of our existing and future Senior Indebtedness (as defined below). However, payment from the money or the proceeds from the U.S. government securities pledged to the trustee as security for the notes and for the exclusive benefit of the holders of the notes, as described under "-- Security" or amounts deposited with the trustee to pay and discharge all outstanding notes, as described under "-- Satisfaction and Discharge," will not be subordinated to any Senior Indebtedness or subject to the subordination restrictions described in this prospectus. The notes will rank equally with all our existing and future senior subordinated indebtedness. The notes will be convertible into shares of our common stock as described under "-- Conversion Rights." The notes are limited to $200 million aggregate principal amount, and will mature on October 17, 2008, unless earlier redeemed by us or repurchased by us at the option of the holder upon the occurrence of a Change of Control (as defined below). The notes bear interest from October 17, 2001 at the rate of 5 1/2% per year. Interest is payable semi-annually on April 17 and October 17 of each year to holders of record at the close of business on the immediately preceding April 2 and October 2, respectively, beginning April 17, 2002. We may pay interest on notes represented by certificated notes by check mailed to such holders. However, a holder of notes with an aggregate principal amount in excess of $10 million may elect to be paid by wire transfer in immediately available funds. Interest will be computed on the basis of a 360-day year comprised of twelve 30-day months. Principal will be payable, and the notes may be presented for conversion, registration of transfer and exchange, without service charge, at our office or agency in New York City, which shall initially be the office or agency of the trustee in New York, New York. The indenture does not contain any financial covenants or any restrictions on the payment of dividends, the repurchase of our securities or the incurrence of Senior Indebtedness or any other indebtedness. The indenture also does not contain any covenants or other provisions that afford protection to holders of notes in the event of a highly leveraged transaction or a change of control of Regeneron except to the extent described under "-- Repurchase at Option of Holders Upon a Change of Control" below. SECURITY On October 17, 2001, we purchased and pledged to the trustee as security for the notes and for the exclusive benefit of the holders of the notes (and not for the benefit of our other creditors), $31.6 million of U.S. government securities. These securities, when held and invested by the trustee in accordance with the terms of the pledge agreement that we entered into with the trustee, will be sufficient upon receipt of scheduled interest and principal payments of such securities to provide for payment in full of the first six scheduled interest payments due on the notes when due. 15

The U.S. government securities were pledged by us to the trustee for the exclusive benefit of the holders of the notes and are being held by the trustee in a pledge account. Immediately prior to an interest payment date, the trustee will release from the pledge account proceeds sufficient to pay interest then due on the notes. We may also make additional payments to the trustee to ensure that sufficient funds are available to pay interest then due on the notes if necessary. A failure to pay interest on the notes when due through the first six scheduled interest payment dates will constitute an Event of Default (as defined below) under the indenture. The pledged U.S. government securities and the pledge account will also secure the repayment of the principal amount on the notes. If prior to October 17, 2004: - an Event of Default under the notes or the indenture occurs and is continuing; and - the trustee or the holders of 25% in aggregate principal amount of the notes accelerate the notes by declaring the principal amount of the notes to be immediately due and payable (by written consent, at a meeting of note holders or otherwise), except for the occurrence of an Event of Default relating to our bankruptcy, insolvency or reorganization, upon which the notes will be accelerated automatically, then the proceeds from the pledged U.S. government securities will be promptly released for payment to note holders, subject to the automatic stay provisions of bankruptcy law, if applicable. Distributions from the pledge account will be applied: - first, to any accrued and unpaid interest on the notes; and - second, to the extent available, to the repayment of a portion of the principal amount of the notes. If any Event of Default is not cured prior to the acceleration of the notes by the trustee or holders of the notes referred to above, the trustee and the holders of the notes will be able to accelerate the notes as a result of that Event of Default. For example, if the first two interest payments were made when due but the third interest payment was not made when due and the note holders promptly exercised their right to declare the principal amount of the notes to be immediately due and payable, then, assuming automatic stay provisions of bankruptcy law are inapplicable and the proceeds of the pledged U.S. government securities are promptly distributed from the pledge account, - an amount equal to the interest payment due on the third interest payment would be distributed from the pledge account as accrued interest; and - the balance of the proceeds of the pledge account would be distributed as a portion of the principal amount of the notes. In addition, note holders would have an unsecured claim against us for the remainder of the principal amount of their notes. Once we make the first six scheduled interest payments on the notes, all of the remaining pledged U.S. government securities and cash, if any, will be released to us from the pledge account and thereafter the notes will be unsecured. CONVERSION RIGHTS The holders of notes may, at any time prior to the close of business on the final maturity date of the notes, convert any outstanding notes (or portions thereof) into shares of our common stock, initially at the conversion price of $30.2512 per share is subject to adjustment as described below. Holders may convert notes only in denominations of $1,000 and whole multiples of $1,000. Except as described below, no adjustment will be made to the conversion price of any notes for interest accrued thereon or dividends paid on any common stock. 16

If notes are converted after a record date for an interest payment but prior to the next interest payment date, those notes, other than notes called for provisional or optional redemption, must be accompanied by funds equal to the interest payable on the next interest payment date on the principal amount so converted. No such payment will be required from a holder if we exercise our right to redeem such notes. We are not required to issue fractional shares of our common stock upon conversion of the notes. Instead, we will pay a cash adjustment based upon the market price of our common stock on the last business day before the date of the conversion. In the case of notes called for redemption, conversion rights will expire at the close of business on the business day preceding the date fixed for redemption, and in the case of notes tendered for repurchase in connection with a Change of Control, conversion rights will expire at the close of business on the date specified in the Change of Control notice, unless we default in payment of the redemption or Change of Control repurchase price. The conversion price will be adjusted for certain events, including: (1) the issuance of our common stock as a dividend or distribution on our common stock; (2) certain subdivisions and combinations of our common stock; (3) the issuance to all holders of our common stock of certain rights or warrants to purchase our common stock (or securities convertible into our common stock) at less than (or having a conversion price per share less than) the then current market price of our common stock; (4) the dividend or other distribution to all holders of our common stock of shares of our capital stock (other than common stock) or our debt instruments or our assets (including securities, but excluding: (A) those rights and warrants referred to in item (3) above, (B) dividends or distributions in connection with a reclassification, consolidation, merger, combination, sale or conveyance resulting in a change in the conversion consideration pursuant to the second succeeding paragraph and (C) dividends or distributions paid exclusively in cash); (5) dividends or other distributions consisting exclusively of cash to all holders of our common stock to the extent that such distributions, combined together with (A) all other such all-cash distributions made within the preceding 12 months for which no adjustment has been made plus (B) any cash and the fair market value of other consideration paid for any tender offers by us or any of our subsidiaries for our common stock concluded within the preceding 12 months for which no adjustment has been made, exceeds 5% of our market capitalization on the record date for such distribution; market capitalization is the product of the then current market price of our common stock and the number of shares of our common stock then outstanding; and (6) the purchase of our common stock pursuant to a tender offer made by us or any of our subsidiaries which involves an aggregate consideration that, together with (A) any cash and the fair market value of any other consideration paid in any other tender offer by us or any of our subsidiaries for our common stock expiring within the 12 months preceding such tender offer for which no adjustment has been made plus (B) the aggregate amount of any all-cash distributions referred to in clause (5) above to all holders of our common stock within 12 months preceding the expiration of that tender offer for which no adjustments have been made, exceeds 5% of our market capitalization on the expiration of such tender offer. In the event that we pay a dividend or make a distribution on shares of our common stock consisting of capital stock of, or similar equity interests in, a subsidiary or other business unit of ours, the conversion rate will be adjusted based on the market value of the securities so distributed relative to the market value of our common stock, in each case, based on the average closing prices of those securities for the 10 trading days commencing on and including the fifth trading day after the date on which the "ex-dividend trading" commences for such dividend or distribution on the principal United States securities exchange or market on which the securities are then listed or quoted. No adjustment in the conversion price will be required unless such adjustment would require a change of at least 1% in the conversion price then in effect at such time. However, any adjustment that would 17

otherwise be required to be made but for the fact that such 1% threshold has not been met shall be carried forward and taken into account for the purposes of any subsequent adjustments. Except as stated above, the conversion price will not be adjusted for the issuance of our common stock or any securities convertible into or exchangeable for our common stock or carrying the right to purchase any of the foregoing. In the case of: - any reclassification of or change in our common stock (other than changes resulting from a subdivision or combination); or - a consolidation, merger or combination involving us or a sale or conveyance to another corporation of all or substantially all of our property and assets, in each case, as a result of which holders of our common stock are entitled to receive stock, other securities, other property or assets (including cash or any combination thereof) with respect to or in exchange for our common stock, the holders of the notes then outstanding will be entitled thereafter to convert those notes into the kind and amount of shares of stock, other securities or other property or assets (including cash or any combination thereof) which they would have owned or been entitled to receive upon such reclassification, change, consolidation, merger, combination, sale or conveyance had such notes been converted into our common stock immediately prior to such reclassification, change, consolidation, merger, combination, sale or conveyance. We may not become a party to any such transaction unless its terms are consistent with the foregoing. If a taxable distribution to holders of our common stock or other transaction occurs which results in any adjustment of the conversion price, the holders of notes may, in certain circumstances, be deemed to have received a distribution subject to United States federal income tax as a dividend. In certain other circumstances, the absence of an adjustment may result in a taxable dividend to the holders of common stock. See "Certain United States Federal Income Tax Considerations." We may from time to time, to the extent permitted by law, reduce the conversion price of the notes by any amount for any period of at least 20 days. In that case, we will give at least 15 days' notice of such decrease. We may make such reductions in the conversion price, in addition to those set forth above, as our board of directors deems advisable to avoid or diminish any income tax to holders of our common stock resulting from any dividend or distribution of stock (or rights to acquire stock) or from any event treated as such for income tax purposes. PROVISIONAL REDEMPTION BY REGENERON We may redeem the notes, in whole or in part, at any time prior to October 17, 2004, at a redemption price equal to $1,000 per $1,000 principal amount of notes to be redeemed plus accrued and unpaid interest, if any, to, but excluding, the provisional redemption date if: - the closing price of our common stock has exceeded 150% of the conversion price then in effect for at least 20 trading days within a period of 30 consecutive trading days ending on the trading day prior to the date on which we mail the provisional redemption notice (which date shall be at least 30 days but not more than 60 days prior to the provisional redemption date); and - during the period that we are obligated under the registration rights agreement to keep the shelf registration statement effective, such shelf registration statement covering resales of the notes and the common stock issuable upon conversion of the notes is effective and available for use as of, and including, the date on which we mail the provisional redemption notice through and including the provisional redemption date. If we do not redeem all of the notes, the trustee will select the notes to be redeemed in principal amounts of $1,000 or whole multiples of $1,000 by lot or on a pro rata basis. If any notes are to be redeemed in part only, a new note or notes in principal amount equal to the unredeemed principal portion thereof will be issued. If a portion of a holder's notes is selected for partial redemption and the holder 18

thereafter converts a portion of its notes, the converted portion will be deemed to be taken from the portion selected for redemption. Upon any provisional redemption, we will make an additional "make-whole" payment in cash with respect to the notes called for redemption to holders on the notice date in an amount equal to $165 per $1,000 principal amount of notes, less the amount of any interest actually paid on the notes on or prior to the provisional redemption date. We will be obligated to make this additional payment on all notes called for provisional redemption, including any notes converted after the notice date and before the provisional redemption date. OPTIONAL REDEMPTION BY REGENERON At any time on or after October 17, 2004, we may redeem some or all of the notes on at least 30 days' but not more than 60 days' notice, at a price equal to $1,000 per $1,000 principal amount, plus accrued and unpaid interest to, but excluding, the date fixed for redemption, subject to the right of holders of record on the relevant record dates to receive interest payments due on an interest payment date, if the closing price of our common stock has exceeded 140% of the conversion price then in effect for at least 20 trading days within a period of 30 consecutive trading days ending on the trading day prior to the date on which we mail the optional redemption notice. If we do not redeem all of the notes, the trustee will select the notes to be redeemed in principal amounts of $1,000 or whole multiples of $1,000 by lot or on a pro rata basis. If any notes are to be redeemed in part only, a new note or notes in principal amount equal to the unredeemed principal portion thereof will be issued. If a portion of a holder's notes is selected for partial redemption and the holder thereafter converts a portion of its notes, the converted portion will be deemed to be taken from the portion selected for redemption. SINKING FUND No sinking fund is provided for the notes. REPURCHASE AT OPTION OF HOLDERS UPON A CHANGE OF CONTROL If a Change of Control (as defined below) occurs, each holder of notes will have the right to require us to repurchase all of that holder's notes not previously called for redemption, or any portion of those notes that is equal to $1,000 or a whole multiple of $1,000, on the date that is no later than 30 days after the date we give notice of the occurrence of a Change in Control (such date being the repurchase date) at a repurchase price equal to 100% of the principal amount of the notes to be repurchased, together with interest accrued and unpaid to, but excluding, the repurchase date. We may elect to pay the repurchase price in common stock instead of cash if we so specify in our Change of Control notice referred to below. The number of shares of common stock a holder will receive will equal the repurchase price divided by 95% of the average of the closing prices of our common stock for the five-trading-day period ending on the third business day prior to the repurchase date. However, we may not pay in common stock unless we satisfy certain conditions prior to the repurchase date, as provided in the indenture. Within 30 days after the occurrence of a Change of Control, we are required to give notice to all holders of notes, as provided in the indenture, of the occurrence of the Change of Control and of their resulting repurchase right and specifying our form of payment. We must also deliver a copy of our notice to the trustee. In order to exercise the repurchase right, a holder of notes must deliver, on or prior to the 30th day after the date of our notice, written notice to the trustee of the holder's exercise of the holder's repurchase right, together with the notes with respect to which the repurchase right is being exercised. 19

Under the indenture, a "Change of Control" of Regeneron will be deemed to have occurred at such time after the original issuance of the notes when the following has occurred: - the acquisition by any person (other than permitted holders) of beneficial ownership, directly or indirectly, through a purchase, merger or other acquisition transaction or series of transactions of shares of our capital stock entitling that person to exercise 50% or more of the total voting power of all shares of our capital stock entitled to vote generally in elections of directors, other than any acquisition by us, any of our subsidiaries or any of our employee benefit plans; - any permitted holder files a schedule, form or report in connection with a transaction or event disclosing that such person has become the beneficial owner of 50% or more of the total voting power of all shares of our capital stock entitled to vote generally in elections of directors, as a result of which (i) our common stock ceases (or, upon consummation of or immediately following such transaction or event, will cease) to be listed on a United States national securities exchange or approved for quotation on the Nasdaq National Market or any similar United States system for automated dissemination of quotations of securities prices or (ii) less than 5 million shares of our common stock remain held by persons other than permitted holders; or - our consolidation or merger with or into any other person, any merger of another person into us, or any conveyance, transfer, sale, lease or other disposition of all or substantially all of our properties and assets to another person, other than: (1) any transaction pursuant to which holders of our capital stock immediately prior to the transaction have the entitlement to exercise, directly or indirectly, 50% or more of the total voting power of all shares of our capital stock entitled to vote generally in the election of directors of the continuing or surviving person immediately after the transaction; and (2) any merger solely for the purpose of changing our jurisdiction of incorporation and resulting in a reclassification, conversion or exchange of outstanding shares of common stock solely into shares of common stock of the surviving entity. For the purposes of the foregoing, "permitted holders" shall mean (A) Leonard S. Schleifer, M.D., Ph.D., our Chief Executive Officer and President, and P. Roy Vagelos, M.D., our Chairman of the Board, and their respective spouses, immediate family members, estates, lineal descendants, executors or administrators, or (B) any trust, corporation or other entity, the beneficiaries, stockholders or other persons beneficially holding an 80% or more controlling interest of which consist of persons or entities referred to in clause (A). The beneficial owner shall be determined in accordance with Rule 13d-3 promulgated by the SEC under the Exchange Act. The term "person" includes any syndicate or group which would be deemed to be a "person" under Section 13(d)(3) of the Exchange Act. Rule 13e-4 under the Exchange Act, as amended, requires the dissemination of information to security holders if an issuer tender offer occurs and may apply if the repurchase option becomes available to holders of the notes. We will comply with this rule to the extent applicable at that time. The foregoing provisions would not necessarily protect holders of the notes if highly leveraged or other transactions involving us occur that may adversely affect holders. Our ability to repurchase notes upon the occurrence of a Change of Control is subject to important limitations. The occurrence of a Change of Control could cause an Event of Default under, or be prohibited or limited by, the terms of our existing or future senior debt. As a result, any repurchase of the notes would, absent a waiver, be prohibited under the subordination provisions of the indenture until all of our senior debt is paid in full. Further, we cannot assure you that we would have the financial resources, or would be able to arrange financing, to pay the repurchase price for all the notes that might be delivered by holders of notes seeking to exercise the repurchase right. Any failure by us to repurchase the notes when required following a Change of Control would result in an event of default under the indenture, whether or 20

not such repurchase is permitted by the subordination provisions of the indenture. Any such default may, in turn, cause a default under our existing or future senior debt. See "-- Subordination" below. SUBORDINATION The payment of principal of, premium, if any, and interest on the notes (other than payments made toward the first six scheduled interest payments due on the notes, which payments are derived from the U.S. government securities pledged by us to the trustee for the exclusive benefit of the holders of the notes (hereinafter referred to as "Permitted Interest Payments")) will be subordinated in right of payment, as set forth in the indenture, to the prior payment in full in cash or cash equivalents of all Senior Indebtedness (as defined below), whether outstanding on the date of the indenture or thereafter incurred. In the event of any insolvency or bankruptcy case or proceeding, or any receivership, liquidation, reorganization or other similar case or proceeding in connection therewith, relating to Regeneron or to its assets, or any liquidation, dissolution or other winding-up of Regeneron, whether voluntary or involuntary, or any assignment for the benefit of creditors or other marshaling of assets or liabilities of Regeneron (except in connection with the consolidation or merger of Regeneron or its liquidation or dissolution following the conveyance, transfer or lease of all or substantially all of its properties and assets upon the terms and conditions described under "-- Mergers and Sales of Assets" below), the holders of Senior Indebtedness will be entitled to receive payment in full in cash or cash equivalents of all Senior Indebtedness, or provision shall be made for such payment in full, before the holders of notes will be entitled to receive any payment or distribution of any kind or character (other than Permitted Interest Payments and other than any payment or distribution in the form of equity securities or subordinated securities of Regeneron or any successor obligor that, in the case of any such subordinated securities, are subordinated in right of payment to all Senior Indebtedness that may at the time be outstanding to at least the same extent as the notes are so subordinated (such equity securities or subordinated securities hereinafter being "Permitted Junior Securities")) on account of principal of, or premium, if any, or interest on the notes; and any payment or distribution of assets of Regeneron of any kind or character, whether in cash, property or securities (other than a payment or distribution in the form of Permitted Junior Securities), by set-off or otherwise, to which the holders of the notes or the trustee would be entitled but for the provisions of the indenture relating to subordination shall be paid by the liquidating trustee or agent or other person making such payment or distribution directly to the holders of Senior Indebtedness or their representatives ratably according to the aggregate amounts remaining unpaid on account of the Senior Indebtedness to the extent necessary to make payment in full of all Senior Indebtedness remaining unpaid, after giving effect to any current payment or distribution to the holders of such Senior Indebtedness. No payment or distribution of any assets of Regeneron of any kind or character, whether in cash, property or securities (other than Permitted Interest Payments and Permitted Junior Securities), may be made by or on behalf of Regeneron on account of principal of, premium, if any, or interest on the notes or on account of the purchase, redemption or other acquisition of notes upon the occurrence of any default in payment (whether at scheduled maturity, upon scheduled installment, by acceleration or otherwise) of principal of, premium, if any, or interest on Designated Senior Indebtedness (as defined below) beyond any applicable grace period (a "Payment Default") until such Payment Default shall have been cured or waived in writing or shall have ceased to exist or such Designated Senior Indebtedness shall have been discharged or paid in full in cash or cash equivalents. No payment or distribution of any assets of Regeneron of any kind or character, whether in cash, property or securities (other than Permitted Interest Payments and Permitted Junior Securities), may be made by or on behalf of Regeneron on account of principal of, premium, if any, or interest on the notes or on account of the purchase, redemption or other acquisition of notes during the period specified below (a "Payment Blockage Period") upon the occurrence of any default or event of default with respect to any Designated Senior Indebtedness other than any Payment Default, pursuant to which the maturity thereof may be accelerated (a "Non-Payment Default"), and receipt by the trustee of written notice thereof from 21

Regeneron or the representative of holders of the Designated Senior Indebtedness or the trustee for any such holder. The Payment Blockage Period will commence upon the date of receipt by the trustee of written notice from Regeneron or the representative of the holders of the Designated Senior Indebtedness in respect of which the Non-Payment Default exists, or the trustee for any such holder, and shall end on the earliest of: (1) 179 days thereafter (provided that any Designated Senior Indebtedness as to which such written notice was given shall not theretofore have been accelerated); (2) the date on which such Non-Payment Default is cured, waived or ceases to exist; (3) the date on which such Designated Senior Indebtedness is discharged or paid in full; or (4) the date on which such Payment Blockage Period shall have been terminated by written notice to the trustee or Regeneron from the trustee or such other representative initiating such Payment Blockage Period, after which Regeneron will resume making any and all required payments in respect of the notes, including any missed payments. In any event, not more than one Payment Blockage Period may be commenced during any period of 365 consecutive days. No Non-Payment Default that existed or was continuing on the date of the commencement of any Payment Blockage Period will be, or can be made, the basis for the commencement of a subsequent Payment Blockage Period, unless such Non-Payment Default has been cured or waived for a period of not less than 90 consecutive days subsequent to the commencement of such initial Payment Blockage Period. In the event that, notwithstanding the provisions of the preceding four paragraphs, if any payment or distribution shall be received by the trustee or any holder of the notes that is prohibited by such provisions, then and in such event such payment shall be paid over and delivered by such trustee or holder to the trustee or any other representative of holders of Senior Indebtedness, as their interest may appear, for application toward our Senior Indebtedness. Until all of our Senior Indebtedness is paid in full, holders of the notes shall be subrogated (equally and ratably with all other indebtedness that is equal in right of payment to the notes) to the rights of holders of Senior Indebtedness to receive distributions. Failure by Regeneron to make any required payment in respect of the notes when due or within any applicable grace period, whether or not occurring during a Payment Blockage Period, will result in an Event of Default (as defined below) and, thereafter, holders of the notes will have the right to accelerate the maturity thereof. See "-- Events of Default." By reason of such subordination, in the event of liquidation, receivership, reorganization or insolvency of Regeneron, our general creditors may recover less, ratably, than holders of senior debt and such general creditors may recover more, ratably, than holders of notes. At September 30, 2001, on a pro forma basis, giving effect to the offering of notes: - the total outstanding Senior Indebtedness of Regeneron would have been approximately $223.6 million; and - Regeneron would have had no subordinated indebtedness other than the notes. "Designated Senior Indebtedness" means any Senior Indebtedness which, at the time of determination, has an aggregate principal amount outstanding of at least $25.0 million and that has been specifically designated in the instrument evidencing such Senior Indebtedness as "Designated Senior Indebtedness" of Regeneron. "indebtedness" means, with respect to any person, without duplication: - all liabilities of such person for borrowed money (including overdrafts) or for the deferred purchase price of property or services, excluding any trade payables and other accrued current liabilities incurred in the ordinary course of business, but including, without limitation, all obligations, 22

contingent or otherwise, of such person in connection with any letters of credit and acceptances issued under letter of credit facilities, acceptance facilities or other similar facilities; - all obligations of such person evidenced by bonds, notes, debentures or other similar instruments; - indebtedness of such person created or arising under any conditional sale or other title retention agreement with respect to property acquired by such person (even if the rights and remedies of the seller or lender under such agreement in the event of default are limited to repossession or sale of such property), but excluding trade payables arising in the ordinary course of business; - all capitalized lease obligations of such person; - all obligations of such person under or in respect of interest rate agreements or currency agreements; - all indebtedness referred to in (but not excluded from) the preceding clauses of other persons and all dividends of other persons, the payment of which is secured by (or for which the holder of such indebtedness has an existing right, contingent or otherwise, to be secured by) any lien or with respect to property (including, without limitation, accounts and contract rights) owned by such person, even though such person has not assumed or become liable for the payment of such indebtedness (the amount of such obligation being deemed to be the lesser of the value of such property or asset or the amount of the obligation so secured); - all guarantees by such person of indebtedness referred to in this definition or of any other person; - all Redeemable Capital Stock of such person valued at the greater of its voluntary or involuntary maximum fixed repurchase price plus accrued and unpaid dividends; and - the present value of the obligation of such person as lessee for net rental payments (excluding all amounts required to be paid on account of maintenance and repairs, insurance, taxes, assessments, water, utilities and similar charges to the extent included in such rental payments) during the remaining term of the lease included in such sale and leaseback transaction including any period for which such lease has been extended or may, at the option of the lessor, be extended. Such present value shall be calculated using a discount rate equal to the rate of interest implicit in such transaction, determined in accordance with accounting principles generally accepted in the United States. "Redeemable Capital Stock" means any class of our capital stock that, either by its terms, by the terms of any securities into which it is convertible or exchangeable or by contract or otherwise, is, or upon the happening of an event or passage of time would be, required to be redeemed (whether by sinking fund or otherwise) prior to the date that is 91 days after the final scheduled maturity of the notes or is redeemable at the option of the holder thereof at any time prior to such date, or is convertible into or exchangeable for debt securities at any time prior to such date (unless it is convertible or exchangeable solely at our option). "Senior Indebtedness" or "senior debt" means: - all obligations of Regeneron, now or hereafter existing, under or in respect of the documents and instruments executed in connection therewith, whether for principal, premium, if any, interest (including interest accruing after the filing of, or which would have accrued but for the filing of, a petition by or against Regeneron under bankruptcy law, whether or not such interest is allowed as a claim after such filing in any proceeding under such law) and other amounts due in connection therewith (including, without limitation, any fees, premiums, expenses, reimbursement obligations with respect to letters of credit and indemnities), whether outstanding on the date of the indenture or thereafter created, incurred or assumed; and - the principal of, premium, if any, and interest on all other indebtedness of Regeneron (other than the notes), whether outstanding on the date of the indenture or thereafter created, incurred or assumed, unless, in the case of any particular indebtedness, the instrument creating or evidencing 23

the same or pursuant to which the same is outstanding expressly provides that such indebtedness shall not be senior in right of payment to the notes. Notwithstanding the foregoing, "Senior Indebtedness" and "senior debt" shall not include: - indebtedness evidenced by the notes offered hereby; - indebtedness of Regeneron that is expressly subordinated in right of payment to Senior Indebtedness of Regeneron; - indebtedness of Regeneron that by operation of law is subordinate to any general unsecured obligations of Regeneron; - any liability for federal, state or local taxes or other taxes, owed or owing by Regeneron; - accounts payable or other liabilities owed or owing by Regeneron to trade creditors (including guarantees thereof or instruments evidencing such liabilities); - amounts owed by Regeneron for compensation to employees or for services rendered to Regeneron; - indebtedness of Regeneron to any subsidiary or any other affiliate of Regeneron or any of such affiliate's subsidiaries; - capital stock of Regeneron; - indebtedness evidenced by any guarantee of any indebtedness ranking equal or junior in right of payment to the notes; and - indebtedness which, when incurred and without respect to any election under Section 1111(b) of Title 11 of the United States Code, is without recourse to Regeneron. EVENTS OF DEFAULT Each of the following constitutes an "Event of Default" under the indenture: (1) our failure to pay when due the principal of or premium, if any, on any of the notes at maturity, upon redemption or exercise of a repurchase right or otherwise, whether or not such payment is prohibited by the subordination provisions of the indenture; (2) our failure to pay an installment of interest (including liquidated damages, if any) on any of the notes that continues for 30 days after the date when due, whether or not such payment is prohibited by the subordination provisions of the indenture; provided that a failure to make any of the first six scheduled interest payments on the notes within three business days of the applicable interest payment dates will constitute an Event of Default with no additional grace or cure period; (3) our failure to deliver shares of common stock, together with cash in lieu of fractional shares, when such common stock or cash in lieu of fractional shares is required to be delivered upon conversion of a note or upon the exercise of a repurchase right that continues for ten days after such delivery date; (4) our failure to perform or observe any other term, covenant or agreement contained in the notes or the indenture for a period of 60 days after written notice of such failure, requiring us to remedy the same, shall have been given to us by the trustee, or to us and the trustee by the holders of at least 25% in aggregate principal amount of the notes then outstanding; (5) (A) one or more defaults in the payment of principal of or premium, if any, on any of our indebtedness aggregating $10.0 million or more, when the same becomes due and payable at the scheduled maturity thereof, and such default or defaults shall have continued after any applicable grace period and shall not have been cured or waived within a thirty day period after the date of such default or (B) any of our indebtedness aggregating $10.0 million or more shall have been accelerated or otherwise declared due and payable, or required to be prepaid or repurchased (other than by 24

regularly scheduled required prepayment) prior to the scheduled maturity thereof and such acceleration is not rescinded or annulled within a thirty-day period after the date of such acceleration; (6) certain events of our bankruptcy, insolvency or reorganization or that of any significant subsidiaries; (7) our filing of a voluntary petition seeking liquidation, reorganization arrangement, readjustment of debts or for any other relief under the federal bankruptcy code; and (8) the agreement made by us in favor of the trustee governing the disbursements of funds from the pledge account, as such agreement may be amended, restated, supplemented or otherwise modified from time to time, shall cease to be in full force and effect or enforceable in accordance with its terms, other than in accordance with its terms. The indenture provides that the trustee shall, within 90 days of the occurrence of a default, give to the registered holders of the notes notice of all uncured defaults known to it, but the trustee shall be protected in withholding such notice if it, in good faith, determines that the withholding of such notice is in the best interest of such registered holders, except in the case of a default in the payment of the principal of, or premium, if any, or interest on any of the notes when due or in the payment of any redemption or repurchase obligation. If an Event of Default specified in clause (6) or clause (7) above occurs and is continuing, then, automatically, the principal of all the notes and the interest thereon shall become immediately due and payable. If an Event of Default shall occur and be continuing, other than with respect to clause (6) or clause (7) above (such default not having been cured or waived as provided under "-- Modifications and Waiver" below), the trustee or the holders of at least 25% in aggregate principal amount of the notes then outstanding may declare the notes due and payable at their principal amount together with accrued interest, and thereupon the trustee may, at its discretion, proceed to protect and enforce the rights of the holders of notes by appropriate judicial proceedings. Such declaration may be rescinded or annulled with the written consent of the holders of a majority in aggregate principal amount of the notes then outstanding upon the conditions provided in the indenture. The indenture contains a provision entitling the trustee, subject to the duty of the trustee during default to act with the required standard of care, to be indemnified by the holders of notes before proceeding to exercise any right or power under the indenture at the request of such holders. The indenture provides that the holders of a majority in aggregate principal amount of the notes then outstanding through their written consent may direct the time, method and place of conducting any proceeding for any remedy available to the trustee or exercising any trust or power conferred upon the trustee. We will be required to furnish annually to the trustee a statement as to the fulfillment of our obligations under the indenture. CERTAIN COVENANTS The indenture provides that we will not, and will not permit our subsidiaries or other business units to, incur, create, assume, guarantee or in any other manner become directly or indirectly liable with respect to or responsible for, or permit to remain outstanding (other than if required by law), any indebtedness that is subordinate or junior in right of payment to Senior Indebtedness unless such indebtedness ranks equal or junior in right of payment to the notes. We have the right to incur, create, assume or guarantee or in any other manner become directly or indirectly liable with respect to, or responsible for, or permit to remain outstanding, different layers of Senior Indebtedness that may be subordinate to other Senior Indebtedness. 25

MERGERS AND SALES OF ASSETS We may, without the consent of the holders of notes, consolidate with, merge into or transfer all or substantially all of our assets to any other corporation organized under the laws of the United States or any of its political subdivisions provided that: - the surviving corporation assumes all our obligations under the indenture and the notes; - at the time of such transaction, no Event of Default, and no event which, after notice or lapse of time, would become an Event of Default, shall have happened and be continuing; and - certain other conditions are met. MODIFICATIONS AND WAIVER The indenture (including the terms and conditions of the notes) may be modified or amended by us and the trustee, without the consent of the holder of any note, for the purposes of, among other things: - adding to our covenants for the benefit of the holders of notes; - surrendering any right or power conferred upon us; - providing for conversion rights of holders of notes if any reclassification or change of our common stock or any consolidation, merger or sale of all or substantially all of our assets occurs; - providing for the assumption of our obligations to the holders of notes in the case of a merger, consolidation, conveyance, transfer or lease; - reducing the conversion price, provided that the reduction will not adversely affect the interests of holders of notes in any material respect; - complying with the requirements of the SEC in order to effect or maintain the qualification of the indenture under the Trust Indenture Act of 1939, as amended; - making any changes or modifications to the indenture necessary in connection with the registration of the notes under the Securities Act, as contemplated by the registration rights agreement, provided that this action does not adversely affect the interests of the holders of the notes in any material respect; - curing any ambiguity or correcting or supplementing any defective provision contained in the indenture; provided that such modification or amendment does not, in the good faith opinion of our board of directors and the trustee, adversely affect the interests of the holders of the notes in any material respect; - adding or modifying any other provisions which we and the trustee may deem necessary or desirable and which will not adversely affect the interests of the holders of notes in any material respect; or - to evidence and provide for the appointment of a successor trustee. Modifications and amendments to the indenture or to the terms and conditions of the notes may also be made, and past default by us may be waived, with the written consent of the holders of at least a majority in aggregate principal amount of the notes at the time outstanding. However, no such modification, amendment or waiver may, without the written consent of the holder of each note affected: - change the maturity of the principal of or any installment of interest on any note (including any payment of liquidated damages); - reduce the principal amount of, or any premium or interest on (including any payment of liquidated damages), any note; - change the currency of payment of such note or interest thereon; 26

- impair the right to institute suit for the enforcement of any payment on or with respect to any note; - modify our obligations to maintain an office or agency in New York City; - except as otherwise permitted or contemplated by provisions concerning corporate reorganizations, adversely affect the repurchase option of holders upon a change of control or the conversion rights of holders of the notes; - modify the subordination provisions of the notes in a manner adverse to the holders of notes; or - reduce the percentage in aggregate principal amount of notes outstanding necessary to modify or amend the indenture or to waive any past default. SATISFACTION AND DISCHARGE We may discharge our obligations under the indenture while notes remain outstanding, subject to certain conditions, if: - all outstanding notes have become due and payable or will become due and payable at their scheduled maturity within one year, or - all outstanding notes are scheduled for redemption within one year; and - in either case, we have deposited with the trustee an amount sufficient to pay and discharge all outstanding notes on the date of their scheduled maturity or the scheduled date of redemption; provided that we shall remain obligated to issue shares upon conversion of the notes. GOVERNING LAW The indenture and the notes are governed by, and will be construed in accordance with, the law of the State of New York. INFORMATION CONCERNING THE TRUSTEE American Stock Transfer & Trust Company, as trustee under the indenture, has been appointed by us as paying agent, conversion agent, registrar and custodian with regard to the notes. American Stock Transfer & Trust Company is also the transfer agent and registrar for our common stock. The trustee or its affiliates may from time to time in the future provide other services to us in the ordinary course of their business. REGISTRATION RIGHTS We entered into a registration rights agreement with the initial purchasers of the notes. If you sell the notes or shares of common stock issued upon conversion of the notes under this registration statement, you generally will be required to be named as a selling securityholder in this prospectus, deliver this prospectus to purchasers and be bound by applicable provisions of the registration rights agreement, including some indemnification provisions. In the registration rights agreement, we agreed to use our reasonable best efforts to keep the registration statement effective until the earlier of (1) October 17, 2003; (2) the date when the holders of the notes and the common stock issuable upon conversion of the notes are able to sell all such securities immediately without restriction pursuant to the volume limitation provisions of Rule 144 under the Securities Act or any successor rule thereto or otherwise; or (3) the sale pursuant to this shelf registration statement of all securities registered hereunder. We may suspend the use of this prospectus under certain circumstances relating to pending corporate developments, public filings with the SEC and similar events for a period not to exceed 45 days in any three-month period and not to exceed an aggregate of 120 days in any 12-month period. We also agreed to pay liquidated damages to holders of the notes and shares of common stock issued upon conversion of the 27

notes if this registration statement is not timely filed or made effective or if the prospectus is unavailable for periods in excess of those permitted above. You should refer to the registrations rights agreement for a description of these liquidated damages. BOOK-ENTRY SYSTEM The notes were originally issued in the form of a global security issued in reliance on Rule 144A. Upon the issuance of a global security, DTC (referred to as the depository) or its nominee credited the accounts of persons holding through it with the respective principal amounts of the notes represented by such global security. Such accounts were designated by the initial purchasers with respect to notes placed by the initial purchasers for us. The notes that are sold under this prospectus will be represented by a new unrestricted global security. Upon issuance of this new global security, the depository or its nominee will credit the accounts of persons holding through it with the respective principal amounts of the notes represented by the new unrestricted global security. Ownership of beneficial interests in a global security is limited to persons that have accounts with the depository ("participants") or persons that may hold interests through participants. Ownership of beneficial interests by participants in a global security is shown on, and the transfer of that ownership interest will be effected only through, records maintained by the depository for such global security. Ownership of beneficial interests in such global security by persons that hold through participants will be shown on, and the transfer of those ownership interests through such participant will be effected only through, records maintained by such participant. The foregoing may impair the ability to transfer beneficial interests in a global security. We will make payment of principal, premium, if any, and interest on notes represented by any such global security to the depository or its nominee, as the case may be, as the sole holder of the notes represented thereby for all purposes under the indenture. None of Regeneron, the trustee, any agent of Regeneron, or the trustee or the initial purchasers will have any responsibility or liability for any aspect of the depository's records relating to or payments made on account of beneficial ownership interests in global security representing any notes or for maintaining, supervising or reviewing any of the depository's records relating to such beneficial ownership interests. We have been advised by the depository that, upon receipt of any payment of principal, premium, if any, or interest on any global security, the depository will immediately credit, on its book-entry registration and transfer system, the accounts of participants with payments in amounts proportionate to their respective beneficial interests in the principal amount of such global security as shown on the records of the depository. Payments by participants to owners of beneficial interests in a global security held through such participants will be governed by standing instructions and customary practices as is now the case with securities held for customer accounts registered in "street name," and will be the sole responsibility of such participants. A global security may not be transferred except as a whole by the depository for such global security to a nominee of such depository or by a nominee of such depository to such depository or another nominee of such depository or by such depository or any such nominee to a successor of such depository or a nominee of such successor. If the depository is at any time unwilling or unable to continue as depository and a successor depository is not appointed by us or the depository within 90 days, we will issue notes in definitive form in exchange for the global security. In either instance, an owner of a beneficial interest in the global security will be entitled to have notes equal in principal amount to such beneficial interest registered in its name and will be entitled to physical delivery of such notes in definitive form. Notes so issued in definitive form will be issued in denominations of $1,000 and integral multiples thereof and will be issued in registered form only, without coupons. We will pay principal, premium, if any, and interest on the notes and the notes may be presented for registration of transfer or exchange, at the offices of the trustee. So long as the depository for a global security, or its nominee, is the registered owner of such global security, such depository or such nominee, as the case may be, will be considered the sole holder of the notes represented by such global security for the purposes of receiving payment on the notes, receiving notices and for all other purposes under the indenture and the notes. Beneficial interests in notes will be evidenced only by, and transfers thereof will be effected only through, records maintained by the 28

depository and its participants. The depository has nominated Cede & Co. as the nominee. Except as provided above, owners of beneficial interests in a global security will not be entitled to have the notes represented by the global security registered in their name, will not be entitled to receive physical delivery of certificated notes and will not be considered the holders thereof for any purposes under the indenture. Accordingly any such person owning a beneficial interest in such a global security must rely on the procedures of the depository, and, if any such person is not a participant, on the procedures the participant through which such person owns its interest, to exercise any rights of a holder under the indenture. The indenture provides that the depository may grant proxies and otherwise authorize participants to give or take any request, demand, authorization, direction, notice, consent, waiver or other action which a holder is entitled to give or take under the indenture. We understand that under existing industry practices, in the event that we request any action of holders or that an owner of a beneficial interest in such a global security desires to give or take any action which a holder is entitled to give or take under the indenture, the depository would authorize the participants holding the relevant beneficial interest to give or take such action and such participants would authorize beneficial owners owning through such participants to give or take such action or would otherwise act upon the instructions of beneficial owners owning through them. The depository has advised us that the depository is a limited-purpose trust company organized under the laws of the State of New York, a member of the Federal Reserve System, a "clearing corporation" within the meaning of the New York Uniform Commercial Code, and a "clearing agency" registered under the Exchange Act. The depository was created to hold the securities of its participants and to facilitate the clearance and settlement of securities transactions among its participants in such securities through electronic book-entry changes in accounts of the participants, thereby eliminating the need for physical movement of securities certificates. The depository's participants include securities brokers and dealers (including the initial purchasers), banks, trust companies, clearing corporations and certain other organizations, some of whom (and/or their representatives) own the depository. Access to the depository's book-entry system is also available to others, such as banks, brokers, dealers and trust companies, that clear through or maintain a custodial relationship with a participant, either directly or indirectly. 29

DESCRIPTION OF CAPITAL STOCK Our authorized capital stock consists of 60,000,000 shares of common stock, par value $.001 per share, 40,000,000 shares of Class A stock, par value $.001 per share, and 30,000,000 shares of preferred stock, par value $.01 per share. As of October 31, 2001, 41,163,133 shares of our common stock were outstanding and held by 617 shareholders of record and 2,570,789 shares of our Class A stock were outstanding and held by 63 shareholders of record. The following is a summary description of our capital stock. For more information, see our Restated Certificate of Incorporation, a copy of which is incorporated by reference as an exhibit to our annual report on Form 10-K for the fiscal year ended December 31, 2000. COMMON STOCK AND CLASS A STOCK General. The rights of holders of common stock and holders of Class A stock are identical except for voting and conversion rights, and restrictions on transferability. Voting Rights. The holders of Class A stock are entitled to ten votes per share and the holders of common stock are entitled to one vote per share. Except as otherwise required by law or as described below, holders of Class A stock will vote together as a single class on all matters presented to the shareholders for their vote or approval, including the election of directors. Shareholders are not entitled to vote cumulatively for the election of directors and no class of outstanding common stock acting alone is entitled to elect any directors. Transfer Restrictions. Class A stock is subject to certain limitations on transfer that do not apply to the common stock. Dividends and Liquidation. Holders of Class A stock and holders of our common stock have an equal right to receive dividends when and if declared by our board of directors out of funds legally available therefor. If a dividend or distribution payable in Class A stock is made on the Class A stock, we must also make a pro rata and simultaneous dividend or distribution on the common stock payable in shares of common stock. Conversely, if a dividend or distribution payable in common stock is made on the common stock, we must also make a pro rata and simultaneous dividend or distribution on the Class A stock payable in shares of Class A stock. In the event of our liquidation, dissolution, or winding up, holders of the shares of Class A stock and common stock are entitled to share equally, share-for-share, in the assets available for distribution after payment of all creditors and the liquidation preferences of our preferred stock. Optional Conversion Rights. Each share of Class A stock may, at any time and at the option of the holder, be converted into one fully paid and nonassessable share of common stock. Upon conversion, such shares of common stock would not be subject to restrictions on transfer that applied to the shares of Class A stock prior to conversion except to the extent such restrictions are imposed under applicable securities laws. The shares of common stock are not convertible into or exchangeable for shares of Class A stock or any other of our shares or securities. Other Provisions. Holders of Class A stock and common stock have no preemptive rights to subscribe to any additional securities of any class which we may issue and there are no redemption provisions or sinking fund provisions applicable to either such class, nor is the Class A stock or the common stock subject to calls or assessments. Nasdaq National Market Listing. Our common stock is quoted on the Nasdaq National Market. The current rules of the National Association of Securities Dealers, Inc. (the "NASD") effectively preclude the trading or quotation through the Nasdaq National Market of any securities of an issuer which has issued securities or taken other corporate action that would have the effect of nullifying, restricting, or disparately reducing the per share voting of an outstanding class or classes of equity securities registered under section 12 of the Exchange Act. Certain national securities exchanges have adopted similar rules or 30

policies. We do not intend to issue any additional shares of any stock that would make it ineligible for inclusion on the Nasdaq National Market or any national securities exchange. However, if we issue additional stock that causes us to become ineligible for continued inclusion on the Nasdaq National Market, then the ineligibility would be likely to materially reduce the liquidity of an investment in our common stock and would likely depress its market value below that which would otherwise prevail. Transfer Agent and Registrar. The Transfer Agent and Registrar for our common stock is American Stock Transfer & Trust Company. PREFERRED STOCK Our Restated Certificate of Incorporation allows us to issue up to 30,000,000 shares of preferred stock in one or more series and as may be determined by our board of directors who may establish from time to time the number of shares to be included in each such series, to fix the designation, powers, preference and rights of the shares of each such series and any qualifications, limitations, or restrictions thereof and to increase or decrease the number of shares of any such series without any further vote or action by the shareholders. Our board of directors may authorize, without shareholder approval, the issuance of preferred stock with voting and conversion rights that could adversely affect the voting power and other rights of holders of our common stock. Preferred stock could thus be issued quickly with terms designed to delay or prevent a change in control or to make the removal of management more difficult. In certain circumstances, this could have the effect of decreasing the market price of our common stock. REGISTRATION RIGHTS OF CERTAIN HOLDERS Certain of our shareholders have registration rights. Under the agreements between us and the holders of registration rights, certain holders may under certain circumstances request that we file a registration statement under the Securities Act and, upon such request and subject to certain minimum size conditions, we will generally be required to use our best efforts to effect any such registration. We are not generally required to effect more than two such registrations. However, we are required under certain circumstances to effect an unlimited number of Form S-3 or similar short form registrations for such holders. We are generally obligated to bear the expenses, other than underwriting discounts and sales commissions, of all of these registrations. In addition, if we propose to register any of our securities, either for our own account or for the account of other shareholders, with certain exceptions, we are required to notify the holders noted above and to include in such registration all of the shares of our common stock requested to be included by such holders. In connection with this shelf registration statement, we have notified each of the holders who have registration rights and each holder, other than the selling securityholders listed in this prospectus or any supplement thereto, has either waived its rights to exercise its respective registration rights or is subject to a lock-up agreement. RIGHTS PLAN In September 1996, we adopted a Shareholder Rights Plan. Our rights agreement provides that each of our common shares will have one right to purchase a unit consisting of one-thousandth of a preferred share at a purchase price of $120 per unit. Initially, the rights under our rights agreement are attached to outstanding certificates representing our common shares and no separate certificates representing the rights will be distributed. The rights will separate from our common shares and be represented by separate certificates approximately 10 days after someone acquires or commences a tender offer for 20% of our outstanding common shares. After the rights separate from our common shares, certificates representing the rights will be mailed to record holders of our common stock. Once distributed, the rights certificates alone will represent the rights. 31

All of our common shares issued prior to the date the rights separate from the common shares will be issued with the rights attached. The rights are not exercisable until the date the rights separate from the common shares. We may redeem the rights by action of the Board of Directors, at which time the rights will terminate and the holder of the rights will have only the right to receive $0.01 per right. The rights will expire automatically on October 18, 2006 unless earlier redeemed or exchanged by us. If an acquiror obtains or has the right to obtain 20% or more of our common shares, then each right will entitle the holder to purchase a number of our common shares initially equal to two times the purchase price of each right, unless the acquisition is made pursuant to a tender or exchange offer for all of our outstanding shares at a price determined by a majority of our independent directors. In this event, rights held by the acquiring person shall become null and void. In certain circumstances, a right will entitle the holder to purchase a number of shares of common stock of the acquiror having a then current market value of twice the right's purchase price. Holders of rights will have no rights as our shareholders, including the right to vote or receive dividends, simply by virtue of holding the rights. Our rights agreement may have anti-takeover effects. The rights may cause substantial dilution to a person or group that attempts to acquire us. Accordingly, the existence of the rights may deter acquirors from making takeover proposals or tender offers. However, the rights are not intended to prevent a takeover, but rather are designed to enhance the ability of our board to negotiate with an acquiror on behalf of all the shareholders. In addition, the rights should not interfere with a proxy contest. SELLING SECURITYHOLDERS The notes were originally issued by us and sold by Merrill Lynch, Pierce, Fenner & Smith Incorporated and Robertson Stephens, Inc. (the "initial purchasers") in transactions exempt from the registration requirements of the Securities Act to persons reasonably believed by the initial purchasers to be "qualified institutional buyers" as defined by Rule 144A under the Securities Act. The selling securityholders may from time to time offer and sell pursuant to this prospectus any or all of the notes listed below and the shares of common stock issued upon conversion of such notes. When we refer to the "selling securityholders" in this prospectus, we mean those persons listed in the table below, as well as the pledgees, donees, assignees, transferees, successors and others who later hold any of the selling securityholders' interests. The table below sets forth the name of each selling securityholder, the principal amount at maturity of notes that each selling securityholder may offer pursuant to this prospectus and the number of shares of common stock into which such notes are convertible. Unless set forth below, to our knowledge, none of the selling securityholders has, or within the past three years has had, any material relationship with us or any of our predecessors or affiliates or beneficially owns in excess of 1% of the outstanding common stock. The principal amounts of the notes provided in the table below is based on information provided to us by each of the selling securityholders as of December 4, 2001, and the percentages are based on $200,000,000 principal amount at maturity of notes outstanding. The number of shares of common stock that may be sold is calculated based on the current conversion price of $30.2512 per share. Since the date on which each selling securityholder provided this information, each selling securityholder identified below may have sold, transferred or otherwise disposed of all or a portion of its notes in a transaction exempt from the registration requirements of the Securities Act. Information concerning the selling securityholders may change from time to time and any changed information will be set forth in supplements to this prospectus to the extent required. In addition, the conversion ratio, and therefore the number of shares of our common stock issuable upon conversion of the notes, is subject to adjustment. Accordingly, the number of shares of common stock issuable upon conversion of the notes may increase or decrease. 32

The selling securityholders may from time to time offer and sell any or all of the securities under this prospectus. Because the selling securityholders are not obligated to sell the notes or the shares of common stock issuable upon conversion of the notes, we cannot estimate the amount of the notes or how many shares of common stock that the selling securityholders will hold upon consummation of any such sales.

AGGREGATE PRINCIPAL NUMBER OF SHARES PERCENTAGE OF AMOUNT AT PERCENTAGE OF OF COMMON STOCK SHARES OF MATURITY OF NOTES NOTES THAT MAY COMMON STOCK NAME THAT MAY BE SOLD OUTSTANDING BE SOLD(1) OUTSTANDING(2) - ---- ------------------- ------------- ---------------- ----------------- $ $ All other holders of notes or future transferees, pledges, donees, assignees or successors of any such holders(3)(4).............. $ % ------------ ----- --------- --- Total........................ $200,000,000 100% 6,611,300(5) %(6) ============ ===== ========= ===
- --------------- * Less than one percent (1%). (1) Assumes conversion of all of the holder's notes at a conversion rate of 33.0565 shares of common stock per $1,000 principal amount at maturity of the notes. This conversion rate is subject to adjustment, however, as described under "Description of the Notes -- Conversion Rights." As a result, the number of shares of common stock issuable upon conversion of the notes may increase or decrease in the future. (2) Calculated based on Rule 13d-3(d)(i) of the Exchange Act, using 43,733,922 common shares outstanding as of October 31, 2001. In calculating this amount for each holder, we treated as outstanding the number of shares of common stock issuable upon conversion of all that holder's notes, but we did not assume conversion of any other holder's notes. (3) Information about other selling shareholders will be set forth in prospectus supplements, if required. (4) Assumes that any other holders of the notes or any future pledges, donees, assignees, transferees or successors of or from any other such holders of the notes, do not beneficially own any shares of common stock other than the common stock issuable upon conversion of the notes at the initial conversion rate. (5) Represents the number of shares of common stock into which $200,000,000 of notes would be convertible at the conversion rate described in footnote 1 above. (6) Represents the amount which the selling securityholders may sell under this prospectus divided by the sum of the common stock outstanding as of October 31, 2001 plus the 6,611,300 shares of common stock into which the $200,000,000 notes are convertible. 33

PLAN OF DISTRIBUTION The selling securityholders will be offering and selling all of the securities offered and sold under this prospectus. We will not receive any of the proceeds from the offering of the notes or the shares of common stock by the selling securityholders. In connection with the initial offering of the notes, we entered into a registration rights agreement dated October 17, 2001 with the initial purchasers of the notes. Securities may only be offered or sold under this prospectus pursuant to the terms of the registration rights agreement. However, selling securityholders may resell all or a portion of the securities in open market transactions in reliance upon Rule 144 or Rule 144A under the Securities Act, provided they meet the criteria and conform to the requirements of one of these rules. We are registering the notes and shares of common stock covered by this prospectus to permit holders to conduct public secondary trading of these securities from time to time after the date of this prospectus. We have agreed, among other things, to bear all expenses, other than underwriting discounts and selling commissions, in connection with the registration and sale of the notes and the shares of common stock covered by this prospectus. The selling securityholders may sell all or a portion of the notes and shares of common stock beneficially owned by them and offered hereby from time to time: - directly; or - through underwriters, broker-dealers or agents, who may receive compensation in the form of discounts, commissions or concessions from the selling securityholders and/or from the purchasers of the notes and shares of common stock for whom they may act as agent. The notes and the shares of common stock may be sold from time to time in one or more transactions at: - fixed prices, which may be changed; - prevailing market prices at the time of sale; - varying prices determined at the time of sale; or - negotiated prices. These prices will be determined by the holders of the securities or by agreement between these holders and underwriters or dealers who may receive fees or commissions in connection with the sale. The aggregate proceeds to the selling securityholders from the sale of the notes or shares of common stock offered by them hereby will be the purchase price of the notes or shares of common stock less discounts and commissions, if any. The sales described in the preceding paragraph may be effected in transactions: - on any national securities exchange or quotation service on which the notes or shares of common stock may be listed or quoted at the time of sale, including the Nasdaq National Market in the case of the shares of common stock; - in the over-the counter market; - in transactions otherwise than on such exchanges or services or in the over-the-counter market; or - through the writing of options. These transactions may include block transactions or crosses. Crosses are transactions in which the same broker acts as an agent on both sides of the trade. In connection with sales of the notes and shares of common stock or otherwise, the selling securityholders may enter into hedging transactions with broker-dealers. These broker-dealers may in turn engage in short sales of the notes and shares of common stock in the course of hedging their positions. The selling securityholders may also sell the notes and shares of common stock short and deliver the notes 34

and shares of common stock to close out short positions, or loan or pledge notes and shares of common stock to broker-dealers that in turn may sell the notes and shares of common stock. To our knowledge, there are currently no plans, arrangements or understandings between any selling securityholders and any underwriter, broker-dealer or agent regarding the sale of the notes and the shares of common stock by the selling securityholders. Selling securityholders may not sell any, or may not sell all, of the notes and the shares of common stock offered by them pursuant to this prospectus. In addition, we cannot assure you that a selling securityholder will not transfer, devise or gift the notes and the shares of common stock by other means not described in this prospectus. In addition, any securities covered by this prospectus which qualify for sale pursuant to Rule 144 or Rule 144A of the Securities Act may be sold under Rule 144 or Rule 144A rather than pursuant to this prospectus. The notes were issued and sold in October 2001 in transactions exempt from the registration requirements of the Securities Act to persons reasonably believed by the initial purchasers to be "qualified institutional buyers," as defined in Rule 144A under the Securities Act. Pursuant to the registration rights agreement, we have agreed to indemnify the initial purchasers and each selling securityholder, and each selling securityholder has agreed to indemnify us against specified liabilities arising under the Securities Act. The selling securityholders may also agree to indemnify any broker-dealer or agent that participates in transactions involving sales of the securities against some liabilities, including liabilities that arise under the Securities Act. The selling securityholders and any other person participating in such distribution will be subject to the Exchange Act. The Exchange Act rules include, without limitation, Regulation M, which may limit the timing of purchases and sales of any of the notes and the underlying shares of common stock by the selling securityholders and any such other person. In addition, Regulation M of the Exchange Act may restrict the ability of any person engaged in the distribution of the notes and the underlying shares of common stock to engage in market-making activities with respect to the particular notes and the underlying shares of common stock being distributed for a period of up to five business days prior to the commencement of distribution. This may affect the marketability of the notes and the underlying shares of common stock and the ability of any person or entity to engage in market-making activities with respect to the notes and the underlying shares of common stock. Under the registration rights agreement, we are obligated to use our reasonable best efforts to keep the registration statement of which this prospectus is a part effective until the earlier of: - October 17, 2003; - the date when the notes and the shares of common stock issuable upon conversion of the notes (i) may be resold immediately without restriction pursuant to the volume limitation provisions of Rule 144(k) under the Securities Act or (ii) cease to be outstanding; and - the sale, pursuant to the registration statement to which this prospectus relates, of all the securities registered thereunder. Our obligation to keep the registration statement to which this prospectus relates effective is subject to specified, permitted exceptions set forth in the registration rights agreement. In these cases, we may prohibit offers and sales of the notes and shares of common stock pursuant to the registration statement to which this prospectus relates. We may suspend the use of this prospectus if we learn of any event that causes this prospectus to include an untrue statement of a material fact required to be stated in the prospectus or necessary to make the statements in the prospectus not misleading in light of the circumstances then existing. If this type of event occurs, a prospectus supplement or post-effective amendment, if required, will be distributed to each selling securityholder. Each selling securityholder has agreed not to trade securities from the time the selling securityholder receives notice from us of this type of event until the selling securityholder receives a prospectus supplement or amendment. This time period will not exceed 45 days in any three-month period and will not exceed an aggregate of 120 days in any 12 month-period. 35

LEGAL MATTERS Certain legal matters regarding the notes and the shares of common stock into which those notes are convertible will be passed upon for Regeneron by Skadden, Arps, Slate, Meagher & Flom LLP, New York, New York. EXPERTS The financial statements of Regeneron Pharmaceuticals, Inc. incorporated in this prospectus by reference to the Annual Report on Form 10-K of Regeneron Pharmaceuticals, Inc. for the year ended December 31, 2000, except as they relate to Amgen-Regeneron Partners, have been audited by PricewaterhouseCoopers LLP, independent accountants, and, insofar as they relate to Amgen-Regeneron Partners, by Ernst & Young LLP, independent auditors, whose report thereon is incorporated by reference herein. Such financial statements have been so incorporated in reliance on the report of such independent accountants given on the authority of such firm as experts in auditing and accounting. Ernst & Young LLP, independent auditors, have audited the financial statements of Amgen-Regeneron Partners included in our Annual Report on Form 10-K for the year ended December 31, 2000, as set forth in their report, which is incorporated by reference in this prospectus and elsewhere in the registration statement. The Amgen-Regeneron Partners' financial statements are incorporated by reference in reliance on Ernst & Young LLP's report, given on their authority as experts in accounting and auditing. 36

PART II INFORMATION NOT REQUIRED IN PROSPECTUS ITEM 14. OTHER EXPENSES OF ISSUANCE AND DISTRIBUTION. The following table sets forth all fees and expenses in connection with the issuance and distribution of the securities being registered hereby (other than underwriting discounts and commissions). All of such expenses, except the Securities and Exchange Commission registration fee are estimated.

Securities and Exchange Commission registration fee......... $ 52,800 Legal fees and expenses..................................... 75,000 Accounting fees and expenses................................ 75,000 Printing expenses........................................... 100,000 Miscellaneous............................................... 27,200 -------- Total............................................. $330,000 ========
ITEM 15. INDEMNIFICATION OF DIRECTORS AND OFFICERS. Article Seven of the Registrant's Restated Certificate of Incorporation requires indemnification of the Registrant's officers and directs that such indemnification be made to the fullest extent permitted by the New York Business Corporation Law. Section 722 of the New York Business Corporation Law permits a corporation to provide for the indemnification of the members of its board of directors and its officers against actions or proceedings, or the threat thereof, by or in the right of the corporation. In order to receive indemnification, such director or officer must have (i) acted in good faith for a purpose which he reasonably believed was in the best interest of the corporation, and (ii) in the case of a criminal proceeding, also had no reasonable belief that such conduct was unlawful. Article IV of the Company's By-Laws provides that the directors and certain other personnel of the Company shall be indemnified against expenses and certain other liabilities arising out of legal actions brought or threatened against them for their conduct on behalf of the Company, subject to certain qualifications and provided that each such person acted in good faith and in a manner that they reasonably believed was in the Company's best interest. Each of the directors has entered into an agreement with the Company that provides that the Company will indemnify such director to the fullest extent permitted by the New York Business Corporation Law. The Company maintains directors' and officers' liability insurance which insures against liabilities that directors or officers of the Company may incur in such capacities. Reference is made to the proposed Underwriting Agreement filed as Exhibit 1 to this Registration Statement for certain provisions relating to the indemnification of directors and officers of the Company against certain liabilities under the Securities Act of 1933. ITEM 16. EXHIBITS.
EXHIBIT NUMBER DESCRIPTION - ------- ----------- 4.1 -- Indenture dated as of October 17, 2001 between Regeneron Pharmaceuticals, Inc. and American Stock Transfer & Trust Company, as trustee. 4.2 -- Form of 5 1/2% Convertible Senior Subordinated Note (included in Exhibit 4.1). 4.3 -- Pledge Agreement dated as of October 17, 2001 between Regeneron Pharmaceuticals, Inc. and American Stock Transfer & Trust Company, as trustee.
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EXHIBIT NUMBER DESCRIPTION - ------- ----------- 4.4 -- Registration Rights Agreement dated as of October 17, 2001, among Regeneron Pharmaceuticals, Inc., Merrill Lynch & Co., Merrill Lynch, Pierce, Fenner & Smith Incorporated and Robertson Stephens, Inc. 4.5 -- Stock Purchase Agreement dated January 13, 1988, by and between the Company, Leonard S. Schleifer and ML Venture Partners II, L.P. (the "Stock Purchase Agreement"). Incorporated by reference to Exhibit 10.1 to Regeneron's Registration Statement on Form S-1 (File No. 33-39043) (the "Regeneron S-1"). 4.6 -- Amendment to the Stock Purchase Agreement dated March 3, 1989. Incorporated by reference to Exhibit 10.2 to the Regeneron S-1. 4.7 -- Letter Agreement dated November 27, 1989, amending the Stock Purchase Agreement. Incorporated by reference to Exhibit 10.13 to the Regeneron S-1. 4.8 -- Class B Convertible Preferred Stock Purchase Agreement dated November 22, 1988, by and between the Company and each purchaser set forth on Exhibit A thereto. Incorporated by reference to Exhibit 10.3 to the Regeneron S-1. 4.9 -- Class D Convertible Preferred Stock Purchase Agreement dated August 31, 1990, by and between the Company and Amgen Inc. Incorporated by reference to Exhibit 10.9 to the Regeneron S-1. 4.10 -- Registration Rights Agreement, dated as of July 22, 1993, by and between the Company and Glaxo Group Limited. Incorporated by reference to Exhibit 4.7 to Regeneron's Registration Statement on Form S-3 (File No. 33-66788). 4.11 -- Registration Rights Agreement, dated as of April 15, 1996, by and between the Company and Amgen Inc. Incorporated by reference to Exhibit 10.3 to Regeneron's Form 10-Q for the quarter ended June 30, 1996, filed August 14, 1996. 4.12 -- Registration Rights Agreement, dated as of June 27, 1996, by and between the Company and Medtronic, Inc. Incorporated by reference to Exhibit 10.6 to Regeneron's Form 10-Q for the quarter ended June 30, 1996, filed August 14, 1996. 4.13 -- Registration Rights Agreement, dated as of December 11, 1996, by and between the Company and Procter & Gamble Pharmaceuticals. Incorporated by reference to Exhibit 10.30 to Regeneron's Form 10-K for the fiscal year ended December 31, 1996, filed March 26, 1997. 4.14 -- Registration Rights Agreement, dated as of May 13, 1997, by and between the Company and Procter & Gamble Pharmaceuticals. Incorporated by reference to Exhibit 10.3 to Regeneron's Form 10-Q for the quarter ended June 30, 1997, filed August 12, 1997. 4.15 -- Form of Certificate of shares of common stock. Incorporated by reference to Exhibit (a) to the Company's Form 8-A, filed with the Commission on February 20, 1991. 5 -- Opinion of Skadden, Arps, Slate, Meagher & Flom LLP. 12 -- Computation of Ratio of Earnings to Fixed Charges 23.1 -- Consent of PricewaterhouseCoopers LLP, Independent Accountants. 23.2 -- Consent of Ernst & Young LLP, Independent Auditors. 23.3 -- Consent of Skadden, Arps, Slate, Meagher & Flom LLP. Included in Exhibit 5. 24 -- Powers of Attorney. Included in the signature page of this Registration Statement. 25 -- A statement of Eligibility on Form T-1 under the Trust Indenture Act of 1939, as amended, of American Stock Transfer & Trust Company, trustee under the Indenture.
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ITEM 17. UNDERTAKINGS. The undersigned Registrant hereby undertakes: (1) To file, during any period in which offers or sales are being made, a post-effective amendment to this Registration Statement: (a) To include any prospectus required by Section 10(a)(3) of the Securities Act of 1933, as amended; (b) To reflect in the prospectus any facts or events arising after the effective date of the Registration Statement (or the most recent post-effective amendment thereof) which, individually or in the aggregate, represent a fundamental change in the information set forth in the Registration Statement. Notwithstanding the foregoing, any increase or decrease in volume of securities offered (if the total dollar value of securities offered would not exceed that which was registered) and any deviation from the low or high end of the estimated maximum offering range may be reflected in the form of prospectus filed with the Securities and Exchange Commission pursuant to Rule 424(b) if, in the aggregate, the changes in volume and price represent no more than a 20% change in the maximum aggregate offering price set forth in the "Calculation of Registration Fee" table in the effective Registration Statement; and (c) To include any material information with respect to the plan of distribution not previously disclosed in the Registration Statement or any material change to such information in the Registration Statement; provided, however, that paragraphs (1)(a) and (1)(b) shall not apply if the information required to be included in a post-effective amendment by those paragraphs is contained in periodic reports filed with or furnished to the Securities and Exchange Commission by the Registrant pursuant to Section 13 or Section 15(d) of the Securities Exchange Act of 1934 that are incorporated by reference in the Registration Statement. (2) That, for the purpose of determining any liability under the Securities Act of 1933, as amended, each such post-effective amendment shall be deemed to be a new registration statement relating to the securities offered therein, and the offering of such securities at that time shall be deemed to be the initial bona fide offering thereof. (3) To remove from registration by means of a post-effective amendment any of the securities being registered which remain unsold at the termination of the offering. The undersigned Registrant hereby undertakes that, for purposes of determining any liability under the Securities Act of 1933 (the "Securities Act"), each filing of the Registrant's annual report pursuant to section 13(a) or section 15(d) of the Securities Exchange Act of 1934 (and, where applicable, each filing of an employee benefit plan's annual report pursuant to section 15(d) of the Securities Exchange Act of 1934) that is incorporated by reference in the Registration Statement shall be deemed to be a new registration statement relating to the securities offered therein, and the offering of such securities at that time shall be deemed to be the initial bona fide offering thereof. Insofar as indemnification for liabilities arising under the Securities Act may be permitted to directors, officers and controlling persons of the Registrant pursuant to the provisions described in "Item 14 -- Indemnification of Directors and Officers" above, or otherwise, the Registrant has been advised that in the opinion of the Commission such indemnification is against public policy as expressed in the Securities Act and is, therefore, unenforceable. In the event that a claim for indemnification against such liabilities (other than the payment by the Registrant of expenses incurred or paid by a director, officer, or controlling person of the Registrant in the successful defense of any action, suit, or proceeding) is asserted by such director, officer, or controlling person in connection with the securities being registered, the Registrant will, unless in the opinion of its counsel the matter has been settled by controlling precedent, submit to a court of appropriate jurisdiction the question whether such indemnification by it is against public policy as expressed in the Securities Act and will be governed by the final adjudication of such issue. II-3

SIGNATURES Pursuant to the requirements of the Securities Act of 1933, the Registrant certifies that it has reasonable grounds to believe that it meets all of the requirements for filing on Form S-3 and has duly caused this Registration Statement to be signed on its behalf by the undersigned, thereunto duly authorized, in the Village of Tarrytown, State of New York on December 4, 2001. REGENERON PHARMACEUTICALS, INC. By: /s/ LEONARD S. SCHLEIFER, M.D., PH.D. ------------------------------------------------- Leonard S. Schleifer, M.D., Ph.D. President and Chief Executive Officer PURSUANT TO THE REQUIREMENTS OF THE SECURITIES ACT OF 1933, THIS REGISTRATION STATEMENT HAS BEEN SIGNED BY THE FOLLOWING PERSONS IN THE CAPACITIES AND ON THE DATES INDICATED. EACH PERSON WHOSE SIGNATURE APPEARS BELOW HEREBY AUTHORIZES LEONARD S. SCHLEIFER, AND MURRAY A. GOLDBERG, JOINTLY AND SEVERALLY, WITH FULL POWER TO EACH, TO EXECUTE IN THE NAME AND ON BEHALF OF SUCH PERSON ANY AMENDMENT (INCLUDING ANY POST-EFFECTIVE AMENDMENTS) TO THIS REGISTRATION STATEMENT (OR ANY OTHER REGISTRATION STATEMENT FOR THE SAME OFFERING THAT IS TO BE EFFECTIVE UPON FILING PURSUANT TO RULE 462(B) UNDER THE SECURITIES ACT) AND TO FILE THE SAME, WITH EXHIBITS THERETO AND OTHER DOCUMENTS IN CONNECTION THEREWITH, MAKING SUCH CHANGES IN THIS REGISTRATION STATEMENT AS THE PERSON(S) SO ACTING DEEMS APPROPRIATE AND APPOINTS EACH OF SUCH PERSONS, EACH WITH FULL POWER OF SUBSTITUTION, ATTORNEY-IN-FACT TO SIGN ANY AMENDMENT (INCLUDING ANY POST-EFFECTIVE AMENDMENT) TO THIS REGISTRATION STATEMENT (OR ANY OTHER REGISTRATION STATEMENT FOR THE SAME OFFERING THAT IS TO BE EFFECTIVE UPON FILING PURSUANT TO RULE 462(B) UNDER THE SECURITIES ACT) AND TO FILE THE SAME, WITH EXHIBITS THERETO AND OTHER DOCUMENTS IN CONNECTION THEREIN.

SIGNATURE TITLE DATE --------- ----- ---- /s/ P. ROY VAGELOS, M.D. Chairman of the Board December 4, 2001 - --------------------------------------------------- P. Roy Vagelos, M.D. /s/ LEONARD S. SCHLEIFER, M.D., PH.D President, Chief Executive December 4, 2001 - --------------------------------------------------- Officer and Director Leonard S. Schleifer, M.D., Ph.D (Principal Executive Officer) /s/ GEORGE D. YANCOPOULOS, M.D., PH.D. Executive Vice President, December 4, 2001 - --------------------------------------------------- Chief Scientific Officer, George D. Yancopoulos, M.D., Ph.D. President, Regeneron Research Laboratories and Director
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SIGNATURE TITLE DATE --------- ----- ---- /s/ MURRAY A. GOLDBERG Senior Vice President, Finance December 4, 2001 - --------------------------------------------------- & Administration, Chief Murray A. Goldberg Financial Officer, Treasurer, and Assistant Secretary (Principal Financial Officer) /s/ DOUGLAS S. MCCORKLE Controller and Assistant December 4, 2001 - --------------------------------------------------- Treasurer (Principal Douglas S. McCorkle Accounting Officer) /s/ CHARLES A. BAKER Director December 4, 2001 - --------------------------------------------------- Charles A. Baker /s/ MICHAEL S. BROWN, M.D. Director December 4, 2001 - --------------------------------------------------- Michael S. Brown, M.D. /s/ ALFRED G. GILMAN, M.D., PH.D. Director December 4, 2001 - --------------------------------------------------- Alfred G. Gilman, M.D., Ph.D. /s/ JOSEPH L. GOLDSTEIN, M.D. Director December 4, 2001 - --------------------------------------------------- Joseph L. Goldstein, M.D. /s/ ERIC M. SHOOTER, PH.D. Director December 4, 2001 - --------------------------------------------------- Eric M. Shooter, Ph.D. /s/ GEORGE L. SING Director December 4, 2001 - --------------------------------------------------- George L. Sing
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EXHIBIT INDEX

EXHIBIT NUMBER DESCRIPTION - ------- ----------- 4.1 -- Indenture dated as of October 17, 2001 between Regeneron Pharmaceuticals, Inc. and American Stock Transfer & Trust Company, as trustee. 4.2 -- Form of 5 1/2% Convertible Senior Subordinated Note (included in Exhibit 4.1(b). 4.3 -- Pledge Agreement dated as of October 17, 2001 between Regeneron Pharmaceuticals, Inc. and American Stock Transfer & Trust Company, as trustee. 4.4 -- Registration Rights Agreement dated as of October 17, 2001, among Regeneron Pharmaceuticals, Inc., Merrill Lynch & Co., Merrill Lynch, Pierce, Fenner & Smith Incorporated and Robertson Stephens, Inc. 4.5 -- Stock Purchase Agreement dated January 13, 1988, by and between the Company, Leonard S. Schleifer and ML Venture Partners II, L.P. (the "Stock Purchase Agreement"). Incorporated by reference to Exhibit 10.1 to Regeneron's Registration Statement on Form S-1 (File No. 33-39043) (the "Regeneron S-1"). 4.6 -- Amendment to the Stock Purchase Agreement dated March 3, 1989. Incorporated by reference to Exhibit 10.2 to the Regeneron S-1. 4.7 -- Letter Agreement dated November 27, 1989, amending the Stock Purchase Agreement. Incorporated by reference to Exhibit 10.13 to the Regeneron S-1. 4.8 -- Class B Convertible Preferred Stock Purchase Agreement dated November 22, 1988, by and between the Company and each purchaser set forth on Exhibit A thereto. Incorporated by reference to Exhibit 10.3 to the Regeneron S-1. 4.9 -- Class D Convertible Preferred Stock Purchase Agreement dated August 31, 1990, by and between the Company and Amgen Inc. Incorporated by reference to Exhibit 10.9 to the Regeneron S-1. 4.10 -- Registration Rights Agreement, dated as of July 22, 1993, by and between the Company and Glaxo Group Limited. Incorporated by reference to Exhibit 4.7 to Regeneron's Registration Statement on Form S-3 (File No. 33-66788). 4.11 -- Registration Rights Agreement, dated as of April 15, 1996, by and between the Company and Amgen Inc. Incorporated by reference to Exhibit 10.3 to Regeneron's Form 10-Q for the quarter ended June 30, 1996, filed August 14, 1996. 4.12 -- Registration Rights Agreement, dated as of June 27, 1996, by and between the Company and Medtronic, Inc. Incorporated by reference to Exhibit 10.6 to Regeneron's Form 10-Q for the quarter ended June 30, 1996, filed August 14, 1996. 4.13 -- Registration Rights Agreement, dated as of December 11, 1996, by and between the Company and Procter & Gamble Pharmaceuticals. Incorporated by reference to Exhibit 10.30 to Regeneron's Form 10-K for the fiscal year ended December 31, 1996, filed March 26, 1997. 4.14 -- Registration Rights Agreement, dated as of May 13, 1997, by and between the Company and Procter & Gamble Pharmaceuticals. Incorporated by reference to Exhibit 10.3 to Regeneron's Form 10-Q for the quarter ended June 30, 1997, filed August 12, 1997. 4.15 -- Form of Certificate of shares of common stock. Incorporated by reference to Exhibit (a) to the Company's Form 8-A, filed with the Commission on February 20, 1991. 5 -- Opinion of Skadden, Arps, Slate, Meagher & Flom LLP. 12 -- Computation of Ratio of Earnings to Fixed Charges 23.1 -- Consent of PricewaterhouseCoopers LLP, Independent Accountants. 23.2 -- Consent of Ernst & Young LLP, Independent Auditors.

EXHIBIT NUMBER DESCRIPTION - ------- ----------- 23.3 -- Consent of Skadden, Arps, Slate, Meagher & Flom LLP. Included in Exhibit 5. 24 -- Powers of Attorney. Included in the signature page of this Registration Statement. 25 -- A statement of Eligibility on Form T-1 under the Trust Indenture Act of 1939, as amended, of American Stock Transfer & Trust Company, trustee under the Indenture.

EXHIBIT 4.1 EXECUTION COPY REGENERON PHARMACEUTICALS, INC. 5-1/2% Convertible Senior Subordinated Notes due 2008 ---------------------------------------------------------- INDENTURE Dated as of October 17, 2001 ---------------------------------------------------------- AMERICAN STOCK TRANSFER & TRUST COMPANY TRUSTEE ----------------------------------------------------------

CROSS REFERENCE TABLE* TIA SECTION ......................... INDENTURE SECTION 310(a)(1) ........................... 7.09 (a)(2) ........................... 7.09 (a)(3) ........................... N.A. (a)(4) ........................... N.A. (b) .............................. 7.08; 7.10 (c) .............................. N.A. 311(a) .............................. 7.13 (b) .............................. 7.13 (c) .............................. N.A. 312(a) .............................. 2.05 (b) .............................. 12.03 (c) .............................. 12.03 313(a) .............................. 7.14 (b)(1) ........................... N.A. (b)(2) ........................... 7.14 (c) .............................. 12.02 (d) .............................. 7.14 314(a) .............................. 4.02; 4.03; 12.02 (b) .............................. N.A. (c)(1) ........................... 12.04 (c)(2) ........................... 12.04 (c)(3) ........................... N.A. (d) .............................. N.A. (e) .............................. 12.05 (f) .............................. N.A. 315(a) .............................. 7.01 (b) .............................. 7.15; 12.02 (c) .............................. 7.01 (d) .............................. 7.01 (e) .............................. 6.11 316(a) (last sentence) . .... ....... 2.08 (a)(1)(A) ........................ 6.05 (a)(1)(B) ........................ 6.04 (a)(2) ........................... N.A. (b) .............................. 6.07 317(a)(1) ........................... 6.08 (a)(2) ........................... 6.09 (b) .............................. 2.04 318(a) .............................. 12.01 N.A. means Not Applicable. - ---------- * Note: This Cross Reference Table shall not, for any purpose, be deemed to be part of the Indenture.

TABLE OF CONTENTS* PAGE ARTICLE 1 DEFINITIONS AND OTHER PROVISIONS OF GENERAL APPLICATION.......... 1 SECTION 1.01 Definitions............................................... 1 SECTION 1.02 Other Definitions......................................... 11 SECTION 1.03 Incorporation by Reference of Trust Indenture Act......... 11 SECTION 1.04 Rules of Construction..................................... 12 SECTION 1.05 Acts of Holders........................................... 12 ARTICLE 2 THE NOTES........................................................ 13 SECTION 2.01 Form and Dating........................................... 13 SECTION 2.02 Execution and Authentication.............................. 15 SECTION 2.03 Registrar, Paying Agent and Conversion Agent.............. 15 SECTION 2.04 Paying Agent to Hold Money and Notes in Trust............. 16 SECTION 2.05 Noteholder Lists.......................................... 16 SECTION 2.06 Transfer and Exchange..................................... 17 SECTION 2.07 Replacement Notes......................................... 18 SECTION 2.08 Outstanding Notes; Determinations of Holders' Action...... 19 SECTION 2.09 Temporary Notes........................................... 19 SECTION 2.10 Cancellation.............................................. 20 SECTION 2.11 Persons Deemed Owners..................................... 20 SECTION 2.12 Global Notes.............................................. 20 SECTION 2.13 CUSIP Numbers............................................. 24 SECTION 2.14 Defaulted Interest........................................ 25 ARTICLE 3 REDEMPTION AND PURCHASES......................................... 25 SECTION 3.01 Provisional Redemption.................................... 25 SECTION 3.02 Optional Redemption....................................... 26 SECTION 3.03 Notice of Trustee......................................... 26 SECTION 3.04 Selection of Notes to be Redeemed......................... 26 SECTION 3.05 Notice of Redemption...................................... 27 SECTION 3.06 Effect of Notice of Redemption............................ 27 SECTION 3.07 Deposit of Redemption Price............................... 28 SECTION 3.08 Notes Redeemed in Part.................................... 28 SECTION 3.09 Conversion Arrangement on Call for Redemption............. 29 SECTION 3.10 Repurchase of Notes at Option of the Holder upon Change of Control................................................... 29 SECTION 3.11 Effect of Change of Control Repurchase Notice............. 33 SECTION 3.12 Deposit of Change of Control Repurchase Price............. 34 - ---------- * Note: This Table of Contents shall not, for any purpose, be deemed to be part of the Indenture. i

SECTION 3.13 Notes Purchased in Part................................... 34 SECTION 3.14 Covenant to Comply with Securities Laws upon Purchase of Notes..................................................... 35 SECTION 3.15 Repayment to the Company.................................. 35 ARTICLE 4 COVENANTS........................................................ 35 SECTION 4.01 Payment of Principal, Premium, Interest on the Notes...... 35 SECTION 4.02 SEC and Other Reports..................................... 36 SECTION 4.03 Compliance Certificate.................................... 36 SECTION 4.04 Further Instruments and Acts.............................. 36 SECTION 4.05 Maintenance of Office or Agency........................... 36 SECTION 4.06 Delivery of Certain Information........................... 37 SECTION 4.07 Subordination............................................. 37 ARTICLE 5 SUCCESSOR CORPORATION............................................ 37 SECTION 5.01 When Company May Merge or Transfer Assets................. 37 ARTICLE 6 DEFAULTS AND REMEDIES............................................ 38 SECTION 6.01 Events of Default......................................... 38 SECTION 6.02 Acceleration.............................................. 40 SECTION 6.03 Other Remedies............................................ 40 SECTION 6.04 Waiver of Past Defaults................................... 41 SECTION 6.05 Control by Majority....................................... 41 SECTION 6.06 Limitation on Suits....................................... 41 SECTION 6.07 Rights of Holders to Receive Payment...................... 42 SECTION 6.08 Collection Suit by Trustee................................ 42 SECTION 6.09 Trustee May File Proofs of Claim.......................... 42 SECTION 6.10 Priorities................................................ 43 SECTION 6.11 Undertaking for Costs..................................... 43 SECTION 6.12 Waiver of Stay, Extension or Usury Laws................... 43 ARTICLE 7 TRUSTEE.......................................................... 44 SECTION 7.01 Duties and Responsibilities of the Trustee; During Default; Prior to Default................................. 44 SECTION 7.02 Certain Rights of the Trustee............................. 45 SECTION 7.03 Trustee Not Responsible for Recitals, Disposition of Notes or Application of Proceeds Thereof........................ 46 SECTION 7.04 Trustee and Agents May Hold Notes; Collections, etc....... 46 SECTION 7.05 Moneys Held by Trustee.................................... 46 SECTION 7.06 Compensation and Indemnification of Trustee and Its Prior Claim..................................................... 47 SECTION 7.07 Right of Trustee to Rely on Officers' Certificate, etc.... 47 SECTION 7.08 Conflicting Interests..................................... 47 SECTION 7.09 Persons Eligible for Appointment as Trustee............... 48 SECTION 7.10 Resignation and Removal; Appointment of Successor Trustee. 48 SECTION 7.11 Acceptance of Appointment by Successor Trustee............ 49 ii

SECTION 7.12 Merger, Conversion, Consolidation or Succession to Business of Trustee....................................... 50 SECTION 7.13 Preferential Collection of Claims Against the Company..... 50 SECTION 7.14 Reports by the Trustee.................................... 50 SECTION 7.15 Trustee to Give Notice of Default, But May Withhold in Certain Circumstances..................................... 50 ARTICLE 8 DISCHARGE OF INDENTURE........................................... 51 SECTION 8.01 Termination of the Company's Obligations.................. 51 SECTION 8.02 Defeasance and Discharge of Indenture..................... 52 SECTION 8.03 Defeasance of Certain Obligations......................... 53 SECTION 8.04 Application of Trust Money................................ 53 SECTION 8.05 Reinstatement............................................. 54 SECTION 8.06 Defeasance and Certain Other Events of Default............ 54 SECTION 8.07 Repayment of the Company.................................. 54 SECTION 8.08 Conversion of Notes Upon Discharge........................ 54 ARTICLE 9 AMENDMENTS....................................................... 55 SECTION 9.01 Without Consent of Holders................................ 55 SECTION 9.02 With Consent of Holders................................... 56 SECTION 9.03 Compliance with Trust Indenture Act....................... 57 SECTION 9.04 Revocation and Effect of Consents, Waivers and Actions.... 57 SECTION 9.05 Notation on or Exchange of Notes.......................... 57 SECTION 9.06 Trustee to Sign Supplemental Indentures................... 57 SECTION 9.07 Effect of Supplemental Indentures......................... 57 ARTICLE 10 CONVERSION...................................................... 58 SECTION 10.01 Conversion Right and Conversion Price..................... 58 SECTION 10.02 Exercise of Conversion Right.............................. 58 SECTION 10.03 Fractions of Shares....................................... 59 SECTION 10.04 Adjustment of Conversion Price............................ 59 SECTION 10.05 Notice of Adjustments of Conversion Price................. 70 SECTION 10.06 Notice Prior to Certain Actions........................... 70 SECTION 10.07 Company to Reserve Common Stock........................... 71 SECTION 10.08 Taxes on Conversions...................................... 71 SECTION 10.09 Covenant as to Common Stock............................... 71 SECTION 10.10 Cancellation of Converted Notes........................... 72 SECTION 10.11 Effect of Reclassification, Consolidation, Merger or Sale. 72 SECTION 10.12 Responsibility of Trustee for Conversion Provisions....... 73 ARTICLE 11 SUBORDINATION................................................... 74 SECTION 11.01 Agreement to Subordinate.................................. 74 SECTION 11.02 Liquidation; Dissolution; Bankruptcy...................... 74 SECTION 11.03 Default on Designated Senior Indebtedness................. 74 SECTION 11.04 Acceleration of Notes..................................... 75 iii

SECTION 11.05 When Distribution Must Be Paid Over....................... 75 SECTION 11.06 Notice by the Company..................................... 76 SECTION 11.07 Subrogation............................................... 76 SECTION 11.08 Relative Rights........................................... 76 SECTION 11.09 Subordination May Not Be Impaired by the Company.......... 77 SECTION 11.10 Distribution or Notice to Representative.................. 77 SECTION 11.11 Rights of Trustee and Paying Agent........................ 77 ARTICLE 12 SECURITY........................................................ 78 SECTION 12.01 Security.................................................. 78 ARTICLE 13 MISCELLANEOUS................................................... 79 SECTION 13.01 Trust Indenture Act Controls.............................. 79 SECTION 13.02 Notices................................................... 79 SECTION 13.03 Communication by Holders with Other Holders............... 80 SECTION 13.04 Certificate and Opinion as to Conditions Precedent........ 80 SECTION 13.05 Statements Required in Certificate or Opinion............. 80 SECTION 13.06 Separability Clause....................................... 81 SECTION 13.07 Rules by Trustee, Paying Agent, Conversion Agent and Registrar................................................. 81 SECTION 13.08 Legal Holidays............................................ 81 SECTION 13.09 GOVERNING LAW............................................. 81 SECTION 13.10 No Recourse Against Others................................ 81 SECTION 13.11 Successors................................................ 81 SECTION 13.12 Multiple Originals........................................ 82 EXHIBITS Exhibit A-1 Form of Face of Global Note Exhibit A-2 Form of Certificated Note Exhibit B-1 Transfer Certificate Exhibit B-2 Form of Letter to Be Delivered by Accredited Investors iv

INDENTURE dated as of October 17, 2001 between REGENERON PHARMACEUTICALS, INC., a New York corporation (the "Company"), and AMERICAN STOCK TRANSFER & TRUST COMPANY, a New York corporation with trust powers, as Trustee hereunder (the "Trustee"). RECITALS OF THE COMPANY The Company has duly authorized the creation of an issue of its 5-1/2% Convertible Senior Subordinated Notes due 2008 (herein called the "Notes") of substantially the tenor and amount hereinafter set forth, and to provide therefor the Company has duly authorized the execution and delivery of this Indenture. All things necessary to make the Notes, when the Notes are executed by the Company and authenticated and delivered hereunder, the valid obligations of the Company, and to make this Indenture a valid agreement of the Company, in accordance with their and its terms, have been done. Further, all things necessary to duly authorize the issuance of the Common Stock of the Company issuable upon the conversion of the Notes, and to duly reserve for issuance the number of shares of Common Stock issuable upon such conversion, have been done. NOW, THEREFORE, THIS INDENTURE WITNESSETH: For and in consideration of the premises and the purchase of the Notes by the Holders thereof, it is mutually covenanted and agreed, for the equal and proportionate benefit of all Holders of the Notes, as follows: ARTICLE 1 DEFINITIONS AND OTHER PROVISIONS OF GENERAL APPLICATION SECTION 1.01 Definitions. For all purposes of this Indenture, except as otherwise expressly provided or unless the context otherwise requires: (1) the terms defined in this Article have the meanings assigned to them in this Article and include the plural as well as the singular; (2) all accounting terms not otherwise defined herein have the meanings assigned to them in accordance with GAAP; and (3) the words "herein", "hereof" and "hereunder" and other words of similar import refer to this Indenture as a whole and not to any particular Article, Section or other subdivision. "Adjusted Interest Rate" means, with respect to any Registration Default, initially 5.75% but from and after the 91st day following the day on which a Registration Default has occurred and is continuing it shall be increased to 6.00%. 1

"Affiliate" of any specified person means any other person directly or indirectly controlling or controlled by or under direct or indirect common control with such specified person. For purposes of this definition, "control" when used with respect to any specified person means the power to direct or cause the direction of the management and policies of such person, directly or indirectly, whether through the ownership of voting securities, by contract or otherwise; and the terms "controlling" and "controlled" have meanings correlative to the foregoing. "Applicable Procedures" means, with respect to any transfer or transaction involving a Global Note or beneficial interest therein, the rules and procedures of the Depositary for such Note, in each case to the extent applicable to such transaction and as in effect from time to time. "Board of Directors" means either the board of directors of the Company or any duly authorized committee of such board. "Board Resolution" means a resolution duly adopted by the Board of Directors, a copy of which, certified by the Secretary or an Assistant Secretary of the Company to be in full force and effect on the date of such certification, shall have been delivered to the Trustee. "Business Day" means each day of the year other than a Saturday or a Sunday on which banking institutions are not required or authorized to close in the City of New York. "Capital Stock" of any corporation means any and all shares, interests, rights to purchase, warrants, options, participations or other equivalents of or interests in (however designated) stock issued by that corporation. "Certificated Notes" means Notes that are in the form of the Notes attached hereto as Exhibit A-2. "Closing Price" of any security on any date of determination means: (1) the closing sale price (or, if no closing sale price is reported, the last reported sale price) of such security on the New York Stock Exchange on such date; (2) if such security is not listed for trading on the New York Stock Exchange on any such date, the closing sale price as reported in the composite transactions for the principal U.S. securities exchange on which such security is so listed; (3) if such security is not so listed on a U.S. national or regional securities exchange, the closing bid price as reported by the NASDAQ Stock Market; (4) if such security is not so reported, the last quoted bid price for such security in the over-the-counter market as reported by the National Quotation Bureau or similar organization; or 2

(5) if such bid price is not available, the average of the mid-point of the last bid and ask prices of such security on such date from at least three nationally recognized independent investment banking firms retained for this purpose by the Company. "Common Stock" means the Common Stock, par value $0.001 per share, of the Company authorized at the date of this instrument as originally executed, excluding the Company's Class A Stock. Subject to the provisions of Section 10.11, shares issuable on conversion, redemption or repurchase of Notes shall include only shares of Common Stock or shares of any class or classes of common stock resulting from any reclassification or reclassifications thereof; provided, however, that if at any time there shall be more than one such resulting class, the shares so issuable on conversion of Notes shall include shares of all such classes, and the shares of each such class then so issuable shall be substantially in the proportion which the total number of shares of such class resulting from all such reclassifications bears to the total number of shares of all such classes resulting from all such reclassifications. "common stock" means any stock of any class of Capital Stock which has no preference in respect of dividends or of amounts payable in the event of any voluntary or involuntary liquidation, dissolution or winding up of the issuer. "Company" means the party named as the "Company" in the first paragraph of this Indenture until a successor replaces it pursuant to the applicable provisions of this Indenture and, thereafter, shall mean such successor. The foregoing sentence shall likewise apply to any subsequent such successor or successors. "Company Request" or "Company Order" means a written request or order signed in the name of the Company by any two Officers. "Conversion Agent" means any person authorized by the Company to convert Notes in accordance with Article 10 hereof. "Corporate Trust Office" means the principal office of the Trustee at which at any time its corporate trust business shall be administered, which office at the date hereof is located at 59 Maiden Lane, New York, New York, 10038, or such other address as the Trustee may designate from time to time by notice to the Holders and the Company, or the principal corporate trust office of any successor Trustee (or such other address as a successor Trustee may designate from time to time by notice to the Holders and the Company). "Default" means any event which is, or after notice or passage of time or both would be, an Event of Default. "Designated Senior Indebtedness" means any Senior Indebtedness which, at the time of determination, has an aggregate principal amount outstanding of at least $25.0 million and that has been specifically designated in the instrument evidencing such Senior Indebtedness as "Designated Senior Indebtedness" of the Company. "Dollar" or "U.S.$" means a dollar or other equivalent unit in such coin or currency of the United States as at the time shall be legal tender for the payment of public and private debts. 3

"Exchange Act" means the United States Securities Exchange Act of 1934 (or any successor statute), as amended from time to time. "GAAP" means United States generally accepted accounting principles as in effect from time to time. "Global Notes" means Notes that are in the form of the Notes attached hereto as Exhibit A-1, and to the extent that such Notes are required to bear the Legend required by Section 2.06(f), such Notes will be in the form of a 144A Global Note. "Government Securities" means the direct obligations of, obligations fully guaranteed by, or participations in pools consisting solely of obligations of or obligations guaranteed by the United States of America for the payment of which guarantee or obligations the full faith and credit of the United States of America is pledged and which are not callable or redeemable at the option of the issuer thereof. "Guarantee" means a guarantee (other than by endorsement of negotiable instruments for collection in the ordinary course of business), direct or indirect, in any manner (including, without limitation, letters of credit and reimbursement agreements in respect thereof), of all or any part of any Indebtedness. "Holder" or "Noteholder" means a person in whose name a Note is registered on the Registrar's books. "Indebtedness" means, with respect to any person, without duplication: (a) all liabilities of such person for borrowed money (including overdrafts) or for the deferred purchase price of property or services, excluding any trade payables and other accrued current liabilities incurred in the ordinary course of business, but including, without limitation, all obligations, contingent or otherwise, of such person in connection with any letters of credit and acceptances issued under letter of credit facilities, acceptance facilities or other similar facilities; (b) all obligations of such person evidenced by bonds, notes, debentures or other similar instruments; (c) indebtedness of such person created or arising under any conditional sale or other title retention agreement with respect to property acquired by such person (even if the rights and remedies of the seller or lender under such agreement in the event of default are limited to repossession or sale of such property), but excluding trade payables arising in the ordinary course of business; (d) all capitalized lease obligations of such person; (e) all obligations of such person under or in respect of interest rate agreements or currency agreements; 4

(f) all indebtedness referred to in (but not excluded from) the preceding clauses of other persons and all dividends of other persons, the payment of which is secured by (or for which the holder of such indebtedness has an existing right, contingent or otherwise, to be secured by) any Lien or with respect to property (including, without limitation, accounts and contract rights) owned by such person, even though such person has not assumed or become liable for the payment of such indebtedness (the amount of such obligation being deemed to be the lesser of the value of such property or asset or the amount of the obligation so secured); (g) all Guarantees by such person of indebtedness referred to in this definition or of any other person; (h) all Redeemable Capital Stock of such person valued at the greater of its voluntary or involuntary maximum fixed repurchase price plus accrued and unpaid dividends; and (i) the present value of the obligation of such person as lessee for net rental payments (excluding all amounts required to be paid on account of maintenance and repairs, insurance, taxes, assessments, water, utilities and similar charges to the extent included in such rental payments) during the remaining term of the lease included in such sale and leaseback transaction including any period for which such lease has been extended or may, at the option of the lessor, be extended. Such present value shall be calculated using a discount rate equal to the rate of interest implicit in such transaction, determined in accordance with GAAP. "Indenture" means this Indenture, as amended or supplemented from time to time in accordance with the terms hereof, including the provisions of the TIA that are deemed to be a part hereof. "Institutional Accredited Investor" means an institutional "accredited investor" as described in Rule 501(a)(1), (2), (3) or (7) under the Securities Act. "Interest Payment Date" means the Stated Maturity of an installment of interest on the Notes. "Interest Rate" means 5-1/2% per annum. "Issue Date" of any Note means the date on which the Note was originally issued or deemed issued as set forth on the face of the Note. "Lien" means, with respect to any asset, any mortgage, lien, pledge, charge, security interest or encumbrance of any kind in respect of such asset given to secure Indebtedness, whether or not filed, recorded or otherwise perfected under applicable law (including any conditional sale or other title retention agreement, any lease in the nature thereof, any option or other agreement to sell or give a security interest in and any filing of or agreement to give any financing statement under the Uniform Commercial Code (or equivalent statutes) of any jurisdiction with respect to any such lien, pledge, charge or security interest). 5

"Notes" has the meaning ascribed to it in the first paragraph under the caption "Recitals of the Company". "Officer" means the Chairman of the Board, the Vice Chairman, the Chief Executive Officer, the President, any Executive Vice President, any Senior Vice President, any Vice President, the Treasurer or the Secretary or any Assistant Treasurer or Assistant Secretary of the Company. "Officers' Certificate" means a written certificate containing the information specified in Sections 13.04 and 13.05, signed in the name of the Company by any two Officers, and delivered to the Trustee. An Officers' Certificate given pursuant to Section 4.03 shall be signed by an authorized financial or accounting Officer of the Company but need not contain the information specified in Sections 13.04 and 13.05. "Optional Redemption" has the meaning specified in Section 3.02. "Optional Redemption Date" means the date specified for Optional Redemption of the Notes in accordance with the terms of the Notes and this Indenture. "144A Global Note" means a permanent Global Note in the form of the Note attached hereto as Exhibit A-1, and that is deposited with and registered in the name of the Depositary, representing Notes sold in reliance on Rule 144A under the Securities Act. "Opinion of Counsel" means a written opinion containing the information specified in Sections 13.04 and 13.05, from legal counsel who is acceptable to the Trustee and such acceptance shall not be unreasonably withheld. The counsel may be an employee of, or counsel to, the Company or the Trustee. "Permitted Holders" shall mean (i) each of Leonard S. Schleifer, M.D., Ph.D. and P. Roy Vagelos, M.D., and their respective spouses, immediate family members, estates, lineal descendants, executors or administrators, or (ii) any trust, corporation or other entity, the beneficiaries, stockholders or other persons beneficially holding an 80% or more controlling interest of which consist of any persons or entities referred to in clause (i). "Permitted Payments" shall mean payments on the Notes derived from the Pledged Securities which are pledged for the benefit of the Holders of the Notes in accordance with the terms and provisions of the Pledge Agreement. "Permitted Junior Securities" shall mean any payment or distribution in the form of equity securities or subordinated securities of the Company or any successor obligor that, in the case of any such subordinated securities, are subordinated in right of payment to all Senior Indebtedness that may at the time be outstanding to at least the same extent as the Notes are so subordinated. "person" or "Person" means any individual, corporation, limited liability company, partnership, joint venture, association, joint-stock company, trust, unincorporated organization, or government or any agency or political subdivision thereof. 6

"Pledge Account" means an account established by the Trustee pursuant to the terms of the Pledge Agreement for the deposit of the Pledged Securities purchased by the Company with a portion of the proceeds from the sale of the Notes. "Pledge Agreement" means the Pledge Agreement, dated as of the date hereof, made by the Company in favor of the Trustee, governing the disbursement of funds from the Pledge Account, as such agreement may be amended, restated, supplemented or otherwise modified from time to time. "Pledged Securities" means the Government Securities to be purchased by the Company and held in the Pledge Account in accordance with the Pledge Agreement. "principal" of a Note means the principal amount due on the Stated Maturity as set forth on the face of the Note. "Provisional Redemption" has the meaning specified in Section 3.01. "Provisional Redemption Date" means the date specified for Provisional Redemption of the Notes in accordance with the terms of the Notes and this Indenture. "Redeemable Capital Stock" means any class of the Company's Capital Stock that, either by its terms, by the terms of any securities into which it is convertible or exchangeable or by contract or otherwise, is, or upon the happening of an event or passage of time would be, required to be redeemed (whether by sinking fund or otherwise) prior to the date that is 91 days after the final scheduled maturity of the Notes or is redeemable at the option of the Holder thereof at any time prior to such date, or is convertible into or exchangeable for debt securities at any time prior to such date (unless it is convertible or exchangeable solely at the Company's option). "Redemption Date" or "redemption date" means the date specified for redemption of the Notes in accordance with the terms of the Notes and this Indenture. "Redemption Price" or "redemption price" when used with respect to any security to be redeemed, means the price at which it is redeemed pursuant to this Indenture. "Registration Default" has the meaning given to such term in the Registration Rights Agreement. "Registration Rights Agreement" shall mean the registration rights agreement dated the date hereof between the Company, Merrill Lynch, Pierce, Fenner & Smith Incorporated and Robertson Stephens, Inc. "Regular Record Date" means, with respect to the interest payable on any Interest Payment Date, the close of business on April 2 or October 2 (whether or not a Business Day), as the case may be, next preceding such Interest Payment Date. "Responsible Officer" means, when used with respect to the Trustee, any officer within the corporate trust department of the Trustee, including any vice president, assistant vice 7

president, assistant secretary, assistant treasurer, trust officer or any other officer of the Trustee who customarily performs functions similar to those performed by the Persons who at the time shall be such officers, respectively, or to whom any corporate trust matter is referred because of such person's knowledge of and familiarity with the particular subject. "Restricted Note" means a Note required to bear the restrictive legend set forth in the form of Note set forth in Exhibits A-1 and A-2 of this Indenture. "Rule 144A" means Rule 144A under the Securities Act (or any successor provision), as it may be amended from time to time. "SEC" means the Securities and Exchange Commission. "Securities Act" means the United States Securities Act of 1933 (or any successor statute), as amended from time to time. "Senior Indebtedness" means: (a) all obligations of the Company, now or hereafter existing, under or in respect of the documents and instruments executed in connection therewith, whether for principal, premium, if any, interest (including interest accruing after the filing of, or which would have accrued but for the filing of, a petition by or against the Company under bankruptcy law, whether or not such interest is allowed as a claim after such filing in any proceeding under such law) and other amounts due in connection therewith (including, without limitation, any fees, premiums, expenses, reimbursement obligations with respect to letters of credit and indemnities), whether outstanding on the date of this Indenture or thereafter created, incurred or assumed; and (b) the principal of, premium, if any, and interest on all other Indebtedness of the Company (other than the Notes), whether outstanding on the date of this Indenture or thereafter created, incurred or assumed, unless, in the case of any particular Indebtedness, the instrument creating or evidencing the same or pursuant to which the same is outstanding expressly provides that such Indebtedness shall not be senior in right of payment to the Notes. Notwithstanding the foregoing, "Senior Indebtedness" shall not include: (c) Indebtedness evidenced by the Notes; (d) Indebtedness of the Company that is expressly subordinated in right of payment to Senior Indebtedness; (e) Indebtedness of the Company that by operation of law is subordinate to any general unsecured obligations of the Company; (f) any liability for federal, state or local taxes or other taxes, owed or owing by the Company; 8

(g) accounts payable or other liabilities owed or owing by the Company to trade creditors (including guarantees thereof or instruments evidencing such liabilities); (h) amounts owed by the Company for compensation to employees or for services rendered to the Company; (i) Indebtedness of the Company to any Subsidiary or any other Affiliate of the Company or any of such affiliate's subsidiaries; (j) Capital Stock of the Company; (k) Indebtedness evidenced by any guarantee of any Indebtedness ranking equal or junior in right of payment to the Notes; and (l) Indebtedness which, when incurred and without respect to any election under Section 1111(b) of Title 11 of the United States Code, is without recourse to the Company. "Significant Subsidiary" means a Subsidiary of the Company, including its Subsidiaries, which meets any of the following conditions: (m) the Company's and its other Subsidiaries' investments in and advances to the Subsidiary exceed 10 percent of the total assets of the Company and its Subsidiaries consolidated as of the end of any two of the three most recently completed fiscal years; or (n) the Company's and its other Subsidiaries' proportionate share of the total assets of the Subsidiary exceeds 10 percent of the total assets of the Company and its Subsidiaries consolidated as of the end of any two of the three most recently completed fiscal years; or (o) the Company's and its other Subsidiaries' equity in the income from continuing operations before income taxes, extraordinary items and cumulative effect of a change in accounting principles of the Subsidiary exceeds 10 percent of such income of the Company and its Subsidiaries consolidated as of the end of any two of the three most recently completed fiscal years. "Stated Maturity" when used with respect to any Note or any installment of interest thereon, means the date specified in such Note as the fixed date on which the principal of such Note or such installment of interest is due and payable. "Subsidiary" means (i) a corporation, a majority of whose Capital Stock with voting power, under ordinary circumstances, to elect directors is, at the date of determination, directly or indirectly owned by the Company, by one or more Subsidiaries of the Company or by the Company and one or more Subsidiaries of the Company, (ii) a partnership in which the Company or a Subsidiary of the Company holds a majority interest in the equity capital or profits of such partnership, or (iii) any other person (other than a corporation) in which the Company, a Subsidiary of the Company or the Company and one or more Subsidiaries of the Company, directly or indirectly, at the date of determination, has (x) at least a majority ownership interest 9

or (y) the power to elect or direct the election of a majority of the directors or other governing body of such person. "TIA" means the Trust Indenture Act of 1939 as in effect on the date of this Indenture, provided, however, that in the event the TIA is amended after such date, TIA means, to the extent required by any such amendment, the TIA as so amended. "Trading Day" means a day during which trading in Notes generally occurs on the New York Stock Exchange or, if the Common Stock is not listed on the New York Stock Exchange, on the principal other national or regional securities exchange on which the Common Stock is then listed or, if the Common Stock is not listed on a national or regional securities exchange, on the National Association of Notes Dealers Automated Quotation System or, if the Common Stock is not quoted on the National Association of Securities Dealers Automated Quotation System, on the principal other market on which the Common Stock is then traded. "Trustee" means the party named as the "Trustee" in the first paragraph of this Indenture until a successor replaces it pursuant to the applicable provisions of this Indenture and, thereafter, shall mean such successor. The foregoing sentence shall likewise apply to any subsequent such successor or successors. "United States" means the United States of America (including the States and the District of Columbia), its territories, its possessions and other areas subject to its jurisdiction (its "possessions" including Puerto Rico, the U.S. Virgin Islands, Guam, American Samoa, Wake Island and the Northern Mariana Islands). "U.S. Government Obligations" means securities that are (i) direct obligations of the United States of America for the payment of which its full faith and credit is pledged or (ii) obligations of a Person controlled or supervised by and acting as an agency or instrumentality of the United States of America the payment of which is unconditionally guaranteed as a full faith and credit obligation by the United States of America, which, in either case, are not callable or redeemable at the option of the issuer thereof at any time prior to the Stated Maturity of the Notes, and shall also include depository receipts issued by a bank or trust company as custodian with respect to any such U.S. Government Obligation or a specific payment of interest on or principal of any such U.S. Government Obligation held by such custodian for the account of the holder of a depository receipt; provided that (except as required by law) such custodian is not authorized to make any deduction from the amount payable to the holder of such depository receipt from any amount received by the custodian in respect of the U.S. Government Obligation or the specific payment of interest on or principal of the U.S. Government Obligation evidenced by such depository receipt. 10

SECTION 1.02 Other Definitions. Defined in Term Section - ---- ------- "Act"................................................. 1.05(a) "Agent Members"....................................... 2.12(f) "Bankruptcy Law"...................................... 6.01 "Change of Control"................................... 3.08(a) "Change of Control Repurchase Date"................... 3.08(a) "Change of Control Repurchase Notice"................. 3.08(d) "Change of Control Repurchase Price".................. 3.08(a) "Conversion Price".................................... 10.01 "Current Market Price"................................ 10.04(g) "Custodian"........................................... 6.01 "Depositary".......................................... 2.01(a) "DTC"................................................. 2.01(a) "Event of Default".................................... 6.01 "Exchange Act"........................................ 3.08(a) "excluded securities"................................. 10.04(d) "Expiration Time"..................................... 10.04(f) "fair market value"................................... 10.04(g) "Institutional Accredited Investors".................. 2.01(b) "Legal Holiday"....................................... 12.08 "Legend".............................................. 2.06(f) "Non-Electing Share".................................. 10.11 "Non-Payment Default"................................. 11.03(b) "Notice of Default"................................... 6.01 "Paying Agent"........................................ 2.03 "Payment Blockage Period"............................. 11.03(b) "Payment Default"..................................... 11.03(a) "Purchased Shares".................................... 10.04(f) "Permitted Junior Securities" ........................ 11.02 "QIB"................................................. 2.01(a) "Record Date"......................................... 10.04(g) "Reference Period".................................... 10.04(d) "Registrar"........................................... 2.03 "Rule 144A Information"............................... 4.06 "Trigger Event"....................................... 10.04(d) SECTION 1.03 Incorporation by Reference of Trust Indenture Act. Whenever this Indenture refers to a provision of the TIA, the provision is incorporated by reference in and made a part of this Indenture. The following TIA terms used in this Indenture have the following meanings: "Commission" means the SEC. "indenture Notes" means the Notes. "indenture Note holder" means a Noteholder. "indenture to be qualified" means this Indenture. "indenture trustee" or "institutional trustee" means the Trustee. 11

"obligor" on the indenture Notes means the Company. All other TIA terms used in this Indenture that are defined by the TIA, defined by TIA reference to another statute or defined by SEC rule have the meanings assigned to them by such definitions. SECTION 1.04 Rules of Construction. Unless the context otherwise requires: (a) a term has the meaning assigned to it; (b) an accounting term not otherwise defined has the meaning assigned to it in accordance with generally accepted accounting principles as in effect from time to time; (c) "or" is not exclusive; (d) "including" means including, without limitation; and (e) words in the singular include the plural, and words in the plural include the singular. SECTION 1.05 Acts of Holders. (a) Any request, demand, authorization, direction, notice, consent, waiver or other action provided by this Indenture to be given or taken by Holders may be embodied in and evidenced by one or more instruments of substantially similar tenor signed by such Holders in person or by their agent duly appointed in writing; and, except as herein otherwise expressly provided, such action shall become effective when such instrument or instruments are delivered to the Trustee and, where it is hereby expressly required, to the Company. Such instrument or instruments (and the action embodied therein and evidenced thereby) are herein sometimes referred to as the "Act" of Holders signing such instrument or instruments. Proof of execution of any such instrument or of a writing appointing any such agent shall be sufficient for any purpose of this Indenture and conclusive in favor of the Trustee and the Company, if made in the manner provided in this Section. (b) The fact and date of the execution by any Person of any such instrument or writing may be proved by the affidavit of a witness of such execution or by a certificate of a notary public or other officer authorized by law to take acknowledgments of deeds, certifying that the individual signing such instrument or writing acknowledged to such officer the execution thereof. Where such execution is by a signer acting in a capacity other than such signer's individual capacity, such certificate or affidavit shall also constitute sufficient proof of such signer's authority. The fact and date of the execution of any such instrument or writing, or the authority of the Person executing the same, may also be proved in any other manner which the Trustee deems sufficient. The ownership of Notes shall be proved by the register for the Notes or by a certificate of the Registrar. Any request, demand, authorization, direction, notice, consent, waiver or other Act of the Holder of any Note shall bind every future Holder of the same Note and the holder of 12

every Note issued upon the registration of transfer thereof or in exchange therefor or in lieu thereof in respect of anything done, omitted or suffered to be done by the Trustee or the Company in reliance thereon, whether or not notation of such action is made upon such Note. If the Company shall solicit from the Holders any request, demand, authorization, direction, notice, consent, waiver or other Act, the Company may, at its option, by or pursuant to a resolution of the Board of Directors, fix in advance a record date for the determination of Holders entitled to give such request, demand, authorization, direction, notice, consent, waiver or other Act, but the Company shall have no obligation to do so. If such a record date is fixed, such request, demand, authorization, direction, notice, consent, waiver or other Act may be given before or after such record date, but only the Holders of record at the close of business on such record date shall be deemed to be Holders for purposes of determining whether Holders of the requisite proportion of outstanding Notes have authorized or agreed or consented to such request, demand, authorization, direction, notice, consent, waiver or other Act, and for that purpose the outstanding Notes shall be computed as of such record date; provided that no such authorization, agreement or consent by the Holders on such record date shall be deemed effective unless it shall become effective pursuant to the provisions of this Indenture not later than six months after the record date. ARTICLE 2 THE NOTES SECTION 2.01 Form and Dating. The Notes and the Trustee's certificate of authentication to be borne by such Notes shall be substantially in the form annexed hereto as Exhibits A-1 and A-2, which are incorporated in and made a part of this Indenture. The terms and provisions contained in the form of Note shall constitute, and are hereby expressly made, a part of this Indenture and to the extent applicable, the Company and the Trustee, by their execution and delivery of this Indenture, expressly agree to such terms and provisions and to be bound thereby. Any of the Notes may have such letters, numbers or other marks of identification and such notations, legends and endorsements as the officers executing the same may approve (execution thereof to be conclusive evidence of such approval) and as are not inconsistent with the provisions of this Indenture, or as may be required to comply with any law or with any rule or regulation made pursuant thereto or with any rule or regulation of any securities exchange or automated quotation system on which the notes may be listed or designated for issuance, or to conform to usage. (a) 144A Global Notes. Notes offered and sold within the United States to qualified institutional investors as defined in Rule 144A ("QIBs") in reliance on Rule 144A shall be issued, initially in the form of one or more 144A Global Notes, which shall be deposited with the Trustee at its Corporate Trust Office, as custodian for the Depositary and registered in the name of The Depository Trust Company ("DTC") or the nominee thereof (such depositary, or any successor thereto, and any such nominee being hereinafter referred to as the "Depositary"), duly executed by the Company and authenticated by the Trustee as hereinafter provided. The aggregate principal amount of the 144A Global Notes may from time to time be increased or 13

decreased by adjustments made on the records of the Trustee and the Depositary as hereinafter provided. (b) Certificated Notes. Notes not issued as interests in the Global Notes will be issued in certificated form substantially in the form of Exhibit A-2 attached hereto. Except as provided in this Section 2.01, 2.06 or 2.12, owners of beneficial interests in Global Notes will not be entitled to receive physical delivery of Certificated Notes. Notes offered and sold within the United States to institutional accredited investors as defined in Rule 501(a)(1), (2), (3) and (7) under the Securities Act ("Institutional Accredited Investors") shall be issued, initially in the form of a Certificated Note, duly executed by the Company and authenticated by the Trustee as hereinafter provided. (c) Global Notes in General. Each Global Note shall represent such of the outstanding Notes as shall be specified therein and each shall provide that it shall represent the aggregate amount of outstanding Notes from time to time endorsed thereon and that the aggregate amount of outstanding Notes represented thereby may from time to time be reduced or increased, as appropriate, to reflect exchanges, redemptions and conversions. Any adjustment of the aggregate principal amount of a Global Note to reflect the amount of any increase or decrease in the amount of outstanding Notes represented thereby shall be made by the Trustee in accordance with instructions given by the Holder thereof as required by Section 2.12 hereof and shall be made on the records of the Trustee and the Depositary. (d) Book-Entry Provisions. This Section 2.01(d) shall apply only to Global Notes deposited with or on behalf of the Depositary. The Company shall execute and the Trustee shall, in accordance with this Section 2.01(d), authenticate and deliver initially one or more Global Notes that (a) shall be registered in the name of the Depositary, (b) shall be delivered by the Trustee to the Depositary or pursuant to the Depositary's instructions and (c) shall bear legends substantially to the following effect: "UNLESS THIS CERTIFICATE IS PRESENTED BY AN AUTHORIZED REPRESENTATIVE OF THE DEPOSITORY TRUST COMPANY TO THE ISSUER OR ITS AGENT FOR REGISTRATION OF TRANSFER, EXCHANGE OR PAYMENT, AND ANY CERTIFICATE ISSUED IS REGISTERED IN THE NAME OF CEDE & CO. OR IN SUCH OTHER NAME AS IS REQUESTED BY AN AUTHORIZED REPRESENTATIVE OF THE DEPOSITORY TRUST COMPANY (AND ANY PAYMENT HEREON IS MADE TO CEDE & CO. OR TO SUCH OTHER ENTITY AS IS REQUESTED BY AN AUTHORIZED REPRESENTATIVE OF THE DEPOSITORY TRUST COMPANY), ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO ANY PERSON IS WRONGFUL SINCE THE REGISTERED OWNER HEREOF, CEDE & CO., HAS AN INTEREST HEREIN. TRANSFERS OF THIS GLOBAL NOTE SHALL BE LIMITED TO TRANSFERS IN WHOLE, BUT NOT IN PART, TO NOMINEES OF THE 14

DEPOSITORY TRUST COMPANY OR TO A SUCCESSOR THEREOF OR SUCH SUCCESSOR'S NOMINEE AND TRANSFERS OF PORTIONS OF THIS GLOBAL NOTE SHALL BE LIMITED TO TRANSFERS MADE IN ACCORDANCE WITH THE RESTRICTIONS SET FORTH IN ARTICLE TWO OF THE INDENTURE REFERRED TO ON THE REVERSE HEREOF." SECTION 2.02 Execution and Authentication. The Notes shall be executed on behalf of the Company by any Officer, under its corporate seal reproduced thereon. The signature of the Officer on the Notes may be manual or facsimile. Notes bearing the manual or facsimile signatures of individuals who were at the time of the execution of the Notes the proper Officers of the Company shall bind the Company, notwithstanding that such individuals or any of them have ceased to hold such offices prior to the authentication and delivery of such Notes or did not hold such offices at the date of authentication of such Notes. No Note shall be entitled to any benefit under this Indenture or be valid or obligatory for any purpose unless there appears on such Note a certificate of authentication substantially in the form provided for herein duly executed by the Trustee by manual signature of an authorized officer, and such certificate upon any Note shall be conclusive evidence, and the only evidence, that such Note has been duly authenticated and delivered hereunder. The Trustee shall authenticate and deliver Notes for original issue in an aggregate principal amount of up to $250,000,000 upon a Company Order without any further action by the Company. The aggregate principal amount of Notes outstanding at any time may not exceed the amount set forth in the foregoing sentence, except as provided in Section 2.07. The Notes shall be issued only in registered form without coupons and only in denominations of $1,000 in principal amount and any integral multiple thereof. SECTION 2.03 Registrar, Paying Agent and Conversion Agent. The Company shall maintain an office or agency where Notes may be presented for registration of transfer or for exchange ("Registrar"), an office or agency where Notes may be presented for purchase or payment ("Paying Agent") and an office or agency where Notes may be presented for conversion ("Conversion Agent"). The Registrar shall keep a register of the Notes and of their transfer and exchange. The Company may have one or more co-registrars, one or more additional paying agents and one or more additional conversion agents. The term Paying Agent includes any additional paying agent, including any named pursuant to Section 4.05. The term Conversion Agent includes any additional conversion agent, including any named pursuant to Section 4.05. The Company shall enter into an appropriate agency agreement with any Registrar, Paying Agent, Conversion Agent or co-registrar (other than the Trustee). The agreement shall implement the provisions of this Indenture that relate to such agent. The Company shall notify the Trustee of the name and address of any such agent. If the Company fails to maintain a Registrar, Paying Agent or Conversion Agent, the Trustee shall act as such and shall be entitled to appropriate compensation therefor pursuant to Section 7.06. The 15

Company or any Subsidiary or an Affiliate of either of them may act as Paying Agent, Registrar, Conversion Agent or co-registrar. The Company initially appoints the Trustee as Registrar, Conversion Agent and Paying Agent in connection with the Notes. SECTION 2.04 Paying Agent to Hold Money and Notes in Trust. Except as otherwise provided herein, on or prior to each due date of payments in respect of any Note, the Company shall deposit with the Paying Agent a sum of money (in immediately available funds if deposited on the due date) or Common Stock (pursuant to Section 3.10 hereof) sufficient to make such payments when so becoming due. The Company shall require each Paying Agent (other than the Trustee) to agree in writing that the Paying Agent shall hold in trust for the benefit of Noteholders or the Trustee all money and Common Stock held by the Paying Agent for the making of payments in respect of the Notes and shall notify the Trustee of any default by the Company in making any such payment. At any time during the continuance of any such default, the Paying Agent shall, upon the written request of the Trustee, forthwith pay to the Trustee all money and Common Stock so held in trust. If the Company, a Subsidiary or an Affiliate of either of them acts as Paying Agent, it shall segregate the money and Common Stock held by it as Paying Agent and hold it as a separate trust fund. The Company at any time may require a Paying Agent to pay all money and Common Stock held by it to the Trustee and to account for any funds and Common Stock disbursed by it. Upon doing so, the Paying Agent shall have no further liability for the money or Common Stock. SECTION 2.05 Noteholder Lists. The Trustee shall preserve in as current a form as is reasonably practicable the most recent list available to it of the names and addresses of Noteholders. If the Trustee is not the Registrar, the Company shall cause to be furnished to the Trustee at least semiannually on April 2 and October 2 a listing of Noteholders dated within 15 days of the date on which the list is furnished and at such other times as the Trustee may request in writing a list in such form and as of such date as the Trustee may reasonably require of the names and addresses of Noteholders. SECTION 2.06 Transfer and Exchange. Subject to Section 2.12 hereof, (a) upon surrender for registration of transfer of any Note, together with a written instrument of transfer satisfactory to the Registrar duly executed by the Noteholder or such Noteholder's attorney duly authorized in writing, at the office or agency of the company designated as Registrar or co-registrar pursuant to Section 2.03, the Company shall execute, and the Trustee shall authenticate and deliver, in the name of the designated transferee or transferees, one or more new Notes of any authorized denomination or denominations, of a like aggregate principal amount. The Company shall not charge a service charge for any registration of transfer or exchange, but the Company may require payment of a sum sufficient to pay all taxes, assessments or other governmental charges that may be imposed in connection with the transfer or exchange of the Notes from the Noteholder requesting such transfer or exchange. At the option of the Holder, Notes may be exchanged for other Notes of any authorized denomination or denominations, of a like aggregate principal amount, upon surrender of the Notes to be exchanged, together with a written instrument of transfer satisfactory to the Registrar duly executed by the Noteholder or such Noteholder's attorney duly authorized in 16

writing, at such office or agency. Whenever any Notes are so surrendered for exchange, the Company shall execute, and the Trustee shall authenticate and deliver, the Notes which the Holder making the exchange is entitled to receive. The Company shall not be required to make, and the Registrar need not register, transfers or exchanges of Notes selected for redemption (except, in the case of Notes to be redeemed in part, the portion thereof not to be redeemed) or any Notes in respect of which a Change of Control Repurchase Notice (as defined in Section 3.08(d)) has been given and not withdrawn by the Holder thereof in accordance with the terms of this Indenture (except, in the case of Notes to be purchased in part, the portion thereof not to be purchased) or any Notes for a period of 15 days before the mailing of a notice of redemption of Notes to be redeemed. (b) Notwithstanding any provision to the contrary herein, so long as a Global Note remains outstanding and is held by or on behalf of the Depositary, transfers of a Global Note, in whole or in part, shall be made only in accordance with Section 2.12 and this Section 2.06(b). Transfers of a Global Note shall be limited to transfers of such Global Note in whole, or in part, to nominees of the Depositary or to a successor of the Depositary or such successor's nominee. (c) Successive registrations and registrations of transfers and exchanges as aforesaid may be made from time to time as desired, and each such registration shall be noted on the register for the Notes. (d) Any Registrar appointed pursuant to Section 2.03 hereof shall provide to the Trustee such information as the Trustee may reasonably require in connection with the delivery by such Registrar of Notes upon transfer or exchange of Notes. (e) No Registrar shall be required to make registrations of transfer or exchange of Notes during any periods designated in the text of the Notes or in this Indenture as periods during which such registration of transfers and exchanges need not be made. (f) If Notes are issued upon the transfer, exchange or replacement of Notes subject to restrictions on transfer and bearing the legends set forth on the form of Note attached hereto as Exhibits A-1 and A-2 setting forth such restrictions (collectively, the "Legend"), or if a request is made to remove the Legend on a Note, the Notes so issued shall bear the Legend, or the Legend shall not be removed, as the case may be, unless there is delivered to the Company and the Registrar such satisfactory evidence, which shall include an Opinion of Counsel, as may be reasonably required by the Company and the Registrar, that neither the Legend nor the restrictions on transfer set forth therein are required to ensure that transfers thereof comply with the provisions of Rule 144A or Rule 144 under the Securities Act or that such Notes are not "restricted" within the meaning of Rule 144 under the Securities Act. Upon (i) provision of such satisfactory evidence, or (ii) notification by the Company to the Trustee and Registrar of the sale of such Note pursuant to a registration statement that is effective at the time of such sale, the Trustee, at the written direction of the Company, shall authenticate and deliver a Note that does not bear the Legend. If the Legend is removed from the face of a Note and the Note is subsequently held by an Affiliate of the Company, the Legend shall be reinstated. 17

SECTION 2.07 Replacement Notes. If (a) any mutilated Note is surrendered to the Trustee, or (b) the Company and the Trustee receive evidence to their satisfaction of the destruction, loss or theft of any Note, and there is delivered to the Company and the Trustee such Note or indemnity as may be required by them to save each of them harmless, then, in the absence of notice to the Company or the Trustee that such Note has been acquired by a bona fide purchaser, the Company shall execute and upon its written request the Trustee shall authenticate and deliver, in exchange for any such mutilated Note or in lieu of any such destroyed, lost or stolen Note, a new Note of like tenor and principal amount, bearing a number not contemporaneously outstanding. In case any such mutilated, destroyed, lost or stolen Note has become or is about to become due and payable, or is about to be purchased by the Company pursuant to Article 3 hereof, the Company in its discretion may, instead of issuing a new Note, pay or purchase such Note, as the case may be. Upon the issuance of any new Notes under this Section 2.07, the Company may require the payment of a sum sufficient to cover any tax or other governmental charge that may be imposed in relation thereto and any other expenses (including the fees and expenses of the Trustee) connected therewith. Every new Note issued pursuant to this Section 2.07 in lieu of any mutilated, destroyed, lost or stolen Note shall constitute an original additional contractual obligation of the Company, whether or not the destroyed, lost or stolen Note shall be at any time enforceable by anyone, and shall be entitled to all benefits of this Indenture equally and proportionately with any and all other Notes duly issued hereunder. The provisions of this Section 2.07 are exclusive and shall preclude (to the extent lawful) all other rights and remedies with respect to the replacement or payment of mutilated, destroyed, lost or stolen Notes. SECTION 2.08 Outstanding Notes; Determinations of Holders' Action. Notes outstanding at any time are all the Notes authenticated by the Trustee except for those cancelled by it or delivered to it for cancellation, those paid pursuant to Section 2.07 and those described in this Section 2.08 as not outstanding. A Note does not cease to be outstanding because the Company or an Affiliate thereof holds the Note; provided, however, that in determining whether the Holders of the requisite principal amount of the outstanding Notes have given or concurred in any request, demand, authorization, direction, notice, consent or waiver hereunder, Notes owned by the Company or any other obligor upon the Notes or any Affiliate of the Company or such other obligor shall be disregarded and deemed not to be outstanding, except that, in determining whether the Trustee shall be protected in relying upon any such request, demand, authorization, direction, notice, consent or waiver, only Notes which a Responsible Officer of the Trustee knows to be so owned shall be so disregarded. Subject to the foregoing, only Notes outstanding at the time of such determination shall be considered in any such determination (including, without limitation, determinations pursuant to Articles 6 and 9). 18

If a Note is replaced pursuant to Section 2.07, it ceases to be outstanding unless the Trustee receives proof satisfactory to it that the replaced Note is held by a bona fide purchaser. If the Paying Agent holds, in accordance with this Indenture, on a Redemption Date, or on the Business Day following the Change of Control Repurchase Date, or on Stated Maturity, money or securities, if permitted hereunder, sufficient to pay Notes payable on that date, then immediately after such Redemption Date, Change of Control Repurchase Date or Stated Maturity, as the case may be, such Notes shall cease to be outstanding and interest on such Notes shall cease to accrue; provided that, if such Notes are to be redeemed, notice of such redemption has been duly given pursuant to this Indenture or provision therefor satisfactory to the Trustee has been made. If a Note is converted in accordance with Article 10, then from and after the time of conversion on the conversion date, such Note shall cease to be outstanding and interest shall cease to accrue on such Note. SECTION 2.09 Temporary Notes. Pending the preparation of definitive Notes, the Company may execute, and upon Company Order the Trustee shall authenticate and deliver, temporary Notes which are printed, lithographed, typewritten, mimeographed or otherwise produced, in any authorized denomination, substantially of the tenor of the definitive Notes in lieu of which they are issued and with such appropriate insertions, omissions, substitutions and other variations as the officers executing such Notes may determine, as conclusively evidenced by their execution of such Notes. If temporary Notes are issued, the Company will cause definitive Notes to be prepared without unreasonable delay. After the preparation of definitive Notes, the temporary Notes shall be exchangeable for definitive Notes upon surrender of the temporary Notes at the office or agency of the Company designated for such purpose pursuant to Section 2.03, without charge to the Holder. Upon surrender for cancellation of any one or more temporary Notes the Company shall execute and the Trustee shall authenticate and deliver in exchange therefor a like principal amount of definitive Notes of authorized denominations. Until so exchanged the temporary Notes shall in all respects be entitled to the same benefits under this Indenture as definitive Notes. SECTION 2.10 Cancellation. All Notes surrendered for payment, purchase by the Company pursuant to Article 3, conversion, redemption or registration of transfer or exchange shall, if surrendered to any person other than the Trustee, be delivered to the Trustee and shall be promptly cancelled by it. The Company may at any time deliver to the Trustee for cancellation any Notes previously authenticated and delivered hereunder which the Company may have acquired in any manner whatsoever, and all Notes so delivered shall be promptly cancelled by the Trustee. The Company may not issue new Notes to replace Notes it has paid or delivered to the Trustee for cancellation or that any Holder has converted pursuant to Article 10. No Notes shall be authenticated in lieu of or in exchange for any Notes cancelled as provided in this Section 2.10, except as expressly permitted by this Indenture. All cancelled Notes held by the Trustee shall be destroyed by the Trustee and the Trustee shall deliver a certificate of destruction to the Company. 19

SECTION 2.11 Persons Deemed Owners. Prior to due presentment of a Note for registration of transfer, the Company, the Trustee and any agent of the Company or the Trustee may treat the Person in whose name such Note is registered as the owner of such Note for the purpose of receiving payment of principal of the Note or the payment of any Redemption Price or Change of Control Repurchase Price in respect thereof, and interest thereon, for the purpose of conversion and for all other purposes whatsoever, whether or not such Note be overdue, and neither the Company, the Trustee nor any agent of the Company or the Trustee shall be affected by notice to the contrary. SECTION 2.12 Global Notes. (a) Notwithstanding any other provisions of this Indenture or the Notes, (A) transfers of a Global Note, in whole or in part, shall be made only in accordance with Section 2.06 and Section 2.12(a)(i), (B) transfer of a beneficial interest in a Global Note for a Certificated Note shall comply with Section 2.06 and Section 2.12(a)(ii) below, and (C) transfers of a Certificated Note shall comply with Section 2.06 and Section 2.12(a)(iii) and (iv) below. (i) Transfer of Global Note. A Global Note may not be transferred, in whole or in part, to any Person other than the Depositary or a nominee or any successor thereof, and no such transfer to any such other Person may be registered; provided that this clause (i) shall not prohibit any transfer of a Note that is issued in exchange for a Global Note but is not itself a Global Note. No transfer of a Note to any Person shall be effective under this Indenture or the Notes unless and until such Note has been registered in the name of such Person. Nothing in this Section 2.12(a)(i) shall prohibit or render ineffective any transfer of a beneficial interest in a Global Note effected in accordance with the other provisions of this Section 2.12(a). (ii) Restrictions on Transfer of a Beneficial Interest in a Global Note for a Certificated Note. A beneficial interest in a Global Note may not be exchanged for a Certificated Note except upon satisfaction of the requirements set forth below. Upon receipt by the Trustee of a transfer of a beneficial interest in a Global Note in accordance with Applicable Procedures for a Certificated Note in the form satisfactory to the Trustee, together with: (a) so long as the Notes are Restricted Notes, certification, in the form set forth in Exhibit B-1, and, if requested by the Company or the Registrar, certification in the form set forth in Exhibit B-2, that such beneficial interest in the Global Note is being transferred to an Institutional Accredited Investor; (b) written instructions to the Trustee to make, or direct the Registrar to make, an adjustment on its books and records with respect to such Global Note to reflect a decrease in the aggregate principal amount of the Notes represented by the Global Note, such instructions to contain information regarding the Depositary account to be credited with such decrease; and (c) if the Company or Registrar so requests, an opinion of counsel or other evidence reasonably satisfactory to them as to the compliance with the restrictions set forth in the Legend, 20

then the Trustee shall cause, or direct the Registrar to cause, in accordance with the standing instructions and procedures existing between the Depositary and the Registrar, the aggregate principal amount of Notes represented by the Global Note to be decreased by the aggregate principal amount of the Certificated Note to be issued, shall issue such Certificated Note and shall debit or cause to be debited to the account of the Person specified in such instructions a beneficial interest in the Global Note equal to the principal amount of the Certificated Note so issued. (iii) Transfer and Exchange of Certificated Notes. When Certificated Notes are presented to the Registrar with a request: (x) to register the transfer of such Certificated Notes; or (y) to exchange such Certificated Notes for an equal principal amount of Certificated Notes of other authorized denominations, the Registrar shall register the transfer or make the exchange as requested if its reasonable requirements for such transaction are met; provided, however, that the Certificated Notes surrendered for transfer or exchange: (a) shall be duly endorsed or accompanied by a written instrument of transfer in form reasonably satisfactory to the Company and the Registrar, duly executed by the Holder thereof or his attorney duly authorized in writing; and (b) so long as such Notes are Restricted Notes, such Notes are being transferred or exchanged pursuant to an effective registration statement under the Securities Act or pursuant to clause (A), (B) or (C) below, and are accompanied by the following additional information and documents, as applicable: (A) if such Certificated Notes are being delivered to the Registrar by a Holder for registration in the name of such Holder, without transfer, a certification from such Holder to that effect; or (B) if such Certificated Notes are being transferred to the Company, a certification to that effect; or (C) if such Certificated Notes are being transferred pursuant to an exemption from registration, (i) a certification to that effect (in the form set forth in Exhibits B-1 and B-2, if applicable) and (ii) if the Company or Registrar so requests, an opinion of counsel or other evidence reasonably satisfactory to them as to the compliance with the restrictions set forth in the Legend. (iv) Restrictions on Transfer of a Certificated Note for a Beneficial Interest in a Global Note. A Certificated Note may not be exchanged for a beneficial interest in a Global Note except upon satisfaction of the requirements set forth below. 21

Upon receipt by the Trustee of a Certificated Note, duly endorsed or accompanied by appropriate instruments of transfer, in form satisfactory to the Trustee, together with: (a) so long as the Notes are Restricted Notes, certification, in the form set forth in Exhibit B-1, that such Certificated Note is being transferred to a Qualified Institutional Buyer in accordance with Rule 144A; and (b) written instructions directing the Trustee to make, or to direct the Registrar to make, an adjustment on its books and records with respect to such Global Note to reflect an increase in the aggregate principal amount of the Notes represented by the Global Note, such instructions to contain information regarding the Depositary account to be credited with such increase, then the Trustee shall cancel such Certificated Note and cause, or direct the Registrar to cause, in accordance with the standing instructions and procedures existing between the Depositary and the Registrar, the aggregate principal amount of Notes represented by the Global Note to be increased by the aggregate principal amount of the Certificated Note to be exchanged, and shall credit or cause to be credited to the account of the Person specified in such instructions a beneficial interest in the Global Note equal to the principal amount of the Certificated Note so cancelled. If no Global Notes are then outstanding, the Company shall issue and the Trustee shall authenticate, upon written order of the Company in the form of an Officers' Certificate, a new Global Note in the appropriate principal amount. (c) Subject to the succeeding paragraph, every Note shall be subject to the restrictions on transfer provided in the Legend including the delivery of an opinion of counsel, if so provided. Whenever any Restricted Note is presented or surrendered for registration of transfer or for exchange for a Note registered in a name other than that of the Holder, such Note must be accompanied by a certificate in substantially the form set forth in Exhibit B-1, dated the date of such surrender and signed by the Holder of such Note, as to compliance with such restrictions on transfer. The Registrar shall not be required to accept for such registration of transfer or exchange any Note not so accompanied by a properly completed certificate. (d) The restrictions imposed by the Legend upon the transferability of any Note shall cease and terminate when such Note has been sold pursuant to an effective registration statement under the Securities Act or transferred in compliance with Rule 144 under the Securities Act (or any successor provision thereto) or, if earlier, upon the expiration of the holding period applicable to sales thereof under Rule 144(k) under the Securities Act (or any successor provision). Any Note as to which such restrictions on transfer shall have expired in accordance with their terms or shall have terminated may, upon a surrender of such Note for exchange to the Registrar in accordance with the provisions of this Section 2.12 (accompanied, in the event that such restrictions on transfer have terminated by reason of a transfer in compliance with Rule 144 or any successor provision, by an opinion of counsel having substantial experience in practice under the Securities Act and otherwise reasonably acceptable to the Company, addressed to the Company and in form acceptable to the Company, to the effect that the transfer of such Note has been made in compliance with Rule 144 or such successor provision), be exchanged for a new Note, of like tenor and aggregate principal amount, which shall not bear the restrictive Legend. The Company shall inform the Trustee of the effective date 22

of any registration statement registering the Notes under the Securities Act. The Trustee shall not be liable for any action taken or omitted to be taken by it in good faith in accordance with the aforementioned opinion of counsel or registration statement. (e) As used in the preceding two paragraphs of this Section 2.12, the term "transfer" encompasses any sale, pledge, transfer, hypothecation or other disposition of any Note. (f) The provisions of clauses (1), (2), (3) and (4) below shall apply only to Global Notes: (1) Notwithstanding any other provisions of this Indenture or the Notes, except as provided in Section 2.12(a)(ii), a Global Note shall not be exchanged in whole or in part for a Note registered in the name of any Person other than the Depositary or one or more nominees thereof, provided that a Global Note may be exchanged for Notes registered in the names of any person designated by the Depositary in the event that (i) the Depositary has notified the Company that it is unwilling or unable to continue as Depositary for such Global Note or such Depositary has ceased to be a "clearing agency" registered under the Exchange Act, and a successor Depositary is not appointed by the Company within 90 days or (ii) an Event of Default has occurred and is continuing with respect to the Notes. Any Global Note exchanged pursuant to clause (i) above shall be so exchanged in whole and not in part, and any Global Note exchanged pursuant to clause (ii) above may be exchanged in whole or from time to time in part as directed by the Depositary. Any Note issued in exchange for a Global Note or any portion thereof shall be a Global Note; provided that any such Note so issued that is registered in the name of a Person other than the Depositary or a nominee thereof shall not be a Global Note. (2) Notes issued in exchange for a Global Note or any portion thereof shall be issued in definitive, fully registered form, without interest coupons, shall have an aggregate principal amount equal to that of such Global Note or portion thereof to be so exchanged, shall be registered in such names and be in such authorized denominations as the Depositary shall designate and shall bear the applicable legends provided for herein. Any Global Note to be exchanged in whole shall be surrendered by the Depositary to the Trustee, as Registrar. With regard to any Global Note to be exchanged in part, either such Global Note shall be so surrendered for exchange or, if the Trustee is acting as custodian for the Depositary or its nominee with respect to such Global Note, the principal amount thereof shall be reduced, by an amount equal to the portion thereof to be so exchanged, by means of an appropriate adjustment made on the records of the Trustee. Upon any such surrender or adjustment, the Trustee shall authenticate and deliver the Note issuable on such exchange to or upon the order of the Depositary or an authorized representative thereof. (3) Subject to the provisions of clause (5) below, the registered Holder may grant proxies and otherwise authorize any Person, including Agent Members (as defined below) and persons that may hold interests through Agent Members, to take any action which a holder is entitled to take under this Indenture or the Notes. 23

(4) In the event of the occurrence of any of the events specified in clause (1) above, the Company will promptly make available to the Trustee a reasonable supply of Certificated Notes in definitive, fully registered form, without interest coupons. (5) Neither any members of, or participants in, the Depositary (collectively, the "Agent Members") nor any other Persons on whose behalf Agent Members may act shall have any rights under this Indenture with respect to any Global Note registered in the name of the Depositary or any nominee thereof, or under any such Global Note, and the Depositary or such nominee, as the case may be, may be treated by the Company, the Trustee and any agent of the Company or the Trustee as the absolute owner and holder of such Global Note for all purposes whatsoever. Notwithstanding the foregoing, nothing herein shall prevent the Company, the Trustee or any agent of the Company or the Trustee from giving effect to any written certification, proxy or other authorization furnished by the Depositary or such nominee, as the case may be, or impair, as between the Depositary, its Agent Members and any other person on whose behalf an Agent Member may act, the operation of customary practices of such Persons governing the exercise of the rights of a holder of any Note. SECTION 2.13 CUSIP Numbers. The Company in issuing the Notes may use "CUSIP" numbers (if then generally in use), and, if so, the Trustee shall use "CUSIP" numbers in notices of redemption as a convenience to Holders; provided that any such notice may state that no representation is made as to the correctness of such numbers either as printed on the Notes or as contained in any notice of a redemption and that reliance may be placed only on the other identification numbers printed on the Notes, and any such redemption shall not be affected by any defect in or omission of such numbers. The Company will promptly notify the Trustee of any change in the CUSIP numbers. SECTION 2.14 Defaulted Interest. If the Company defaults in a payment of interest on the Notes, it shall pay, or shall deposit with the Paying Agent money in immediately available funds sufficient to pay, the defaulted interest, plus (to the extent lawful) any interest payable on the defaulted interest, to the Persons who are Holders on a subsequent special record date. A special record date, as used in this Section 2.14 with respect to the payment of any defaulted interest, shall mean the 15th day next preceding the date fixed by the Company for the payment of defaulted interest, whether or not such day is a Business Day. At least 15 days before the subsequent special record date, the Company shall mail to each Holder and to the Trustee a notice that states the subsequent special record date, the payment date and the amount of defaulted interest to be paid. ARTICLE 3 REDEMPTION AND PURCHASES SECTION 3.01 Provisional Redemption. Any time prior to October 17, 2004, the Company may, at its option, redeem the Notes in whole or in part on any date from time to time, upon notice as set forth in Section 3.05, at a redemption price equal to $1,000 per $1,000 principal amount of the Notes redeemed plus accrued and unpaid interest, if any (such amount, together with the Make-Whole Payment described below, the "Provisional Redemption 24

Price"), to but excluding the date of redemption (the "Provisional Redemption Date") if (i) the Closing Price of the Common Stock has exceeded 150% of the Conversion Price (as defined in Article 10 and as such may be adjusted from time to time) then in effect for at least 20 Trading Days in any consecutive 30-Trading Day period ending on the Trading Day prior to the date of mailing of the provisional notice of redemption pursuant to Section 3.05 (the "Notice Date") and (ii) during the period that the Company is obligated, under the Registration Rights Agreement, to keep a registration statement covering resales of the Notes and the Common Stock issuable upon conversion thereof effective, such registration statement is effective (the "Registration Period") and available for use as of, and including, the Notice Date through and including the Provisional Redemption Date provided that this date is within the Registration Period (such redemption, a "Provisional Redemption"). Upon any such Provisional Redemption, the Company shall make an additional payment (the "Make-Whole Payment") in cash with respect to the Notes called for redemption to Holders on the Notice Date in an amount equal to $165 per $1,000 principal amount of the Notes less the amount of any interest actually paid on such Notes prior to or on the Provisional Redemption Date. The Company shall make the Make-Whole Payment on all Notes called for Provisional Redemption, including those Notes converted into Common Stock between the Notice Date and the Provisional Redemption Date. SECTION 3.02 Optional Redemption. Except as set forth under Section 3.01, the Notes are not redeemable prior to October 17, 2004. On and after October 17, 2004, the Company may, at its option, redeem the Notes in whole at any time or in part from time to time, on any date prior to maturity, upon notice as set forth in Section 3.05, at a redemption price equal to $1,000 per $1,000 principal amount (the "Optional Redemption Price"), plus any interest accrued but not paid prior to the date of redemption (the "Optional Redemption Date"), subject to the right of Holders of record on the immediately preceding Regular Record Date to receive the interest due on the succeeding Interest Payment Date if the Closing Price of the Common Stock has exceeded 140% of the Conversion Price (as defined in Article 10 and as such may be adjusted from time to time) then in effect for at least 20 Trading Days in any consecutive 30-Trading Day period ending on the Trading Day prior to the date of mailing of the notice of optional redemption pursuant to Section 3.05. SECTION 3.03 Notice of Trustee. If the Company elects to redeem Notes pursuant to the redemption provisions of Section 3.01 or Section 3.02 hereof, it shall notify the Trustee at least 30 days prior but not more than 60 days prior to the Redemption Date of such intended Redemption Date, the principal amount of Notes to be redeemed and the CUSIP numbers of the Notes to be redeemed. SECTION 3.04 Selection of Notes to be Redeemed. If fewer than all the Notes are to be redeemed, the Trustee shall select the particular Notes to be redeemed from the Outstanding Notes by a method that complies with the requirements of any exchange on which the Notes are listed, or, if the Notes are not listed on an exchange, on a pro rata basis or by lot or in accordance with any other method of Trustee considers fair and appropriate. Notes and portions thereof that the Trustee selects shall be in principal amounts equal to $1,000 or any whole multiple thereof. 25

If any Note selected for partial redemption is converted in part before termination of the conversion right with respect to the portion of the Note so selected, the converted portion of such Note shall be deemed to be the portion selected for redemption (provided, however, that the Holder of such Note so converted and deemed redeemed shall not be entitled to any additional interest payment as a result of such deemed redemption than such Holder would have otherwise been entitled to receive upon conversion of such Note). Notes which have been converted during a selection of Notes to be redeemed may be treated by the Trustee as Outstanding for the purpose of such selection. The Trustee shall promptly notify the Company and the Registrar in writing of the Notes selected for redemption and, in the case of any Notes selected for partial redemption, the principal amount thereof to be redeemed. For all purposes of this Indenture, unless the context otherwise requires, all provisions relating to the redemption of Notes shall relate, in the case of any Notes redeemed or to be redeemed only in part, to the portion of the principal amount of such Notes which has been or is to be redeemed. SECTION 3.05 Notice of Redemption. Notice of redemption shall be given in the manner provided in Section 13.02 hereof to the Holders of Notes to be redeemed. Such notice shall be given not less than 30 nor more than 60 days prior to the Redemption Date for redemption pursuant to Section 3.01 or Section 3.02. All notices of redemption shall state: (1) the Redemption Date; (2) the Redemption Price and interest accrued and unpaid to the Redemption Date, if any, and, with respect to Notes called for Provisional Redemption, the Make-Whole Payment; (3) if fewer than all the outstanding Notes are to be redeemed, the aggregate principal amount of Notes to be redeemed and the aggregate principal amount of Notes which will be outstanding after such partial redemption; (4) that on the Redemption Date the Redemption Price and interest accrued and unpaid to the Redemption Date, if any, and, with respect to Notes called for Provisional Redemption, the Make-Whole Payment, will become due and payable upon each such Note to be redeemed, and that interest thereon shall cease to accrue on and after such date; (5) the Conversion Price, the date on which the right to convert the principal of the Notes to be redeemed will terminate and the places where such Notes may be surrendered for conversion; (6) the place or places where such Notes are to be surrendered for payment of the Redemption Price and accrued and unpaid interest, if any; and 26

(7) the CUSIP number of the Notes. The notice given shall specify the last date on which exchanges or transfers of Notes may be made pursuant to Section 2.06 hereof, and shall specify the serial numbers of Notes and the portions thereof called for redemption. Notice of redemption of Notes to be redeemed at the election of the Company shall be given by the Company. SECTION 3.06 Effect of Notice of Redemption. Notice of redemption having been given as provided in Section 3.05 hereof, the Notes so to be redeemed shall, on the Redemption Date, become due and payable at the Redemption Price therein specified and from and after such date (unless the Company shall default in the payment of the Redemption Price and accrued and unpaid interest) such Notes shall cease to bear interest. Upon surrender of any such Note for redemption in accordance with such notice, such Note shall be paid by the Company at the Redemption Price plus accrued and unpaid interest, if any; provided, however, that the installments of interest on Notes whose Stated Maturity is prior to or on the Redemption Date shall be payable to the Holders of such Notes, or one or more Predecessor Notes, registered as such on the relevant Record Date according to their terms and the provisions of Section 2.01 hereof and, with respect to a Provisional Redemption, the Holder on the Notice Date of any Note converted into Common Stock between the Notice Date and the Provisional Redemption Date shall have the right to receive the Make-Whole Payment regardless of the conversion of such Note. If any Note called for redemption shall not be so paid upon surrender thereof for redemption, the principal and premium, if any, shall, until paid, bear interest from the Redemption Date at the Interest Rate. SECTION 3.07 Deposit of Redemption Price. Prior to or on any Redemption Date, the Company shall deposit with the Trustee or with a Paying Agent an amount of money sufficient to pay the Redemption Price of all the Notes to be redeemed on that Redemption Date (including, with respect to a Provisional Redemption, Make-Whole Payments due on the Provisional Redemption Date with respect to the Notes), other than any Notes called for redemption on that date which have been converted prior to the date of such deposit (except with respect to a Provisional Redemption as provided in Sections 3.01 and 3.06 hereof), and accrued and unpaid interest, if any, on such Notes. If any Note called for redemption is converted, any money deposited with the Trustee or with a Paying Agent or so segregated and held in trust for the redemption of such Note shall (subject to any right of the Holder of such Note or any Predecessor Note to receive interest as provided in Section 4.01 hereof or Make-Whole Payments as provided in Section 3.01) be paid to the Company on a Company Request or, if then held by the Company, shall be discharged from such trust. SECTION 3.08 Notes Redeemed in Part. Any Note which is to be redeemed only in part shall be surrendered at an office or agency of the Company designated for that purpose pursuant to Section 4.05 hereof (with, if the Company or the Trustee so requires, 27

due endorsement by, or a written instrument of transfer in form satisfactory to the Company and the Trustee duly executed by, the Holder thereof or the Holder's attorney duly authorized in writing), and the Company shall execute, and the Trustee shall authenticate and deliver to the Holder of such Note without service charge, a new Note or Notes of any authorized denomination as requested by such Holder in aggregate principal amount equal to and in exchange for the unredeemed portion of the principal of the Note so surrendered. SECTION 3.09 Conversion Arrangement on Call for Redemption. In connection with any redemption of Notes, the Company may arrange for the purchase and conversion of any Notes called for redemption by an agreement with one or more investment banks or other purchasers to purchase such Notes by paying to the Trustee in trust for the Noteholders, on or prior to 10:00 a.m. New York City time on the Redemption Date, an amount that, together with any amounts deposited with the Trustee by the Company for the redemption of such Notes, is not less than the Redemption Price of such Notes. Notwithstanding anything to the contrary contained in this Article 3, the obligation of the Company to pay the Redemption Price of such Notes shall be deemed to be satisfied and discharged to the extent such amount is so paid by such purchasers. If such an agreement is entered into, any Notes not duly surrendered for conversion by the Holders thereof may, at the option of the Company, be deemed, to the fullest extent permitted by law, acquired by such purchasers from such Holders and (notwithstanding anything to the contrary contained in Article 10) surrendered by such purchasers for conversion, all as of immediately prior to the close of business on the Redemption Date, subject to payment of the above amount as aforesaid. The Trustee shall hold and pay to the Holders whose Notes are selected for redemption any such amount paid to it for purchase and conversion in the same manner as it would moneys deposited with it by the Company for the redemption of Notes. Without the Trustee's prior written consent, no arrangement between the Company and such purchasers for the purchase and conversion of any Notes shall increase or otherwise affect any of the powers, duties, responsibilities or obligations of the Trustee as set forth in this Indenture, and the Company agrees to indemnify the Trustee from, and hold it harmless against, any loss, liability or expense arising out of or in connection with any such arrangement for the purchase and conversion of any Notes between the Company and such purchasers, including the costs and expenses incurred by the Trustee in the defense of any claim or liability arising out of or in connection with the exercise or performance of any of its powers, duties, responsibilities or obligations under this Indenture. SECTION 3.10 Repurchase of Notes at Option of the Holder upon Change of Control. (a) If there shall have occurred a Change of Control, all or any portion of the Notes of any Holder equal to $1,000 or a whole multiple of $1,000, not previously called for redemption, shall be repurchased by the Company, at the option of such Holder, at a repurchase price equal to 100% of the principal amount of the Notes to be repurchased, together with interest accrued and unpaid to, but excluding, the repurchase date (the "Change of Control Repurchase Price"), on the date (the "Change of Control Repurchase Date") that is 30 days after the Change of Control Repurchase Notice; provided, however, that installments of interest on Notes whose Stated Maturity is prior to or on the Change of Control Repurchase Date shall be payable to the Holders of such Notes, or one or more predecessor Notes, registered as such on the relevant Regular Record Date according to their terms. Such right to require the repurchase of the Notes shall not continue after a discharge of the Company from its obligations with respect 28

to the Notes in accordance with Article 8, unless a Change of Control shall have occurred prior to such discharge. Subject to the fulfillment by the Company of the conditions set forth in this Section 3.10(b), the Company may elect to pay the Change of Control Repurchase Price by delivering the number of shares of Common Stock equal to (i) the Change of Control Repurchase Price divided by (ii) 95% of the average of the Closing Prices per share of Common Stock for the five consecutive Trading Days ending on the third Trading Day prior to the Change of Control Repurchase Date. Whenever in this Indenture (including Sections 2.01, 6.01(a) and 6.07 hereof) or Exhibit A-1 annexed hereto there is a reference, in any context, to the principal of any Note as of any time, such reference shall be deemed to include reference to the Change of Control Repurchase Price payable in respect to such Note to the extent that such Change of Control Repurchase Price is, was or would be so payable at such time, and express mention of the Change of Control Repurchase Price in any provision of this Indenture shall not be construed as excluding the Change of Control Repurchase Price in those provisions of this Indenture when such express mention is not made; provided, however, that, for the purposes of Article 11 hereof, such reference shall be deemed to include reference to the Change of Control Repurchase Price only to the extent the Change of Control Repurchase Price is payable in cash. A "Change of Control" of the Company shall be deemed to have occurred at such time as either of the following events shall occur: (i) the acquisition by any person, including any syndicate or group deemed to be a "person" under Section 13(d)(3) of the Securities Exchange Act of 1934, as amended (the "Exchange Act"), (other than Permitted Holders) of beneficial ownership, directly or indirectly, through a purchase, merger or other acquisition transaction or series of transactions of shares of the Capital Stock of the Company entitling that person to exercise 50% or more of the total voting power of all shares of Capital Stock entitled to vote generally in elections of directors, other than any acquisition by the Company, any of its subsidiaries or any of the employee benefit plans; (ii) any Permitted Holder files a schedule, form or report in connection with a transaction or event disclosing that such person has become the beneficial owner of 50% or more of the total voting power of all shares of Capital Stock entitled to vote generally in elections of directors, as a result of which (i) the Common Stock ceases (or, upon consummation of or immediately following such transaction or event, will cease) to be listed on a United States national securities exchange or approved for quotation on the Nasdaq National Market or any similar United States system for automated dissemination of quotations of securities prices or (ii) less than 5 million shares of the Company's Common Stock remain held by persons other than Permitted Holders; or (iii) any consolidation or merger of the Company with or into any other person, any merger of another person into the Company, or any conveyance, transfer, sale, lease or other disposition of all or substantially all of the Company's properties and assets to another person, other than: 29

(A) any transaction pursuant to which holders of the Capital Stock immediately prior to the transaction have the entitlement to exercise, directly or indirectly, 50% or more of the total voting power of all shares of the Capital Stock entitled to vote generally in the election of directors of the continuing or surviving person immediately after the transaction; and (B) any merger solely for the purpose of changing the Company's jurisdiction of incorporation and resulting in a reclassification, conversion or exchange of outstanding shares of Common Stock solely into shares of Common Stock of the surviving entity. (b) The following are conditions to the Company's election to pay for the Change of Control Repurchase Price in Common Stock: (i) The shares of Common Stock to be issued upon repurchase of Notes hereunder: (A) shall not require registration under any federal securities law before such shares may be freely transferable without being subject to any transfer restrictions under the Securities Act upon repurchase or, if such registration is required, such registration shall be completed and shall become effective prior to the Change of Control Repurchase Date; and (B) shall not require registration with, or approval of, any governmental authority under any state law or any other federal law before shares may be validly issued or delivered upon repurchase or if such registration is required or such approval must be obtained, such registration shall be completed or such approval shall be obtained prior to the Change of Control Repurchase Date. (ii) The shares of Common Stock to be listed upon repurchase of Notes hereunder are, or shall have been, approved for listing on the Nasdaq National Market or the New York Stock Exchange or listed on another national securities exchange, in any case, prior to the Change of Control Repurchase Date. (iii) All shares of Common Stock which may be issued upon repurchase of Notes will be issued out of the Company's authorized but unissued Common Stock and will, upon issue, be duly and validly issued and fully paid and nonassessable and free of any preemptive or similar rights. (iv) If any of the conditions set forth in clauses (i) through (iii) of this Section 3.10(b) are not satisfied in accordance with the terms thereof, the Change of Control Repurchase Price shall be paid by the Company only in cash. (c) Unless the Company shall have theretofore called for redemption all of the outstanding Notes, prior to or on the 30th day after the occurrence of a Change of Control, the Company, or, at the written request and expense of the Company, the Trustee, shall give to all Noteholders, in the manner provided in Section 13.02 hereof, notice of the occurrence of the Change of Control and of the repurchase right set forth herein arising as a result thereof. If the 30

Trustee is requested to give such notice the Company will provide the written request at least 1 day prior. The Company shall also deliver a copy of such notice of a repurchase right to the Trustee. The notice shall include a form of Change of Control Repurchase Notice (as defined in Section 3.10(d)) to be completed by the Noteholder and shall state: (1) briefly, the events causing a Change of Control and the date of such Change of Control; (2) the date by which the Change of Control Repurchase Notice pursuant to this Section 3.10 must be given; (3) the Change of Control Repurchase Date; (4) the Change of Control Repurchase Price and the form of payment; (5) the name and address of the Paying Agent and the Conversion Agent; (6) the Conversion Price and any adjustments thereto; (7) that Notes as to which a Change of Control Repurchase Notice has been given may be converted pursuant to Article 10 hereof only if the Change of Control Repurchase Notice has been withdrawn in accordance with the terms of this Indenture; (8) that Notes must be surrendered to the Paying Agent to collect payment; (9) that the Change of Control Repurchase Price for any Note as to which a Change of Control Repurchase Notice has been duly given and not withdrawn will be paid promptly following the later of the Change of Control Repurchase Date and the time of surrender of such Note as described in (8) above; (10) briefly, the procedures the Holder must follow to exercise rights under this Section 3.10; (11) briefly, the conversion rights of the Notes; (12) the procedures for withdrawing a Change of Control Repurchase Notice; (13) that, unless the Company defaults in making payment of such Redemption Price, interest on Notes called for redemption will cease to accrue on and after the Redemption Date; and (14) the CUSIP number of the Notes. (d) A Holder may exercise its rights specified in Section 3.10(a) hereof upon delivery of a written notice of purchase (a "Change of Control Repurchase Notice") to the Paying Agent at any time prior to the close of business on the Change of Control Repurchase Date, stating: 31

(1) the certificate number of the Note which the Holder will deliver to be purchased; (2) the portion of the principal amount of the Note which the Holder will deliver to be purchased, which portion must be $1,000 or an integral multiple thereof; and (3) that such Note shall be purchased pursuant to the terms and conditions specified in paragraph 6 of the Notes. The delivery of such Note to the Paying Agent prior to, on or after the Change of Control Repurchase Date (together with all necessary endorsements) at the offices of the Paying Agent shall be a condition to the receipt by the Holder of the Change of Control Repurchase Price therefor; provided, however, that such Change of Control Repurchase Price shall be so paid pursuant to this Section 3.10 only if the Note so delivered to the Paying Agent shall conform in all respects to the description thereof set forth in the related Change of Control Repurchase Notice. The Company shall purchase from the Holder thereof, pursuant to this Section 3.10, a portion of a Note if the principal amount of such portion is $1,000 or an integral multiple of $1,000. Provisions of this Indenture that apply to the purchase of all of a Note also apply to the purchase of such portion of such Note. Any purchase by the Company contemplated pursuant to the provisions of this Section 3.10 shall be consummated by the delivery of the consideration to be received by the Holder promptly following the later of the Change of Control Repurchase Date and the time of delivery of the Note to the Paying Agent in accordance with this Section 3.10. Notwithstanding anything herein to the contrary, any Holder delivering to the Paying Agent the Change of Control Repurchase Notice contemplated by this Section 3.10(d) shall have the right to withdraw such Change of Control Repurchase Notice at any time prior to the close of business on the Change of Control Repurchase Date by delivery of a written notice of withdrawal to the Paying Agent in accordance with Section 3.11. The Paying Agent shall promptly notify the Company of the receipt by it of any Change of Control Repurchase Notice or written withdrawal thereof. SECTION 3.11 Effect of Change of Control Repurchase Notice. Upon receipt by the Paying Agent of the Change of Control Repurchase Notice specified in Section 3.10(d), the Holder of the Note in respect of which such Change of Control Repurchase Notice was given shall (unless such Change of Control Repurchase Notice is withdrawn as specified in the following two paragraphs) thereafter be entitled to receive solely the Change of Control Repurchase Price with respect to such Note. Such Change of Control Repurchase Price shall be paid to such Holder, subject to receipts of funds and/or Notes by the Paying Agent, promptly following the later of (x) the Change of Control Repurchase Date with respect to such Note (provided the conditions in Section 3.10(d) have been satisfied) and (y) the time of delivery of such Note to the Paying Agent by the Holder thereof in the manner required by Section 3.10(d). Notes in respect of which a Change of Control Repurchase Notice, has been given by the Holder thereof may not be converted pursuant to Article 10 hereof on or after the date of the delivery of 32

such Change of Control Repurchase Notice unless such Change of Control Repurchase Notice has first been validly withdrawn as specified in the following two paragraphs. A Change of Control Repurchase Notice may be withdrawn by means of a written notice of withdrawal delivered to the office of the Paying Agent in accordance with the Change of Control Repurchase Notice at any time prior to the close of business on the Change of Control Repurchase Date specifying: (1) the certificate number of the Note in respect of which such notice of withdrawal is being submitted, (2) the principal amount of the Note with respect to which such notice of withdrawal is being submitted, and (3) the principal amount, if any, of such Note which remains subject to the original Change of Control Repurchase Notice and which has been or will be delivered for purchase by the Company. There shall be no repurchase of any Notes pursuant to Section 3.10 if there has occurred (prior to, on or after, as the case may be, the giving, by the Holders of such Notes, of the required Change of Control Repurchase Notice) and is continuing an Event of Default (other than a default in the payment of the Change of Control Repurchase Price with respect to such Notes). The Paying Agent will promptly return to the respective Holders thereof any Notes (x) with respect to which a Change of Control Repurchase Notice has been withdrawn in compliance with this Indenture, or (y) held by it during the continuance of an Event of Default (other than a default in the payment of the Change of Control Repurchase Price with respect to such Notes) in which case, upon such return, the Change of Control Repurchase Notice with respect thereto shall be deemed to have been withdrawn. SECTION 3.12 Deposit of Change of Control Repurchase Price. Prior to 10:00 a.m. (New York City time) on the Business Day following the Change of Control Repurchase Date the Company shall deposit with the Trustee or with the Paying Agent (or, if the Company or a Subsidiary or an Affiliate of either of them is acting as the Paying Agent, shall segregate and hold in trust as provided in Section 2.04) an amount of money (in immediately available funds if deposited on such Business Day) or Common Stock, if permitted hereunder, sufficient to pay the aggregate Change of Control Repurchase Price of all the Notes or portions thereof which are to be purchased as of the Change of Control Repurchase Date. SECTION 3.13 Notes Purchased in Part. Any Note which is to be purchased only in part shall be surrendered at the office of the Paying Agent (with, if the Company or the Trustee so requires, due endorsement by, or a written instrument of transfer in form satisfactory to the Company and the Trustee duly executed by, the Holder thereof or such Holder's attorney duly authorized in writing) and the Company shall execute and the Trustee shall authenticate and deliver to the Holder of such Note, without service charge, a new Note or Notes, of any authorized denomination as requested by such Holder in aggregate principal amount equal to, and in exchange for, the portion of the principal amount of the Note so surrendered which is not purchased. 33

SECTION 3.14 Covenant to Comply with Securities Laws upon Purchase of Notes. In connection with any offer to purchase or repurchase Notes under Section 3.10 hereof (provided that such offer or purchase constitutes an "issuer tender offer" for purposes of Rule 13e-4 (which term, as used herein, includes any successor provision thereto) under the Exchange Act at the time of such offer or purchase), the Company shall (i) comply with Rule 13e-4, Rule 14e-1 and any other tender offer rules under the Exchange Act which may then be applicable, (ii) file the related Schedule 13E-3 (or any successor schedule, form or report) or any other schedule required under the Exchange Act, and (iii) otherwise comply with all federal and state securities laws so as to permit the rights and obligations under Section 3.10 to be exercised in the time and in the manner specified in Section 3.10. SECTION 3.15 Repayment to the Company. The Trustee and the Paying Agent shall return to the Company any cash or shares of Common Stock that remain unclaimed as provided in paragraph 12 of the Notes, together with interest or dividends, if any, thereon, held by them for the payment of the Change of Control Repurchase Price; provided, however, that to the extent that the aggregate amount of cash or shares of Common Stock deposited by the Company pursuant to Section 3.12 exceeds the aggregate Change of Control Repurchase Price of the Notes or portions thereof which the Company is obligated to purchase as of the Change of Control Repurchase Date then promptly after the Business Day following the Change of Control Repurchase Date the Trustee shall return any such excess to the Company together with interest or dividends, if any, thereon. ARTICLE 4 COVENANTS SECTION 4.01 Payment of Principal, Premium, Interest on the Notes. The Company will duly and punctually pay the principal of and premium, if any, and interest in respect of the Notes in accordance with the terms of the Notes and this Indenture. The Company will deposit or cause to be deposited with the Trustee as directed by the Trustee, no later than the day of the Stated Maturity of any Note or installment of interest, all payments so due. Principal amount, Redemption Price, Change of Control Repurchase Price, and cash interest shall be considered paid on the applicable date due if on such date (or, in the case of a Change of Control Repurchase Price on the Business Day following the applicable Change of Control Repurchase Date) the Trustee or the Paying Agent holds, in accordance with this Indenture, money or Notes, if permitted hereunder, sufficient to pay all such amounts then due. The Company shall, to the extent permitted by law, pay cash interest on overdue amounts at the rate per annum set forth in paragraph 1 of the Notes, compounded semiannually, which interest shall accrue from the date such overdue amount was originally due to the date payment of such amount, including interest thereon, has been made or duly provided for. All such interest shall be payable on demand. SECTION 4.02 SEC and Other Reports. The Company shall file with the Trustee, within 15 days after it files such annual and quarterly reports, information, documents and other reports with the SEC, copies of its annual report and of the information, documents and other reports (or copies of such portions of any of the foregoing as the SEC may by rules and 34

regulations prescribe) which the Company is required to file with the SEC pursuant to Section 13 or 15(d) of the Exchange Act. In such event, such reports shall be provided at the times the Company would have been required to provide reports had it continued to have been subject to such reporting requirements. The Company also shall comply with the other provisions of TIA Section 314(a). SECTION 4.03 Compliance Certificate. The Company shall deliver to the Trustee within 120 days after the end of each fiscal year of the Company (beginning with the fiscal year ending on December 31, 2001) an Officer's Certificate, stating whether or not to the best knowledge of the signer thereof the Company is in default in the performance and observance of any of the terms, provisions and conditions of this Indenture (without regard to any period of grace or requirement of notice provided hereunder) and if the Company shall be in default, specifying all such defaults and the nature and status thereof of which they may have knowledge. SECTION 4.04 Further Instruments and Acts. Upon request of the Trustee, the Company will execute and deliver such further instruments and do such further acts as may be reasonably necessary or proper to carry out more effectively the purposes of this Indenture. SECTION 4.05 Maintenance of Office or Agency. The Company will maintain in the Borough of Manhattan, the City of New York, an office or agency of the Trustee, Registrar, Paying Agent and Conversion Agent where Notes may be presented or surrendered for payment, where Notes may be surrendered for registration of transfer, exchange, purchase, redemption or conversion and where notices and demands to or upon the Company in respect of the Notes and this Indenture may be served. The office of American Stock Transfer & Trust Company, located at 59 Maiden Lane, New York, New York 10038, attention: Corporate Trust Department, shall initially be such office or agency for all of the aforesaid purposes. The Company shall give prompt written notice to the Trustee of the location, and of any change in the location, of any such office or agency (other than a change in the location of the office of the Trustee). If at any time the Company shall fail to maintain any such required office or agency or shall fail to furnish the Trustee with the address thereof, such presentations, surrenders, notices and demands may be made or served at the address of the Trustee set forth in Section 13.02. The Company may also from time to time designate one or more other offices or agencies where the Notes may be presented or surrendered for any or all such purposes and may from time to time rescind such designations; provided, however, that no such designation or rescission shall in any manner relieve the Company of its obligation to maintain an office or agency in the Borough of Manhattan, the City of New York, for such purposes. SECTION 4.06 Delivery of Certain Information. At any time when the Company is not subject to Section 13 or 15(d) of the Exchange Act, upon the request of a holder or any beneficial holder of Notes or shares of Common Stock issued upon conversion thereof, the Company will promptly furnish or cause to be furnished Rule 144A Information (as defined below) to such Holder or any beneficial holder of Notes or holder of shares of Common Stock issued upon conversion of Notes, or to a prospective purchaser of any such security designated by any such holder, as the case may be, to the extent required to permit compliance by such Holder or holder with Rule 144A under the Securities Act in connection with the resale of any 35

such security. "Rule 144A Information" shall be such information as is specified pursuant to Rule 144A(d)(4) under the Securities Act. SECTION 4.07 Subordination. The Company shall not and will not permit its subsidiaries or other business units to incur, create, assume, guarantee or in any other manner become directly or indirectly liable with respect to or responsible for, or permit to remain outstanding (other than if required by law), any Indebtedness that is subordinated or junior in right of payment to Senior Indebtedness unless such Indebtedness ranks equal or junior in right of payment to the Notes. It being understood that the Company shall have the right to incur, create, assume or guarantee or in any other manner become directly or indirectly liable with respect to or responsible for, or permit to remain outstanding Senior Indebtedness that may be subordinate to other Senior Indebtedness. ARTICLE 5 SUCCESSOR CORPORATION SECTION 5.01 When Company May Merge or Transfer Assets. The Company shall not consolidate with, merge with or into any other person or convey, transfer or lease its properties and assets substantially as an entirety to any person, unless: (a) either (1) the Company shall be the continuing corporation or (2) the person (if other than the Company) formed by such consolidation or into which the Company is merged or the person which acquires by conveyance, transfer or lease the properties and assets of the Company substantially as an entirety (i) shall be organized and validly existing under the laws of the United States or any State thereof or the District of Columbia and (ii) shall expressly assume, by an indenture supplemental hereto, executed and delivered to the Trustee, in form reasonably satisfactory to the Trustee, all of the obligations of the Company under the Notes and this Indenture; (b) at the time of such transaction, no Event of Default and no event which, after notice or lapse of time, would become an Event of Default, shall have happened and be continuing; and (c) the Company shall have delivered to the Trustee an Officers' Certificate and an Opinion of Counsel, each stating that such consolidation, merger, conveyance, transfer or lease and, if a supplemental indenture is required in connection with such transaction, such supplemental indenture, comply with this Article 5 and that all conditions precedent herein provided for relating to such transaction have been satisfied. For purposes of the foregoing, the transfer (by lease, assignment, sale or otherwise) of the properties and assets of one or more Subsidiaries (other than to the Company or another Subsidiary), which, if such assets were owned by the Company, would constitute all or substantially all of the properties and assets of the Company, shall be deemed to be the transfer of all or substantially all of the properties and assets of the Company. 36

The successor person formed by such consolidation or into which the Company is merged or the successor person to which such conveyance, transfer or lease is made shall succeed to, and be substituted for, and may exercise every right and power of, the Company under this Indenture with the same effect as if such successor had been named as the Company herein; and thereafter, except in the case of a lease and obligations the Company may have under a supplemental indenture pursuant to Section 10.11, the Company shall be discharged from all obligations and covenants under this Indenture and the Notes. Subject to Section 9.06, the Company, the Trustee and the successor person shall enter into a supplemental indenture to evidence the succession and substitution of such successor person and such discharge and release of the Company. ARTICLE 6 DEFAULTS AND REMEDIES SECTION 6.01 Events of Default. An "Event of Default" occurs if: (1) the Company fails to pay when due the principal of or premium, if any, on any of the Notes at maturity, upon redemption or exercise of a repurchase right or otherwise, whether or not such payment is prohibited by Article 11 of this Indenture; (2) the Company fails to pay an installment of interest (including liquidated damages, if any) on any of the Notes that continues for 30 days after the date when due, whether or not such payment is prohibited by Article 11 of this Indenture, provided that a failure to make any of the first six scheduled interest payments on the Notes within three Business Days after an Interest Payment Date will constitute an Event of Default with no additional grace or cure period; (3) the Company fails to deliver shares of Common Stock, together with cash in lieu of fractional shares, when such Common Stock or cash in lieu of fractional shares is required to be delivered upon conversion of a Note or upon exercise of a repurchase right pursuant to Section 3.10 and such failure continues for 10 days after such delivery date; (4) the Company fails to perform or observe any other term, covenant or agreement contained in the Notes or this Indenture for a period of 60 days after receipt by the Company of a Notice of Default (as defined in this Section 6.01); (5) (A) one or more defaults in the payment of principal of or premium, if any, on any of the Company's Indebtedness aggregating $10.0 million or more, when the same becomes due and payable at the scheduled maturity thereof, and such default or defaults shall have continued after any applicable grace period and shall not have been cured or waived within a 30-day period after the date of such default or (B) any of the Company's Indebtedness aggregating $10.0 million or more shall have been accelerated or otherwise declared due and payable, or required to be prepaid or repurchased (other than by regularly scheduled required prepayment) prior to the scheduled maturity thereof and such acceleration is not rescinded or annulled within a 30-day period after the date of such acceleration; 37

(6) the Company, or any Significant Subsidiary pursuant to or under or within the meaning of any Bankruptcy Law: (A) commences a voluntary case or proceeding; (B) consents to the entry of an order for relief against it in an involuntary case or proceeding or the commencement of any case against it; (C) consents to the appointment of a Custodian of it or for any substantial part of its property; (D) makes a general assignment for the benefit of its creditors; (E) files a petition in bankruptcy or answer or consent seeking reorganization or relief; or (F) consents to the filing of such a petition or the appointment of or taking possession by a Custodian; and (7) a court of competent jurisdiction enters an order or decree under any Bankruptcy Law that: (A) is for relief against the Company or any Significant Subsidiary in an involuntary case or proceeding, or adjudicates the Company or any Significant Subsidiary insolvent or bankrupt; (B) appoints a Custodian of the Company or any Significant Subsidiary or for any substantial part of its or their properties; or (C) orders the winding up or liquidation of the Company or any Significant Subsidiary; and the order or decree remains unstayed and in effect for 60 days. "Bankruptcy Law" means Title 11, United States Code, or any similar federal or state law for the relief of debtors. "Custodian" means any receiver, trustee, assignee, liquidator, custodian or similar official under any Bankruptcy Law. (8) the Pledge Agreement shall cease to be in full force and effect or enforceable in accordance with its terms. A Default under clause (4) above is not an Event of Default until the Trustee notifies the Company, or the Holders of at least 25% in aggregate principal amount of the Notes at the time outstanding notify the Company and the Trustee, of the Default and the Company does not cure such Default (and such Default is not waived) within the time specified in clause 38

(4) above after actual receipt of such notice. Any such notice must specify the Default, demand that it be remedied and state that such notice is a "Notice of Default". The Company will deliver to the Trustee, within five Business Days of becoming aware of the occurrence of an Event of Default, written notice thereof. In addition, the Company shall deliver to the Trustee, within 30 days after it becomes aware of the occurrence thereof, written notice of any event which with the lapse of time would become an Event of Default under clause (4) above, its status and what action the Company is taking or proposes to take with respect thereto. SECTION 6.02 Acceleration. If an Event of Default (other than an Event of Default specified in Section 6.01(6) or (7)) occurs and is continuing, the Trustee by Notice to the Company, or the Holders of at least 25% in aggregate principal amount of the Notes at the time outstanding by notice to the Company and the Trustee, may declare the notes due and payable at their principal amount together with accrued and unpaid interest. Upon a declaration of acceleration, such principal and accrued and unpaid interest to the date of payment shall be immediately due and payable. If an Event of Default specified in Section 6.01(6) or (7) above occurs and is continuing, then the principal and the interest on all the Notes shall become and be immediately due and payable without any declaration or other act on the part of the Trustee or any Noteholders. The Holders of a majority in aggregate principal amount of the Notes at the time outstanding, by notice to the Trustee (and without notice to any other Noteholder) may rescind or annul an acceleration and its consequences if the rescission would not conflict with any judgment or decree and if all existing Events of Default have been cured or waived except nonpayment of the principal and any accrued cash interest that have become due solely as a result of acceleration and if all amounts due to the Trustee under Section 7.06 have been paid. No such rescission shall affect any subsequent Default or impair any right consequent thereto. SECTION 6.03 Other Remedies. If an Event of Default occurs and is continuing, the Trustee may pursue any available remedy to collect the payment of the principal, the premium, if any, and any accrued cash interest on the Notes or to enforce the performance of any provision of the Notes or this Indenture. The Trustee may maintain a proceeding even if the Trustee does not possess any of the Notes or produce any of the Notes in the proceeding. A delay or omission by the Trustee or any Noteholder in exercising any right or remedy accruing upon an Event of Default shall not impair the right or remedy or constitute a waiver of, or acquiescence in, the Event of Default. No remedy is exclusive of any other remedy. All available remedies are cumulative. SECTION 6.04 Waiver of Past Defaults. The Holders of a majority in aggregate principal amount of the Notes at the time outstanding, by notice to the Trustee (and without notice to any other Noteholder), may waive an existing Default and its consequences except (1) an Event of Default described in Section 6.01(1) or (2), (2) a Default in respect of a provision that under Section 9.02 cannot be amended without the consent of each Noteholder 39

affected or (3) a Default which consists of a failure to convert any Note in accordance with the terms of Article 11. When a Default is waived, it is deemed cured, but no such waiver shall extend to any subsequent or other Default or impair any consequent right. This Section 6.04 shall be in lieu of Section 316(a)1(B) of the TIA and such Section 316(a)1(B) is hereby expressly excluded from this Indenture, as permitted by the TIA. SECTION 6.05 Control by Majority. The Holders of a majority in aggregate principal amount of the Notes at the time outstanding may direct the time, method and place of conducting any proceeding for any remedy available to the Trustee or of exercising any trust or power conferred on the Trustee. However, the Trustee may refuse to follow any direction that conflicts with law or this Indenture or that the Trustee determines in good faith is unduly prejudicial to the rights of other Noteholders or would involve the Trustee in personal liability unless the Trustee is offered indemnity satisfactory to it against loss, liability or expense. This Section 6.05 shall be in lieu of Section 316(a)1(A) of the TIA and such Section 316(a)1(A) is hereby expressly excluded from this Indenture, as permitted by the TIA. SECTION 6.06 Limitation on Suits. A Noteholder may not pursue any remedy with respect to this Indenture or the Notes unless: (1) the Holder gives to the Trustee written notice stating that an Event of Default is continuing; (2) the Holders of at least 25% in aggregate principal amount of the Notes at the time outstanding make a written request to the Trustee to pursue the remedy; (3) such Holder or Holders offer to the Trustee reasonable security or indemnity satisfactory to the Trustee against any loss, liability or expense; (4) the Trustee does not comply with the request within 60 days after receipt of such notice, request and offer of security or indemnity; and (5) the Holders of a majority in aggregate principal amount of the Notes at the time outstanding do not give the Trustee a direction inconsistent with the request during such 60-day period. A Noteholder may not use this Indenture to prejudice the rights of any other Noteholder or to obtain a preference or priority over any other Noteholder. SECTION 6.07 Rights of Holders to Receive Payment. Notwithstanding any other provision of this Indenture, the right of any Holder to receive payment of the principal amount, premium, if any, plus Redemption Price, Change of Control Repurchase Price or any accrued cash interest in respect of the Notes held by such Holder, on or after the respective due dates expressed in the Notes or any Redemption Date, and to convert the Notes in accordance with Article 10, or to bring suit for the enforcement of any such payment on or after such respective dates or the right to convert, shall not be impaired or affected adversely without the consent of such Holder. 40

SECTION 6.08 Collection Suit by Trustee. If an Event of Default described in Section 6.01(1) or (2) occurs and is continuing, the Trustee may recover judgment in its own name and as trustee of an express trust against the Company for the whole amount owing with respect to the Notes and the amounts provided for in Section 7.06. SECTION 6.09 Trustee May File Proofs of Claim. In case of the pendency of any receivership, insolvency, liquidation, bankruptcy, reorganization, arrangement, adjustment, composition or other judicial proceeding relative to the Company or any other obligor upon the Notes or the property of the Company or of such other obligor or their creditors, the Trustee (irrespective of whether the principal amount, Redemption Price, Change of Control Repurchase Price or any accrued cash interest in respect of the Notes shall then be due and payable as therein expressed or by declaration or otherwise and irrespective of whether the Trustee shall have made any demand on the Company for the payment of any such amount) shall be entitled and empowered, by intervention in such proceeding or otherwise, (a) to file and prove a claim for the whole amount of the principal amount, Redemption Price, Change of Control Repurchase Price or any accrued cash interest and to file such other papers or documents as may be necessary or advisable in order to have the claims of the Trustee (including any claim for the reasonable compensation, expenses, disbursements and advances of the Trustee, its agents and counsel or any other amounts due the Trustee under Section 7.06) and of the Holders allowed in such judicial proceeding, and (b) to collect and receive any moneys or other property payable or deliverable on any such claims and to distribute the same; and any custodian, receiver, assignee, trustee, liquidator, sequestrator or similar official in any such judicial proceeding is hereby authorized by each Holder to make such payments to the Trustee and, in the event that the Trustee shall consent to the making of such payments directly to the Holders, to pay the Trustee any amount due it for the reasonable compensation, expenses, disbursements and advances of the Trustee, its agents and counsel, and any other amounts due the Trustee under Section 7.06. Nothing herein contained shall be deemed to authorize the Trustee to authorize or consent to or accept or adopt on behalf of any Holder any plan of reorganization, arrangement, adjustment or composition affecting the Notes or the rights of any Holder thereof, or to authorize the Trustee to vote in respect of the claim of any Holder in any such proceeding. SECTION 6.10 Priorities. If the Trustee collects any money pursuant to this Article 6, it shall pay out the money in the following order: (1) to the Trustee for amounts due under Section 7.06; (2) to Noteholders for amounts due and unpaid on the Notes for the principal amount, Redemption Price, Change of Control Purchase Price or any accrued cash interest as the case may be, ratably, without preference or priority of any kind, according to such amounts due and payable on the Notes; and 41

(3) the balance, if any, to the Company. The Trustee may fix a record date and payment date for any payment to Noteholders pursuant to this Section 6.10. At least 15 days before such record date, the Trustee shall mail to each Noteholder and the Company a notice that states the record date, the payment date and the amount to be paid. SECTION 6.11 Undertaking for Costs. In any suit for the enforcement of any right or remedy under this Indenture or in any suit against the Trustee for any action taken or omitted by it as Trustee, a court in its discretion may require the filing by any party litigant (other than the Trustee) in the suit of an undertaking to pay the costs of the suit, and the court in its discretion may assess reasonable costs, including reasonable attorneys' fees and expenses, against any party litigant in the suit, having due regard to the merits and good faith of the claims or defenses made by the party litigant. This Section 6.11 does not apply to a suit by the Trustee, a suit by a Holder pursuant to Section 6.07 or a suit by Holders of more than 10% in aggregate principal amount of the Notes at the time outstanding. This Section 6.11 shall be in lieu of Section 315(e) of the TIA and such Section 315(e) is hereby expressly excluded from this Indenture, as permitted by the TIA. SECTION 6.12 Waiver of Stay, Extension or Usury Laws. The Company covenants (to the extent that it may lawfully do so) that it will not at any time insist upon, or plead, or in any manner whatsoever claim or take the benefit or advantage of, any stay or extension law or any usury or other law wherever enacted, now or at any time hereafter in force, which would prohibit or forgive the Company from paying all or any portion of the principal amount, Redemption Price, Change of Control Repurchase Price or any accrued cash interest in respect of Notes, or any interest on such amounts, as contemplated herein, or which may affect the covenants or the performance of this Indenture; and the Company (to the extent that it may lawfully do so) hereby expressly waives all benefit or advantage of any such law, and covenants that it will not hinder, delay or impede the execution of any power herein granted to the Trustee, but will suffer and permit the execution of every such power as though no such law had been enacted. ARTICLE 7 TRUSTEE SECTION 7.01 Duties and Responsibilities of the Trustee; During Default; Prior to Default. The Trustee, prior to the occurrence of an Event of Default hereunder and after the curing or waiving of all such Events of Default which may have occurred, undertakes to perform such duties and only such duties as are specifically set forth in this Indenture. In case an Event of Default hereunder has occurred (which has not been cured or waived), the Trustee shall exercise such of the rights and powers vested in it by this Indenture, and use the same degree of care and skill in their exercise, as a prudent man would exercise or use under the circumstances in the conduct of his own affairs. 42

No provision of this Indenture shall be construed to relieve the Trustee from liability for its own negligent action, its own negligent failure to act or its own willful misconduct, except that (a) prior to the occurrence of an Event of Default hereunder and after the curing or waiving of all such Events of Default which may have occurred: (i) the duties and obligations of the Trustee shall be determined solely by the express provisions of this Indenture, and the Trustee shall not be liable except for the performance of such duties and obligations as are specifically set forth in this Indenture, and no implied covenants or obligations shall be read into this Indenture against the Trustee; and (ii) in the absence of bad faith on the part of the Trustee, the Trustee may conclusively rely, as to the truth of the statements and the correctness of the opinions expressed therein, upon any statements, certificates or opinions furnished to the Trustee and conforming to the requirements of this Indenture; but in the case of any such statements, certificates or opinions which by any provision hereof are specifically required to be furnished to the Trustee, the Trustee shall be under a duty to examine the same to determine whether or not they conform to the requirements of this Indenture; (b) the Trustee shall not be liable for any error of judgment made in good faith by a Responsible Officer or Responsible Officers of the Trustee, unless it shall be proved that the Trustee was negligent in ascertaining the pertinent facts; and (c) the Trustee shall not be liable with respect to any action taken or omitted to be taken by it in good faith in accordance with the direction of the Holders pursuant to Section 6.05 relating to the time, method and place of conducting any proceeding for any remedy available to the Trustee, or exercising any trust or power conferred upon the Trustee, under this Indenture. None of the provisions contained in this Indenture shall require the Trustee to expend or risk its own funds or otherwise incur personal financial liability in the performance of any of its duties or in the exercise of any of its rights or powers, if there shall be reasonable ground for believing that the repayment of such funds or adequate indemnity against such liability is not reasonably assured to it. The provisions of this Section 7.01 are in furtherance of and subject to Sections 315 and 316 of the TIA. SECTION 7.02 Certain Rights of the Trustee. In furtherance of and subject to the TIA and subject to Section 7.01: (a) the Trustee may rely and shall be protected in acting or refraining from acting upon any resolution, Officers' Certificate or any other certificate, statement, instrument, opinion, report, notice, request, consent, order, bond, debenture, note, coupon, Note or 43

other paper or document believed by it to be genuine and to have been signed or presented by the proper party or parties; (b) any request, direction, order or demand of the Company mentioned herein shall be sufficiently evidenced by an Officers' Certificate (unless other evidence in respect thereof be herein specifically prescribed); and any resolution of the Board of Directors may be evidenced to the Trustee by a copy thereof certified by the secretary or an assistant secretary of the Company; (c) the Trustee may consult with counsel of its selection and any advice or Opinion of Counsel shall be full and complete authorization and protection in respect of any action taken, suffered or omitted to be taken by it hereunder in good faith and in accordance with such advice or Opinion of Counsel; (d) the Trustee shall be under no obligation to exercise any of the trusts or powers vested in it by this Indenture with the request, order or direction of any of the Noteholders pursuant to the provisions of this Indenture, unless such Noteholders shall have offered to the Trustee reasonable security or indemnity against the costs, expenses and liabilities which might be incurred therein or thereby; (e) the Trustee shall not be liable for any action taken or omitted by it in good faith and believed by it to be authorized or within the discretion, rights or powers conferred upon it by this Indenture; (f) prior to the occurrence of an Event of Default hereunder and after the curing or waiving of all such Events of Default, the Trustee shall not be bound to make any investigation into the facts or matters stated in any resolution, certificate, statement, instrument, opinion, report, notice, request, consent, order, approval, appraisal, bond, debenture, note, coupon, security, or other paper or document unless requested in writing to do so by the Holders of not less than a majority in aggregate principal amount of the Notes then outstanding; provided that, if the payment within a reasonable time to the Trustee of the costs, expenses or liabilities likely to be incurred by it in the making of such investigation is, in the opinion of the Trustee, not reasonably assured to the Trustee by the security afforded to it by the terms of this Indenture, the Trustee may require reasonable indemnity against such expenses or liabilities as a condition to proceeding; the reasonable expenses of every such investigation shall be paid by the Company or, if paid by the Trustee or any predecessor trustee, shall be repaid by the Company upon demand; and (g) the Trustee may execute any of the trusts or powers hereunder or perform any duties hereunder either directly or by or through agents or attorneys not regularly in its employ and the Trustee shall not be responsible for any misconduct or negligence on the part of any such agent or attorney appointed with due care by it hereunder. SECTION 7.03 Trustee Not Responsible for Recitals, Disposition of Notes or Application of Proceeds Thereof. The recitals contained herein and in the Notes, except the Trustee's certificates of authentication, shall be taken as the statements of the Company, and the 44

Trustee assumes no responsibility for the correctness of the same. The Trustee makes no representation as to the validity or sufficiency of this Indenture or of the Notes. The Trustee shall not be accountable for the use or application by the Company of any of the Notes or of the proceeds thereof. SECTION 7.04 Trustee and Agents May Hold Notes; Collections, etc. The Trustee or any agent of the Company or the Trustee, in its individual or any other capacity, may become the owner or pledgee of Notes with the same rights it would have if it were not the Trustee or such agent and, subject to Sections 7.08 and 7.13, if operative, may otherwise deal with the Company and receive, collect, hold and retain collections from the Company with the same rights it would have if it were not the Trustee or such agent. SECTION 7.05 Moneys Held by Trustee. Subject to the provisions of Section 8.02 hereof, all moneys received by the Trustee shall, until used or applied as herein provided, be held in trust for the purposes for which they were received, but need not be segregated from other funds except to the extent required by mandatory provisions of law. Neither the Trustee nor any agent of the Company or the Trustee shall be under any liability for interest on any moneys received by it hereunder. SECTION 7.06 Compensation and Indemnification of Trustee and Its Prior Claim. The Company covenants and agrees to pay to the Trustee from time to time, and the Trustee shall be entitled to, such compensation (which shall not be limited by any provision of law in regard to the compensation of a trustee of an express trust) to be agreed to in writing by the Trustee and the Company, and the Company covenants and agrees to pay or reimburse the Trustee and each predecessor Trustee upon its request for all reasonable expenses, disbursements and advances incurred or made by or on behalf of it in accordance with any of the provisions of this Indenture (including (i) the reasonable compensation and the expenses and disbursements of its counsel and of all agents and other persons not regularly in its employ and (ii) interest at the prime rate on any disbursements and advances made by the Trustee and not paid by the Company within 5 days after receipt of an invoice for such disbursement or advance) except any such expense, disbursement or advance as may arise from its negligence or bad faith. The Company also covenants to indemnify the Trustee and each predecessor Trustee for, and to hold it harmless against, any loss, liability or expense incurred without negligence or bad faith on its part, arising out of or in connection with the acceptance or administration of this Indenture or the trusts hereunder and its duties hereunder, including the costs and expenses of defending itself against or investigating any claim of liability in the premises. The obligations of the Company under this Section 7.06 to compensate and indemnify the Trustee and each predecessor Trustee and to pay or reimburse the Trustee and each predecessor Trustee for expenses, disbursements and advances shall constitute additional indebtedness hereunder and shall survive the satisfaction and discharge of this Indenture. Such additional indebtedness shall be a senior claim to that of the Notes upon all property and funds held or collected by the Trustee as such, except funds held in trust for the benefit of the Holders of particular Notes, and the Notes are hereby effectively subordinated to such senior claim to such extent. The provisions of this Section 7.06 shall survive the termination of this Indenture. When the Trustee incurs expenses or renders services in connection with an Event of Default specified in Section 6.01 or in connection with Article Six hereof, the expenses (including the reasonable fees and expenses of its counsel) and the 45

compensation for services in connection therewith are to constitute the expenses of administration under any bankruptcy law. SECTION 7.07 Right of Trustee to Rely on Officers' Certificate, etc. Subject to Sections 7.01 and 7.02, whenever in the administration of the trusts of this Indenture the Trustee shall deem it necessary or desirable that a matter be proved or established prior to taking or suffering or omitting any action hereunder, such matter (unless other evidence in respect thereof be herein specifically prescribed) may, in the absence of negligence or bad faith on the part of the Trustee, be deemed to be conclusively proved and established by an Officers' Certificate delivered to the Trustee, and such certificate, in the absence of negligence or bad faith on the part of the Trustee, shall be full warrant to the Trustee for any action taken, suffered or omitted by it under the provisions of this Indenture upon the faith thereof. SECTION 7.08 Conflicting Interests. If the Trustee has or shall acquire a conflicting interest within the meaning of the TIA, the Trustee shall either eliminate such interest or resign, to the extent and in the manner provided by, and subject to the provisions of, the TIA. SECTION 7.09 Persons Eligible for Appointment as Trustee. The Trustee shall at all times be a corporation or banking association having a combined capital and surplus of at least $10,000,000. If such corporation or banking association publishes reports of condition at least annually, pursuant to law or to the requirements of the aforesaid supervising or examining authority, then, for the purposes of this Section 7.09, the combined capital and surplus of such corporation shall be deemed to be its combined capital and surplus as set forth in its most recent report of condition so published. In case at any time the Trustee shall cease to be eligible in accordance with the provisions of this Section 7.09, the Trustee shall resign immediately in the manner and with the effect specified in Section 7.10. SECTION 7.10 Resignation and Removal; Appointment of Successor Trustee. (a) The Trustee, or any trustee or trustees hereafter appointed, may at any time resign with respect to one or more or all series of Notes by giving written notice of resignation to the Company and by mailing notice thereof by first class mail to the Holders of Notes at their last addresses as they shall appear on the Note register. Upon receiving such notice of resignation, the Company shall promptly appoint a successor trustee or trustees by written instrument in duplicate, executed by authority of the Board of Directors, one copy of which instrument shall be delivered to the resigning Trustee and one copy to the successor trustee or trustees. If no successor trustee shall have been so appointed and have accepted appointment within 30 days after the mailing of such notice of resignation, the resigning trustee may petition any court of competent jurisdiction for the appointment of a successor trustee, or any Noteholder who has been a bona fide Holder of a Note for at least six months may, subject to the provisions of Section 7.11, on behalf of himself and all others similarly situated, petition any such court for the appointment of a successor trustee. Such court may thereupon, after such notice, if any, as it may deem proper and prescribe, appoint a successor trustee. (b) In case at any time any of the following shall occur: 46

(i) the Trustee shall fail to comply with the provisions of Section 7.08 with respect to any Notes after written request therefor by the Company or by any Noteholder who has been a bona fide Holder of a Note for at least six months; or (ii) the Trustee shall cease to be eligible in accordance with the provisions of Section 7.09 and shall fail to resign after written request therefor by the Company or by any Noteholder; or (iii) the Trustee shall become incapable of acting or shall be adjudged a bankrupt or insolvent, or a receiver or liquidator of the Trustee or of its property shall be appointed, or any public officer shall take charge or control of the Trustee or of its property or affairs for the purpose of rehabilitation, conservation or liquidation; or (iv) the Company shall determine that the Trustee has failed to perform its obligations under this Indenture in any material respect; then, in any such case, the Company may remove the Trustee and appoint a successor trustee by written instrument, in duplicate, executed by order of the Board of Directors of the Company, one copy of which instrument shall be delivered to the Trustee so removed and one copy to the successor trustee, or, subject to the provisions of Section 7.11, any Noteholder who has been a bona fide Holder of a Note for at least six months may on behalf of himself and all others similarly situated, petition any court of competent jurisdiction for the removal of the Trustee and the appointment of a successor trustee. Such court may thereupon, after such notice, if any, as it may deem proper and prescribe, remove the Trustee and appoint a successor trustee. If no successor trustee shall have been appointed and have accepted appointment within 30 days after a notice of removal has been given, the removed trustee may petition a court of competent jurisdiction for the appointment of a successor trustee. (c) The Holders of a majority in aggregate principal amount of the Notes at the time outstanding may at any time remove the Trustee and appoint a successor trustee by delivering to the Trustee so removed, to the successor trustee so appointed and to the Company the evidence provided for in Section 1.05 of the action in that regard taken by the Noteholders. (d) Any resignation or removal of the Trustee and any appointment of a successor trustee pursuant to any of the provisions of this Section 7.10 shall become effective upon acceptance of appointment by the successor trustee as provided in Section 7.11. SECTION 7.11 Acceptance of Appointment by Successor Trustee. Any successor trustee appointed as provided in Section 7.10 shall execute and deliver to the Company and to its predecessor trustee an instrument accepting such appointment hereunder, and thereupon the resignation or removal of the predecessor trustee shall become effective and such successor trustee, without any further act, deed or conveyance, shall become vested with all rights, powers, duties and obligations of its predecessor hereunder, with like effect as if originally named as trustee hereunder; but, nevertheless, on the written request of the Company or of the successor trustee, upon payment of its charges then unpaid, the trustee ceasing to act shall pay over to the successor trustee all moneys at the time held by it hereunder and shall execute and deliver an instrument transferring to such successor trustee all such rights, powers, 47

duties and obligations. Upon request of any such successor trustee, the Company shall execute any and all instruments in writing for more fully and certainly vesting in and confirming to such successor trustee all such rights and powers. Any trustee ceasing to act shall, nevertheless, retain a prior claim upon all property or funds held or collected by such trustee to secure any amounts then due it pursuant to the provisions of Section 7.06. No successor trustee shall accept appointment as provided in this Section 7.11 unless at the time of such acceptance such successor trustee shall be qualified under the provisions of Section 7.08 and eligible under the provisions of Section 7.09. Upon acceptance of appointment by any successor trustee as provided in this Section 7.11, the Company shall mail notice thereof by first class mail to the Holders of Notes at their last addresses as they shall appear in the register. If the acceptance of appointment is substantially contemporaneous with the resignation, then the notice called for by the preceding sentence may be combined with the notice called for by Section 7.10. If the Company fails to mail such notice within ten days after acceptance of appointment by the successor trustee, the successor trustee shall cause such notice to be mailed at the expense of the Company. SECTION 7.12 Merger, Conversion, Consolidation or Succession to Business of Trustee. Any corporation or banking association into which the Trustee may be merged or converted or with which it may be consolidated, or any corporation or banking association resulting from any merger, conversion or consolidation to which the Trustee shall be a party, or any corporation or banking association succeeding to all or substantially all of the corporate trust business of the Trustee, shall be the successor of the Trustee hereunder, provided that such corporation or banking association shall be qualified under the provisions of Section 7.08 and eligible under the provisions of Section 7.09, without the execution or filing of any paper or any further act on the part of any of the parties hereto, anything herein to the contrary notwithstanding. In case at the time such successor to the Trustee shall succeed to the trusts created by this Indenture any of the Notes shall have been authenticated but not delivered, any such successor to the Trustee may adopt the certificate of authentication of any predecessor Trustee and deliver such Notes so authenticated; and, in case at that time any of the Notes shall not have been authenticated, any successor to the Trustee may authenticate such Notes either in the name of any predecessor hereunder or in the name of the successor Trustee; and in all such cases such certificate shall have the full force and effect that this Indenture provides for the certificate of authentication of the Trustee; provided, that the right to adopt the certificate of authentication of any predecessor Trustee or to authenticate Notes in the name of any predecessor Trustee shall apply only to its successor or successors by merger, conversion or consolidation. SECTION 7.13 Preferential Collection of Claims Against the Company. The Trustee shall comply with the provisions of Section 311 of the TIA. SECTION 7.14 Reports by the Trustee. (a) The Trustee shall transmit to Holders and other persons such reports concerning the Trustee and its actions under this Indenture as may be required pursuant to the TIA on or before July 15 in each year that such report is required, such reports to be dated as of the immediately preceding May 15. 48

(b) A copy of each such report shall, at the time of such transmission to Noteholders, be furnished to the Company and be filed by the Trustee with each stock exchange upon which the Notes are listed and also with the SEC. The Company agrees to notify the Trustee when and as the Notes become admitted to trading on any national securities exchange. SECTION 7.15 Trustee to Give Notice of Default, But May Withhold in Certain Circumstances. The Trustee shall transmit to the Noteholders, as the names and addresses of such Holders appear on the Note register, notice by mail of all Defaults which have occurred, such notice to be transmitted within 90 days after the occurrence thereof, unless such defaults shall have been cured before the giving of such notice; provided that, except in the case of Default in the payment of the principal of, interest on, or other similar obligation with respect to, any of the Notes, the Trustee shall be protected in withholding such notice if and so long as the board of directors, the executive committee, or a trust committee of directors or trustees and/or Responsible Officers of the Trustee in good faith determines that the withholding of such notice is in the best interests of the Noteholders. ARTICLE 8 DISCHARGE OF INDENTURE SECTION 8.01 Termination of the Company's Obligations. Except as otherwise provided in this Section 8.01, the Company may terminate its obligations under the Notes and this Indenture if: (i) all Notes previously authenticated and delivered (other than destroyed, lost or stolen Notes that have been replaced or Notes that are paid pursuant to Section 2.07 hereof or Notes for whose payment money or securities have theretofore been held in trust and thereafter repaid to the Company, as provided in Section 8.05 hereof) have been delivered to the Trustee for cancellation and the Company has paid all sums payable by it hereunder; or (ii) (A) all of the Notes mature within one year or all of them are to be called for redemption within one year under arrangements satisfactory to the Trustee for giving the notice of redemption, (B) the Company deposits in trust with the Trustee during such one-year period, under the terms of an irrevocable trust agreement in form and substance satisfactory to the Trustee, as trust funds solely for the benefit of the Holders for that purpose, money or U.S. Government Obligations sufficient to pay principal, premium, if, any, and interest on the Notes to maturity or redemption, as the case may be, and to pay all other sums payable by it hereunder, (C) no Default or Event of Default with respect to the Notes shall have occurred and be continuing on the date of such deposit, (D) such deposit will not result in a breach or violation of, or constitute a default under, this Indenture or any other agreement or instrument to which the Company is a party or by which it is bound and (E) the Company has delivered to the Trustee an Officers' Certificate and an Opinion of Counsel, in each case stating that all conditions precedent provided for herein relating to the satisfaction and discharge of this Indenture have been complied with. 49

With respect to the foregoing clause (i), the Company's obligations under Section 7.06 hereof shall survive. With respect to the foregoing clause (ii), the Company's obligations in Sections 2.02, 2.03, 2.04, 2.05, 2.06, 2.07, 4.01, 4.05, 7.06, 7.10 8.04, 8.05 and 8.06 of this Indenture shall survive until the Notes are no longer outstanding. Thereafter, only the Company's obligations in Sections 7.06, 8.05 and 8.06 of this Indenture shall survive. After any such irrevocable deposit, the Trustee upon request shall acknowledge in writing the discharge of the Company's obligations, as the case may be, under the Notes and this Indenture, except for those surviving obligations specified above. SECTION 8.02 Defeasance and Discharge of Indenture. Subject to Section 8.08, the Company will be deemed to have paid and will be discharged from any and all obligations in respect of the Notes on the 123rd day after the deposit referred to below, and the provisions of this Indenture will no longer be in effect with respect to the Notes (except for, among other matters, certain obligations to register the transfer or exchange of the Notes, to replace stolen, lost or mutilated Notes, to maintain paying agencies and to hold monies for payment in trust) if, among other things: (A) the Company has deposited with the Trustee, in trust, money and/or U.S. Government Obligations that through the payment of interest and principal in respect thereof in accordance with their terms will provide money in an amount sufficient in the opinion of a nationally recognized independent public accounting firm to pay the principal of, premium, if any, and accrued interest on the Notes on the Stated Maturity of such payments in accordance with the terms of this Indenture and the Notes; (B) the Company has delivered to the Trustee (i) either (x) an Opinion of Counsel to the effect that Holders will not recognize income, gain or loss for federal income tax purposes as a result of the Company's exercise of its option under this Section 8.02 and will be subject to federal income tax on the same amount and in the same manner and at the same times as would have been the case if such deposit, defeasance and discharge had not occurred, which Opinion of Counsel must be based upon (and accompanied by a copy of) a ruling of the Internal Revenue Service to the same effect unless there has been a change in applicable federal income tax law after the Closing Date such that a ruling is no longer required or (y) a ruling directed to the Trustee received from the Internal Revenue Service to the same effect as the aforementioned Opinion of Counsel and (ii) an Opinion of Counsel to the effect that the creation of the defeasance trust does not violate the Investment Company Act of 1940 and after the passage of 123 days following the deposit, the trust fund will not be subject to the effect of Section 547 of the United States Bankruptcy Code or Section 15 of the New York Debtor and Creditor Law; and (C) immediately after giving effect to such deposit on a pro forma basis, no Event of Default, or event that after the giving of notice or lapse of time or both would become an Event of Default, shall have occurred and be continuing on the date of such deposit or during the period ending on the 123rd day after the date of such deposit, and such deposit shall not result in a breach or violation of, 50

or constitute a default under, any other agreement or instrument to which the Company or any of its Subsidiaries is a party or by which the Company or any of its Subsidiaries is bound. Notwithstanding the foregoing, prior to the end of the 123-day period referred to in clause (B)(ii) of this Section 8.02, none of the Company's obligations under this Indenture shall be discharged. Subsequent to the end of such 123-day period with respect to this Section 8.02, the Company's obligations in Sections 2.02, 2.03, 2.04, 2.05, 2.06, 2.07, 4.01, 4.05, 7.06, 7.10, 8.04, 8.05, 8.06, 8.08 and Article 10 shall survive until the Notes are no longer outstanding. Thereafter, only the Company's obligations in Sections 7.06, 8.05 and 8.06 shall survive. If and when a ruling from the Internal Revenue Service or an Opinion of Counsel referred to in clause (B)(i) of this Section 8.02 may be provided specifically without regard to, and not in reliance upon, the continuance of the Company's obligations under Section 4.01, then the Company's obligations under such Section 4.01 shall cease upon delivery to the Trustee of such ruling or Opinion of Counsel and compliance with the other conditions precedent provided for herein relating to the defeasance contemplated by this Section 8.02. After the 123 day period referred to in clause (B)(ii) of this Section 8.02, the Trustee upon Company Order shall acknowledge in writing the discharge of the Company's obligations under the Notes and this Indenture except for those surviving obligations in the immediately preceding paragraph. SECTION 8.03 Defeasance of Certain Obligations. The Company may omit to comply with any term, provision or condition set forth in clause 4.07 upon: (a) the deposit, in trust, with the Trustee (or another trustee satisfying the requirements of Section 7.10 hereof) of money and/or U.S. Government Obligations that, through the payment of interest and principal in respect thereof in accordance with their terms, will provide money in an amount sufficient in the opinion of a nationally recognized independent public accounting firm to pay the principal of, premium, if any, and accrued interest on the Notes on the Stated Maturity of such payments in accordance with the terms of this Indenture and the Notes; (b) the satisfaction of the provisions described in clauses B(ii), (C) and (D) of Section 8.02 hereof; (c) delivery by the Company to the Trustee of an Opinion of Counsel to the effect that, the Holders will not recognize income, gain or loss for federal income tax purposes as a result of such deposit and defeasance and will be subject to federal income tax on the same amount and in the same manner and at the same times as would have been the case if such deposit and defeasance had not occurred; and (d) the Company shall have delivered to the Trustee an Officers' Certificate and an Opinion of Counsel, in each case stating that all conditions precedent provided for herein relating to the defeasance contemplated by this Section 8.03 have been complied with. SECTION 8.04 Application of Trust Money. Subject to Section 8.06, the Trustee or Paying Agent shall hold in trust money or U.S. Government Obligations deposited 51

with it pursuant to Section 8.01, 8.02 or 8.03, as the case may be, and shall apply the deposited money and the money from U.S. Government Obligations in accordance with the Notes and this Indenture to the payment of principal of, premium, if any, and interest on the Notes; but such money need not be segregated from other funds except to the extent required by law. SECTION 8.05 Reinstatement. If the Trustee or the Paying Agent is unable to apply any money or U.S. Government Obligations in accordance with Section 8.01, 8.02 or 8.03, as the case may be, by reason of any legal proceeding or by reason of any order or judgment of any court or governmental authority enjoining, restraining or otherwise prohibiting such application, the Company's obligations under this Indenture and the Notes shall be revived and reinstated as though no deposit had occurred pursuant to Section 8.01, 8.02 or 8.03, as the case may be, until such time as the Trustee or Paying Agent is permitted to apply all such money or U.S. Government Obligations in accordance with Section 8.01, 8.02 or 8.03, as the case may be; provided that, if the Company has made any payment of principal of, premium, if any, or interest on any Notes because of the reinstatement of its obligations, the Company shall be subrogated to the rights of the Holders of such Notes to receive such payment from the money or U.S. Government Obligations held by the Trustee or Paying Agent. SECTION 8.06 Defeasance and Certain Other Events of Default. In the event that the Company exercises its option to omit compliance with certain covenants and provisions of this Indenture with respect to the Notes pursuant to Section 8.03 and such Notes are declared due and payable because of the occurrence of an Event of Default that remains applicable, the amount of money and/or U.S. Government Obligations on deposit with the Trustee will be sufficient to pay amounts due on such Notes at the time of their Stated Maturity. If, in the event the Company exercises its option to omit compliance with certain covenants and provisions of this Indenture with respect to the Notes pursuant to Section 8.03 and such Notes are declared due and payable because of the occurrence of an Event of Default that remains applicable, the amount of money and/or U.S. Government Obligations on deposit with the Trustee is insufficient to pay amounts due on the Notes at the time of the acceleration resulting from such Events of Default pursuant to Section 6.02, the Company will remain liable for such payments. SECTION 8.07 Repayment of the Company. The Trustee and the Paying Agent shall return to the Company upon written request any money or securities held by them for the payment of any amount with respect to the Notes that remains unclaimed for two years, subject to applicable unclaimed property law. After return to the Company, Holders entitled to the money or securities must look to the Company for payment as general creditors unless an applicable abandoned property law designates another person and the Trustee and the Paying Agent shall have no further liability to the Noteholders with respect to such money or securities for that period commencing after the return thereof. SECTION 8.08 Conversion of Notes Upon Discharge. Notwithstanding any satisfaction, defeasance or discharge of this Indenture pursuant to the provisions of this Article 8, for so long as any of the Notes are outstanding, the conversion right of Noteholders set forth in this Indenture shall not expire until the close of business on October 17, 2008 and the Company shall remain obligated to issue duly authorized, fully paid and nonassessable shares of Common Stock upon conversion of the Notes in accordance with the terms of this Indenture. 52

ARTICLE 9 AMENDMENTS SECTION 9.01 Without Consent of Holders. The Company and the Trustee may amend this Indenture or the Notes without the consent of any Noteholder for the purposes of, among other things: (1) adding to the Company's covenants or obligations under this Indenture for the benefit of the Holders; (2) surrendering any right, power or option conferred upon the Company by this Indenture; (3) providing for conversion rights of Holders if any reclassification or change of Common Stock or any consolidation, merger or sale of all or substantially all of the Company's assets occurs; (4) providing for the assumption of the Company's obligations to the Holders in the case of a merger, consolidation, conveyance, transfer or lease; (5) reducing the Conversion Price, provided that the reduction will not adversely affect the interests of Holders in any material respect; (6) complying with the requirements of the SEC in order to effect or maintain the qualification of this Indenture under the TIA; (7) making any changes or modifications to this Indenture necessary in connection with the registration of the Notes under the Securities Act as contemplated by the registration rights agreement, provided that this action does not adversely affect the interests of the Holders in any material respect; (8) curing any ambiguity or correcting or supplementing any defective provision contained in this Indenture; provided that such modification or amendment does not, in the good faith opinion of the Board of Directors and the Trustee, adversely affect the interests of the Holders in any material respect; (9) adding or modifying any other provisions which the Company and the Trustee may deem necessary or desirable and which will not adversely affect the interests of the Holders in any material respect; or (10) to evidence and provide for the acceptance of appointment of a successor Trustee. SECTION 9.02 With Consent of Holders. With the written consent of the Holders of at least a majority in aggregate principal amount of the Notes at the time outstanding, the Company and the Trustee may amend this Indenture or the Notes. However, without the consent of each Noteholder affected, an amendment to this Indenture or the Notes may not: 53

(1) change the maturity of the principal of or any installment of interest on any Note (including any payment of liquidated damages); (2) reduce the principal amount of, or any premium or interest on (including any payment of liquidated damages), any Note; (3) change the currency of payment of such Note or interest thereon; (4) impair the right to institute suit for the enforcement of any payment on or with respect to any Note; (5) modify the Company's obligations to maintain an office or agency in New York City; (6) except as otherwise permitted or contemplated by provisions concerning corporate reorganizations, adversely affect the repurchase option of Holders upon a Change of Control or the conversion rights of Holders; (7) modify the subordination provisions of the Notes in a manner adverse to the Holders; or (8) reduce the percentage in aggregate principal amount of Notes outstanding necessary to modify or amend this Indenture or to waive any past default. It shall not be necessary for the consent of the Holders under this Section 9.02 to approve the particular form of any proposed amendment, but it shall be sufficient if such consent approves the substance thereof. After an amendment under this Section 9.02 becomes effective, the Company shall mail to each Holder a notice briefly describing the amendment. SECTION 9.03 Compliance with Trust Indenture Act. Every supplemental indenture executed pursuant to this Article shall comply with the TIA. SECTION 9.04 Revocation and Effect of Consents, Waivers and Actions. Until an amendment, waiver or other action by Holders becomes effective, a consent thereto by a Holder of a Note hereunder is a continuing consent by the Holder and every subsequent Holder of that Note or portion of the Note that evidences the same obligation as the consenting Holder's Note, even if notation of the consent, waiver or action is not made on the Note. However, any such Holder or subsequent Holder may revoke the consent, waiver or action as to such Holder's Note or portion of the Note if the Trustee receives the notice of revocation before the date the amendment, waiver or action becomes effective. After an amendment, waiver or action becomes effective, it shall bind every Noteholder. SECTION 9.05 Notation on or Exchange of Notes. Notes authenticated and delivered after the execution of any supplemental indenture pursuant to this Article may, and shall if required by the Trustee, bear a notation in form approved by the Trustee as to any matter provided for in such supplemental indenture. If the Company shall so determine, new Notes so 54

modified as to conform, in the opinion of the Trustee and the Board of Directors, to any such supplemental indenture may be prepared and executed by the Company and authenticated and delivered by the Trustee in exchange for outstanding Notes. SECTION 9.06 Trustee to Sign Supplemental Indentures. The Trustee shall sign any supplemental indenture authorized pursuant to this Article 9 if the amendment contained therein does not adversely affect the rights, duties, liabilities or immunities of the Trustee. If it does, the Trustee may, but need not, sign such supplemental indenture. In signing such supplemental indenture the Trustee shall be entitled to receive, and (subject to the provisions of Section 7.01) shall be fully protected in relying upon, an Officers' Certificate and an Opinion of Counsel stating that such amendment is authorized or permitted by this Indenture. SECTION 9.07 Effect of Supplemental Indentures. Upon the execution of any supplemental indenture under this Article, this Indenture shall be modified in accordance therewith, and such supplemental indenture shall form a part of this Indenture for all purposes; and every Holder of Notes theretofore or thereafter authenticated and delivered hereunder shall be bound thereby. ARTICLE 10 CONVERSION SECTION 10.01 Conversion Right and Conversion Price. Subject to and upon compliance with the provisions of this Article, at the option of the Holder thereof, any Note or any portion of the principal amount thereof which is $1,000 or an integral multiple of $1,000 may be converted at the principal amount thereof, or of such portion thereof, into duly authorized, fully paid and nonassessable shares of Common Stock, at the Conversion Price, determined as hereinafter provided, in effect at the time of conversion. Such conversion right shall expire at the close of business on October 17, 2008. In case a Note or portion thereof is called for redemption, such conversion right in respect of the Note or the portion so called, shall expire at the close of business on the Business Day preceding the Redemption Date, unless the Company defaults in making the payment due upon redemption. In the case of a Change of Control for which the Holder exercises its repurchase right with respect to a Note or portion thereof, such conversion right in respect of the Note or portion thereof shall expire at the close of business on the Business Day immediately preceding the Change of Control Repurchase Date. The price at which shares of Common Stock shall be delivered upon conversion (the "Conversion Price") shall be initially equal to $30.2512 per share of Common Stock. The Conversion Price shall be adjusted in certain instances as provided in paragraphs (a), (b), (c), (d), (e), (f), (h) and (i) of Section 10.04 hereof. SECTION 10.02 Exercise of Conversion Right. To exercise the conversion right, the Holder of any Note to be converted shall surrender such Note duly endorsed or assigned to the Company or in blank, at the office of any Conversion Agent, accompanied by a duly signed conversion notice substantially in the form attached to the Note to the Company 55

stating that the Holder elects to convert such Note or, if less than the entire principal amount thereof is to be converted, the portion thereof to be converted. Notes surrendered for conversion, other than those called for Provisional Redemption or Optional Redemption, during the period from the close of business on any Regular Record Date to the opening of business on the next succeeding Interest Payment Date shall be accompanied by payment in New York Clearing House funds or other funds acceptable to the Company of an amount equal to the interest to be received on such Interest Payment Date on the principal amount of Notes being surrendered for conversion. No such payment will be required if the Notes are called for Provisional Redemption or Optional Redemption. Notes shall be deemed to have been converted immediately prior to the close of business on the day of surrender of such Notes for conversion in accordance with the foregoing provisions, and at such time the rights of the Holders of such Notes as Holders shall cease, and the Person or Persons entitled to receive the Common Stock issuable upon conversion shall be treated for all purposes as the record holder or holders of such Common Stock at such time. As promptly as practicable on or after the conversion date, the Company shall cause to be issued and delivered to such Conversion Agent a certificate or certificates for the number of full shares of Common Stock issuable upon conversion, together with payment in lieu of any fraction of a share as provided in Section 10.03 hereof. In the case of any Note which is converted in part only, upon such conversion the Company shall execute and the Trustee shall authenticate and deliver to the Holder thereof, at the expense of the Company, a new Note or Notes of authorized denominations in aggregate principal amount equal to the unconverted portion of the principal amount of such Notes. If shares of Common Stock to be issued upon conversion of a Restricted Note, or securities to be issued upon conversion of a Restricted Note in part only, are to be registered in a name other than that of the Holder of such Restricted Note, such Holder must deliver to the Conversion Agent a certificate in substantially the form set forth in the form of Note set forth in Exhibit A annexed hereto, dated the date of surrender of such Restricted Note and signed by such Holder, as to compliance with the restrictions on transfer applicable to such Restricted Note. Neither the Trustee nor any Conversion Agent, Registrar or Transfer Agent shall be required to register in a name other than that of the Holder shares of Common Stock or Notes issued upon conversion of any such Restricted Note not so accompanied by a properly completed certificate. The Company hereby initially appoints the Trustee as the Conversion Agent. SECTION 10.03 Fractions of Shares. No fractional shares of Common Stock shall be issued upon conversion of any Note or Notes. If more than one Note shall be surrendered for conversion at one time by the same Holder, the number of full shares which shall be issued upon conversion thereof shall be computed on the basis of the aggregate principal amount of the Notes (or specified portions thereof) so surrendered. Instead of any fractional share of Common Stock which would otherwise be issued upon conversion of any Note or Notes (or specified portions thereof), the Company shall pay a cash adjustment in respect of such fraction (calculated to the nearest one-100th of a share) in an amount equal to the same fraction 56

of the quoted price of the Common Stock as of the Trading Day preceding the date of conversion. SECTION 10.04 Adjustment of Conversion Price. The Conversion Price shall be subject to adjustments, calculated by the Company, from time to time as follows: (a) In case the Company shall hereafter pay a dividend or make a distribution to all holders of the outstanding Common Stock in shares of Common Stock, the Conversion Price in effect at the opening of business on the date following the date fixed for the determination of holders of Common Stock entitled to receive such dividend or other distribution shall be reduced by multiplying such Conversion Price by a fraction: (1) the numerator of which shall be the number of shares of Common Stock outstanding at the close of business on the Record Date (as defined in Section 10.4(g)) fixed for such determination, and (2) the denominator of which shall be the sum of such number of shares and the total number of shares constituting such dividend or other distribution payable to the holders of Common Stock. Such reduction shall become effective immediately after the opening of business on the day following the Record Date. If any dividend or distribution of the type described in this Section 10.04(a) is declared but not so paid or made, the Conversion Price shall again be adjusted to the Conversion Price which would then be in effect if such dividend or distribution had not been declared. (b) In case the outstanding shares of Common Stock shall be subdivided into a greater number of shares of Common Stock, the Conversion Price in effect at the opening of business on the day following the day upon which such subdivision becomes effective shall be proportionately reduced, and conversely, in case outstanding shares of Common Stock shall be combined into a smaller number of shares of Common Stock, the Conversion Price in effect at the opening of business on the day following the day upon which such combination becomes effective shall be proportionately increased, such reduction or increase, as the case may be, to become effective immediately after the opening of business on the day following the day upon which such subdivision or combination becomes effective. (c) In case the Company shall issue rights or warrants (other than any rights or warrants referred to in Section 10.04(d)) to all holders of its outstanding shares of Common Stock entitling them to subscribe for or purchase shares of Common Stock (or securities convertible into Common Stock) at a price per share (or having a conversion price per share) less than the Current Market Price (as defined in Section 10.04(g)) on the Record Date fixed for the determination of stockholders entitled to receive such rights or warrants, the Conversion Price shall be adjusted so that the same shall equal the price determined by multiplying the Conversion Price in effect at the opening of business on the date after such Record Date by a fraction: 57

(1) the numerator of which shall be the number of shares of Common Stock outstanding at the close of business on the Record Date plus the number of shares which the aggregate offering price of the total number of shares so offered for subscription or purchase (or the aggregate conversion price of the convertible securities so offered) would purchase at such Current Market Price, and (2) the denominator of which shall be the number of shares of Common Stock outstanding on the close of business on the Record Date plus the total number of additional shares of Common Stock so offered to the holders of Common Stock for subscription or purchase (or into which the convertible securities so offered are convertible). Such adjustment shall become effective immediately after the opening of business on the day following the Record Date fixed for determination of stockholders entitled to receive such rights or warrants. To the extent that shares of Common Stock (or securities convertible into Common Stock) are not delivered pursuant to such rights or warrants, upon the expiration or termination of such rights or warrants the Conversion Price shall be readjusted to the Conversion Price which would then be in effect had the adjustments made upon the issuance of such rights or warrants been made on the basis of the delivery of only the number of shares of Common Stock (or securities convertible into Common Stock) actually delivered. In the event that such rights or warrants are not so issued, the Conversion Price shall again be adjusted to be the Conversion Price which would then be in effect if such date fixed for the determination of holders of Common Stock entitled to receive such rights or warrants had not been fixed. In determining whether any rights or warrants entitle the holders to subscribe for or purchase shares of Common Stock at less than such Current Market Price, and in determining the aggregate offering price of such shares of Common Stock, there shall be taken into account any consideration received for such rights or warrants, the value of such consideration if other than cash, to be determined by the Board of Directors. (d) In case the Company shall, by dividend or otherwise, distribute to all holders of its Common Stock shares of any class of Capital Stock of the Company (other than any dividends or distributions to which Section 10.04(a) or Section 10.4(g) applies) or evidences of its indebtedness, cash or other assets, including securities, but excluding (1) any rights or warrants referred to in Section 10.04(c), (2) any stock, securities or other property or assets (including cash) distributed in connection with a reclassification, merger, consolidation, statutory share exchange, combination, sale or conveyance to which Section 10.11 hereof applies and (3) dividends and distributions paid exclusively in cash (the securities described in foregoing clauses (1), (2) and (3) hereinafter in this Section 10.04(d) called the "excluded securities"), then, in each such case, subject to the second succeeding paragraph of this Section 10.04(d), the Conversion Price shall be adjusted so that the same shall be equal to the price determined by multiplying the Conversion Price in effect immediately prior to the close of business on the Record Date (as defined in Section 10.04(g)) with respect to such distribution by a fraction: (1) the numerator of which shall be the Current Market Price (determined as provided in Section 10.04(g)) on such date less the fair market 58

value (as determined by the Board of Directors, whose determination shall be conclusive and set forth in a Board Resolution) on such date of the portion of the securities so distributed (other than excluded securities) applicable to one share of Common Stock (determined on the basis of the number of shares of the Common Stock outstanding on the Record Date), and (2) the denominator of which shall be such Current Market Price. Such reduction shall become effective immediately prior to the opening of business on the day following the Record Date. However, in the event that the then fair market value (as so determined) of the portion of the securities so distributed (other than excluded securities) applicable to one share of Common Stock is equal to or greater than the Current Market Price on the Record Date, in lieu of the foregoing adjustment, adequate provision shall be made so that each Holder shall have the right to receive upon conversion of a Note (or any portion thereof) the amount of securities so distributed (other than excluded securities) such Holder would have received had such Holder converted such Note (or portion thereof) immediately prior to such Record Date. In the event that such dividend or distribution is not so paid or made, the Conversion Price shall again be adjusted to be the Conversion Price which would then be in effect if such dividend or distribution had not been declared. If the Board of Directors determines the fair market value of any distribution for purposes of this Section 10.04(d) by reference to the actual or when issued trading market for any securities comprising all or part of such distribution (other than excluded securities), it must in doing so consider the prices in such market over the same period (the "Reference Period") used in computing the Current Market Price pursuant to Section 10.04(g) to the extent possible, unless the Board of Directors in a Board Resolution determines in good faith that determining the fair market value during the Reference Period would not be in the best interest of the Holder. Rights or warrants distributed by the Company to all holders of Common Stock entitling the holders thereof to subscribe for or purchase shares of the Company's Capital Stock (either initially or under certain circumstances), which rights or warrants, until the occurrence of a specified event or events ("Trigger Event"): (i) are deemed to be transferred with such shares of Common Stock; (ii) are not exercisable; and (iii) are also issued in respect of future issuances of Common Stock, shall be deemed not to have been distributed for purposes of this Section 10.04(d) (and no adjustment to the Conversion Price under this Section 10.04(d) will be required) until the occurrence of the earliest Trigger Event. If such right or warrant is subject to subsequent events, upon the occurrence of which such right or warrant shall become exercisable to purchase different securities, evidences of indebtedness or other assets or entitle the holder to purchase a different number or amount of the foregoing or to purchase any of the foregoing at a different purchase price, then the occurrence of each such event shall 59

be deemed to be the date of issuance and record date with respect to a new right or warrant (and a termination or expiration of the existing right or warrant without exercise by the holder thereof). In addition, in the event of any distribution (or deemed distribution) of rights or warrants, or any Trigger Event or other event (of the type described in the preceding sentence) with respect thereto, that resulted in an adjustment to the Conversion Price under this Section 10.04(d): (1) in the case of any such rights or warrants which shall all have been redeemed or repurchased without exercise by any holders thereof, the Conversion Price shall be readjusted upon such final redemption or repurchase to give effect to such distribution or Trigger Event, as the case may be, as though it were a cash distribution, equal to the per share redemption or repurchase price received by a holder of Common Stock with respect to such rights or warrant (assuming such holder had retained such rights or warrants), made to all holders of Common Stock as of the date of such redemption or repurchase, and (2) in the case of such rights or warrants all of which shall have expired or been terminated without exercise, the Conversion Price shall be readjusted as if such rights and warrants had never been issued. For purposes of this Section 10.04(d) and Sections 10.04(a), 10.04(b) and 10.04(c), any dividend or distribution to which this Section 10.04(d) is applicable that also includes shares of Common Stock, a subdivision or combination of Common Stock to which Section 10.04(b) applies, or rights or warrants to subscribe for or purchase shares of Common Stock to which Section 10.04(c) applies (or any combination thereof), shall be deemed instead to be: (3) a dividend or distribution of the evidences of indebtedness, assets, shares of Capital Stock, rights or warrants other than such shares of Common Stock, such subdivision or combination or such rights or warrants to which Sections 10.04(a), 10.04(b) and 10.04(c) apply, respectively (and any Conversion Price reduction required by this Section 10.04(d) with respect to such dividend or distribution shall then be made), immediately followed by (4) a dividend or distribution of such shares of Common Stock, such subdivision or combination or such rights or warrants (and any further Conversion Price reduction required by Sections 10.04(a), 10.04(b) and 10.04(c) with respect to such dividend or distribution shall then be made), except: (A) the Record Date of such dividend or distribution shall be substituted as (x) "the date fixed for the determination of stockholders entitled to receive such dividend or other distribution", "Record Date fixed for such determinations" and "Record Date" within the meaning of Section 10.04(a), (y) "the day upon which such subdivision becomes effective" and "the day upon which such combination becomes effective" within the meaning of Section 10.04(b), and (z) as "the date fixed for the determination of stockholders entitled to receive such rights or warrants", 60

"the Record Date fixed for the determination of the stockholders entitled to receive such rights or warrants" and such "Record Date" within the meaning of Section 10.04(c), and (B) any shares of Common Stock included in such dividend or distribution shall not be deemed "outstanding at the close of business on the date fixed for such determination" within the meaning of Section 10.04(a) and any reduction or increase in the number of shares of Common Stock resulting from such subdivision or combination shall be disregarded in connection with such dividend or distribution. With respect to any shareholder rights plan existing on the date hereof or in the event that the Company implements any other shareholder rights plan, upon conversion of the Notes the Holders will receive, in addition to the Common Stock issuable upon such conversion, the rights issued under such rights plan (notwithstanding the occurrence of an event causing such rights to separate from the Common Stock at or prior to the time of conversion); provided, a Holder who is a holder of Common Stock (or direct or indirect interests therein) at the time of conversion, but who is not entitled as such a holder to such rights pursuant to the terms of any such plan, shall not be eligible to receive any such rights hereunder. Any distribution of rights or warrants pursuant to a shareholder rights plan complying with the requirements set forth in the immediately preceding sentence of this paragraph shall not constitute a distribution of rights or warrants for the purposes of the other provisions of this section 10.04(d). (e) In case the Company shall, by dividend or otherwise, distribute to all holders of its Common Stock cash (excluding any cash that is distributed upon a reclassification, merger, consolidation, statutory share exchange, combination, sale or conveyance to which Section 10.11 hereof applies or as part of a distribution referred to in Section 10.04(d) hereof), in an aggregate amount that, combined together with: (1) the aggregate amount of any other such distributions to all holders of Common Stock made exclusively in cash within the 12 months preceding the date of payment of such distribution, and in respect of which no adjustment pursuant to this Section 10.04(e) has been made, and (2) the aggregate of any cash plus the fair market value (as determined by the Board of Directors, whose determination shall be conclusive and set forth in a Board Resolution) of consideration payable in respect of any tender offer by the Company or any of its subsidiaries for all or any portion of the Common Stock concluded within the 12 months preceding the date of such distribution, and in respect of which no adjustment pursuant to Section 10.04(f) hereof has been made, exceeds 5% of the product of the Current Market Price (determined as provided in Section 10.04(g)) on the Record Date with respect to such distribution times the number of shares of Common Stock outstanding on such date, then and in each such case, immediately after the close of business on such date, the Conversion Price shall be reduced so that the same shall equal the price determined by multiplying the Conversion Price in effect immediately prior to the close of business on such Record Date by a fraction: 61

(i) the numerator of which shall be equal to the Current Market Price on the Record Date less an amount equal to the quotient of (x) the excess of such combined amount over such 5% and (y) the number of shares of Common Stock outstanding on the Record Date, and (ii) the denominator of which shall be equal to the Current Market Price on such date. However, in the event that the then fair market value (as so determined) of the portion of the securities so distributed (other than excluded securities) applicable to one share of Common Stock is equal to or greater than the Current Market Price on the Record Date, in lieu of the foregoing adjustment, adequate provision shall be made so that each Holder shall have the right to receive upon conversion of a Note (or any portion thereof) the amount of cash such Holder would have received had such Holder converted such Note (or portion thereof) immediately prior to such Record Date. In the event that such dividend or distribution is not so paid or made, the Conversion Price shall again be adjusted to be the Conversion Price which would then be in effect if such dividend or distribution had not been declared. (f) In case a tender offer made by the Company or any of its subsidiaries for all or any portion of the Common Stock shall expire and such tender offer (as amended upon the expiration thereof) shall require the payment to stockholders (based on the acceptance (up to any maximum specified in the terms of the tender offer) of Purchased Shares (as defined below)) of an aggregate consideration having a fair market value (as determined by the Board of Directors, whose determination shall be conclusive and set forth in a Board Resolution) that combined together with: (1) the aggregate of the cash plus the fair market value (as determined by the Board of Directors, whose determination shall be conclusive and set forth in a Board Resolution), as of the expiration of such tender offer, of consideration payable in respect of any other tender offers, by the Company or any of its subsidiaries for all or any portion of the Common Stock expiring within the 12 months preceding the expiration of such tender offer and in respect of which no adjustment pursuant to this Section 10.04(f) has been made, and (2) the aggregate amount of any distributions to all holders of the Company's Common Stock made exclusively in cash within 12 months preceding the expiration of such tender offer and in respect of which no adjustment pursuant to Section 10.04(e) has been made, exceeds 5% of the product of the Current Market Price (determined as provided in Section 10.04(g)) as of the last time (the "Expiration Time") tenders could have been made pursuant to such tender offer (as it may be amended) times the number of shares of Common Stock outstanding (including any tendered shares) on the Expiration Time, then, and in each such case, immediately prior to the opening of business on the day after the date of the Expiration Time, the Conversion Price shall be adjusted so that the same shall equal the price determined by multiplying the Conversion Price in effect 62

immediately prior to close of business on the date of the Expiration Time by a fraction: (i) the numerator of which shall be the number of shares of Common Stock outstanding (including any tendered shares) at the Expiration Time multiplied by the Current Market Price of the Common Stock on the Trading Day next succeeding the Expiration Time, and (ii) the denominator shall be the sum of (x) the fair market value (determined as aforesaid) of the aggregate consideration payable to stockholders based on the acceptance (up to any maximum specified in the terms of the tender offer) of all shares of Common Stock validly tendered and not withdrawn as of the Expiration Time (the shares of Common Stock deemed so accepted, up to any such maximum, being referred to as the "Purchased Shares") and (y) the product of the number of shares of Common Stock outstanding (less any Purchased Shares) on the Expiration Time and the Current Market Price of the Common Stock on the Trading Day next succeeding the Expiration Time. Such reduction (if any) shall become effective immediately prior to the opening of business on the day following the Expiration Time. In the event that the Company is obligated to purchase shares pursuant to any such tender offer, but the Company is permanently prevented by applicable law from effecting any such purchases or all such purchases are rescinded, the Conversion Price shall again be adjusted to be the Conversion Price which would then be in effect if such tender offer had not been made. If the application of this Section 10.04(f) to any tender offer would result in an increase in the Conversion Price, no adjustment shall be made for such tender offer under this Section 10.04(f). (g) If, after the date of issuance of the Notes, the Company pays a dividend or makes a distribution to all holders of its Common Stock consisting of Capital Stock of any class or series, or similar equity interests, of or relating to a subsidiary or other business unit of the Company, the Conversion Rate shall be adjusted in accordance with the formula: R' = R x (1 + F/M) where: R' = the adjusted Conversion Rate. R = the current Conversion Rate. "Conversion Rate" means the number of shares of Common Stock issuable upon conversion of $1,000 aggregate principal amount of Notes, which shall initially be 33.0565 shares per $1,000 aggregate principal amount of Notes. 63

M = the average of the Post-Distribution Prices of the Common Stock for the 10 trading days commencing on and including the fifth trading day after the date on which "ex-dividend trading" commences for such dividend or distribution on the principal United States exchange or market which such securities are then listed or quoted (the "Ex-Dividend Date"). F = the fair market value of the securities distributed in respect of each share of Common Stock for which this Section [___] shall mean the number of securities distributed in respect of each share of Common Stock multiplied by the average of the Post-Distribution Prices of those securities distributed for the 10 trading days commencing on and including the fifth trading day after the Ex-Dividend Date. "Post-Distribution Price" of Capital Stock or any similar equity interest on any date means the closing per unit sale price (or, if no closing sale price is reported, the average of the bid and ask prices or, if more than one in either case, the average of the average bid and the average ask prices) on such date for trading of such units on a "when issued" basis without due bills (or similar concept) as reported in the composite transactions for the principal United States securities exchange on which such Capital Stock or equity interest is traded or, if the Capital Stock or equity interest, as the case may be, is not listed on a United States national or regional securities exchange, as reported by the National Association of Securities Dealers Automated Quotation System or by the National Quotation Bureau Incorporated; provided that if on any date such units have not traded on a "when issued" basis, the Post-Distribution Price shall be the closing per unit sale price (or, if no closing sale price is reported, the average of the bid and ask prices or, if more than one in either case, the average of the average bid and the average ask prices) on such date for trading of such units on a "regular way" basis without due bills (or similar concept) as reported in the composite transactions for the principal United States securities exchange on which such Capital Stock or equity interest is traded or, if the Capital Stock or equity interest, as the case may be, is not listed on a United States national or regional securities exchange, as reported by the National Association of Securities Dealers Automated Quotation System or by the National Quotation Bureau Incorporated. In the absence of such quotation, the Company shall be entitled to determine the Post-Distribution Price on the basis of such quotations that reflect the post-distribution value of the Capital Stock or equity interests as it considers appropriate. (h) For purposes of this Section 10.04, the following terms shall have the meanings indicated: (1) "Current Market Price" shall mean the average of the daily Closing Prices per share of Common Stock for the ten consecutive Trading Days immediately prior to the date in question; provided, however, that if: (i) the "ex" date (as hereinafter defined) for any event (other than the issuance or distribution requiring such computation) that requires an adjustment to the Conversion Price pursuant to Section 10.04(a), (b), (c), (d), (e) or (f) occurs during such ten consecutive Trading Days, the Closing Price for each Trading Day prior to the "ex" date for such other event shall be adjusted by multiplying such Closing Price by the same 64

fraction by which the Conversion Price is so required to be adjusted as a result of such other event; (ii) the "ex" date for any event (other than the issuance or distribution requiring such computation) that requires an adjustment to the Conversion Price pursuant to Section 10.04(a), (b), (c), (d), (e) or (f) occurs on or after the "ex" date for the issuance or distribution requiring such computation and prior to the day in question, the Closing Price for each Trading Day on and after the "ex" date for such other event shall be adjusted by multiplying such Closing Price by the reciprocal of the fraction by which the Conversion Price is so required to be adjusted as a result of such other event; and (iii) the "ex" date for the issuance or distribution requiring such computation is prior to the day in question, after taking into account any adjustment required pursuant to clause (i) or (ii) of this proviso, the Closing Price for each Trading Day on or after such "ex" date shall be adjusted by adding thereto the amount of any cash and the fair market value (as determined by the Board of Directors in a manner consistent with any determination of such value for purposes of Section 10.04(d) or (f), whose determination shall be conclusive and set forth in a Board Resolution) of the evidences of indebtedness, shares of Capital Stock or assets being distributed applicable to one share of Common Stock as of the close of business on the day before such "ex" date. For purposes of any computation under Section 10.04(f), the Current Market Price of the Common Stock on any date shall be deemed to be the average of the daily Closing Prices per share of Common Stock for such day and the next two succeeding Trading Days; provided, however, that if the "ex" date for any event (other than the tender offer requiring such computation) that requires an adjustment to the Conversion Price pursuant to Section 10.04(a), (b), (c), (d), (e) or (f) occurs on or after the Expiration Time for the tender or exchange offer requiring such computation and prior to the day in question, the Closing Price for each Trading Day on and after the "ex" date for such other event shall be adjusted by multiplying such Closing Price by the reciprocal of the fraction by which the Conversion Price is so required to be adjusted as a result of such other event. For purposes of this paragraph, the term "ex" date, when used: (A) with respect to any issuance or distribution, means the first date on which the Common Stock trades regular way on the relevant exchange or in the relevant market from which the Closing Price was obtained without the right to receive such issuance or distribution; (B) with respect to any subdivision or combination of shares of Common Stock, means the first date on which the Common Stock trades regular way on such exchange or in such market after the time at which such subdivision or combination becomes effective, and 65

(C) with respect to any tender or exchange offer, means the first date on which the Common Stock trades regular way on such exchange or in such market after the Expiration Time of such offer. Notwithstanding the foregoing, whenever successive adjustments to the Conversion Price are called for pursuant to this Section 10.04, such adjustments shall be made to the Current Market Price as may be necessary or appropriate to effectuate the intent of this Section 10.04 and to avoid unjust or inequitable results as determined in good faith by the Board of Directors. (2) "fair market value" shall mean the amount which a willing buyer would pay a willing seller in an arm's length transaction. (3) "Record Date" shall mean, with respect to any dividend, distribution or other transaction or event in which the holders of Common Stock have the right to receive any cash, securities or other property or in which the Common Stock (or other applicable security) is exchanged for or converted into any combination of cash, securities or other property, the date fixed for determination of stockholders entitled to receive such cash, securities or other property (whether such date is fixed by the Board of Directors or by statute, contract or otherwise). (i) The Company may make such reductions in the Conversion Price, in addition to those required by Section 10.04(a), (b), (c), (d), (e) or (f), as the Board of Directors considers to be advisable to avoid or diminish any income tax to holders of Common Stock or rights to purchase Common Stock resulting from any dividend or distribution of stock (or rights to acquire stock) or from any event treated as such for income tax purposes. To the extent permitted by applicable law, the Company from time to time may reduce the Conversion Price by any amount for any period of time if the period is at least 20 days and the reduction is irrevocable during the period and the Board of Directors determines in good faith that such reduction would be in the best interests of the Company, which determination shall be conclusive and set forth in a Board Resolution. Whenever the Conversion Price is reduced pursuant to the preceding sentence, the Company shall mail to the Trustee and each Holder at the address of such Holder as it appears in the Register a notice of the reduction at least 15 days prior to the date the reduced Conversion Price takes effect, and such notice shall state the reduced Conversion Price and the period during which it will be in effect. (j) No adjustment in the Conversion Price shall be required unless such adjustment would require an increase or decrease of at least 1% in such price; provided, however, that any adjustments which by reason of this Section 10.04(j) are not required to be made shall be carried forward and taken into account in any subsequent adjustment. All calculations under this Article 10 shall be made by the Company and shall be made to the nearest cent or to the nearest one hundredth of a share, as the case may be. No 66

adjustment need be made for a change in the par value or no par value of the Common Stock. (k) In any case in which this Section 10.04 provides that an adjustment shall become effective immediately after a Record Date for an event, the Company may defer until the occurrence of such event (i) issuing to the Holder of any Note converted after such Record Date and before the occurrence of such event the additional shares of Common Stock issuable upon such conversion by reason of the adjustment required by such event over and above the Common Stock issuable upon such conversion before giving effect to such adjustment and (ii) paying to such holder any amount in cash in lieu of any fraction pursuant to Section 10.03 hereof. (l) For purposes of this Section 10.04, the number of shares of Common Stock at any time outstanding shall not include shares held in the treasury of the Company but shall include shares issuable in respect of scrip certificates issued in lieu of fractions of shares of Common Stock. The Company will not pay any dividend or make any distribution on shares of Common Stock held in the treasury of the Company. (m) If the distribution date for the rights provided in the Company's rights agreement, if any, occurs prior to the date a Note is converted, the Holder of the Note who converts such Note after the distribution date is not entitled to receive the rights that would otherwise be attached (but for the date of conversion) to the shares of Common Stock received upon such conversion; provided, however, that an adjustment shall be made to the Conversion Price pursuant to Section 10.04(b) as if the rights were being distributed to the common stockholders of the Company immediately prior to such conversion. If such an adjustment is made and the rights are later redeemed, invalidated or terminated, then a corresponding reversing adjustment shall be made to the Conversion Price, on an equitable basis, to take account of such event. SECTION 10.05 Notice of Adjustments of Conversion Price. Whenever the Conversion Price is adjusted as herein provided (other than in the case of an adjustment pursuant to the second paragraph of Section 10.04(i) for which the notice required by such paragraph has been provided), the Company shall promptly file with the Trustee and any Conversion Agent other than the Trustee an Officers' Certificate setting forth the adjusted Conversion Price and showing in reasonable detail the facts upon which such adjustment is based. Promptly after delivery of such Officers' Certificate, the Company shall prepare a notice stating that the Conversion Price has been adjusted and setting forth the adjusted Conversion Price and the date on which each adjustment becomes effective, and shall mail such notice to each Holder at the address of such Holder as it appears in the Register within 20 days of the effective date of such adjustment. Failure to deliver such notice shall not effect the legality or validity of any such adjustment. SECTION 10.06 Notice Prior to Certain Actions. In case at any time after the date hereof: 67

(1) the Company shall declare a dividend (or any other distribution) on its Common Stock payable otherwise than in cash out of its capital surplus or its consolidated retained earnings; (2) the Company shall authorize the granting to the holders of its Common Stock of rights or warrants to subscribe for or purchase any shares of Capital Stock of any class (or of securities convertible into shares of Capital Stock of any class) or of any other rights; (3) there shall occur any reclassification of the Common Stock of the Company (other than a subdivision or combination of its outstanding Common Stock, a change in par value, a change from par value to no par value or a change from no par value to par value), or any merger, consolidation, statutory share exchange or combination to which the Company is a party and for which approval of any shareholders of the Company is required, or the sale, transfer or conveyance of all or substantially all of the assets of the Company; or (4) there shall occur the voluntary or involuntary dissolution, liquidation or winding up of the Company; the Company shall cause to be filed at each office or agency maintained for the purpose of conversion of Notes pursuant to Section 4.05 hereof, and shall cause to be provided to the Trustee and all Holders in accordance with Section 13.02 hereof, at least 20 days (or 10 days in any case specified in clause (1) or (2) above) prior to the applicable record or effective date hereinafter specified, a notice stating: (A) the date on which a record is to be taken for the purpose of such dividend, distribution, rights or warrants, or, if a record is not to be taken, the date as of which the holders of Common Stock of record to be entitled to such dividend, distribution, rights or warrants are to be determined, or (B) the date on which such reclassification, merger, consolidation, statutory share exchange, combination, sale, transfer, conveyance, dissolution, liquidation or winding up is expected to become effective, and the date as of which it is expected that holders of Common Stock of record shall be entitled to exchange their shares of Common Stock for securities, cash or other property deliverable upon such reclassification, merger, consolidation, statutory share exchange, sale, transfer, dissolution, liquidation or winding up. Neither the failure to give such notice nor any defect therein shall affect the legality or validity of the proceedings or actions described in clauses (1) through (4) of this Section 10.06. SECTION 10.07 Company to Reserve Common Stock. The Company shall at all times use its best efforts to reserve and keep available, free from preemptive rights, out of its authorized but unissued Common Stock, for the purpose of effecting the conversion of Notes, 68

the full number of shares of fully paid and nonassessable Common Stock then issuable upon the conversion of all Notes outstanding. SECTION 10.08 Taxes on Conversions. Except as provided in the next sentence, the Company will pay any and all taxes (other than taxes on income) and duties that may be payable in respect of the issue or delivery of shares of Common Stock on conversion of Notes pursuant hereto. A Holder delivering a Note for conversion shall be liable for and will be required to pay any tax or duty which may be payable in respect of any transfer involved in the issue and delivery of shares of Common Stock in a name other than that of the Holder of the Note or Notes to be converted, and no such issue or delivery shall be made unless the Person requesting such issue has paid to the Company the amount of any such tax or duty, or has established to the satisfaction of the Company that such tax or duty has been paid. SECTION 10.09 Covenant as to Common Stock. The Company covenants that all shares of Common Stock which may be issued upon conversion of Notes will upon issue be fully paid and nonassessable and, except as provided in Section 10.08, the Company will pay all taxes, liens and charges with respect to the issue thereof. SECTION 10.10 Cancellation of Converted Notes. All Notes delivered for conversion shall be delivered to the Trustee to be canceled by or at the direction of the Trustee, which shall dispose of the same as provided in Section 2.10. SECTION 10.11 Effect of Reclassification, Consolidation, Merger or Sale. If any of following events occur, namely: (1) any reclassification or change of the outstanding shares of Common Stock (other than a change in par value, or from par value to no par value, or from no par value to par value, or as a result of a subdivision or combination), (2) any merger, consolidation, statutory share exchange or combination of the Company with another corporation as a result of which holders of Common Stock shall be entitled to receive stock, securities or other property or assets (including cash or any combination thereof) with respect to or in exchange for such Common Stock or (3) any sale or conveyance of the properties and assets of the Company as, or substantially as, an entirety to any other corporation as a result of which holders of Common Stock shall be entitled to receive stock, securities or other property or assets (including cash or any combination thereof) with respect to or in exchange for such Common Stock, the Company or the successor or purchasing corporation, as the case may be, shall execute with the Trustee a supplemental indenture (which shall comply with the TIA as in force at the date of execution of such supplemental indenture if such supplemental indenture is then required to so comply) providing that such Note shall be convertible into the kind and amount of shares of stock and other securities or property or assets (including cash or any combination thereof) which such Holder would have been entitled to receive upon such reclassification, change, 69

merger, consolidation, statutory share exchange, combination, sale or conveyance had such Notes been converted into Common Stock immediately prior to such reclassification, change, merger, consolidation, statutory share exchange, combination, sale or conveyance assuming such holder of Common Stock did not exercise its rights of election, if any, as to the kind or amount of securities, cash or other property receivable upon such reclassification, change, merger, consolidation, statutory share exchange, combination, sale or conveyance (provided that, if the kind or amount of securities, cash or other property receivable upon such reclassification, change, merger, consolidation, statutory share exchange, combination, sale or conveyance is not the same for each share of Common Stock in respect of which such rights of election shall not have been exercised ("Non-Electing Share"), then for the purposes of this Section 10.11 the kind and amount of securities, cash or other property receivable upon such reclassification, change, merger, consolidation, statutory share exchange, combination, sale or conveyance for each Non-Electing Share shall be deemed to be the kind and amount so receivable per share by a plurality of the Non-Electing Shares). Such supplemental indenture shall provide for adjustments which shall be as nearly equivalent as may be practicable to the adjustments provided for in this Article 10. If, in the case of any such reclassification, change, merger, consolidation, statutory share exchange, combination, sale or conveyance, the stock or other securities and assets receivable thereupon by a holder of shares of Common Stock includes shares of stock or other securities and assets of a corporation other than the successor or purchasing corporation, as the case may be, in such reclassification, change, merger, consolidation, statutory share exchange, combination, sale or conveyance, then such supplemental indenture shall also be executed by such other corporation and shall contain such additional provisions to protect the interests of the Holders of the Notes as the Board of Directors shall reasonably consider necessary by reason of the foregoing, including to the extent practicable the provisions providing for the repurchase rights set forth in Section 3.10 hereof. The Company shall cause notice of the execution of such supplemental indenture to be mailed to each Holder, at the address of such Holder as it appears on the Register, within 20 days after execution thereof. Failure to deliver such notice shall not affect the legality or validity of such supplemental indenture. The above provisions of this Section 10.11 shall similarly apply to successive reclassifications, mergers, consolidations, statutory share exchanges, combinations, sales and conveyances. If this Section 10.11 applies to any event or occurrence, Section 10.04 hereof shall not apply. SECTION 10.12 Responsibility of Trustee for Conversion Provisions. The Trustee, subject to the provisions of Section 7.01 hereof, and any Conversion Agent shall not at any time be under any duty or responsibility to any Holder of Notes to determine whether any facts exist which may require any adjustment of the Conversion Price, or with respect to the nature or intent of any such adjustments when made, or with respect to the method employed, or herein or in any supplemental indenture provided to be employed, in making the same. Neither the Trustee, subject to the provisions of Section 7.01 hereof, nor any Conversion Agent shall be accountable with respect to the validity or value (of the kind or amount) of any Common Stock, or of any other securities or property, which may at any time be issued or delivered upon the conversion of any Note; and it or they do not make any representation with respect thereto. Neither the Trustee, subject to the provisions of Section 7.01 hereof, nor any Conversion Agent 70

shall be responsible for any failure of the Company to make any cash payment or to issue, transfer or deliver any shares of stock or share certificates or other securities or property upon the surrender of any Note for the purpose of conversion; and the Trustee, subject to the provisions of Section 7.01 hereof, and any Conversion Agent shall not be responsible or liable for any failure of the Company to comply with any of the covenants of the Company contained in this Article. ARTICLE 11 SUBORDINATION SECTION 11.01 Agreement to Subordinate. The Company agrees, and each Holder by accepting a Note agrees, that the Indebtedness, interest and other obligations of any kind evidenced by the Notes and this Indenture (except as set forth in this Section 11, with respect to Permitted Payments) are subordinated in right of payment, to the extent and in the manner provided in this Article 11, to the prior payment in full in cash or cash equivalents of all Senior Indebtedness (whether outstanding on the date hereof or hereafter created, incurred, assumed or guaranteed), and that the subordination is for the benefit of the holders of Senior Indebtedness. SECTION 11.02 Liquidation; Dissolution; Bankruptcy. In the event of any insolvency or bankruptcy case or proceeding, or any receivership, liquidation, reorganization or other similar case or proceeding in connection therewith, relating to the Company or to its assets, or any liquidation, dissolution or other winding-up of the Company, whether voluntary or involuntary, or any assignment for the benefit of creditors or other marshaling of assets or liabilities of the Company (except in connection with the consolidation or merger of the Company or its liquidation or dissolution following the conveyance, transfer or lease of all or substantially all of its properties and assets upon the terms and conditions described in Article 5), the holders of Senior Indebtedness will be entitled to receive payment in full of all Senior Indebtedness, or provision shall be made for such payment in full, before the Noteholders will be entitled to receive any payment or distribution of any kind or character (other than Permitted Payments and Permitted Junior Securities) on account of principal of, or premium, if any, or additional interest, if any, or interest on the Notes; and any payment or distribution of assets of the Company of any kind or character, whether in cash, property or securities (other than a payment or distribution in the form of Permitted Payments and Permitted Junior Securities), by set-off or otherwise, to which the Noteholders or the Trustee would be entitled but for the provisions of this Article 11 shall be paid by the liquidating trustee or agent or other person making such payment or distribution, whether a trustee in bankruptcy, a receiver or liquidating trustee or otherwise, directly to the holders of Senior Indebtedness or their representative or representatives ratably according to the aggregate amounts remaining unpaid on account of the Senior Indebtedness to the extent necessary to make payment in full of all Senior Indebtedness remaining unpaid, after giving effect to any concurrent payment or distribution to the holders of such Senior Indebtedness. SECTION 11.03 Default on Designated Senior Indebtedness. (a) No payment or distribution of any assets of the Company of any kind or character, whether in cash, property or securities (other than Permitted Payments and Permitted Junior Securities), may be made by or on behalf of the Company on account of principal of, premium, if any, or interest on 71

the Notes or on account of the purchase, redemption or other acquisition of Notes upon the occurrence of any default in payment (whether at Stated Maturity, upon scheduled installment, by acceleration or otherwise) of principal of, premium, if any, or interest on Designated Senior Indebtedness beyond any applicable grace period (a "Payment Default") until such Payment Default shall have been cured or waived in writing or shall have ceased to exist or such Designated Senior Indebtedness shall have been discharged or paid in full in cash or cash equivalents. (b) No payment or distribution of any assets of the Company of any kind or character, whether in cash, property or securities (other than Permitted Payments and Permitted Junior Securities), may be made by or on behalf of the Company on account of principal of, premium, if any, or interest on the Notes or on account of the purchase, redemption or other acquisition of Notes for the period specified below (a "Payment Blockage Period") upon the occurrence of any default or event of default with respect to any Designated Senior Indebtedness other than any Payment Default pursuant to which the maturity thereof may be accelerated (a "Non-Payment Default") and receipt by the Trustee of written notice thereof from the Company or the trustee or other representative of holders of Designated Senior Indebtedness. The Payment Blockage Period will commence upon the date of receipt by the Trustee of written notice from the trustee or such other representative of the holders of the Designated Senior Indebtedness in respect of which the Non-Payment Default exists and shall end on the earliest of: (i) 179 days thereafter (provided that any Designated Senior Indebtedness as to which notice was given shall not theretofore have been accelerated); (ii) the date on which such Non-Payment Default is cured, waived or ceases to exist; (iii) the date on which such Designated Senior Indebtedness is discharged or paid in full; or (iv) the date on which such Payment Blockage Period shall have been terminated by written notice to the Trustee or the Company from the trustee or such other representative initiating such Payment Blockage Period, after which the Company will resume making any and all required payments in respect of the Notes, including any missed payments. In any event, not more than one Payment Blockage Period may be commenced during any period of 365 consecutive days. No Non-Payment Default that existed or was continuing on the date of the commencement of any Payment Blockage Period will be, or can be made, the basis for the commencement of a subsequent Payment Blockage Period, unless such Non-Payment Default has been cured or waived for a period of not less than 90 consecutive days subsequent to the commencement of such initial Payment Blockage Period. SECTION 11.04 Acceleration of Notes. If payment of the Notes is accelerated because of an Event of Default, the Company shall promptly notify holders of Senior Indebtedness of the acceleration. 72

SECTION 11.05 When Distribution Must Be Paid Over. In the event that, notwithstanding the provisions of Sections 11.02 and 11.03, any payment or distribution of any kind or character, whether in cash, property or securities, shall be received by the Trustee or any Noteholder which is prohibited by such provisions, then and in such event such payment shall be held in trust for the benefit of, and shall be paid over and delivered by such Trustee or Noteholder to, the trustee or any other representative of holders of Senior Indebtedness, as their interest may appear, for application to Senior Indebtedness remaining unpaid until all such Senior Indebtedness has been paid in full in cash or cash equivalents after giving effect to any concurrent distribution to or for the holders of Senior Indebtedness. With respect to the holders of Senior Indebtedness, the Trustee undertakes to perform only such obligations on the part of the Trustee as are specifically set forth in this Article 11, and no implied covenants or obligations with respect to the holders of Senior Indebtedness shall be read into this Indenture against the Trustee. The Trustee shall not be deemed to owe any fiduciary duty to the holders of Senior Indebtedness, and shall not be liable to any such holders if the Trustee shall pay over or distribute to or on behalf of Noteholders or the Company or any other Person money or assets to which any holders of Senior Indebtedness shall be entitled by virtue of this Article 11, except if such payment is made as a result of the willful misconduct or gross negligence of the Trustee. SECTION 11.06 Notice by the Company. The Company shall promptly notify the Trustee and the Paying Agent of any facts known to the Company that would cause a payment of any obligations with respect to the Notes to violate this Article 11, but failure to give such notice shall not affect the subordination of the Notes to the Senior Indebtedness as provided in this Article 11. SECTION 11.07 Subrogation. After all Senior Indebtedness is paid in full and until the Notes are paid in full, Noteholders shall be subrogated (equally and ratably with all other Indebtedness that is equal in right of payment to the Notes) to the rights of holders of Senior Indebtedness to receive distributions applicable to Senior Indebtedness to the extent that distributions otherwise payable to the Noteholders have been applied to the payment of Senior Indebtedness. A distribution made under this Article 11 to holders of Senior Indebtedness that otherwise would have been made to Noteholders is not, as between the Company and Noteholders, a payment by the Company of the Notes. SECTION 11.08 Relative Rights. This Article 11 defines the relative rights of Holders and holders of Senior Indebtedness. Nothing in this Indenture shall: (i) impair, as between the Company and Holders, the obligation of the Company, which is absolute and unconditional, to pay principal of and interest on the Notes in accordance with their terms; (ii) affect the relative rights of Holders and creditors of Holdings other than their rights in relation to holders of Senior Indebtedness; or (iii) prevent the Trustee or any Holder from exercising its available remedies upon a Default or Event of Default, subject to the rights of holders and owners of Senior Indebtedness to receive distributions and payments otherwise payable to Holders of Notes. If the Company fails because of this Article 11 to pay principal of or interest on a Note on the due date, the failure is still a Default or Event of Default. 73

SECTION 11.09 Subordination May Not Be Impaired by the Company. No right of any holder of Senior Indebtedness to enforce the subordination of the Indebtedness evidenced by the Notes shall be impaired by any act or failure to act by the Company or any Holder or by the failure of the Company or any Holder to comply with this Indenture. Without in any way limiting the generality of this Section 11.09, the holders of Senior Indebtedness may, at any time and from time to time, without the consent of or notice to the Trustee or the Holders, without incurring responsibility to the Trustee or the Holders and without impairing or releasing the subordination provided in this Article 11 or the obligations hereunder of the Holders to the holders of Senior Indebtedness, do any one or more of the following: (a) change the manner, place or terms of payment or extend the time of payment of, or renew or alter, Senior Indebtedness or any instrument evidencing the same or any agreement under which Senior Indebtedness is outstanding or secured; (b) sell, exchange, release, foreclose against or otherwise deal with any property pledged, mortgaged or otherwise securing Senior Indebtedness; (c) release any Person liable in any manner for the collection of Senior Indebtedness; and (d) exercise or refrain from exercising any rights against the Company, any Subsidiary thereof or any other Person. SECTION 11.10 Distribution or Notice to Representative. Whenever a distribution is to be made or a notice given to holders of any Senior Indebtedness, the distribution may be made and the notice given to their representative. Upon any payment or distribution of assets of the Company referred to in this Article 11, the Trustee and the Holders of Notes shall be entitled to rely upon any order or decree made by any court of competent jurisdiction or upon any certificate of such representative(s) or of the liquidating trustee or agent or other Person making any distribution to the Trustee or to the Holders for the purpose of ascertaining the Persons entitled to participate in such distribution, all holders of the Senior Indebtedness and other Indebtedness of the Company, the amount thereof or payable thereon, the amount or amounts paid or distributed thereon and all other facts pertinent thereto or to this Article 11. SECTION 11.11 Rights of Trustee and Paying Agent. Notwithstanding the provisions of this Article 11 or any other provision of this Indenture, the Trustee shall not be charged with knowledge of the existence of any facts that would prohibit the making of any payment or distribution by the Trustee, and the Trustee and the Paying Agent may continue to make payments on the Notes, unless a Responsible Officer of the Trustee shall have received at its Corporate Trust Office at least three Business Days prior to the date of such payment written notice of facts that would cause the payment of any obligations with respect to the Notes to violate this Article 11. Only the Company or representative may give the notice. Nothing in this Article 11 shall impair the claims of, or payments to, the Trustee under or pursuant to Section 7.06. The Trustee in its individual or any other capacity may hold Senior Indebtedness with the same rights it would have if it were not Trustee. Any Agent may do the same with like rights. 74

ARTICLE 12 SECURITY SECTION 12.01 Security. (a) On the Closing Date, the Company shall (i) enter into the Pledge Agreement and comply with the terms and provisions thereof and (ii) purchase the Pledged Securities to be pledged to the Trustee for the benefit of the Holders in such amount as will be sufficient upon receipt of scheduled interest and/or principal payments of such Pledged Securities to provide for payment in full of the first six scheduled interest payments due on the Notes. The Pledged Securities shall be pledged by the Company to the Trustee for the benefit of the Holders and shall be held by the Trustee in the Pledge Account pending disposition pursuant to the Pledge Agreement. (b) Each Holder, by its acceptance of a Note, consents and agrees to the terms of the Pledge Agreement (including, without limitation, the provisions providing for foreclosure and release of the Pledged Securities) as the same may be in effect or may be amended from time to time in accordance with its terms, and authorizes and directs the Trustee to enter into the Pledge Agreement and to perform its respective obligations and exercise its respective rights thereunder in accordance therewith. The Company will do or cause to be done all such acts and things as may be necessary or reasonably requested by the Trustee, or as may be required by the provisions of the Pledge Agreement, to assure and confirm to the Trustee the security interest in the Pledged Securities contemplated hereby, by the Pledge Agreement or any part thereof, as from time to time constituted, so as to render the same available for the security and benefit of this Indenture and of the Notes secured hereby, according to the intent and purposes herein and therein expressed. The Company shall take, or shall cause to be taken, upon request of the Trustee, any and all actions reasonably required to cause the Pledge Agreement to create and maintain, as security for the obligations of the Company under this Indenture and the Notes, valid and enforceable first priority liens in and on all the Pledged Securities, in favor of the Trustee, superior to and prior to the rights of third Persons and subject to no other Liens. (c) The release of any Pledged Securities pursuant to the Pledge Agreement will not be deemed to impair the security under this Indenture in contravention of the provisions hereof if and to the extent the Pledged Securities are released pursuant to this Indenture and the Pledge Agreement. To the extent applicable, the Company shall cause TIA Section 314(d) relating to the release of property or securities from the Lien and security interest of the Pledge Agreement and relating to the substitution therefor of any property or securities to be subjected to the Lien and security interest of the Pledge Agreement to be complied with. Any certificate or opinion required by TIA Section 314(d) may be made by an Officer of the Company, except in cases where TIA Section 314(d) requires that such certificate or opinion be made by an independent Person, which Person shall be an independent engineer, appraiser or other expert selected by the Company. (d) The Company shall cause TIA Section 314(b), relating to opinions of counsel regarding the Lien under the Pledge Agreement, to be complied with. The Trustee may accept, to the extent permitted by Sections 4.03 and 7.14 as conclusive evidence of compliance with the foregoing provisions, the appropriate statements contained in such instruments. 75

(e) The Trustee may, in its sole discretion and without the consent of the Holders, on behalf of the Holders, take all reasonable actions in accordance with the Pledge Agreement necessary or appropriate in order to (i) enforce any of the terms of the Pledge Agreement and (ii) collect and receive any and all amounts payable in respect of the obligations of the Company thereunder. The Trustee shall have power to institute and to maintain such suits and proceedings as the Trustee may reasonably deem expedient to preserve or protect its interests and the interests of the Holders in the Pledged Securities (including power to institute and maintain suits or proceedings to restrain the enforcement of or compliance with any legislative or other governmental enactment, rule or order that may be unconstitutional or otherwise invalid if the enforcement of, or compliance with, such enactment, rule or order would impair the security interest hereunder or be prejudicial to the interests of the Holders or of the Trustee). ARTICLE 13 MISCELLANEOUS SECTION 13.01 Trust Indenture Act Controls. If any provision of this Indenture limits, qualifies, or conflicts with another provision which is required to be included in this Indenture by the TIA, the required provision shall control. SECTION 13.02 Notices. Any request, demand, authorization, notice, waiver, consent or communication shall be in writing and delivered in person or mailed by first-class mail, postage prepaid, addressed as follows or transmitted by facsimile transmission (confirmed by guaranteed overnight courier) to the following facsimile numbers: if to the Company: Regeneron Pharmaceuticals, Inc. 777 Old Saw Mill River Road Tarrytown, New York 10591 Telephone No. (914) 345-7400 Facsimile No. (914) 345-7721 Attention: General Counsel if to the Trustee: American Stock Transfer & Trust Company 59 Maiden Lane New York, New York 10038 Attention: Corporate Trust Department Telephone No. (718) 921-8209 Facsimile No. (718) 331-1852 The Company or the Trustee by notice given to the other in the manner provided above may designate additional or different addresses for subsequent notices or communications. 76

Any notice or communication given to a Noteholder shall be mailed to the Noteholder, by first-class mail, postage prepaid, at the Noteholder's address as it appears on the registration books of the Registrar and shall be sufficiently given if so mailed within the time prescribed. Failure to mail a notice or communication to a Noteholder or any defect in it shall not affect its sufficiency with respect to other Noteholders. If a notice or communication is mailed in the manner provided above, it is duly given, whether or not received by the addressee. If the Company mails a notice or communication to the Noteholders, it shall mail a copy to the Trustee and each Registrar, Paying Agent, Conversion Agent or co-registrar. SECTION 13.03 Communication by Holders with Other Holders. Noteholders may communicate pursuant to TIA Section 312(b) with other Noteholders with respect to their rights under this Indenture or the Notes. The Company, the Trustee, the Registrar, the Paying Agent, the Conversion Agent and anyone else shall have the protection of TIA Section 312(c). SECTION 13.04 Certificate and Opinion as to Conditions Precedent. Upon any request or application by the Company to the Trustee to take any action under this Indenture, the Company shall furnish to the Trustee: (1) an Officers' Certificate stating that, in the opinion of the signers, all conditions precedent, if any, provided for in this Indenture relating to the proposed action have been complied with; and (2) an Opinion of Counsel stating that, in the opinion of such counsel, all such conditions precedent have been complied with. SECTION 13.05 Statements Required in Certificate or Opinion. Each Officers' Certificate or Opinion of Counsel with respect to compliance with a covenant or condition provided for in this Indenture shall include: (1) a statement that each person making such Officers' Certificate or Opinion of Counsel has read such covenant or condition; (2) a brief statement as to the nature and scope of the examination or investigation upon which the statements or opinions contained in such Officers' Certificate or Opinion of Counsel are based; (3) a statement that, in the opinion of each such person, he has made such examination or investigation as is necessary to enable such person to express an informed opinion as to whether or not such covenant or condition has been complied with; and (4) a statement that, in the opinion of such person, such covenant or condition has been complied with. 77

SECTION 13.06 Separability Clause. In case any provision in this Indenture or in the Notes shall be invalid, illegal or unenforceable, the validity, legality and enforceability of the remaining provisions shall not in any way be affected or impaired thereby. SECTION 13.07 Rules by Trustee, Paying Agent, Conversion Agent and Registrar. The Trustee may make reasonable rules for action by or a meeting of Noteholders. The Registrar, Conversion Agent and the Paying Agent may make reasonable rules for their functions. SECTION 13.08 Legal Holidays. A "Legal Holiday" is any day other than a Business Day. If any specified date (including a date for giving notice) is a Legal Holiday, the action shall be taken on the next succeeding day that is not a Legal Holiday, and, if the action to be taken on such date is a payment in respect of the Notes, no interest, if any, shall accrue for the intervening period. SECTION 13.09 GOVERNING LAW. THIS INDENTURE AND THE NOTES WILL BE GOVERNED BY, AND CONSTRUED IN ACCORDANCE WITH, THE LAWS OF THE STATE OF NEW YORK. SECTION 13.10 No Recourse Against Others. A director, officer, employee or stockholder, as such, of the Company shall not have any liability for any obligations of the Company under the Notes or this Indenture or for any claim based on, in respect of or by reason of such obligations or their creation. By accepting a Note, each Noteholder shall waive and release all such liability. The waiver and release shall be part of the consideration for the issue of the Notes. SECTION 13.11 Successors. All agreements of the Company in this Indenture and the Notes shall bind its successor. All agreements of the Trustee in this Indenture shall bind its successor. SECTION 13.12 Multiple Originals. The parties may sign any number of copies of this Indenture. Each signed copy shall be an original, but all of them together represent the same agreement. One signed copy is enough to prove this Indenture. 78

IN WITNESS WHEREOF, the undersigned, being duly authorized, have executed this Indenture on behalf of the respective parties hereto as of the date first above written. REGENERON PHARMACEUTICALS, INC. By:___________________________ Name: Title: AMERICAN STOCK TRANSFER & TRUST COMPANY, as Trustee By:___________________________ Name: Title:

EXHIBIT A-1 [FORM OF FACE OF GLOBAL NOTE] UNLESS THIS CERTIFICATE IS PRESENTED BY AN AUTHORIZED REPRESENTATIVE OF THE DEPOSITORY TRUST COMPANY TO THE ISSUER OR ITS AGENT FOR REGISTRATION OF TRANSFER, EXCHANGE OR PAYMENT, AND ANY CERTIFICATE ISSUED IS REGISTERED IN THE NAME OF CEDE & CO. OR IN SUCH OTHER NAME AS IS REQUESTED BY AN AUTHORIZED REPRESENTATIVE OF THE DEPOSITORY TRUST COMPANY (AND ANY PAYMENT HEREON IS MADE TO CEDE & CO. OR TO SUCH OTHER ENTITY AS IS REQUESTED BY AN AUTHORIZED REPRESENTATIVE OF THE DEPOSITORY TRUST COMPANY), ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO ANY PERSON IS WRONGFUL SINCE THE REGISTERED OWNER HEREOF, CEDE & CO., HAS AN INTEREST HEREIN. TRANSFERS OF THIS GLOBAL NOTE SHALL BE LIMITED TO TRANSFERS IN WHOLE, BUT NOT IN PART, TO NOMINEES OF THE DEPOSITORY TRUST COMPANY, OR TO A SUCCESSOR THEREOF OR SUCH SUCCESSOR'S NOMINEE AND TRANSFERS OF PORTIONS OF THIS GLOBAL NOTE SHALL BE LIMITED TO TRANSFERS MADE IN ACCORDANCE WITH THE RESTRICTIONS SET FORTH IN ARTICLE TWO OF THE INDENTURE REFERRED TO ON THE REVERSE HEREOF. THIS NOTE AND THE SHARES OF COMMON STOCK ISSUABLE UPON CONVERSION OF THIS NOTE HAVE NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED (THE "SECURITIES ACT"), OR ANY STATE SECURITIES LAWS. NEITHER THIS NOTE, THE SHARES OF COMMON STOCK ISSUABLE UPON CONVERSION OF THIS NOTE NOR ANY INTEREST OR PARTICIPATION HEREIN OR THEREIN MAY BE REOFFERED, SOLD, ASSIGNED, TRANSFERRED, PLEDGED, ENCUMBERED OR OTHERWISE DISPOSED OF IN THE ABSENCE OF SUCH REGISTRATION UNLESS SUCH TRANSACTION IS EXEMPT FROM, OR NOT SUBJECT TO, REGISTRATION. THE HOLDER OF THIS NOTE, BY ITS ACCEPTANCE HEREOF, AGREES TO OFFER, SELL, OR OTHERWISE TRANSFER SUCH NOTE, PRIOR TO THE DATE (THE "RESALE RESTRICTION TERMINATION DATE"), WHICH IS TWO YEARS AFTER THE LATER OF THE ORIGINAL ISSUE DATE HEREOF AND THE LAST DATE ON WHICH REGENERON PHARMACEUTICALS, INC. (THE "COMPANY") OR ANY AFFILIATE OF THE COMPANY WAS THE OWNER OF THIS NOTE (OR ANY PREDECESSOR OF SUCH NOTE) ONLY (A) TO THE COMPANY OR ANY SUBSIDIARY THEREOF, (B) FOR SO LONG AS THIS NOTE AND THE SHARES OF COMMON STOCK ISSUABLE UPON CONVERSION OF THIS NOTE ARE ELIGIBLE FOR RESALE PURSUANT TO RULE 144A, TO A PERSON IT REASONABLY BELIEVES IS A "QUALIFIED INSTITUTIONAL BUYER" AS DEFINED IN RULE 144A UNDER THE SECURITIES ACT THAT PURCHASES FOR ITS OWN ACCOUNT OR FOR THE ACCOUNT OF A QUALIFIED INSTITUTIONAL BUYER TO WHICH NOTICE IS GIVEN THAT THE TRANSFER IS BEING MADE IN RELIANCE ON RULE 144A, (C) PURSUANT TO AN EXEMPTION A-1-1

FROM REGISTRATION PROVIDED BY RULE 144 UNDER THE SECURITIES ACT, IF AVAILABLE, (D) PURSUANT TO A REGISTRATION STATEMENT WHICH HAS BEEN DECLARED EFFECTIVE UNDER THE SECURITIES ACT AND CONTINUES TO BE EFFECTIVE AT THE TIME OF TRANSFER OR (E) IN AN OFFSHORE TRANSACTION IN ACCORDANCE WITH RULE 904 OF REGULATION S UNDER THE SECURITIES ACT. IF THE PROPOSED TRANSFER IS PURSUANT TO CLAUSES (C) OR (E) ABOVE, SUCH TRANSFER IS SUBJECT TO THE COMPANY'S AND THE TRUSTEE'S RIGHTS PRIOR TO ANY SUCH OFFER, SALE OR TRANSFER TO REQUIRE THE DELIVERY OF AN OPINION OF COUNSEL, CERTIFICATION AND/OR OTHER INFORMATION SATISFACTORY TO EACH OF THEM, AND IN EACH OF THE FOREGOING CASES, A CERTIFICATE OF TRANSFER IN THE FORM APPEARING ON THE OTHER SIDE OF THIS NOTE IS COMPLETED AND DELIVERED BY THE TRANSFEROR TO THE TRUSTEE. THE HOLDER AGREES THAT IT WILL DELIVER TO EACH PERSON TO WHOM THE SECURITY EVIDENCED HEREBY IS TRANSFERRED (OTHER THAN PURSUANT TO CLAUSE D ABOVE) A NOTICE SUBSTANTIALLY TO THE EFFECT OF THIS LEGEND. THIS LEGEND WILL BE REMOVED UPON THE REQUEST OF THE HOLDER AFTER THE RESALE RESTRICTION TERMINATION DATE. [THE FOREGOING LEGEND MAY BE REMOVED FROM THIS NOTE ON SATISFACTION OF THE CONDITIONS SPECIFIED IN THE INDENTURE.] A-1-2

REGENERON PHARMACEUTICALS, INC. 5-1/2% Convertible Senior Subordinated Notes due 2008 No.: 1 CUSIP: 75886FAA5 Issue Date: October 17, 2001 REGENERON PHARMACEUTICALS, INC., a New York corporation, promises to pay to Cede & Co. or registered assigns, the principal sum of TWO HUNDRED MILLION DOLLARS ($200,000,000) on October 17, 2008. This Note shall bear interest as specified on the other side of this Note. This Note is convertible as specified on the other side of this Note. Additional provisions of this Note are set forth on the other side of this Note. Dated: October 17, 2001 REGENERON PHARMACEUTICALS, INC. By -------------------------------- Name: Title: TRUSTEE'S CERTIFICATE OF AUTHENTICATION AMERICAN STOCK TRANSFER & TRUST COMPANY, as Trustee, certifies that this is one of the Notes referred to in the within-mentioned Indenture (as defined on the other side of this Note). By ---------------------------------- Authorized Signatory Dated: -------------------------------- A-1-3

[FORM OF REVERSE SIDE OF NOTE] 5-1/2% Convertible Senior Subordinated Note due 2008 1. Cash Interest. The Company promises to pay interest in cash on the principal amount of this Note at the rate per annum of 5-1/2%. The Company will pay cash interest semiannually in arrears on April 17 and October 17 of each year (each an "Interest Payment Date") to Holders of record at the close of business on April 2 and October 2 (whether or not a business day) (each a "Regular Record Date"), as the case may be, immediately preceding such Interest Payment Date. Cash interest on the Notes will accrue from the most recent date to which interest has been paid or duly provided or, if no interest has been paid, from the Issue Date. Cash interest will be computed on the basis of a 360-day year of twelve 30-day months. In accordance with the terms of the Registration Rights Agreement, during the first 90 days following the day on which an Event (as defined in the Registration Rights Agreement) has occurred and is continuing, the Interest Rate borne by the Notes shall be increased by .25% to 5.75%. From and after the 91st day following the day on which an Event has occurred and such Event is continuing, the Interest Rate borne by the Notes shall be increased by an additional .25% to 6.00%. In no event shall the Interest Rate borne by the Notes exceed 6.00%. Any amount of additional interest will be payable in cash semiannually, in arrears, on each Interest Payment Date and will cease to accrue on the date the Event is cured. The Holder of this Security is entitled to the benefits of the Registration Rights Agreement. The Holder of this Note is entitled to the benefits of the Pledge Agreement, dated October 17, 2001, between the Company and the Trustee, pursuant to which the Company has placed in the Pledge Account cash or Pledged Financial Assets sufficient to provide for the payment of the first six interest payments on this Note. The terms capitalized but undefined in this paragraph have the meanings given to them in the Pledge Agreement. 2. Method of Payment. Subject to the terms and conditions of the Indenture, the Company will make payments in respect of the principal of, premium, if any, and cash interest on this Note to a Paying Agent. In respect of Redemption Prices and Change of Control Repurchase Prices, the Company will make payments in respect of the principal of, premium, if any, and cash interest on this Note to Holders who surrender Notes to a Paying Agent to collect such payments in respect of the Notes. The Company will pay cash amounts in money of the United States that at the time of payment is legal tender for payment of public and private debts. However, the Company may make such cash payments by check payable in such money. A holder of Notes with an aggregate principal amount in excess of $10,000,000 will be paid by wire transfer in immediately available funds at the election of such holder. Any payment required to be made on any day that is not a Business Day will be made on the next succeeding Business Day. A-1-4

3. Paying Agent, Conversion Agent and Registrar. Initially, American Stock Transfer & Trust Company (the "Trustee"), will act as Paying Agent, Conversion Agent and Registrar. The Company may appoint and change any Paying Agent, Conversion Agent, Registrar or co-registrar without notice, other than notice to the Trustee, except that the Company will maintain at least one Paying Agent in the State of New York, City of New York, Borough of Manhattan, which shall initially be an office or agency of the Trustee. The Company or any of its Subsidiaries or any of their Affiliates may act as Paying Agent, Conversion Agent, Registrar or co-registrar. 4. Indenture. The Company issued the Notes under an Indenture dated as of October 17, 2001 (the Indenture"), between the Company and the Trustee. The terms of the Notes include those stated in the Indenture and those made part of the Indenture by reference to the Trust Indenture Act of 1939, as in effect from time to time (the "TIA"). Capitalized terms used herein and not defined herein have the meanings ascribed thereto in the Indenture. The Notes are subject to all such terms, and Noteholders are referred to the Indenture and the TIA for a statement of those terms. The Notes are general unsecured obligations of the Company (except as provided in Article 12 of the Indenture) limited to $200,000,000 aggregate principal amount. Subject to Section 4.07 of the Indenture, the Indenture does not limit other indebtedness of the Company, secured or unsecured. 5. Provisional Redemption. The Notes may be redeemed at the election of the Company, as a whole or from time to time in part on any date, upon not less than 30 nor more than 60 days' notice, at any time prior to October 17, 2004, at a Redemption Price equal to $1,000 per $1,000 principal amount of the Notes plus accrued and unpaid interest, if any, to but excluding the Provisional Redemption Date if (i) the Closing Price of the Common Stock has exceeded 150% of the Conversion Price (as defined in Article 10 of the Indenture and as such may be adjusted from time to time) then in effect for at least 20 Trading Days in any consecutive 30-Trading Day period ending on the Trading Day prior to the Notice Date and (ii) during the period that the Company is obligated, under the Registration Rights Agreement, to keep a registration statement covering resales of the Notes and the Common Stock issuable upon conversion thereof effective, such registration statement is effective (the "Registration Period") and available for use as of, and including, the Notice Date through and including the Provisional Redemption Date provided this date is within the Registration Period. Upon any such Provisional Redemption, the Company shall make the Make-Whole Payment with respect to the Notes called for redemption to Holders on the Notice Date in an amount equal to $165 per $1,000 principal amount of the Notes, less the amount of any interest actually paid on such Notes prior to or on the Provisional Redemption Date. The Company shall make the Make-Whole Payment in cash on all Notes called for Provisional Redemption, including those Notes converted into Common Stock between the Notice Date and the Provisional Redemption Date. A-1-5

6. Optional Redemption. At any time on or after October 17, 2004, the Company may redeem the Notes in whole at any time or in part from time to time upon not less than 30 nor more than 60 days' notice, at a redemption price equal to $1,000 per $1,000 principal amount, plus any interest accrued but not paid prior to the Redemption Date, subject to the right of Holders of record on the immediately preceding Regular Record Date to receive the interest due on the succeeding Interest Payment Date if the Closing Price of the Common Stock has exceeded 140% of the Conversion Price (as such may be adjusted from time to time) then in effect for at least 20 Trading Days in any consecutive 30-Trading Day period ending on the Trading Day prior to the date of mailing of the notice of optional redemption pursuant to Section 3.05 of the Indenture. If the Company does not redeem all the Notes, the Trustee will select the Notes to be redeemed in principal amounts of $1,000 or whole multiples of $1,000 by lot or on a pro rata basis. If any Notes are to be redeemed in part only, a new Note or Notes in principal amount equal to the unredeemed principal portion thereof will be issued. If a portion of a Holder's Notes is selected for partial redemption and the Holder converts a portion of its Notes, the converted portion will be deemed to be taken from the portion selected for redemption. No sinking fund is provided for the Notes. 7. Repurchase by the Company at the Option of the Holder. If a Change of Control occurs, the Holder, at the Holder's option, shall have the right, in accordance with the provisions of the Indenture, to require the Company to repurchase the Notes (or any portion of the principal amount hereof that is at least $1,000 or an integral multiple thereof, provided that the portion of the principal amount of this Note to be outstanding after such repurchase is at least equal to $1,000) at the Change of Control Repurchase Price in cash (or Common Stock subject to the following paragraph), plus any interest accrued and unpaid to, but excluding, the Change of Control Repurchase Date. Subject to the conditions provided in the Indenture, the Company may elect to pay the Change of Control Repurchase Price by delivering a number of shares of Common Stock equal to (i) the Change of Control Repurchase Price divided by (ii) 95% of the average of the Closing Prices per share for the five consecutive Trading Days ending on the third Trading Day prior to the Change of Control Repurchase Date. No fractional shares of Common Stock will be issued upon repurchase of any Notes. Instead of any fractional share of Common Stock which would otherwise be issued upon conversion of such Notes, the Company shall pay a cash adjustment as provided in the Indenture. A Change of Control Repurchase Notice will be given by the Company to the Holders as provided in the Indenture. To exercise a repurchase right, a Holder must deliver to the Trustee a written notice as provided in the Indenture. Holders have the right to withdraw any Change of Control Repurchase Notice by delivering to the Paying Agent a written notice of withdrawal in accordance with the provisions of the Indenture. A-1-6

8. Notice of Redemption. Notice of redemption will be mailed not less than 30 days but not more than 60 days before the Redemption Date to each Holder of Notes to be redeemed at the Holder's registered address. If money sufficient to pay the Redemption Price of all Notes (or portions thereof) to be redeemed on the Redemption Date is deposited with the Paying Agent prior to or on the Redemption Date, immediately after such Redemption Date interest ceases to accrue on such Notes or portions thereof. Notes in denominations larger than $1,000 of principal amount may be redeemed in part but only in integral multiples of $1,000 of principal amount. 9. Conversion. Subject to the next two succeeding sentences, a Holder of a Note may convert it into Common Stock of the Company at any time before the close of business on October 17, 2008. If the Note is called for redemption, the Holder may convert it at any time before the close of business on the Business Day preceding the Redemption Date. A Note in respect of which a Holder has delivered a Change of Control Repurchase Notice exercising the option of such Holder to require the Company to purchase such Note may be converted only if such notice of exercise is withdrawn in accordance with the terms of the Indenture. The initial Conversion Price shall be $30.2512 per share of Common Stock, subject to adjustment in certain events described in the Indenture. The Company shall pay a cash adjustment as provided in the Indenture in lieu of any fractional share of Common Stock. To convert a Note, a Holder must (1) complete and manually sign the conversion notice below (or complete and manually sign a facsimile of such notice) and deliver such notice to the Conversion Agent, (2) surrender the Note duly signed and endorsed to the Conversion Agent, (3) furnish appropriate endorsements and transfer documents if required by the Conversion Agent, the Company or the Trustee and (4) pay any transfer or similar tax or payment detailed below, if required. Notes surrendered for conversion, other than those called for Provisional Redemption or Optional Redemption, during the period from the close of business on any Regular Record Date to the opening of business on the next succeeding Interest Payment Date shall be accompanied by payment in New York Clearing House funds or other funds acceptable to the Company of an amount equal to the interest to be received on such Interest Payment Date on the principal amount of Notes being surrendered for conversion. No such payment will be required if the Notes are called for Provisional Redemption or Optional Redemption. 10. Conversion Arrangement on Call for Redemption. Any Notes called for redemption, unless surrendered for conversion before the close of business on the Redemption Date, may be deemed to be purchased from the Holders of such Notes at an amount not less than the Redemption Price, by one or more investment bankers or other purchasers who may agree with the Company to purchase such Notes from the Holders, to convert them into Common Stock of the Company and to make payment for such Notes to the Trustee in trust for such Holders. A-1-7

11. Denominations; Transfer; Exchange. The Notes are in fully registered form, without coupons, in denominations of $1,000 of principal amount and integral multiples of $1,000. A Holder may transfer or exchange Notes in accordance with the Indenture. The Registrar may require a Holder, among other things, to furnish appropriate endorsements and transfer documents and to pay any taxes and fees required by law or permitted by the Indenture. The Registrar need not transfer or exchange (i) any Notes selected for redemption (except, in the case of a Note to be redeemed in part, the portion of the Note not to be redeemed), (ii) any Notes in respect of which a Change of Control Repurchase Notice has been given and not withdrawn (except, in the case of a Note to be purchased in part, the portion of the Note not to be purchased) or (iii) any Notes for a period of 15 days before the mailing of a notice of redemption of Notes to be redeemed. 12. Persons Deemed Owners. The registered Holder of this Note may be treated as the owner of this Note for all purposes. 13. Unclaimed Money or Notes. The Trustee and the Paying Agent shall return to the Company upon written request any money or Notes held by them for the payment of any amount with respect to the Notes that remains unclaimed for two years, subject to applicable unclaimed property law. After return to the Company, Holders entitled to the money or Notes must look to the Company for payment as general creditors unless an applicable abandoned property law designates another person. 14. Amendment; Waiver. Subject to certain exceptions set forth in the Indenture, (i) the Indenture or the Notes may be amended with the written consent of the Holders of at least a majority in aggregate principal amount of the Notes at the time outstanding and (ii) certain Defaults may be waived with the written consent of the Holders of a majority in aggregate principal amount of the Notes at the time outstanding. Subject to certain exceptions set forth in the Indenture, without the consent of any Noteholder, the Company and the Trustee may amend the Indenture or the Notes to cure any ambiguity, omission, defect or inconsistency, or to comply with Article 5 of the Indenture, to make any change that does not adversely affect the rights of any Noteholder, or to comply with any requirement of the SEC in connection with the qualification of the Indenture under the TIA. 15. Defaults and Remedies. Under the Indenture, Events of Default include (1) the Company fails to pay when due the principal of or premium, if any, on any of the Notes at maturity, upon redemption or exercise of a repurchase right or otherwise, whether or not such payment is prohibited by Article 11 of the Indenture; (2) the Company fails to pay an installment of interest (including liquidated damages, if any) on any of the Notes that continues for 30 days after the date when due, whether or not such payment is prohibited by Article 11 of the Indenture, provided that a failure to make any of the first six scheduled interest payments on the Notes within 3 Business Days after an Interest Payment Date will constitute an Event of Default with no additional grace or cure period; (3) the A-1-8

Company fails to deliver shares of Common Stock, together with cash in lieu of fractional shares, when such Common Stock or cash in lieu of fractional shares is required to be delivered upon conversion of a Note and such failure continues for 10 days after such delivery date; (4) the Company fails to perform or observe any other term, covenant or agreement contained in the Notes or the Indenture for a period of 60 days after written notice of such failure, requiring the Company to remedy the same, shall have been given to the Company by the Trustee or to the Company and the Trustee by the Holders of at least 25% in aggregate principal amount of the Notes then outstanding; (5) (A) one or more defaults in the payment of principal of or premium, if any, on any of the Company's Indebtedness aggregating $10.0 million or more, when the same becomes due and payable at the scheduled maturity thereof, and such default or defaults shall have continued after any applicable grace period and shall not have been cured or waived within a 30-day period after the date of such default or (B) any of the Company's Indebtedness aggregating $10.0 million or more shall have been accelerated or otherwise declared due and payable, or required to be prepaid or repurchased (other than by regularly scheduled required prepayment) prior to the scheduled maturity thereof and such acceleration is not rescinded or annulled within a 30-day period after the date of such acceleration; and (6) certain events of bankruptcy, insolvency or reorganization with respect to the Company or any Significant Subsidiary. If an Event of Default (other than an Event of Default specified in clause (6) above) occurs and is continuing, the Trustee, or the Holders of at least 25% in aggregate principal amount of the Notes at the time outstanding, may declare all the Notes to be due and payable immediately. Certain events of bankruptcy or insolvency are Events of Default which will result in the Notes becoming due and payable immediately upon the occurrence of such Events of Default. Noteholders may not enforce the Indenture or the Notes except as provided in the Indenture. The Trustee may refuse to enforce the Indenture or the Notes unless it receives reasonable indemnity or security. Subject to certain limitations, Holders of a majority in aggregate principal amount of the Notes at the time outstanding may direct the Trustee in its exercise of any trust or power. The Trustee may withhold from Noteholders notice of any continuing Default (except a Default in payment of amounts specified in clause (1) or (2) above) if it determines that withholding notice is in their interests. 16. Subordination The payment of principal of, premium, if any, and interest on the Notes will be subordinated (except as provided in Article 12 of the Indenture) in right of payment, as set forth in the Indenture, to the prior payment in full in cash or cash equivalents of all Senior Indebtedness whether outstanding on the date of the Indenture or thereafter incurred. 17. Trustee Dealings with the Company. Subject to certain limitations imposed by the TIA, the Trustee under the Indenture, in its individual or any other capacity, may become the owner or pledgee of Notes and may otherwise deal with and collect obligations owed to it by the Company or its Affiliates and may otherwise deal with the Company or its Affiliates with the same rights it would have if it were not Trustee. A-1-9

18. No Recourse Against Others. A director, officer, employee or stockholder, as such, of the Company shall not have any liability for any obligations of the Company under the Notes or the Indenture or for any claim based on, in respect of or by reason of such obligations or their creation. By accepting a Note, each Noteholder waives and releases all such liability. The waiver and release are part of the consideration for the issue of the Notes. 19. Authentication. This Note shall not be valid until an authorized signatory of the Trustee manually signs the Trustee's Certificate of Authentication on the other side of this Note. 20. Abbreviations. Customary abbreviations may be used in the name of a Noteholder or an assignee, such as TEN COM (=tenants in common), TEN ENT (=tenants by the entireties), JT TEN (=joint tenants with right of survivorship and not as tenants in common), CUST (=custodian), and U/G/M/A (=Uniform Gift to Minors Act). 21. GOVERNING LAW. THE INDENTURE AND THIS NOTE WILL BE GOVERNED BY, AND CONSTRUED IN ACCORDANCE WITH, THE LAWS OF THE STATE OF NEW YORK. The Company will furnish to any Noteholder upon written request and without charge a copy of the Indenture which has in it the text of this Note in larger type. Requests may be made to: General Counsel Regeneron Pharmaceuticals, Inc. 777 Old Saw Mill River Road Tarrytown, New York 10591 A-1-10

ASSIGNMENT FORM To assign this Note, fill in the form below: I or we assign and transfer this Note to - -------------------------------------------------------------------------------- - -------------------------------------------------------------------------------- (Insert assignee's soc. sec. or tax ID no.) - -------------------------------------------------------------------------------- - -------------------------------------------------------------------------------- - -------------------------------------------------------------------------------- (Print or type assignee's name, address and zip code) and irrevocably appoint _____________________ agent to transfer this Note on the books of the Company. The agent may substitute another to act for him. CONVERSION NOTICE To convert this Note into Common Stock of the Company, check the box: 9 To convert only part of this Note, state the principal amount to be converted (which must be $1,000 or an integral multiple of $1,000): $ -------------------------- If you want the stock certificate made out in another person's name, fill in the form below: - ------------------------------------------------------------------------ - -------------------------------------------------------------------------------- (Insert other person's soc. sec. or tax ID no.) - -------------------------------------------------------------------------------- - -------------------------------------------------------------------------------- - -------------------------------------------------------------------------------- - -------------------------------------------------------------------------------- (Print or type other person's name, address and zip code) - ------------------------------------------------------------------------------ Date: Your Signature: ----------------------- ----------------------------------- - ------------------------------------------------------------------------------ (Sign exactly as your name appears on the other side of this Note) A-1-11

EXHIBIT A-2 [Form of Certificated Note] THIS NOTE AND THE SHARES OF COMMON STOCK ISSUABLE UPON CONVERSION OF THIS NOTE HAVE NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED (THE "SECURITIES ACT"), OR ANY STATE SECURITIES LAWS. NEITHER THIS NOTE, THE SHARES OF COMMON STOCK ISSUABLE UPON CONVERSION OF THIS NOTE NOR ANY INTEREST OR PARTICIPATION HEREIN OR THEREIN MAY BE REOFFERED, SOLD, ASSIGNED, TRANSFERRED, PLEDGED, ENCUMBERED OR OTHERWISE DISPOSED OF IN THE ABSENCE OF SUCH REGISTRATION OR UNLESS SUCH TRANSACTION IS EXEMPT FROM, OR NOT SUBJECT TO, REGISTRATION. THE HOLDER OF THIS NOTE, BY ITS ACCEPTANCE HEREOF, AGREES TO OFFER, SELL, OR OTHERWISE TRANSFER SUCH NOTE, PRIOR TO THE DATE (THE "RESALE RESTRICTION TERMINATION DATE"), WHICH IS TWO YEARS AFTER THE LATER OF THE ORIGINAL ISSUE DATE HEREOF AND THE LAST DATE ON WHICH REGENERON PHARMACEUTICALS, INC. (THE "COMPANY") OR ANY AFFILIATE OF THE COMPANY WAS THE OWNER OF THIS NOTE (OR ANY PREDECESSOR OF SUCH NOTE) ONLY (A) TO THE COMPANY OR ANY SUBSIDIARY THEREOF, (B) FOR SO LONG AS THIS NOTE AND THE SHARES OF COMMON STOCK ISSUABLE UPON CONVERSION OF THIS NOTE ARE ELIGIBLE FOR RESALE PURSUANT TO RULE 144A, TO A PERSON IT REASONABLY BELIEVES IS A "QUALIFIED INSTITUTIONAL BUYER" AS DEFINED IN RULE 144A UNDER THE SECURITIES ACT THAT PURCHASES FOR ITS OWN ACCOUNT OR FOR THE ACCOUNT OF A QUALIFIED INSTITUTIONAL BUYER TO WHICH NOTICE IS GIVEN THAT THE TRANSFER IS BEING MADE IN RELIANCE ON RULE 144A, (C) PURSUANT TO AN EXEMPTION FROM REGISTRATION PROVIDED BY RULE 144 UNDER THE SECURITIES ACT, IF AVAILABLE, (D) PURSUANT TO A REGISTRATION STATEMENT WHICH HAS BEEN DECLARED EFFECTIVE UNDER THE SECURITIES ACT AND CONTINUES TO BE EFFECTIVE AT THE TIME OF TRANSFER OR (E) IN AN OFFSHORE TRANSACTION IN ACCORDANCE WITH RULE 904 OF REGULATION S UNDER THE SECURITIES ACT IF THE PROPOSED TRANSFER IS PURSUANT TO CLAUSES (C) OR (E) ABOVE, SUCH TRANSFER IS SUBJECT TO THE COMPANY'S AND THE TRUSTEE'S RIGHTS PRIOR TO ANY SUCH OFFER, SALE OR TRANSFER TO REQUIRE THE DELIVERY OF AN OPINION OF COUNSEL, CERTIFICATION AND/OR OTHER INFORMATION SATISFACTORY TO EACH OF THEM, AND IN EACH OF THE FOREGOING CASES, A CERTIFICATE OF TRANSFER IN THE FORM APPEARING ON THE OTHER SIDE OF THIS NOTE IS COMPLETED AND DELIVERED BY THE TRANSFEROR TO THE TRUSTEE. THE HOLDER AGREES THAT IT WILL DELIVER TO EACH PERSON TO WHOM THE SECURITY EVIDENCED HEREBY IS TRANSFERRED (OTHER THAN PURSUANT TO CLAUSE D ABOVE) A NOTICE SUBSTANTIALLY TO THE EFFECT OF THIS LEGEND. THIS LEGEND WILL BE REMOVED UPON THE REQUEST OF THE HOLDER AFTER THE RESALE RESTRICTION TERMINATION DATE. A-2-1

[THE FOREGOING LEGEND MAY BE REMOVED FROM THIS NOTE ON SATISFACTION OF THE CONDITIONS SPECIFIED IN THE INDENTURE.] A-2-2

REGENERON PHARMACEUTICALS, INC. 5-1/2% Convertible Senior Subordinated Notes due 2008 No. CUSIP: 75886FAA5 Issue Date: October 17, 2001 REGENERON PHARMACEUTICALS, INC., a New York corporation, promises to pay to Cede & Co. or registered assigns, the principal sum of TWO HUNDRED MILLION DOLLARS ($200,000,000) on October 17, 2008. This Note shall bear interest as specified on the other side of this Note. This Note is convertible as specified on the other side of this Note. Additional provisions of this Note are set forth on the other side of this Note. Dated: REGENERON PHARMACEUTICALS, INC. By -------------------------------------- Name: Title: TRUSTEE'S CERTIFICATE OF AUTHENTICATION AMERICAN STOCK TRANSFER & TRUST COMPANY, as Trustee, certifies that this is one of the Notes referred to in the within-mentioned Indenture (as defined on the other side of this Note). By ----------------------------------- Authorized Signatory Dated: -------------------------------- A-2-3

EXHIBIT B-1 Transfer Certificate In connection with any transfer of any of the Notes within the period prior to the expiration of the holding period applicable to the sales thereof under Rule 144(k) under the Securities Act of 1933, as amended (the "Securities Act") (or any successor provision), the undersigned registered owner of this Note hereby certifies with respect to $____________ principal amount of the above-captioned Notes presented or surrendered on the date hereof (the "Surrendered Notes") for registration of transfer, or for exchange or conversion where the Notes issuable upon such exchange or conversion are to be registered in a name other than that of the undersigned registered owner (each such transaction being a "transfer"), that such transfer complies with the restrictive legend set forth on the face of the Surrendered Notes for the reason checked below: [ ] A transfer of the Surrendered Notes is made to the Company or any subsidiaries; or [ ] The transfer of the Surrendered Notes complies with Rule 144A under the U.S. Securities Act of 1933, as amended (the "Securities Act"); or [ ] The transfer of the Surrendered Notes is to an institutional accredited investor, as described in Rule 501(a)(1), (2), (3) or (7) of Regulation D under the Securities Act; or [ ] The transfer of the Surrendered Notes is pursuant to an effective registration statement under the Securities Act, or [ ] The transfer of the Surrendered Notes is pursuant to an offshore transaction in accordance with Rule 904 of Regulation S under the Securities Act; or [ ] The transfer of the Surrendered Notes is pursuant to another available exemption from the registration requirement of the Securities Act. and unless the box below is checked, the undersigned confirms that, to the undersigned's knowledge, such Notes are not being transferred to an "affiliate" of the Company as defined in Rule 144 under the Securities Act (an "Affiliate"). [ ] The transferee is an Affiliate of the Company. DATE: -------------------- -------------------------------------- Signature(s) (If the registered owner is a corporation, partnership or fiduciary, the title of the Person signing on behalf of such registered owner must be stated.) B-1-1

EXHIBIT B-2 Form of Letter to Be Delivered by Accredited Investors Regeneron Pharmaceuticals, Inc. 777 Old Saw Mill River Road Tarrytown, NY 10591 Attention: Stuart Kolinski, General Counsel American Stock Transfer & Trust Company 59 Maiden Lane New York, New York 10038 Attention: Corporate Trust Department Telephone No. (718) 921-8209 Facsimile No. (718) 331-1852 Dear Sirs: We are delivering this letter in connection with the proposed transfer of $_____________ principal amount of the 5-1/2% Convertible Senior Subordinated Notes due 2008 (the "Notes") of Regeneron Pharmaceuticals, Inc. (the "Company"), which are convertible into shares of the Company's Common Stock, $0.001 par value per share (the "Common Stock"). We hereby confirm that: (i) we are an "accredited investor" within the meaning of Rule 501(a)(1), (2) or (3) under the Securities Act of 1933, as amended (the "Securities Act"), or an entity in which all of the equity owners are accredited investors within the meaning of Rule 501(a)(1), (2) or (3) under the Securities Act (an "Institutional Accredited Investor"); (ii) the purchase of Notes by us is for our own account or for the account of one or more other Institutional Accredited Investors or as fiduciary for the account of one or more trusts, each of which is an "accredited investor" within the meaning of Rule 501(a)(7) under the Securities Act and for each of which we exercise sole investment discretion or (B) we are a "bank," within the meaning of Section 3(a)(2) of the Securities Act, or a "savings and loan association" or other institution described in Section 3(a)(5)(A) of the Securities Act that is acquiring Notes fiduciary for the account of one or more institutions for which we exercise sole investment discretion; (iii) we have such knowledge and experience in financial and business matters that we are capable of evaluating the merits and risks of purchasing Notes; and (iv) we are not acquiring Notes with a view to distribution thereof or with any present intention of offering or selling Notes or the Common Stock issuable upon conversion thereof, except as permitted below; provided that the disposition of our B-2-1

property and property of any accounts for which we are acting as fiduciary shall remain at all times within our control. We understand that the Notes were originally offered and sold in a transaction not involving any public offering within the United States within the meaning of the Securities Act and that the Notes and the shares of Common Stock (the "Notes") issuable upon conversion thereof have not been registered under the Securities Act, and we agree, on our own behalf and on behalf of each account for which we acquire any Notes, that if in the future we decide to resell or otherwise transfer such Notes prior to the date (the "Resale Restriction Termination Date") which is two years after the later of the original issuance of the Notes and the last date on which the Company or an affiliate of the Company was the owner of the Note, such Notes may be resold or otherwise transferred only (i) to the Company or any subsidiary thereof, or (ii) for as long as the Notes are eligible for resale pursuant to Rule 144A, to a person it reasonably believes is a "qualified institutional buyer" (as defined in Rule 144A under the Securities Act) that purchases for its own account or for the account of a qualified institutional buyer to which notice is given that the transfer is being made in reliance on Rule 144A, or (iii) to an Institutional Accredited Investor that is acquiring the Note for its own account, or for the account of such Institutional Accredited Investor for investment purposes and not with a view to, or for offer or sale in connection with, any distribution in violation of the Securities Act, or (iv) pursuant to another available exemption from registration under the Securities Act (if applicable), or (v) pursuant to a registration statement which has been declared effective under the Securities Act and, in each case, in accordance with any applicable securities laws of any State of the United States or any other applicable jurisdiction and in accordance with the legends set forth on the Notes. We further agree to provide any person purchasing any of the Notes other than pursuant to clause (v) above from us a notice advising such purchaser that resales of such Notes are restricted as stated herein. We understand that the trustee or the transfer agent, as the case may be, for the Notes will not be required to accept for registration of transfer any Notes pursuant to (iii) or (iv) above except upon presentation of evidence satisfactory to the Company that the foregoing restrictions on transfer have been complied with. We further understand that any Notes will be in the form of definitive physical certificates and that such certificates will bear a legend reflecting the substance of this paragraph other than certificates representing Notes transferred pursuant to clause (v) above. We acknowledge that the Company, others and you will rely upon our confirmations, acknowledgments and agreements set forth herein, and we agree to notify you promptly in writing if any of our representations or warranties herein ceases to be accurate and complete. B-2-2

THIS LETTER SHALL BE GOVERNED BY, AND CONSTRUED IN ACCORDANCE WITH, THE INTERNAL LAWS OF THE STATE OF NEW YORK. (Name of Purchaser) By: ---------------------------------- Name: Title: Address: B-2-3

Exhibit 4.3 EXECUTION COPY PLEDGE AGREEMENT This PLEDGE AGREEMENT (the "Pledge Agreement") is made and entered into as of October 17, 2001 by Regeneron Pharmaceuticals, Inc., a New York corporation (the "Pledgor"), having its principal office at 777 Old Saw Mill River Road, Tarrytown, New York 10591, in favor of American Stock Transfer & Trust Company, a New York corporation with trust power, in its capacity as trustee (the "Trustee") for the holders from time to time (the "Holders") of the Notes (as defined herein), issued by the Pledgor under the Indenture referred to below. Capitalized terms used and not defined in this Pledge Agreement have the meanings set forth or referred to in the Indenture. W I T N E S S E T H WHEREAS, the Pledgor and Merrill Lynch & Co., Merrill Lynch, Pierce, Fenner & Smith Incorporated and Robertson Stephens, Inc. (collectively, the "Initial Purchasers") are parties to a Purchase Agreement dated October 12, 2001 (the "Purchase Agreement"), pursuant to which the Pledgor will issue and sell to the Initial Purchasers $200,000,000 aggregate principal amount of 5-1/2% Convertible Senior Subordinated Notes due 2008 (the "Initial Notes") and pursuant to which the Pledgor has granted to the Initial Purchasers options to purchase all or any part of an additional $50,000,000 aggregate principal amount of the Notes (the "Option Notes" and together with the Initial Notes, the "Notes"); WHEREAS, the Pledgor and the Trustee have entered into that certain indenture dated as of the date hereof (as amended, restated, supplemented or otherwise modified from time to time, the "Indenture"), pursuant to which the Pledgor is issuing the Initial Notes on the date hereof; WHEREAS, the Pledgor is the beneficial owner of security entitlements (the "Pledged Security Entitlements") with respect to (i) the United States Treasury securities identified by CUSIP number in Schedule I hereto, and credited to the Pledgor's account with The Bank of New York (the "Account Holder"), ABA No. 021000018, Account No. 303640 at its office at 101 Barclay Street, New York, New York 10286, in the name of "American Stock Transfer & Trust Company, as Trustee for the benefit of the holders of the 5-1/2% Convertible Senior Subordinated Notes due 2008 of Regeneron Pharmaceuticals Collateral Pledge Account" (the "Pledged Account") and (ii) all other financial assets credited from time to time to the Pledged Account (collectively with the assets described in clause (i) above, the "Pledged Financial Assets"); WHEREAS, to secure the obligation of the Pledgor under the Indenture and the Notes to pay in full each of the first six scheduled interest payments on the Notes when due and to secure repayment of a portion of the principal, premium (if any) and interest on the Notes in the event that the Notes become due and payable prior to such time as the first six scheduled interest payments thereon shall have been paid in full (collectively, the "Obligations"), the

Pledgor has agreed (i) to pledge to the Trustee for its benefit and the ratable benefit of the Holders of the Notes, a security interest in the Collateral (as defined herein) securing the payment and performance by the Pledgor of all of the Obligations and (ii) to execute and deliver this Pledge Agreement; WHEREAS, it is a condition precedent to the initial purchase of the Notes by the initial Holders thereof that the Pledgor shall have executed and delivered this Pledge Agreement; and WHEREAS, unless otherwise defined herein or in the Indenture, terms used in Article 8 or 9 of the Uniform Commercial Code as in effect in the State of New York ("UCC") and/or in the Federal Book Entry Regulations (as defined below) are used in this Pledge Agreement as such terms are defined in such Article 8 or 9 and/or the Federal Book Entry Regulations. The term "Federal Book Entry Regulations" means (a) the federal regulations contained in Subpart B ("Treasury/Reserve Automated Debt Entry System (TRADES)") governing book-entry securities consisting of U.S. Treasury bonds, notes and bills and Subpart D ("Additional Provisions") of 31 C.F.R. Part 357, 31 C.F.R. Section 357.2, Section 357.10 through Section 357.14 and Section 357.41 through Section 357.44 and (b) to the extent substantially identical to the federal regulations referred to in clause (a) above (as in effect from time to time), the federal regulations governing other book-entry securities. AGREEMENT NOW, THEREFORE, in consideration of the premises herein contained, and in order to induce the initial Holders of the Notes to purchase the Notes, the Pledgor hereby agrees with the Trustee, for the benefit of the Trustee and for the ratable benefit of the Holders of the Notes, as follows: SECTION 1. Pledge and Grant of Security Interest. The Pledgor hereby pledges to the Trustee, for its benefit and for the ratable benefit of the Holders of the Notes, and hereby grants to the Trustee, a security interest and continuing lien in, the Pledgor's right, title and interest in and to the following, in each case, whether now owned or hereafter acquired by the Pledgor, wherever located and whether now or hereafter existing or arising (hereinafter collectively referred to as the "Collateral"): (a) the Pledged Financial Assets and the certificates, if any, representing the Pledged Financial Assets, and all dividends, interest, money (as defined in the UCC), instruments (as defined in the UCC, the "Instruments") and other property from time to time received, receivable or otherwise distributed or distributable in respect of or in exchange for any or all of such Pledged Financial Assets; (b) the Pledged Account and all security entitlements with respect thereto, all Pledged Security Entitlements with respect to all Pledged Financial Assets from time to time credited to the Pledged Account, any and all securities accounts in which the Pledged Security Entitlements are carried, and all dividends, interest, cash, instruments and other property from time to time received, receivable or otherwise distributed or 2

distributable in respect of or in exchange for any or all of such Pledged Security Entitlements; (c) all other securities, securities entitlements and other financial assets hereafter acquired by the Pledgor pursuant to Article 12 of the Indenture; and (d) all proceeds of any and all of the foregoing Collateral (including, without limitation, proceeds that constitute property of the types described in clauses (a), (b) and (c) of this Section 1) and, to the extent not otherwise included, all cash. SECTION 2. Security for Obligations. This Pledge Agreement secures, and the Collateral is collateral security for, the prompt and complete payment and performance when due (whether at stated maturity, by acceleration or otherwise) of all the Obligations or other obligations of the Pledgor, whether for principal, interest, fees or otherwise, now or hereafter existing, under this Pledge Agreement, the Notes or the Indenture (all such obligations being the "Secured Obligations"). Without limiting the generality of the foregoing, this Pledge Agreement secures, and the Collateral is collateral security for, the payment of all amounts that constitute part of the Secured Obligations and would be owed by the Pledgor to the Trustee or the Holders under the Notes or the Indenture but for the fact that they are unenforceable or not allowable due to the existence of a bankruptcy, reorganization or similar proceeding involving the Pledgor. SECTION 3. Maintaining the Pledged Account. So long as any Secured Obligation shall remain outstanding: (a) The Pledgor will maintain separately the Pledged Account with The Bank of New York. (b) It shall be a term and condition of the Pledged Agreement, notwithstanding any term or condition to the contrary in any other agreement relating to the Pledged Account, and except as otherwise provided by the provisions of Section 5 and Section 18 hereof, that no funds shall be paid or released to or for the account of, or withdrawn by or for the account of, the Pledgor or any other Person from the Pledged Account. The Pledged Account shall be subject to such applicable laws, and such applicable regulations of the Board of Governors of the Federal Reserve System and of any other appropriate banking or governmental authority, as may now or hereafter be in effect. SECTION 4. Delivery of Collateral. (a) All cash, certificates or instruments representing or evidencing the Pledged Financial Assets, the Pledged Security Entitlements or the Pledged Account shall be delivered to and held by or on behalf of the Trustee pursuant hereto and shall be in suitable form for transfer by delivery, or shall be accompanied by duly executed instruments of transfer or assignment in blank, all in form and substance satisfactory to the Trustee. The Trustee shall have the right, at any time in its discretion and without notice to the Pledgor, to transfer to or to register in the name of the Trustee or any of its nominees any or all of the Collateral. In addition, the Trustee shall have the right at any time to exchange certificates or instruments representing or evidencing any or all of the Collateral for certificates or instruments of smaller or larger denominations. Also, the Trustee shall have the right at any time 3

to convert Collateral consisting of financial assets credited to the Pledged Account to Collateral consisting of financial assets held directly by the Trustee, and to convert Collateral consisting of financial assets held directly by the Trustee to Collateral consisting of financial assets credited to the Pledged Account. (b) With respect to any Collateral in which the Pledgor has any right, title or interest and that constitutes an uncertificated security, the Pledgor shall cause the issuer thereof either (i) to register the Trustee as the registered owner of such security or (ii) to agree in writing with the Pledgor and the Trustee that such issuer will comply with instructions with respect to such security originated by the Trustee without further consent of the Pledgor, such agreement to be in form and substance satisfactory to the Trustee. (c) With respect to any Collateral in which the Pledgor has any right, title or interest and that constitutes a security entitlement, the Pledgor shall cause the securities intermediary with respect to such security entitlement either (i) to identify in its records the Trustee as the entitlement holder of such security entitlement against such securities intermediary or (ii) to agree in writing with the Pledgor and the Trustee that such securities intermediary will comply with entitlement orders (that is, notifications communicated to such securities intermediary directing transfer or redemption of the financial asset to which the Pledgor has a security entitlement) originated by the Trustee without further consent of the Pledgor, such agreement to be in substantially the form of Annex A hereto or otherwise in form and substance satisfactory to the Trustee. (d) With respect to any Collateral that constitutes a securities account, the Pledgor will comply with subsection (c) of this Section 4 with respect to all security entitlements carried in such securities account. (e) Prior to or concurrently with the execution and delivery hereof and prior to the transfer to the Trustee of the Pledged Security Entitlements, as provided in subsections (a) through (c) of this Section 4, the Trustee shall establish the Pledged Account with The Bank of New York. Upon transfer of the Pledged Financial Assets to the Trustee, as confirmed to the Trustee by the securities intermediary, the Trustee shall make appropriate book entries indicating that the Pledged Financial Assets have been credited to and are held in the Pledged Account. Subject to the other terms and conditions of this Pledge Agreement, all funds or other property held by the Trustee pursuant to this Pledge Agreement shall be held in the Pledged Account subject (except as expressly provided in Sections 5(a), (b) and (c) hereof) to the exclusive dominion and control of the Trustee and exclusively for the benefit of the Trustee and for the ratable benefit of the Holders of the Notes and segregated from all other funds or other property otherwise held by the Trustee. (f) All Collateral shall be retained in the appropriate Pledged Account pending disbursement pursuant to the terms hereof. (g) Concurrently with the execution and delivery of this Pledge Agreement, the Trustee is delivering to the Pledgor a duly executed Control Agreement (the "Control Agreement"), in the form of Annex A hereto. 4

(h) Concurrently with the execution and delivery of this Pledge Agreement, the Pledgor is delivering to the Trustee acknowledgment copies or stamped receipt copies of proper financing statements, duly filed on or before the Closing Date under the UCC, covering the Collateral described in this Pledge Agreement. SECTION 5. Disbursements. (a) Three business days prior to the due date of any of the first six scheduled interest payments on the Notes, the Pledgor may, pursuant to written instructions given by the Pledgor to the Trustee (an "Issuer Order"), direct the Trustee to release from the Pledged Account and pay to the Holders of the Notes proceeds sufficient to provide for payment in full of such interest then due on the Notes. Upon receipt of an Issuer Order, the Trustee will (i) issue a Payment Order (as defined in the Control Agreement) to the Account Holder for the release from the Pledged Account funds to the Trustee in an amount sufficient to provide for the payment of the interest on the Notes in accordance with such Issuer Order and (ii) pay such funds to the Holders of the Notes in accordance with the Indenture and the Notes. Nothing in this Section 5 shall affect the Trustee's rights to apply the Collateral to the payments of amounts due on the Notes upon acceleration thereof. (b) If the Pledgor makes any of the first six scheduled interest payments on the Notes or portion of such an interest payment from a source of funds other than the Pledged Account ("Pledgor Funds"), the Pledgor may, after payment in full of such interest payment, direct the Trustee pursuant to an Issuer Order to issue a Payment Order (as defined in the Control Agreement) to the Account Holder for the release to the Pledgor or to another party at the direction of the Pledgor (the "Pledgor's Designee") proceeds from the Pledged Account in an amount less than or equal to the amount of Pledgor Funds applied to such interest payment. Upon receipt by the Trustee of such Issuer Order and provided the Trustee has received such interest payment, the Trustee shall direct the Account Holder pursuant to a Payment Order to pay over to the Pledgor or the Pledgor's Designee, as the case may be, the requested amount from proceeds in the Pledged Account as soon as practicable. (c) At least three Business Days prior to the due date of each of the first six scheduled interest payments on the Notes, the Pledgor shall give the Trustee notice (by Issuer Order) as to whether such interest payment will be made pursuant to Section 5(a) or 5(b) above and the respective amounts of interest that will be paid from the Pledged Account and from Pledgor Funds. Any Pledgor Funds to be used to make any interest payment shall be delivered to the Trustee, in immediately available funds, prior to 10:00 a.m. (New York City time) on such interest payment date. If no such notice is given or such Pledgor Funds have not been so delivered, the Trustee will act pursuant to Section 5(a) above as if it had received an Issuer Order pursuant thereto for the payment in full of the interest then due from the Pledged Account. (d) The Trustee shall instruct the Account Holder to liquidate Collateral in the Pledged Account (pursuant to written instructions from Pledgor) in order to make any of the scheduled payments of interest on the Notes, unless there are sufficient funds in the Pledged Account on such interest payment date. The Trustee shall be entitled to instruct the Account Holder to sell any Collateral as contemplated hereunder prior to the maturity of such Collateral and shall not be responsible for any costs and expenses of such sale. 5

(e) Nothing contained in this Pledge Agreement shall (i) afford the Pledgor any right to issue entitlement orders with respect to any of the Pledged Security Entitlements or any securities account in which any such security entitlement may be carried, or otherwise afford the Pledgor control of any Pledged Security Entitlement or (ii) otherwise give rise to any rights of Pledgor with respect to the Pledged Financial Assets or any securities account in which any such security entitlement may be carried, other than the Pledgor's rights under this Pledge Agreement as the beneficial owner of collateral pledged to and subject to the exclusive dominion and control (except as expressly provided in Sections 5(a) and (b) hereof) of the Trustee in its capacity as such (and not as a securities intermediary) before the payment in full, when due, of the first six scheduled interest payments on the Notes. The Pledgor acknowledges, confirms and agrees that the Trustee is an entitlement holder of the Pledged Security Entitlements solely as Trustee for the Holders of the Notes and not as a securities intermediary. SECTION 6. Investing of Amounts in the Pledged Account. If requested and as directed by the Pledgor, the Trustee will, subject to the provisions of Sections 3, 5 and 13 of this Pledge Agreement, from time to time, instruct the Account Holder to invest interest paid on the Pledged Financial Assets and reinvest other proceeds of any Pledged Financial Assets that may mature or be sold, in each case, in (i) identified United States Treasury securities or (ii) selected shares of a money market fund registered under the Investment Company Act of 1940, as amended, the portfolio of which consists of United States Treasury securities, in each case credited to the Pledged Account. SECTION 7. Representations and Warranties. The Pledgor hereby represents and warrants that: (a) This Pledge Agreement has been duly authorized, validly executed and delivered by the Pledgor and constitutes a valid and binding agreement of the Pledgor, enforceable against the Pledgor in accordance with its terms, except as (i) the enforceability hereof may be limited by bankruptcy, insolvency, fraudulent conveyance, preference, reorganization, moratorium or similar laws now or hereafter in effect relating to or affecting creditors' rights or remedies generally, (ii) the availability of equitable remedies may be limited by equitable principles of general applicability, (iii) the exculpation provisions and rights to indemnification hereunder may be limited by U.S. federal and state securities laws and public policy considerations and (iv) the waiver of rights and defenses contained in Section 13(b), Section 19.8 and Section 19.12 hereof may be limited by applicable law. (b) The Pledgor's exact legal name, as defined in Section 9-503(a) of the UCC, is Regeneron Pharmaceuticals, Inc. The Pledgor is located (within the meaning of Section 9-307 of the UCC) and has its chief executive office in the State of New York. (c) The Pledgor is the legal and beneficial owner of the Collateral free and clear of any Lien, claim, option or right of others (except for the security interests created by this Pledge Agreement). No effective financing statement or instrument similar in effect covering all or any part of the Collateral or listing the Pledgor or any trade name of the Pledgor is on file in any public or recording office, other than the financing statements filed pursuant to this Pledge Agreement. 6

(d) All filings and other actions (including, without limitation, (A) actions necessary to obtain control of the Collateral as provided in Sections 9-104, 9-105, 9-106 and 9-107 of the UCC and (B) actions necessary to perfect the Trustee's security interest with respect to the Collateral evidenced by a certificate of ownership) necessary to perfect the security interest in the Collateral created under this Pledge Agreement have been duly made or taken and are in full force and effect, and this Pledge Agreement creates in favor of the Trustee for its benefit and the ratable benefit of the Holders of the Notes a valid and, together with such filings and other actions, perfected first priority security interest in the Collateral, securing the payment of the Secured Obligations. (e) The execution and delivery by the Pledgor of, and the performance by the Pledgor of its obligations under, this Pledge Agreement will not contravene any provision of applicable law or the Certificate of Incorporation of the Pledgor or any material agreement or other material instrument binding upon the Pledgor or Amgen-Regeneron Partners or any judgment, order or decree of any governmental body, agency or court having jurisdiction over the Pledgor or Amgen-Regeneron Partners, or result in the creation or imposition of any Lien on any assets of the Pledgor, except for the security interests granted under this Pledge Agreement. (f) No consent of any other person and no approval, authorization, order of, action by notice to, filing or qualification with, any governmental authority, regulatory body, agency or other third party is required for (i) the grant by the Pledgor of the assignment, pledge and security interest granted under this Pledge Agreement, (ii) the execution or delivery by the Pledgor of, or the performance by the Pledgor of its obligations under, this Pledge Agreement, (iii) the perfection or maintenance of the assignment, pledge and security interest created hereunder (including the first priority nature of such assignment, pledge or security interest), except for the filing of financing and contribution statements under the UCC, which financing statements have been duly filed and are in full force and effect, or (iv) for the exercise by the Trustee of its voting or other rights provided for in this Pledge Agreement or the remedies in respect of the Collateral pursuant to this Pledge Agreement, except as may be required in connection with the disposition of any portion of the Collateral by laws affecting the offering and sale of securities generally. (g) The Pledgor covenants and agrees with the Trustee and the Holders of the Notes that in the event of a Registration Default, as defined in the Registration Rights Agreement, and the interest rate on the Notes is increased as provided in Section 2(e) of the Registration Rights Agreement, the Company shall purchase and deliver free to the Trustee additional Pledged Security Entitlements in such amount as will be sufficient upon receipt of scheduled interest and/or principal payments of all Pledged Security Entitlements thereafter held in the Pledged Account, in the opinion of a nationally recognized firm of independent public accountants selected by the Pledgor, to provide payment for the first six scheduled interest payments due on the Notes (assuming the additional interest requirement remains in effect for the entire period). The additional Pledged Security Entitlements shall be pledged by the Pledgor to the Trustee for the benefit of the Holders and shall be held by the Trustee in the Pledged Account. 7

(h) There are no legal or governmental proceedings pending or, to the best of the Pledgor's knowledge, threatened to which the Pledgor or Amgen-Regeneron Partners is a party or to which any of the properties of the Pledgor or Amgen-Regeneron Partners is subject that would materially adversely affect the power or ability of the Pledgor to perform its obligations under this Pledge Agreement or to consummate the transactions contemplated hereby. (i) The pledge of the Collateral pursuant to this Pledge Agreement is not prohibited by law or governmental regulation (including, without limitation, Regulations G, T, U and X of the Board of Governors of the Federal Reserve System) applicable to the Pledgor. (j) No Event of Default (as defined below) exists. (k) The jurisdiction (for purposes of Section 8-110(e) of the UCC) of the securities intermediary that maintains the Pledged Account and all securities accounts carrying the Pledged Securities Entitlements is New York. SECTION 8. Further Assurances. (a) The Pledgor agrees that from time to time, at the expense of the Pledgor, the Pledgor will promptly execute and deliver all further instruments and documents, and take all further action, that may be necessary or desirable, or that the Trustee may reasonably request, in order to perfect and protect any pledge or security interest granted or purported to be granted hereunder or to enable the Trustee to exercise and enforce its rights and remedies hereunder with respect to any Collateral. Without limiting the generality of the foregoing, the Pledgor will: (i) if any Collateral shall be evidenced by a promissory note or other instrument, deliver and pledge to the Trustee hereunder such note or instrument, duly indorsed and accompanied by duly executed instruments of transfer or assignment, all in form and substance satisfactory to the Trustee; (ii) execute and file such financing or continuation statements, or amendments thereto, and such other instruments or notices, as may be necessary or desirable, or as the Trustee may reasonably request, in order to perfect and preserve the pledge and security interest granted or purported to be granted hereby; (iii) deliver and pledge to the Trustee for its benefit and the ratable benefit of the Holders of the Notes certificates representing Collateral that constitutes certificated securities, accompanied by undated stock or bond powers executed in blank; and (iv) deliver to the Trustee evidence that all other action that the Trustee may deem reasonably necessary or desirable in order to perfect and protect the security interest created by Pledgor under this Pledge Agreement has been taken. (b) The Pledgor hereby authorizes the Trustee to file one or more financing or continuation statements, and amendments thereto, including, without limitation, one or more financing statements indicating that such financing statements cover all assets or all personal property (or words of similar effect), in each case without the signature of the Pledgor, and regardless of whether any particular asset described in such financing statements falls within the scope of UCC or the granting clause of this Pledge Agreement. A photocopy or other reproduction of this Pledge Agreement or any financing statement covering the Collateral or any part thereof shall be sufficient as a financing statement where permitted by law. The Pledgor ratifies its authorization for the Trustee to have filed such financing statements, continuation statements or amendments filed prior to the date hereof. 8

(c) The Pledgor will furnish to the Trustee from time to time statements and schedules further identifying and describing the Collateral and such other reports in connection with the Collateral as the Trustee may reasonably request, all in reasonable detail. (d) The Pledgor will promptly pay all reasonable costs incurred in connection with any of the foregoing within 45 days of receipt of an invoice therefor. The Pledgor also agrees, whether or not requested by the Trustee, to take all actions that are necessary to perfect or continue the perfection of, or to protect the first priority of, the Trustee's security interest in and to the Collateral, including the filing of all necessary financing and continuation statements, and to protect the Collateral against the rights, claims or interests of third persons (other than any such rights, claims or interests created by or arising through the Trustee). SECTION 9. Covenants. (a) The Pledgor covenants and agrees with the Trustee and the Holders of the Notes that from and after the date of this Pledge Agreement until the earlier of payment in full in cash of (x) each of the first six scheduled interest payments on the Notes when due under the terms of the Indentures or (y) all obligations due and owing under the Indenture and the Notes in the event such obligations become due and payable prior to the payment of the first six scheduled interest payments on the Notes: (i) that (A) it will not (and will not purport to) sell, assign or otherwise dispose of, or grant any option or warrant with respect to, any of the Collateral or its beneficial interest therein, and (B) it will not create or suffer to exist any Lien or other adverse interest upon or with respect to any of the Collateral or its beneficial interest therein (except for the security interests granted under this Pledge Agreement); and (ii) that it will not (A) enter into any agreement or understanding that restricts or inhibits or purports to restrict or inhibit the Trustee's rights or remedies hereunder, including, without limitation, the Trustee's right to sell or otherwise dispose of the Collateral or (B) fail to pay or discharge any tax, assessment or levy of any nature with respect to its beneficial interest in the Collateral not later than five days prior to the date of any proposed sale under any judgment, writ or warrant of attachment with respect to such beneficial interest; (iii) that it will not change its name, type of organization, jurisdiction of organization, organizational identification number or location from those set forth in Section 7(b) hereof without first giving at least 30 days' prior written notice to the Trustee and taking all action required by the Trustee for the purpose of perfecting or protecting the security interest granted by this Pledge Agreement; and (iv) that it will, and cause the Trustee and the Account Holder to, execute and deliver on or prior to any Date of Delivery (as defined in Section 2(b) of the Purchase Agreement) a supplement to this Pledge Agreement, reasonably satisfactory to the Initial Purchasers, providing for the pledge of additional Collateral to secure all Obligations in respect of the Option Notes. SECTION 10. Power of Attorney. In addition to all of the powers granted to the Trustee pursuant to the Indenture, the Pledgor hereby irrevocably appoints the Trustee as the 9

Pledgor's attorney-in-fact (with full power of substitution), with full authority in the place and stead of the Pledgor and in the name of the Pledgor or otherwise, from time to time in the Trustee's discretion, to take any action and to execute any instrument that is necessary or advisable or as the Trustee may deem necessary or advisable to accomplish the purposes of this Pledge Agreement, including, without limitation: (a) to ask for, demand, collect, sue for, recover, compromise, receive and give acquittance and receipts for moneys due and to become due under or in respect of any of the Collateral, (b) to receive, indorse and collect any drafts or other instruments, documents and chattel paper, in connection with clause (a) above, (c) to file any claims or take any action or institute any proceedings that the Trustee may deem necessary or desirable for the collection of any of the Collateral or otherwise to enforce the rights of the Trustee with respect to any of the Collateral, and (d) to pay or discharge taxes or Liens levied or placed upon the Collateral that the Pledgor has failed to pay or discharge in accordance herewith, the legality or validity thereof and the amounts necessary to discharge the same to be determined by the Trustee in its sole reasonable discretion, and such payments made by the Trustee to become part of the Obligations of the Pledgor to the Trustee, due and payable immediately upon demand; provided, however, that the Trustee shall have no obligation to perform any of the foregoing actions. The Trustee's authority under this Section 10 shall include, without limitation, the authority to endorse and negotiate any checks or instruments representing proceeds of Collateral in the name of the Pledgor, execute and give receipt for any certificate of ownership or any document constituting Collateral, transfer title to any item of Collateral, sign the Pledgor's name on all financing statements (to the extent permitted by applicable law) or any other documents deemed necessary or appropriate by the Trustee to preserve, protect or perfect the security interest in the Collateral granted hereunder and to file the same, prepare, file and sign the Pledgor's name on any notice of Lien, and to take any other actions arising from or incident to the powers granted to the Trustee in this Pledge Agreement. This power of attorney is coupled with an interest and is irrevocable by the Pledgor. SECTION 11. No Assumption of Duties; Reasonable Care. The powers conferred on the Trustee hereunder are solely to protect the security interest of the Trustee for its benefit and the ratable benefit of the Holders of the Notes in the Collateral and shall not impose any duty on the Trustee to exercise any such powers. Except for the safe custody of any Collateral in its possession and the accounting for moneys actually received by it hereunder, the Trustee shall have no duty as to any Collateral as to (i) ascertaining or taking action with respect to calls, conversions, exchanges, maturities, tenders or other matters relative to any Collateral, whether or not the Trustee has or is deemed to have knowledge of such matters, (ii) taking of any necessary steps to preserve rights against any parties or any other rights pertaining to any Collateral or (c) investing or reinvesting any of the Collateral or any loss on any investment. The Trustee shall be deemed to have exercised reasonable care in the custody and preservation of any 10

Collateral in its possession if such Collateral is accorded treatment substantially equal to that which it accords its own property. The Trustee shall be entitled to all the rights, benefits, privileges and immunities accorded to it under the Indenture. SECTION 12. Indemnity and Expenses. (a) The Pledgor agrees to indemnify, defend and save and hold harmless the Trustee and its officers, directors, employees, agents and advisors (each, an "Indemnified Party") from and against, and shall pay on demand, any and all claims, damages, losses, liabilities and expenses (including, without limitation, reasonable fees and expenses of counsel) that may be incurred by or asserted or awarded against any Indemnified Party, in each case arising out of or in connection with or resulting from this Pledge Agreement (including, without limitation, enforcement of this Pledge Agreement), except to the extent such claim, damage, loss, liability or expense is found in a final, non-appealable judgment by a court of competent jurisdiction to have resulted from such Indemnified Party's gross negligence or willful misconduct. (b) The Pledgor will upon demand pay to the Trustee the amount of any and all reasonable expenses, including, without limitation, the reasonable fees and expenses of its counsel and of any experts and agents, that the Trustee may incur in connection with (i) the review, negotiation and administration of this Pledge Agreement, (ii) the custody or preservation of, or the sale of, collection from or other realization upon, any of the Collateral, (iii) the exercise or enforcement of any of the rights of the Trustee or the Holders of the Notes hereunder or (iv) the failure by the Pledgor to perform or observe any of the provisions hereof. SECTION 13. Remedies. If any Event of Default under the Indenture or default hereunder (any such Event of Default or default being referred to in this Pledge Agreement as an "Event of Default") shall have occurred and be continuing: (a) The Trustee and the Holders of the Notes may exercise in respect of the Collateral, in addition to all other rights and remedies given by law or by this Pledge Agreement or the Indenture, all of the rights and remedies of a secured party under the UCC (whether or not the UCC applies to the affected Collateral) and also may: (i) require the Pledgor to, and the Pledgor hereby agrees that it will at its expense and upon request of the Trustee forthwith, assemble all or part of the Collateral as directed by the Trustee and make it available to the Trustee at a place and time to be designated by the Trustee that is reasonably convenient to both parties and (ii) without notice except as specified below, sell the Collateral or any part thereof in one or more parcels at any broker's board or at public or private sale, in one or more sales or lots, at any of the Trustee's offices or elsewhere, for cash, on credit or for future delivery, and upon such other terms as the Trustee may deem commercially reasonable. The Pledgor agrees that, to the extent notice of sale shall be required by law, at least ten days' notice to the Pledgor of the time and place of any public sale or the time after which any private sale is to be made shall constitute reasonable notification. The Trustee shall not be obligated to make any sale of Collateral regardless of notice of sale having been given. The Trustee may adjourn any public or private sale from time to time by announcement at the time and place fixed therefor, and such sale may, without further notice, be made at the time and place to which it was so adjourned. The purchaser of any or all Collateral so sold shall thereafter hold the same absolutely, free from any claim, encumbrance or right of any kind 11

whatsoever created by or through the Pledgor. Any sale of the Collateral conducted in conformity with reasonable commercial practices of banks, insurance companies, commercial finance companies, or other financial institutions disposing of property similar to the Collateral shall be deemed to be commercially reasonable. The Trustee or any Holder of Notes may, in its own name or in the name of a designee or nominee, buy any of the Collateral at any public sale and, if permitted by applicable law, at any private sale. All expenses (including court costs and reasonable attorneys' fees, expenses and disbursements) of, or incident to, the enforcement of any of the provisions hereof shall be recoverable from the proceeds of the sale or other disposition of the Collateral. (b) Any cash held by or on behalf of the Trustee and all cash proceeds received by or on behalf of the Trustee in respect of any sale of, collection from, or other realization upon all or any part of the Collateral may, in the discretion of the Trustee, be held by the Trustee as collateral for, and/or then or at any time thereafter applied (after payment of any amounts payable to the Trustee pursuant to Section 12(b) of this Pledge Agreement) in whole or in part by the Trustee for the ratable benefit of the Holders of the Notes against, all or any part of the Secured Obligations in such order as the Trustee shall elect. Any surplus of such cash or cash proceeds held by or on behalf of the Trustee and remaining after payment in full of all the Secured Obligations shall be paid over to the Pledgor or to whomsoever may be lawfully entitled to receive such surplus. (c) The Trustee may, without notice to the Pledgor except as required by law and at any time or from time to time, charge, set-off and otherwise apply all or any part of the Secured Obligations against the Pledged Account or any part thereof. (d) The Pledgor agrees to (i) provide the Trustee with such information as may be necessary, or in the opinion of the Trustee, advisable to enable the Trustee to effect the sale of the Collateral and (ii) use its reasonable best efforts to do or cause to be done all such other acts and things as may be necessary to make such sale or sales of all or any portion of the Collateral pursuant to this Section 13 valid and binding and in compliance with any and all other applicable requirements of law. The Pledgor further agrees that a breach of any of the covenants contained in this Section 13(d) will cause irreparable injury to the Trustee and the Holders of the Notes, that the Trustee and the Holders of the Notes have no adequate remedy at law in respect of such breach and, as a consequence, that each and every covenant contained in this Section 13(d) shall be specifically enforceable against the Pledgor, and the Pledgor hereby waives and agrees not to assert any defenses against an action for specific performance of such covenants except for a defense that no Event of Default has occurred and is continuing. (e) The Pledgor acknowledges the impossibility of ascertaining the amount of damages that would be suffered by the Trustee or any Holders of the Notes by reason of the failure by the Pledgor to perform any of the covenants contained in Section 13(d) above and, consequently, agrees that, if the Pledgor shall fail to perform any of such covenants, it will pay, as liquidated damages and not as a penalty, an amount equal to the value of the Collateral on the date the Trustee shall demand compliance with Section 13(d) above.

SECTION 14. Security Interest Absolute. All rights of the Trustee and the Holders of the Notes and the pledges, assignments and security interests hereunder, and all obligations of the Pledgor hereunder, shall be irrevocable, absolute and unconditional irrespective of, and the Pledgor hereby irrevocably waives (to the maximum extent permitted by applicable law) any defenses it may now have or may hereafter acquire in any way relating to, any or all of the following: (a) any lack of validity or enforceability of the Indenture or Notes or any other agreement or instrument relating thereto; (b) any change in the time, manner or place of payment of, or in any other term of, all or any of the Secured Obligations, or any other amendment or waiver of or any consent to any departure from the Indenture or Notes or any other agreement or instrument relating thereto; (c) any taking, exchange or release of, or non-perfection of any Liens on, any Collateral or any other collateral for all or any of the Secured Obligations; (d) any manner of application of any Collateral or any other collateral, or proceeds thereof, to all or any of the Secured Obligations, or any manner of sale or other disposition of any Collateral or any other collateral for all or any of the Secured Obligations or any other assets of the Pledgor; (e) any change, restructuring or termination of the corporate structure or existence of the Pledgor; or (f) to the extent permitted by applicable law, any other circumstance (including, without limitation, any statute of limitations) or any existence of or reliance on any representation by the Trustee or any Holder of the Notes, which might otherwise constitute a defense available to, or a discharge of, the Pledgor in respect of the Secured Obligations or of this Pledge Agreement. This Pledge Agreement shall continue to be effective or be reinstated, as the case may be, if at any time any payment of any of the Secured Obligations is rescinded or must otherwise be returned by the Trustee or any Holder of the Notes or by any other Person upon the insolvency, bankruptcy or reorganization of the Pledgor or otherwise, all as though such payment had not been made. SECTION 15. Amendments, Waivers and Consents. (a) No amendment or waiver of any provision of this Pledge Agreement, and no consent to any departure by the Pledgor from any provision of this Pledge Agreement, shall in any event be effective unless the same shall be in writing and signed by the Trustee, and then such waiver or consent shall be effective only in the specific instance and for the specific purpose for which given. No failure on the part of the Trustee or any Holder of the Notes to exercise, and no delay in exercising any right hereunder, shall operate as a waiver thereof; nor shall any single or partial exercise of any such right preclude any other or further exercise thereof or the exercise of any other right. 13

SECTION 16. Notices. Any notice or communication given hereunder shall be sufficiently given if in writing and delivered in person or mailed by first class mail, commercial courier service or telecopier communication, addressed as follows; or, as to any party, at such other address as shall be designated by such party in a written notice to the other parties: if to the Pledgor: Regeneron Pharmaceuticals, Inc. 777 Old Saw Mill River Road Tarrytown, New York 10591 Fax: (914) 345-7721 Attention: Stuart Kolinski with a copy to: Skadden, Arps, Slate, Meagher & Flom LLP Four Times Square New York, New York 10036 Fax: (212) 735-2000 Attention: Matthew J. Mallow if to the Trustee: American Stock Transfer & Trust Company 59 Maiden Lane New York, New York 10038 Attn: Corporate Trust Department Fax: (718) 331-1852 All such notices and other communications shall, when mailed, delivered or telecopied, respectively, be effective when deposited in the mails, delivered or telecopied, respectively, addressed as aforesaid. SECTION 17. Continuing Security Interest. This Pledge Agreement shall create a continuing security interest in the Collateral and (a) shall, unless otherwise provided in this Pledge Agreement, remain in full force and effect until the payment in full in cash of the Secured Obligations, (b) be binding upon the Pledgor, its successors and assigns and (c) inure, together with the rights and remedies of the Trustee hereunder, to the benefit of the Trustee and the Holders of the Notes and their respective successors, transferees and assigns. SECTION 18. Termination. So long as no Event of Default shall have occurred and be continuing, this Pledge Agreement (other than Pledgor's obligations under Section 12 hereof) shall terminate upon the earlier of (i) the redemption of the Notes in whole, (ii) the payment in full of each of the first six scheduled interest payments on the Notes when due, or (iii) the discharge of the Indenture. Upon any such termination, without any necessary action on the part of the Pledgor, (i) the Control Agreement(s) will terminate and control of the Pledged Account and the Pledged Security Entitlements shall revert to the Pledgor, (ii) the Trustee shall 14

promptly obtain from the Account Holder and deliver to the Pledgor all certificates and instruments representing any portion of the Pledged Financial Assets constituting certificated securities and (iii) the Trustee shall no longer have any rights in any of the Collateral. SECTION 19. Miscellaneous Provisions. Section 19.1. No Adverse Interpretation of Other Agreements. This Pledge Agreement may not be used to interpret another pledge, security or debt agreement of the Pledgor or any subsidiary thereof. No such pledge, security or debt agreement (other than the Indenture) may be used to interpret this Pledge Agreement. Section 19.2. Severability. The provisions of this Pledge Agreement are severable, and if any clause or provision shall be held invalid, illegal or unenforceable in whole or in part in any jurisdiction, then such invalidity or unenforceability shall affect in that jurisdiction only such clause or provision, or part thereof, and shall not in any manner affect such clause or provision in any other jurisdiction or any other clause or provision of this Pledge Agreement in any jurisdiction. Section 19.3. Headings. The headings in this Pledge Agreement have been inserted for convenience of reference only, are not to be considered a part hereof and shall in no way modify or restrict any of the terms or provisions hereof. Section 19.4. Counterpart Originals. This Pledge Agreement may be signed in two or more counterparts, each of which shall be deemed an original, but all of which shall together constitute one and the same agreement. Delivery of an executed counterpart of a signature page to this Pledge Agreement by telecopier shall be effective as delivery of an original executed counterpart of this Pledge Agreement. Section 19.5. Benefits of Pledge Agreement. Nothing in this Pledge Agreement, express or implied, shall give to any person, other than the parties hereto and their successors hereunder, and the Holders of the Notes and the Account Holder, any benefit or any legal or equitable right, remedy or claim under this Pledge Agreement. Section 19.6. Interpretation of Agreement. To the extent a term or provision of this Pledge Agreement conflicts with the Indenture, the Indenture shall control with respect to the subject matter of such term or provision. Acceptance of or acquiescence in a course of performance rendered under this Pledge Agreement shall not be relevant to determine the meaning of this Pledge Agreement even though the accepting or acquiescing party had knowledge of the nature of the performance and opportunity for objection. Section 19.7. Survival of Representations and Covenants. All representations, warranties and covenants of the Pledgor contained herein shall survive the execution and delivery of this Pledge Agreement, and shall terminate only upon the termination of this Pledge Agreement, except as otherwise specified in such representatives, warranties and covenants. Section 19.8. Waivers. The Pledgor waives presentment and demand for payment of any of the Obligations, protest and notice of dishonor or default with respect to any 15

of the Obligations, and all other notices to which the Pledgor might otherwise be entitled, except as otherwise expressly provided herein or in the Indenture. Section 19.9. Authority of the Trustee. (a) The Trustee shall have and be entitled to exercise all powers hereunder that are specifically granted to the Trustee by the terms hereof, together with such powers as are reasonably incident thereto. The Trustee may perform any of its duties hereunder or in connection with the Collateral by or through agents or employees and shall be entitled to retain counsel and to act in reliance upon the advice of counsel concerning all such matters. Except as otherwise expressly provided in this Pledge Agreement or the Indenture, neither the Trustee nor any director, officer, employee, attorney or agent of the Trustee shall be liable to the Pledgor for any action taken or omitted to be taken by the Trustee, in its capacity as Trustee, hereunder, except for its own bad faith, gross negligence or willful misconduct, and the Trustee shall not be responsible for the validity, effectiveness or sufficiency hereof or of any document or security furnished pursuant hereto. The Trustee and its directors, officers, employees, attorneys and agents shall be entitled to rely on any communication, instrument or document believed by it or them to be genuine and correct and to have been signed or sent by the proper person or persons. (b) The Pledgor acknowledges that the rights and responsibilities of the Trustee under this Pledge Agreement with respect to any action taken by the Trustee or the exercise or non-exercise by the Trustee of any option, right, request, judgment or other right or remedy provided for herein or resulting or arising out of this Pledge Agreement shall, as between the Trustee and the Holders of the Notes, be governed by the Indenture and by such other agreements with respect thereto as may exist from time to time among them, but, as between the Trustee and the Pledgor, the Trustee shall be conclusively presumed to be acting as agent for the Holders of the Notes with full and valid authority so to act or refrain from acting, and the Pledgor shall not be obligated or entitled to make any inquiry respecting such authority. Section 19.10. Final Expression. This Pledge Agreement, together with the Indenture and any other agreement executed in connection herewith, is intended by the parties as a final expression of this Pledge Agreement and is intended as a complete and exclusive statement of the terms and conditions thereof. Section 19.11. Rights of Holders of the Notes. No Holder of Notes shall have any independent rights hereunder other than those rights granted to individual Holders of the Notes pursuant to Section 6.06 of the Indenture; provided that nothing in this subsection shall limit any rights granted to the Trustee under the Notes or the Indenture. Section 19.12. Governing Law; Submission to Jurisdiction; Waiver of Jury Trial; Waiver of Damages. (a) This pledge agreement shall be governed by, and construed in accordance with, the laws of the state of New York. (b) The Pledgor agrees that the Trustee shall, in its capacity as trustee or in the name and on behalf of any Holder of Notes, have the right, to the extent permitted by applicable law, to proceed against the Pledgor or the Collateral in a court in any location reasonably selected in good faith (and having personal or in rem jurisdiction over the Pledgor or the Collateral, as the case may be) to enable the Trustee to realize on the Collateral, or to enforce a 16

judgment or other court order entered in favor of the Trustee. The Pledgor agrees that it will not assert any counterclaims, setoffs or crossclaims in any proceeding brought by the Trustee to realize on such property or to enforce a judgment or other court order in favor of the Trustee, except for such counterclaims, setoffs or crossclaims which, if not asserted in any such proceeding, could not otherwise be brought or asserted. The Pledgor waives any objection that it may have to the location of the court in the city of New York once the Trustee has commenced a proceeding described in this paragraph including, without limitation, any objection to the laying of venue or based on the grounds of forum non conveniens. (c) The Pledgor agrees that neither any Holder of Notes nor (except as otherwise provided in this Pledge Agreement or the Indenture) the Trustee in its capacity as trustee shall have any liability to the Pledgor (whether arising in tort, contract or otherwise) for losses suffered by the Pledgor in connection with, arising out of, or in any way related to, the transactions contemplated and the relationship established by this Pledge Agreement, or any act, omission or event occurring in connection therewith, unless it is determined by a final and nonappealable judgment of a court that is binding on the Trustee or such Holder of Notes, as the case may be, that such losses were the result of acts or omissions on the part of the Trustee or such Holders of Notes, as the case may be, constituting bad faith, gross negligence or willful misconduct. (d) To the extent permitted by applicable law, the Pledgor waives the posting of any bond otherwise required of the Trustee or any Holder of Notes in connection with any judicial process or proceeding to enforce any judgment or other court order pertaining to this Pledge Agreement or any related agreement or document entered in favor of the Trustee or any Holder of Notes, or to enforce by specific performance, temporary restraining order or preliminary or permanent injunction, this Pledge Agreement or any related agreement or document between the Pledgor on the one hand and the Trustee and/or the Holders of the Notes on the other hand. [The remainder of this page intentionally left blank.] 17

IN WITNESS WHEREOF, the Pledgor and the Trustee have each caused this Pledge Agreement to be duly executed and delivered as of the date first above written. Pledgor: REGENERON PHARMACEUTICALS, INC. By: ------------------------------------ Name: Title: Trustee: AMERICAN STOCK TRANSFER & TRUST COMPANY, as Trustee By: ------------------------------------ Name: Title:

SCHEDULE I Pledged Financial Assets Security Coupon Date CUSIP No. -------- ----------- --------- B 4/11/02 04/17/2002 912795JP7 SP 08/15/02 10/17/2002 912820BE6 SP 02/15/03 04/17/2003 912820BF3 SP 08/15/03 10/17/2003 912820BG1 SP 02/15/04 04/17/2003 912820BH9 SP 08/15/04 10/17/2004 912820BK2

ANNEX A CONTROL AGREEMENT This CONTROL AGREEMENT (the "Agreement") dated as of October 17, 2001 by and among Regeneron Pharmaceuticals, Inc. (the "Pledgor") and American Stock Transfer & Trust Company, a New York corporation with trust power, in its capacity as trustee (the "Trustee") and The Bank of New York, a New York banking corporation, in its capacity as securities intermediary and depository bank (the "Account Holder"). PRELIMINARY STATEMENTS: (1) The Pledgor has granted the Trustee a security interest (the "Security Interest") in certain security entitlements (the "Pledged Security Entitlements") with respect to certain U.S. Treasury securities (the "Pledged Financial Assets") identified on Schedule I attached hereto maintained by the Trustee with the Account Holder and carried from time to time in an account with the Account Holder, ABA No. 021000018, Account No. 303640 at its office at 101 Barclay Street, New York, New York 10286, in the name of "American Stock Transfer and Trust Company, as Trustee for the benefit of the holders of the 5-1/2% Convertible Senior Subordinated Notes due 2008 of Regeneron Pharmaceuticals, Inc., Collateral Pledge Account" (the "Pledged Account") and all additions thereto and substitutions and proceeds thereof (collectively, the "Collateral"), pursuant to, and as more particularly described in, a Pledge Agreement dated as of October 17, 2001, among the Pledgor and the Trustee (as the same may hereafter be amended, supplemented or otherwise modified from time to time, the "Pledge Agreement"; terms defined in the Pledge Agreement and not otherwise defined herein are used herein as therein defined). The Pledgor acknowledges having received value for such pledge of the Collateral. (2) Terms defined in Article 8 or 9 of the Uniform Commercial Code as in effect in the State of New York (the "UCC") are used in this Agreement (including, without limitation, paragraph (1) above) as such terms are defined in such Article 8 or 9. (3) The Pledgor, the Trustee and the Account Holder are delivering this Agreement pursuant to the terms of the Pledge Agreement. NOW, THEREFORE, in consideration of the premises and mutual agreements contained herein, the parties hereto hereby agree as follows: SECTION 1. Notice of Exclusive Control. The Pledgor and Trustee are entering into this Agreement to perfect, and confirm the first priority lien of, the Trustee's security interest in the Collateral. The Account Holder agrees to promptly make all necessary entries or notations in its books and records to reflect the Trustee's security interest in the Collateral and to apply any value distributed on account of any Pledged Financial Assets as directed in writing by the Trustee without further consent from the Pledgor. The Account Holder acknowledges that the Trustee has exclusive control over the Pledged Account and all Pledged Security Entitlements contained therein from time to time.

SECTION 2. The Account. The Account Holder represents and warrants to, and agrees with, the Pledgor and the Trustee and the Holders of the Notes that: (a) The Account Holder has established the Pledged Account and shall not change the name or account number of the Pledged Account without the prior written consent of the Trustee. (b) The Account Holder maintains the Pledged Account for the Trustee, and all property (including, without limitation, all funds and financial assets) held by the Account Holder for the account of the Trustee is, and will continue to be, credited to the Pledged Account. (c) To the extent that funds are credited to the Pledged Account, the Pledged Account is a deposit account; and to the extent that financial assets are credited to the Pledged Account, the Pledged Account is a securities account. The Account Holder is (i) the bank with which the Pledged Account is maintained and (ii) the securities intermediary with respect to financial assets held in the Pledged Account. The Trustee is (x) the Account Holder's customer with respect to the Pledged Account and (y) the entitlement holder with respect to financial assets credited from time to time to the Pledged Account. (d) All financial assets in registered form or payable to or to the order of and credited to the Pledged Account shall be registered in the name of, payable to or to the order of, or endorsed to, the Account Holder and in no case during the term of the Pledge Agreement will any financial asset credited to the Pledged Account be registered in the name of, payable to or to the order of, or endorsed to, the Pledgor, except to the extent the foregoing have been subsequently endorsed by the Pledgor to the Account Holder or in blank. (e) Notwithstanding any other agreement to the contrary, the Account Holder's jurisdiction with respect to the Pledged Account for purposes of the UCC is, and will continue to be for so long as the Security Interest shall be in effect, the State of New York. (f) The Account Holder does not know of any claim to or interest in the Pledged Account or any property (including, without limitation, all funds and financial assets) credited to the Pledged Account, except for claims and interests of the parties referred to in this Agreement. SECTION 3. Control by Trustee. (a) The Account Holder will comply with (A) all written instructions directing disposition of the funds in the Pledged Account (such instructions, a "Payment Order"), (B) all notifications and entitlement orders that the Account Holder receives directing it to transfer or redeem any financial asset in the Pledged Account and (C) all other directions concerning the Collateral, including, without limitation, directions to distribute to the Trustee proceeds of any such transfer or redemption or interest on any property in the Pledged Account (any such instruction, notification or direction referred to in clause (A),

(B) or (C) above being an "Account Direction"), in each case of clauses (A), (B) and (C) above originated by the Trustee without further consent by the Pledgor or any other person. (b) The Trustee hereby acknowledges that it shall maintain and exercise control of the Pledged Account on behalf of the Holders of the Notes. (c) The Account Holder will not (i) comply with Account Directions or other directions concerning the Collateral originated by the Pledgor or (ii) distribute to the Pledgor interest or other distributions on or in respect of the Collateral. SECTION 4. Priority of Trustee's Security Interest. (a) The Account Holder (i) subordinates to the Security Interest and in favor of the Trustee any security interest, lien, or right of setoff the Account Holder may have, now or in the future, against the Pledged Account or property in the Pledged Account, and (ii) agrees that it will not exercise any right in respect of any such security interest or lien or any such right of setoff until the Security Interest is terminated, except that the Account Holder will retain its prior lien on property in the Pledged Account to secure payment for property purchased for the Pledged Account and normal commissions and fees for the Pledged Account. (b) The Account Holder will not enter into any other agreement with any Person relating to Account Directions or other directions with respect to the Pledged Account. SECTION 5. Statements, Confirmations, and Notices of Adverse Claims. (a) The Account Holder will send copies of all statements and confirmations for the Pledged Account simultaneously to the Pledgor and the Trustee. (b) When the Account Holder knows of any claim or interest in the Pledged Account or any property credited to the Pledged Account other than the claims and interests of the parties referred to in this Agreement, the Account Holder will promptly notify the Trustee and the Pledgor of such claim or interest. SECTION 6. The Account Holder's Responsibility. (a) The Account Holder will not be liable to the Pledgor or the Trustee or the Holders of the Notes for complying with an Account Direction or other direction concerning the Collateral originated by the Trustee, even if the Pledgor notifies the Account Holder that the Trustee is not legally entitled to issue the Account Direction or such other direction unless the Account Holder takes the action after it is served with an injunction, restraining order, or other legal process enjoining it from doing so, issued by a court of competent jurisdiction, and had a reasonable opportunity to act on the injunction, restraining order or other legal process. (b) This Agreement does not create any obligation of the Account Holder except for those expressly set forth in this Agreement and in Part 5 of Article 8 of the UCC and in Article 4 of the UCC. In particular, the Account Holder need not investigate whether the Trustee is entitled under the Trustee's agreements with the Pledgor to give an Account Direction or other direction concerning the Pledged Account. The Account Holder may conclusively rely on notices and communications it believes given by the appropriate party.

(c) In no event shall the Account Holder or any of its affiliates, shareholders, directors, officers, employees or agents be liable for indirect, special, punitive, incidental or consequential damages of any kind whatsoever even if advised of the possibility of such damages, other than such damages caused by its own bad faith, gross negligence or willful misconduct. (d) Without limiting the foregoing, and notwithstanding any provision to the contrary elsewhere, the Account Holder and its affiliates, shareholders, directors, officers, employees or agents: (i) shall have no responsibilities, obligations or duties in respect of the subject matter hereof other than those expressly set forth in this Agreement, and no implied duties, responsibilities, covenants or obligations shall be read into this Agreement against the Account Holder. Without limiting the foregoing, the Account Holder shall have no duty or authority to determine and/or investigate whether or not an event of default exists under any agreement between the Pledgor and the Trustee, or to determine and/or investigate whether or not the Trustee is entitled to give any Account Direction with respect to the Collateral; (ii) may in any instance where the Account Holder determines that it lacks or is uncertain as to its authority to take or refrain from taking certain action hereunder, or as to any of the requirements of this Agreement under the circumstance before it, delay or refrain from taking any action unless and until it shall have received appropriate written instructions from the Trustee or advice from legal counsel selected by it (or other appropriate advisor), as the case may be, detailing the action required to be taken hereunder and the Account Holder may rely conclusively on any such instructions or advice; (iii) so long as it and they shall have acted (or refrained from acting) in good faith and within the reasonable belief that such action or omission is duly authorized or within the discretion or powers granted to it hereunder, shall not be responsible or liable for any error of judgment in any action taken, suffered or omitted by it or them, or for any act done or step taken or omitted, or for any mistake of fact or law, unless such action constitutes gross negligence or willful misconduct as finally determined by a non-appealable judgment of a court of competent jurisdiction on its (or their) part; (iv) will not be responsible or liable to the Pledgor, the Trustee, or any other person or entity whatsoever for the due execution, legality, validity, enforceability, genuineness, effectiveness or sufficiency of this Agreement (provided, however, that the Account Holder warrants that the Account Holder has legal capacity and has been duly authorized to enter into this Agreement) or for any statement, warranty or representation made by any other party in connection with this Agreement; (v) will not incur any responsibility or liability by acting or not acting in reliance upon advice of counsel, or upon any notice, consent, certificate, instruction, Account Direction, statement, wire instruction, telecopy or other writing reasonably and

in good faith believed by it or them to be genuine and in conformance with this Agreement and signed or sent by the proper party or parties and contemplated herein; (vi) shall not be required to expend or risk its or their own funds, or to take any action (including the institution or defense of legal proceedings) which in its or their reasonable judgment may cause it or them to incur or suffer any expense or liability, unless the Account Holder shall have been provided with security or indemnity, acceptable to Account Holder in its sole discretion, for the payment of the costs, expenses (including reasonable attorneys' fees) and liabilities which may be incurred therein or thereby. (e) If any Collateral subject to this Agreement is at any time attached or levied upon, or in case the transfer or delivery of any such Collateral shall be stayed or enjoined, or in the case of any other legal process or judicial order affecting such Collateral, the Account Holder is authorized to comply with any such order in any manner as the Account Holder or its legal counsel reasonably deems appropriate. The Account Holder shall give prompt written notice to the Pledgor and the Trustee of any such attachment, levy, stay, injunction or legal process. If the Account Holder complies with any process, order, writ, judgment or decree relating to the Collateral subject to this Agreement, then the Account Holder shall not be liable or responsible to the Pledgor, the Trustee, or any other person or entity whatsoever even if such order, writ, judgment, decree or process is subsequently modified, vacated or otherwise determined to have been without legal force or effect. (f) The Account Holder shall not be liable or responsible for any delays or failures in performance of any of its duties hereunder which result from events or conditions beyond its reasonable control and so long as the same exist or continue and cannot reasonably be remedied by the Account Holder in accordance with its normal business practices. Such events or conditions shall include, but shall not be limited to, acts of God, strikes, lockouts, riots, acts of war or terrorism, epidemics, nationalization, expropriation, currency restrictions, governmental regulations superimposed after the fact, fire, communication line failures (including the unavailability of the Federal Reserve Bank wire or telex or other wire or communication facility), power failures, earthquakes or other disasters. SECTION 7. Indemnity. The Pledgor will indemnify the Account Holder, its officers, directors, employees and agents against claims, liabilities and expenses arising out of this Agreement (including, without limitation, reasonable attorney's fees and disbursements), except to the extent the claims, liabilities or expenses are caused by the Account Holder's gross negligence or willful misconduct as found by a court of competent jurisdiction in a final, non-appealable judgment. SECTION 8. Termination; Survival. (a) This Agreement shall terminate automatically upon receipt by the Account Holder of written notice executed by two officers of the Trustee that (i) all of the Secured Obligations have been paid in full in cash or otherwise satisfied or (ii) all of the Collateral has been released, which ever is earlier, and the Account Holder shall thereafter be relieved of all duties and obligations hereunder. The Account Holder may terminate this Agreement on 60 days' prior notice to the Trustee and the Pledgor, provided

that before such termination the Account Holder and the Pledgor shall make arrangements to transfer the property in the Pledged Account to another securities intermediary that shall have executed, together with the Trustee and the Pledgor, a control agreement in favor of the Trustee and the Holders of the Notes in respect of such property in substantially the form of this Agreement or otherwise in form and substance satisfactory to the Trustee. (b) In the event that the Trustee no longer serves as Trustee for the Collateral, the Trustee, the Account Holder and the Pledgor shall make arrangements for another Person to assume the rights and obligations of the Trustee hereunder, and such Person shall have executed, together with the Account Holder and the Pledgor, a control agreement in favor of such Person and the Holders of the Notes in substantially the form of this Agreement or otherwise in form and substance satisfactory to the Trustee. (c) Sections 7 and 8 will survive termination of this Agreement. SECTION 9. Conflict with Other Agreements. (a) In the event of any conflict between this Agreement (or any portion thereof) and any other agreement now existing or hereafter entered into, the terms of this Agreement shall prevail; (b) No amendment or modification of this Agreement or waiver of any right hereunder shall be binding on any party hereto unless it is in writing and is signed by all of the parties hereto; (c) The Account Holder hereby confirms and agrees that: (i) There are no other agreements entered into between the Account Holder and the Pledgor with respect to the Pledged Account; (ii) It has not entered into, and until the termination of the this Agreement will not enter into, any agreement with any other person relating to the Pledged Account and/or any financial assets credited thereto pursuant to which it has agreed to comply with entitlement orders (as defined in Section 8-102(a)(8) of the UCC) of such other person; and (iii) It has not entered into, and until the termination of this Agreement will not enter into, any agreement with the Pledgor or the Trustee purporting to limit or condition the obligation of the Account Holder to comply with Account Directions as set forth in Section 3 hereof. SECTION 10. Permitted Investments. In accordance with the Pledge Agreement, the Trustee shall direct the Account Holder with respect to the selection of investments to be made with the funds in the Pledged Account. SECTION 11. Entire Agreement. This Agreement is the entire agreement, and supersedes any prior agreements, and contemporaneous oral agreements, of the parties

concerning its subject matter. The Trustee and the Account Holder shall be entitled to all the rights, benefits, privileges and immunities accorded to the Trustee under the Indenture. SECTION 12. Amendments. No modification, amendment or waiver of, nor consent to any departure by any party from, any provision of this Agreement will be effective unless made in writing signed by the parties hereto, and then such waiver or consent shall be effective only in the specific instance and for the purpose for which given. SECTION 13. Financial Assets. The Account Holder agrees with Trustee and the Pledgor that, to the fullest extent permitted by applicable law, all property credited from time to time to the Pledged Account will be treated as financial assets under Article 8 of the UCC. SECTION 14. Notices. All notices, demands, requests, consents, approvals and other communications required or permitted hereunder must be in writing and will be effective upon receipt if delivered personally, or if sent by facsimile transmission with confirmation of delivery, or by nationally recognized overnight courier service, to the Pledgor's and the Trustee's addresses as set forth in the Pledge Agreement, and to the Account Holder's address as set forth below, or to such other address as any party may give to the others in writing for such purpose. SECTION 15. Binding Effect. This Agreement shall become effective when it shall have been executed by the Pledgor, the Trustee and the Account Holder, and thereafter shall be binding upon and inure to the benefit of the Pledgor, the Trustee and the Account Holder and their respective successors and assigns. SECTION 16. Execution in Counterparts. This Agreement may be executed in any number of counterparts and by different parties hereto in separate counterparts, each of which when so executed shall be deemed to be an original and all of which taken together shall constitute one and the same agreement. Delivery of an executed counterpart of a signature page to this Agreement by telecopier shall be effective as delivery of an original executed counterpart of this Agreement. SECTION 17. Governing Law and Jurisdiction. THIS AGREEMENT WILL BE GOVERNED BY, AND CONSTRUED IN ACCORDANCE WITH, THE LAWS OF THE STATE OF NEW YORK. Each of the parties hereby irrevocably submits for itself and its property in any legal action or proceeding relating to this Agreement, or for recognition and enforcement of any judgment in respect thereof, to the non-exclusive general jurisdiction and venue of the courts of the State of New York, the courts of the United States of America in New York, and appellate courts from any thereof. SECTION 18. WAIVER OF JURY TRIAL. EACH OF THE PARTIES HERETO IRREVOCABLY WAIVES ANY AND ALL RIGHT IT MAY HAVE TO A TRIAL BY JURY IN ANY ACTION, PROCEEDING OR CLAIM (WHETHER BASED ON CONTRACT, TORT OR OTHERWISE) OF ANY NATURE RELATING TO THIS AGREEMENT, ANY DOCUMENTS EXECUTED IN CONNECTION WITH THIS AGREEMENT OR ANY TRANSACTION CONTEMPLATED IN ANY OF SUCH DOCUMENTS. EACH PARTY HERETO ACKNOWLEDGES THAT THE FOREGOING WAIVER IS KNOWING AND VOLUNTARY.

IN WITNESS WHEREOF, the parties hereto have caused this Agreement to be executed by their respective officers thereunto duly authorized, as of the date first above written. Pledgor: REGENERON PHARMACEUTICALS, INC. By: ------------------------------------ Name: Title: Trustee: AMERICAN STOCK TRANSFER & TRUST COMPANY, as Trustee By: ------------------------------------ Name: Title: Account Holder: THE BANK OF NEW YORK, as Account Holder By: ------------------------------------ Name: Title: Address: 101 Barclay Street New York, New York 10286 Attn: Ming Shiang Fax: (212) 896-7298

SCHEDULE I Pledged Financial Assets Security Coupon Date CUSIP No. -------- ----------- --------- B 4/11/02 04/17/2002 912795JP7 SP 08/15/02 10/17/2002 912820BE6 SP 02/15/03 04/17/2003 912820BF3 SP 08/15/03 10/17/2003 912820BG1 SP 02/15/04 04/17/2003 912820BH9 SP 08/15/04 10/17/2004 912820BK2

EXHIBIT 4.4 EXECUTION COPY REGISTRATION RIGHTS AGREEMENT THIS REGISTRATION RIGHTS AGREEMENT is made and entered into as of October 17, 2001 by and between Regeneron Pharmaceuticals, Inc., a New York corporation (the "Company"), and Merrill Lynch & Co., Merrill Lynch, Pierce, Fenner & Smith Incorporated and Robertson Stephens, Inc. (collectively, the "Initial Purchasers") pursuant to the Purchase Agreement, dated as of October 12, 2001 (the "Purchase Agreement"), between the Company and the Initial Purchasers. In order to induce the Initial Purchasers to enter into the Purchase Agreement, the Company has agreed to provide the registration rights set forth in this Agreement. The execution of this Agreement is a condition to the closing under the Purchase Agreement. The Company agrees with the Initial Purchasers for the benefit of the Initial Purchasers and for the benefit of the beneficial owners (including the Initial Purchasers) from time to time of the Registrable Securities (as defined herein) (each of the foregoing a "Holder" and together the "Holders"), as follows: Section 1. Definitions. Capitalized terms used herein without definition shall have their respective meanings set forth in the Purchase Agreement. As used in this Agreement, the following terms shall have the following meanings: "Affiliate" means, with respect to any specified person, an "affiliate," as defined in Rule 144, of such person. "Amendment Effectiveness Deadline Date" has the meaning specified in Section 2(d) hereof. "Business Day" means each Monday, Tuesday, Wednesday, Thursday and Friday that is not a day on which banking institutions in The City of New York are authorized or obligated by law or executive order to close. "Common Stock" means any shares of Common Stock, par value $0.001 per share, of the Company and any other shares of common stock as may constitute "Common Stock" for purposes of the Indenture, including the Underlying Common Stock. "Conversion Price" has the meaning assigned to that term in the Indenture. "Damages Accrual Period" has the meaning specified in Section 2(e) hereof. "Damages Payment Date" means each October 17 and April 17 in the case of Securities and the Underlying Common Stock. "Deferral Notice" has the meaning specified in Section 3(i) hereof. "Deferral Period" has the meaning specified in Section 3(i) hereof.

"Effectiveness Deadline Date" has the meaning specified in Section 2(a) hereof. "Effectiveness Period" means the period of two years from the Issue Date or such shorter period that will terminate upon the earliest of the following: (A) when all the Securities covered by the Shelf Registration Statement have been sold pursuant to the Shelf Registration Statement or when all shares of Underlying Common Stock have been sold pursuant to the Shelf Registration Statement and (B) when, in the written opinion of counsel to the Company, all outstanding Registrable Securities held by persons which are not affiliates of the Company may be resold without registration under the Securities Act pursuant to Rule 144(k) under the Securities Act or any successor provision thereto. "Event" has the meaning specified in Section 2(e) hereof. "Event Termination Date" has the meaning specified in Section 2(e) hereof. "Event Date" has the meaning specified in Section 2(e) hereof. "Exchange Act" means the Securities Exchange Act of 1934, as amended, and the rules and regulations of the SEC promulgated thereunder. "Filing Deadline Date" has the meaning specified in Section 2(a) hereof. "Holder" has the meaning specified in the second paragraph of this Agreement. "Indenture" means the Indenture dated as of the date hereof between the Company and the Trustee, pursuant to which the Securities are being issued. "Initial Purchasers" has the meaning specified in the first paragraph of this Agreement. "Initial Shelf Registration Statement" has the meaning specified in Section 2(a) hereof. "Issue Date" means October 17, 2001. "Liquidated Damages Amount" has the meaning specified in Section 2(e) hereof. "Material Event" has the meaning specified in Section 3(i) hereof. "Notice and Questionnaire" means a written notice delivered to the Company containing substantially the information called for by the Selling Securityholder Notice and Questionnaire attached as Annex A to the Offering Memorandum of the Company issued October 12, 2001 relating to the Securities. "Notice Holder" means, on any date, any Holder that has delivered a Notice and Questionnaire to the Company on or prior to such date. "Principal Amount" means, with the respect to the Securities, the principal amount due on the maturity date as shown on such Securities. 2

"Prospectus" means the prospectus included in any Registration Statement (including, without limitation, a prospectus that discloses information previously omitted from a prospectus filed as part of an effective registration statement in reliance upon Rule 415 promulgated under the Securities Act), as amended or supplemented by any amendment or prospectus supplement, including post-effective amendments, and all materials incorporated by reference or explicitly deemed to be incorporated by reference in such Prospectus. "Purchase Agreement" has the meaning specified in the first paragraph of this Agreement. "Record Holder" means, with respect to any Damages Payment Date relating to any Securities or Underlying Common Stock as to which any Liquidated Damages Amount has accrued, the registered Holder of such Securities or Underlying Common Stock, as the case may be, 15 days prior to the next succeeding Damages Payment Date. "Registrable Securities" means the Securities, until such Securities have been converted or exchanged, and the Underlying Common Stock and any securities into or for which such securities have been converted or exchanged, and any security issued with respect thereto upon any stock dividend, split or similar event until, in the case of any such security, the earliest of (i) its effective registration under the Securities Act and resale in accordance with the Registration Statement covering it, (ii) expiration of the holding period that would be applicable thereto under Rule 144(k) were it not held by an Affiliate of the Company or (iii) its sale to the public pursuant to Rule 144. "Registration Expenses" means the expenses described in Section 5 hereof. "Registration Statement" means any registration statement of the Company that covers any of the Registrable Securities pursuant to the provisions of this Agreement, including the Prospectus, amendments and supplements to such registration statement, including post-effective amendments, all exhibits, and all materials incorporated by reference or explicitly deemed to be incorporated by reference in such registration statement. "Restricted Securities" has the meaning assigned to that term in Rule 144. "Rule 144" means Rule 144 under the Securities Act, as such Rule may be amended from time to time, or any similar rule or regulation hereafter adopted by the SEC. "Rule 144A" means Rule 144A under the Securities Act, as such Rule may be amended from time to time, or any similar rule or regulation hereafter adopted by the SEC. "SEC" means the U.S. Securities and Exchange Commission and any successor agency. "Securities" means the 5-1/2% Convertible Senior Subordinated Notes due 2008 of the Company to be purchased pursuant to the Purchase Agreement. "Securities Act" means the Securities Act of 1933, as amended, and the rules and regulations promulgated by the SEC thereunder. 3

"Shelf Registration Statement" has the meaning specified in Section 2(a) hereof. "Subsequent Shelf Registration Statement" has the meaning specified in Section 2(b) hereof. "TIA" means the Trust Indenture Act of 1939, as amended. "Trustee" means American Stock Transfer & Trust Company (or any successor entity), the Trustee under the Indenture. "Underlying Common Stock" means the Common Stock into which the Securities are convertible or issued upon any such conversion. Section 2. Shelf Registration. (a) The Company shall prepare and file or cause to be prepared and filed with the SEC, as soon as practicable but in any event by the date (the "Filing Deadline Date") ninety (90) days after the Issue Date, a Registration Statement for an offering to be made on a delayed or continuous basis pursuant to Rule 415 of the Securities Act (a "Shelf Registration Statement") registering the resale from time to time by Holders thereof of all of the Registrable Securities (the "Initial Shelf Registration Statement"). The Initial Shelf Registration Statement shall be on Form S-3 or another appropriate form permitting registration of such Registrable Securities for resale by such Holders in accordance with the methods of distribution elected by the Holders and set forth in the Initial Shelf Registration Statement. The Company shall use its reasonable best efforts to cause the Initial Shelf Registration Statement to be declared effective under the Securities Act as promptly as is practicable but in any event by the date (the "Effectiveness Deadline Date") that is one hundred and eighty (180) days after the Issue Date, and to keep the Initial Shelf Registration Statement (or any Subsequent Shelf Registration Statement) continuously effective under the Securities Act until the expiration of the Effectiveness Period; provided, however, that no Holder shall be entitled to have the Registrable Securities held by it covered by such Shelf Registration Statement unless such Holder shall have provided a Notice and Questionnaire in accordance with Section 2(d) and is in compliance with Section 4. From and after the date hereof, the Company will not grant any existing or future holders of the Company's securities the right to include any of the Company's securities in the Shelf Registration Statement. The Company will use its reasonable best efforts to seek and obtain waivers from its security holders with pre-existing registration rights to effectively waive any such rights with respect to the Shelf Registration Statement; provided that no assurance can be given that any such third-parties shall waive their rights. (b) If the Initial Shelf Registration Statement or any Subsequent Shelf Registration Statement ceases to be effective for any reason at any time during the Effectiveness Period (other than because all Registrable Securities registered thereunder shall have been sold pursuant thereto or shall have otherwise ceased to be Registrable Securities), the Company shall use its reasonable best efforts to obtain the prompt withdrawal of any order suspending the effectiveness thereof, and in any event shall within thirty (30) days of such cessation of effectiveness amend the Shelf Registration Statement in a manner reasonably expected to obtain the withdrawal of the order suspending the effectiveness thereof, or file an additional Shelf Registration Statement covering all of the securities that as of the date of such filing are 4

Registrable Securities (a "Subsequent Shelf Registration Statement"). If a Subsequent Shelf Registration Statement is filed, the Company shall use its reasonable best efforts to cause the Subsequent Shelf Registration Statement to become effective as promptly as is practicable after such filing and to keep such Registration Statement (or another Subsequent Shelf Registration Statement) continuously effective until the end of the Effectiveness Period. (c) The Company shall supplement and amend the Shelf Registration Statement if required by the rules, regulations or instructions applicable to the registration form used by the Company for such Shelf Registration Statement, if required by the Securities Act or, to the extent to which the Company does not reasonably object, as reasonably requested by the Initial Purchasers or by the Trustee on behalf of the registered Holders. (d) Each Holder agrees that if such Holder wishes to sell Registrable Securities pursuant to a Shelf Registration Statement and related Prospectus, it will do so only in accordance with this Section 2(d) and Section 3(i). Each Holder wishing to sell Registrable Securities pursuant to a Shelf Registration Statement and related Prospectus agrees to deliver a Notice and Questionnaire to the Company at least five (5) Business Days prior to any intended distribution of Registrable Securities under the Shelf Registration Statement. From and after the date the Initial Shelf Registration Statement is declared effective, the Company shall, as promptly as is practicable after the date a Notice and Questionnaire is delivered, and in any event within five (5) Business Days after such date, (i) if required by applicable law, file with the SEC a post-effective amendment to the Shelf Registration Statement or prepare and, if required by applicable law, file a supplement to the related Prospectus or a supplement or amendment to any document incorporated therein by reference or file any other required document so that the Holder delivering such Notice and Questionnaire is named as a selling security holder in the Shelf Registration Statement and the related Prospectus in such a manner as to permit such Holder to deliver such Prospectus to purchasers of the Registrable Securities in accordance with applicable law and, if the Company shall file a post-effective amendment to the Shelf Registration Statement, use its reasonable best efforts to cause such post-effective amendment to be declared effective under the Securities Act as promptly as is practicable, but in any event by the date (the "Amendment Effectiveness Deadline Date") that is forty-five (45) days after the date such post-effective amendment is required by this clause to be filed; (ii) provide such Holder copies of any documents filed pursuant to Section 2(d)(i); and (iii) notify such Holder as promptly as practicable after the effectiveness under the Securities Act of any post-effective amendment filed pursuant to Section 2(d)(i); provided, that if such Notice and Questionnaire is delivered during a Deferral Period, the Company shall so inform the Holder delivering such Notice and Questionnaire and shall take the actions set forth in clauses (i), (ii) and (iii) above upon expiration of the Deferral Period in accordance with Section 3(i), provided, further, that if under applicable law the Company has more than one option as to the type or manner of making any such filing, it will make the required filing or filings in the manner or of a type that is reasonably expected to result in the earliest availability of the Prospectus for effecting resales of Registrable Securities. Notwithstanding anything contained herein to the contrary, the Company shall be under no obligation to name any Holder that is not a Notice Holder as a selling security holder in any Registration Statement or related Prospectus; provided, however, that any Holder that becomes a Notice Holder pursuant to the provisions of this Section 2(d) (whether or not such Holder was a Notice Holder at the time the Registration Statement was declared effective) shall 5

be named as a selling security holder in the Registration Statement or related Prospectus in accordance with the requirements of this Section 2(d). (e) The parties hereto agree that the Holders of Registrable Securities will suffer damages, and that it would not be feasible to ascertain the extent of such damages with precision, if (i) the Initial Shelf Registration Statement has not been filed on or prior to the Filing Deadline Date, (ii) the Initial Shelf Registration Statement has not been declared effective under the Securities Act on or prior to the Effectiveness Deadline Date, (iii) the Company has failed to perform its obligations set forth in Section 2(d) hereof within the time period required therein, (iv) the aggregate duration of Deferral Periods in any period exceeds the number of days permitted in respect of such period pursuant to Section 3(i) hereof or (v) the number of Deferral Periods in any period exceeds the number permitted in respect of such periods pursuant to Section 3(i) (each of the events of a type described in any of the foregoing clauses (i) through (v) are individually referred to herein as an "Event," and the Filing Deadline Date in the case of clause (i), the Effectiveness Deadline Date in the case of clause (ii), the date by which the Company is required to perform its obligations set forth in Section 2(d) in the case of clause (iii) (including the filing of any post-effective amendment prior to the Amendment Effectiveness Deadline Date), the date on which the aggregate duration of Deferral Periods in any period exceeds the number of days permitted by Section 3(i) hereof in the case of clause (iv), and the date of the commencement of a Deferral Period that causes the limit on the number of Deferral Periods in any period under Section 3(i) hereof to be exceeded in the case of clause (v), being referred to herein as an "Event Date"). Events shall be deemed to continue until the "Event Termination Date," which shall be the following dates with respect to the respective types of Events: the date the Initial Shelf Registration Statement is filed in the case of an Event of the type described in clause (i), the date the Initial Shelf Registration Statement becomes effective under the Securities Act in the case of an Event of the type described in clause (ii), the date the Company performs its obligations set forth in Section 2(d) in the case of an Event of the type described in clause (iii) (including, without limitation, the date the relevant post-effective amendment to the Shelf Registration Statement is declared effective under the Securities Act), termination of the Deferral Period that caused the limit on the aggregate duration of Deferral Periods in a period set forth in Section 3(i) to be exceeded in the case of the commencement of an Event of the type described in clause (iv), and termination of the Deferral Period the commencement of which caused the number of Deferral Periods in a period permitted by Section 3(i) to be exceeded in the case of an Event of the type described in clause (v). Accordingly, commencing on (and including) any Event Date and ending on (but excluding) the relevant Event Termination Date (a "Damages Accrual Period"), the Company agrees to pay, as liquidated damages and not as a penalty, an amount (the "Liquidated Damages Amount"), payable on the Damages Payment Dates to Record Holders, accruing for each portion of such Damages Accrual Period beginning on and including a Damages Payment Date (or, in respect of the first time that the Liquidation Damages Amount is to be paid to Holders on a Damages Payment Date as a result of the occurrence of any particular Event, from and including the Event Date) and ending on but excluding the first to occur of (A) the date of the end of the Damages Accrual Period or (B) the next Damages Payment Date, at a rate per annum equal to one-quarter of one percent (0.25%) for the first 90-day period from the Event Date, and thereafter at a rate per annum equal to one-half of one percent (0.5%), of the aggregate Principal Amount of such Securities or, if the Holder has converted such Securities into Underlying 6

Common Stock and such shares of Common Stock then constitute Registrable Securities, the Conversion Price of such Securities in effect at the time of such conversion, in each case, determined as of the Business Day immediately preceding the next Damages Payment Date; provided, that in the case of a Damages Accrual Period that is in effect solely as a result of an Event of the type described in clause (iii) of the immediately preceding paragraph, such Liquidated Damages Amount shall be paid only to the Holders that have delivered Notice and Questionnaires that caused the Company to incur the obligations set forth in Section 2(d) the non-performance of which is the basis of such Event; provided further, that any Liquidated Damages Amount accrued with respect to any Securities or portion thereof called for redemption on a redemption date or converted into Underlying Common Stock on a conversion date prior to the Damages Payment Date, shall, in any such event, be paid instead to the Holder who submitted such Securities or portion thereof for redemption or conversion on the applicable redemption date or conversion date, as the case may be, on such date (or promptly following the conversion date, in the case of conversion). Notwithstanding the foregoing, no Liquidated Damages Amounts shall accrue as to any Registrable Security from and after the earlier of (x) the date such security is no longer a Registrable Security and (y) expiration of the Effectiveness Period. The rate of accrual of the Liquidated Damages Amount with respect to any period shall not exceed the applicable rate provided for in this paragraph and shall not exceed one-half of one percent (0.5%), notwithstanding the occurrence of multiple concurrent Events. Following the relevant Event Termination Date, the accrual of Liquidated Damages Amounts will cease (without in any way limiting the effect of any subsequent Event requiring the payment of Liquidated Damages Amount by the Company). The Trustee shall be entitled, on behalf of Holders of Securities or Underlying Common Stock, to seek any available remedy for the enforcement of this Agreement, including for the payment of any Liquidated Damages Amount. Notwithstanding the foregoing, the parties agree that the sole monetary damages payable for a violation of the terms of this Agreement with respect to which liquidated damages are expressly provided shall be such liquidated damages. Nothing shall preclude a Notice Holder or Holder from pursuing or obtaining specific performance or other equitable relief with respect to this Agreement. All of the Company's obligations set forth in this Section 2(e) that are outstanding with respect to any Registrable Security at the time such security ceases to be a Registrable Security shall survive until such time as all such obligations with respect to such security have been satisfied in full (notwithstanding termination of this Agreement pursuant to Section 8(k)). The parties hereto agree that the liquidated damages provided for in this Section 2(e) constitute a reasonable estimate of the damages that may be incurred by Holders of Registrable Securities by reason of the failure of the Shelf Registration Statement to be filed or declared effective or available for effecting resales of Registrable Securities in accordance with the provisions hereof. Section 3. Registration Procedures. In connection with the registration obligations of the Company under Section 2 hereof, the Company shall: (a) Before filing any Registration Statement or Prospectus or any amendments or supplements thereto with the SEC, furnish to the Initial Purchasers copies of all such 7

documents proposed to be filed and use its reasonable best efforts to reflect in each such document when so filed with the SEC such comments as the Initial Purchasers reasonably shall propose within three (3) Business Days of the delivery of such copies to the Initial Purchasers. (b) Prepare and file with the SEC such amendments and post-effective amendments to each Registration Statement as may be necessary to keep such Registration Statement continuously effective for the applicable period specified in Section 2(a); cause the related Prospectus to be supplemented by any required Prospectus supplement, and as so supplemented to be filed pursuant to Rule 424 (or any similar provisions then in force) under the Securities Act; and comply with the provisions of the Securities Act applicable to it with respect to the disposition of all securities covered by such Registration Statement during the Effectiveness Period in accordance with the intended methods of disposition by the sellers thereof set forth in such Registration Statement as so amended or such Prospectus as so supplemented. (c) As promptly as practicable give notice to the Notice Holders and the Initial Purchasers (i) when any Prospectus, Prospectus supplement, Registration Statement or post-effective amendment to a Registration Statement has been filed with the SEC and, with respect to a Registration Statement or any post-effective amendment, when the same has become effective, (ii) of any request, following the effectiveness of the Initial Shelf Registration Statement under the Securities Act, by the SEC or any other federal or state governmental authority for amendments or supplements to any Registration Statement or related Prospectus or for additional information, (iii) of the issuance by the SEC or any other federal or state governmental authority of any stop order suspending the effectiveness of any Registration Statement or, to the Company's knowledge, the initiation or threatening of any proceedings for that purpose, (iv) of the receipt by the Company of any notification with respect to the suspension of the qualification or exemption from qualification of any of the Registrable Securities for sale in any jurisdiction or, to the Company's knowledge, the initiation or threatening of any proceeding for such purpose, (v) of the occurrence of (but not the nature of or details concerning) a Material Event (provided, however, that no notice by the Company shall be required pursuant to this clause (v) in the event that the Company either promptly files a Prospectus supplement to update the Prospectus or a Form 8-K or other appropriate Exchange Act report that is incorporated by reference into the Registration Statement, which, in either case, contains the requisite information with respect to such Material Event that results in such Registration Statement no longer containing any untrue statement of material fact or omitting to state a material fact necessary to make the statements contained therein not misleading) and (vi) of the determination by the Company that a post-effective amendment to a Registration Statement will be filed with the SEC, which notice may, at the discretion of the Company (or as required pursuant to Section 3(i)), state that it constitutes a Deferral Notice, in which event the provisions of Section 3(i) shall apply. (d) Use its reasonable best efforts to prevent the issuance, and if issued to promptly obtain the withdrawal of any order suspending the effectiveness of a Registration Statement or the lifting of any suspension of the qualification (or exemption from qualification) of any of the Registrable Securities for sale in any jurisdiction in which they have been qualified for sale. 8

(e) If reasonably requested by the Initial Purchasers or any Notice Holder, promptly incorporate in a Prospectus supplement or post-effective amendment to a Registration Statement such information as the Initial Purchasers or such Notice Holder shall, on the basis of an opinion of nationally-recognized counsel experienced in such matters, determine to be required to be included therein by applicable law and make any required filings of such Prospectus supplement or such post-effective amendment; provided, that the Company shall not be required to take any actions under this Section 3(e) that are not, in the reasonable opinion of counsel for the Company, in compliance with applicable law. (f) Furnish to each Notice Holder and the Initial Purchasers, upon their request and without charge, at least one (1) conformed copy of the Registration Statement and any amendment thereto, including financial statements but excluding schedules, all documents incorporated or deemed to be incorporated therein by reference and all exhibits (unless requested in writing to the Company by such Notice Holder or the Initial Purchasers, as the case may be). (g) During the Effectiveness Period, deliver to each Notice Holder in connection with any sale of Registrable Securities pursuant to a Registration Statement, without charge, as many copies of the Prospectus or Prospectuses relating to such Registrable Securities (including each preliminary prospectus) and any amendment or supplement thereto as such Notice Holder may reasonably request; and the Company hereby consents (except during such periods that a Deferral Notice is outstanding and has not been revoked) to the use of such Prospectus or each amendment or supplement thereto by each Notice Holder in connection with any offering and sale of the Registrable Securities covered by such Prospectus or any amendment or supplement thereto in the manner set forth therein. (h) Prior to any public offering of the Registrable Securities pursuant to the Shelf Registration Statement, register or qualify or cooperate with the Notice Holders in connection with the registration or qualification (or exemption from such registration or qualification) of such Registrable Securities for offer and sale under the securities or Blue Sky laws of such jurisdictions within the United States as any Notice Holder reasonably requests in writing (which request may be included in the Notice and Questionnaire); prior to any public offering of the Registrable Securities pursuant to the Shelf Registration Statement, use its reasonable best efforts to keep each such registration or qualification (or exemption therefrom) effective during the Effectiveness Period in connection with such Notice Holder's offer and sale of Registrable Securities pursuant to such registration or qualification (or exemption therefrom) and do any and all other acts or things reasonably necessary or advisable to enable the disposition in such jurisdictions of such Registrable Securities in the manner set forth in the relevant Registration Statement and the related Prospectus; provided, that the Company will not be required to (i) qualify as a foreign corporation or as a dealer in securities in any jurisdiction where it would not otherwise be required to qualify but for this Agreement or (ii) take any action that would subject it to general service of process in suits or to taxation in any such jurisdiction where it is not then so subject. (i) Upon (A) the issuance by the SEC of a stop order suspending the effectiveness of the Shelf Registration Statement or the initiation of proceedings with respect to the Shelf Registration Statement under Section 8(d) or 8(e) of the Securities Act, (B) the occurrence of any event or the existence of any fact (a "Material Event") as a result of which any 9

Registration Statement shall contain any untrue statement of a material fact or omit to state any material fact required to be stated therein or necessary to make the statements therein not misleading, or any Prospectus shall contain any untrue statement of a material fact or omit to state any material fact required to be stated therein or necessary to make the statements therein, in the light of the circumstances under which they were made, not misleading, or (C) the occurrence or existence of any pending corporate development that, in the discretion of the Company, makes it appropriate to suspend the availability of the Shelf Registration Statement and the related Prospectus, (i) in the case of clause (B) above, subject to the next sentence, promptly prepare and file a post-effective amendment to such Registration Statement or a supplement to the related Prospectus or any document incorporated therein by reference or file any other required document that would be incorporated by reference into such Registration Statement and Prospectus so that such Registration Statement does not contain any untrue statement of a material fact or omit to state any material fact required to be stated therein or necessary to make the statements therein not misleading, and such Prospectus does not contain any untrue statement of a material fact or omit to state any material fact required to be stated therein or necessary to make the statements therein, in the light of the circumstances under which they were made, not misleading, as thereafter delivered to the purchasers of the Registrable Securities being sold thereunder, and, in the case of a post-effective amendment to a Registration Statement, subject to the next sentence, use its reasonable best efforts to cause it to be declared effective as promptly as is reasonably practicable, and (ii) give notice to the Notice Holders that the availability of the Shelf Registration Statement is suspended (a "Deferral Notice") and, upon receipt of any Deferral Notice, each Notice Holder agrees not to sell any Registrable Securities pursuant to the Registration Statement until such Notice Holder's receipt of copies of the supplemented or amended Prospectus provided for in clause (i) above, or until it is advised in writing by the Company that the Prospectus may be used, and has received copies of any additional or supplemental filings that are incorporated or deemed incorporated by reference in such Prospectus. The Company will use its reasonable best efforts to ensure that the use of the Prospectus may be resumed (x) in the case of clause (A) above, as promptly as is practicable, (y) in the case of clause (B) above, as soon as, in the sole judgment of the Company, public disclosure of such Material Event would not be prejudicial to or contrary to the interests of the Company or, if necessary to avoid unreasonable burden or expense, as soon as reasonably practicable thereafter and (z) in the case of clause (C) above, as soon as, in the sole judgment of the Company, such suspension is no longer appropriate. The period during which the availability of the Registration Statement and any Prospectus is suspended (the "Deferral Period") without the Company incurring any obligation to pay liquidated damages pursuant to Section 2(e) shall not exceed forty-five (45) days in any three (3) month period and one-hundred twenty (120) days in any twelve (12) month period. (j) In the event of a Qualified Underwritten Offering, make available for inspection during normal business hours by a representative for the Notice Holders of such Registrable Securities and any broker-dealers, attorneys and accountants retained by such Notice Holders, all relevant financial and other records, pertinent corporate documents and properties of the Company and its subsidiaries, and cause the appropriate executive officers, directors and designated employees of the Company and its subsidiaries to make available for inspection during normal business hours all relevant information reasonably requested by such representative for the Notice Holders or any such broker-dealers, attorneys or accountants in connection with such disposition, in each case as is customary for similar "due diligence" 10

examinations; provided, however, that such persons shall first agree in writing with the Company that any information that is reasonably and in good faith designated by the Company in writing as confidential at the time of delivery of such information shall be kept confidential by such persons and shall be used solely for the purposes of exercising rights under this Agreement, unless (i) disclosure of such information is required by court or administrative order or is necessary to respond to inquiries of regulatory authorities, (ii) disclosure of such information is required by law (including any disclosure requirements pursuant to federal securities laws in connection with the filing of any Registration Statement or the use of any Prospectus referred to in this Agreement), (iii) such information becomes generally available to the public other than as a result of a disclosure or failure to safeguard by any such person or (iv) such information becomes available to any such person from a source other than the Company and such source is not bound by a confidentiality agreement; and provided further that the foregoing inspection and information gathering shall, to the greatest extent possible, be coordinated on behalf of all the Notice Holders and the other parties entitled thereto by the counsel referred to in Section 5. For the purposes of this paragraph, "Qualified Underwritten Offering" shall mean an underwritten public offering of Registrable Securities in an aggregate amount of at least $25 million. (k) Comply with all applicable rules and regulations of the SEC and make generally available to its securityholders earning statements (which need not be audited) satisfying the provisions of Section 11(a) of the Securities Act and Rule 158 thereunder (or any similar rule promulgated under the Securities Act) commencing on the first day of the first fiscal quarter of the Company commencing after the effective date of a Registration Statement. (l) Cooperate with each Notice Holder to facilitate the timely preparation and delivery of certificates representing Registrable Securities sold pursuant to a Registration Statement, and cause such Registrable Securities to be in such denominations as are permitted by the Indenture and registered in such names as such Notice Holder may request in writing at least two Business Days prior to any sale of such Registrable Securities. (m) Provide a CUSIP number for all Registrable Securities covered by each Registration Statement not later than the effective date of such Registration Statement and provide the Trustee for the Securities and the transfer agent for the Underlying Common Stock the with printed certificates for the Registrable Securities that are in a form eligible for deposit with The Depository Trust Company. (n) Use its reasonable best efforts to provide such information as is required for any filings required to be made with the National Association of Securities Dealers, Inc. (o) Upon (i) the filing of the Initial Shelf Registration Statement and (ii) the effectiveness of the Initial Shelf Registration Statement, announce the same, in each case by release to Reuters Economic Services and Bloomberg Business News. (p) Enter into such customary agreements and take all such other reasonably necessary actions in connection therewith (including those requested by the holders of a majority of the Registrable Securities being sold) in order to expedite or facilitate disposition of such Registrable Securities. 11

(q) Cause the Indenture to be qualified under the TIA not later than the effective date of any Registration Statement; and in connection therewith, cooperate with the Trustee to effect such changes to the Indenture as may be required for the Indenture to be so qualified in accordance with the terms of the TIA and execute, and use its reasonable best efforts to cause the Trustee to execute, all documents as may be required to effect such changes, and all other forms and documents required to be filed with the SEC to enable the Indenture to be so qualified in a timely manner. Section 4. Holder's Obligations. Each Holder agrees, by acquisition of the Registrable Securities, that no Holder shall be entitled to sell any of such Registrable Securities pursuant to a Registration Statement or to receive a Prospectus relating thereto, unless such Holder has furnished the Company with a Notice and Questionnaire as required pursuant to Section 2(d) hereof (including the information required to be included in such Notice and Questionnaire) and the information set forth in the next sentence. Each Notice Holder agrees promptly to furnish to the Company all information required to be disclosed in order to make the information previously furnished to the Company by such Notice Holder not misleading and any other information regarding such Notice Holder and the distribution of such Registrable Securities as may be required to be disclosed in the Registration Statement under applicable law. Section 5. Registration Expenses. The Company shall bear all fees and expenses incurred in connection with the performance by the Company of its obligations under Sections 2 and 3 of this Agreement whether or not any of the Registration Statements are declared effective. Such fees and expenses shall include, without limitation, (i) all registration and filing fees (including, without limitation, fees and expenses (x) with respect to filings required to be made with the National Association of Securities Dealers, Inc. and (y) of compliance with federal and state securities or Blue Sky laws (including, without limitation, fees and disbursements of the counsel specified in the next sentence in connection with Blue Sky qualifications of the Registrable Securities under the laws of such jurisdictions as the Notice Holders of a majority of the Registrable Securities being sold pursuant to a Registration Statement may designate), (ii) printing expenses (including, without limitation, expenses of printing certificates for Registrable Securities in a form eligible for deposit with The Depository Trust Company), (iii) duplication expenses relating to copies of any Registration Statement or Prospectus delivered to any Holders hereunder, (iv) fees and disbursements of counsel for the Company in connection with the Shelf Registration Statement and (v) fees and disbursements of the Trustee and its counsel and of the registrar and transfer agent for the Common Stock. In addition, the Company shall bear or reimburse the Notice Holders for the fees and disbursements of one firm of legal counsel for the Holders, which shall initially be Shearman & Sterling, but which may, upon the written consent of the Initial Purchasers (which shall not be unreasonably withheld), be another nationally recognized law firm experienced in securities law matters designated by the Company. In addition, the Company shall pay the internal expenses of the Company (including, without limitation, all salaries and expenses of officers and employees performing legal or accounting duties), the expense of any annual audit, the fees and expenses incurred in connection with the listing of the Registrable Securities on any securities exchange on which similar securities of the Company are then listed and the fees and expenses of any person, including special experts, retained by the Company. 12

Section 6. Indemnification; Contribution. (a) The Company agrees to indemnify and hold harmless the Initial Purchasers and each Holder and each person, if any, who controls the Initial Purchasers or any Holder within the meaning of either Section 15 of the Securities Act or Section 20 of the Exchange Act, as follows: (i) against any and all loss, liability, claim, damage and expense whatsoever, as incurred, arising out of any untrue statement or alleged untrue statement of a material fact contained in the Registration Statement (or any amendment thereto), or the omission or alleged omission therefrom of a material fact necessary in order to make the statements therein, in light of the circumstances under which they were made, not misleading or arising out of any untrue statement or alleged untrue statement of a material fact included in any preliminary prospectus or the Prospectus (or any amendment or supplement thereto), or the omission or alleged omission therefrom of a material fact necessary in order to make the statements therein, in the light of the circumstances under which they were made, not misleading; (ii) against any and all loss, liability, claim, damage and expense whatsoever, as incurred, to the extent of the aggregate amount paid in settlement of any litigation, or any investigation or proceeding by any governmental agency or body, commenced or threatened, or of any claim whatsoever based upon any such untrue statement or omission, or any such alleged untrue statement or omission, provided that (subject to Section 6(d) below) any such settlement is effected with the prior written consent of the Company; and (iii) against any and all expense whatsoever, as incurred (including the fees and disbursements of counsel), reasonably incurred in investigating, preparing or defending against any litigation, or any investigation or proceeding by any governmental agency or body, commenced or threatened, or any claim whatsoever based upon any such untrue statement or omission, or any such alleged untrue statement or omission, to the extent that any such expense is not paid under (i) or (ii) above; provided, however, that this indemnity shall not apply to any loss, liability, claim, damage or expense to the extent arising out of any untrue statement or omission or alleged untrue statement or omission made in reliance upon and in conformity with written information furnished to the Company by the Initial Purchasers or such Holder (which also acknowledges the indemnity provisions herein) and each person, if any, who controls the Initial Purchasers or any such Holder expressly for use in the Registration Statement (or any amendment thereto), or any preliminary prospectus or the Prospectus (or any amendment or supplement thereto), and provided further that any amounts payable by the Company to the Initial Purchasers or the Holders shall be net of any insurance proceeds actually recovered by the Initial Purchasers or the Holders in connection therewith. (b) In connection with any Shelf Registration in which a Holder, including, without limitation, the Initial Purchasers, is participating, in furnishing information relating to such Holder to the Company in writing expressly for use in such Registration Statement, any preliminary prospectus, the Prospectus or any amendments or supplements thereto, such Holders agree, severally and not jointly, to indemnify and hold harmless the Initial Purchasers and each 13

person, if any, who controls the Initial Purchasers within the meaning of either Section 15 of the Securities Act or Section 20 of the Exchange Act and the Company, and each person, if any, who controls the Company within the meaning of either such Section, against any and all loss, liability, claim, damage and expense described in the indemnity contained in subsection (a) of this Section, as incurred, but only with respect to untrue statements or omissions, or alleged untrue statements or omissions, made in the Registration Statement (or any amendment thereto), or any preliminary prospectus or the Prospectus (or any amendment or supplement thereto) in reliance upon and in conformity with written information furnished to the Company by such Holder (which also acknowledges the indemnity provisions herein) and each person, if any, who controls any such Holder expressly for use in the Registration Statement (or any amendment thereto) or such preliminary prospectus or the Prospectus (or any amendment or supplement thereto). Each of the Initial Purchasers agrees to indemnify and hold harmless the Company, the Holders, and each person, if any, who controls the Company or any Holder within the meaning of either Section 15 of the Securities Act or Section 20 of the Exchange Act against any and all loss, liability, claim, damage and expense described in the indemnity contained in subsection (a) of this Section, as incurred, but only with respect to untrue statements or omissions, or alleged untrue statements or omissions, made in the Registration Statement (or any amendment thereto), or any preliminary prospectus or the Prospectus (or any amendment or supplement thereto) in reliance upon and in conformity with written information furnished to the Company by the Initial Purchasers expressly for use in the Registration Statement (or any amendment thereto) or such preliminary prospectus or the Prospectus (or any amendment or supplement thereto). (c) Each indemnified party shall give notice as promptly as reasonably practicable to each indemnifying party of any action commenced against it in respect of which indemnity may be sought hereunder, but failure to so notify an indemnifying party shall not relieve such indemnifying party from any liability hereunder to the extent it is not materially prejudiced as a result thereof and in any event shall not relieve it from any liability which it may have otherwise than on account of this indemnity agreement. An indemnifying party may participate at its own expense in the defense of any such action; provided, however, that counsel to the indemnifying party shall not (except with the consent of the indemnified party) also be counsel to the indemnified party. In no event shall the indemnifying parties be liable for fees and expenses of more than one counsel (in addition to any local counsel) separate from their own counsel for all indemnified parties in connection with any one action or separate but similar or related actions in the same jurisdiction arising out of the same general allegations or circumstances. Counsel for the indemnified party shall be legal counsel acceptable to the indemnifying party; provided that the indemnifying party shall not unreasonably object to the legal counsel selected by the indemnified party. With respect to any action commenced, the parties hereto agree that it shall not be deemed to be an "unreasonable objection" if the indemnifying party objects to the choice of legal counsel selected by the indemnified party if such legal counsel is unable, for any reason, to also act as legal counsel to the indemnifying party; provided that the indemnifying party shall not raise such objection with respect to more than two legal counsels selected by the indemnified party. No indemnifying party shall, without the prior written consent of the indemnified parties, settle or compromise or consent to the entry of any judgment with respect to any litigation, or any investigation or proceeding by any 14

governmental agency or body, commenced or threatened, or any claim whatsoever in respect of which indemnification or contribution could be sought under this Section 6 hereof (whether or not the indemnified parties are actual or potential parties thereto), unless such settlement, compromise or consent (i) includes an unconditional release of each indemnified party from all liability arising out of such litigation, investigation, proceeding or claim and (ii) does not include a statement as to or an admission of fault, culpability or a failure to act by or on behalf of any indemnified party. (d) If at any time an indemnified party shall have requested an indemnifying party to reimburse the indemnified party for fees and expenses of counsel, such indemnifying party agrees that it shall be liable for any settlement of the nature contemplated by Section 6(a)(ii) effected without its written consent if (i) such settlement is entered into more than 45 days after receipt by such indemnifying party of aforesaid request, (ii) such indemnifying party shall have received notice of the terms of such settlement at least 30 days prior to such settlement being entered into and (iii) such indemnifying party shall not have reimbursed such indemnified party in accordance with such request prior to the date of such settlement. (e) If the indemnification provided for in this Section 6 is for any reason unavailable to or insufficient to hold harmless an indemnified party in respect of any losses, liabilities, claims, damages or expenses referred to therein, then each indemnifying party shall contribute to the aggregate amount of such losses, liabilities, claims, damages and expenses incurred by such indemnified party, as incurred, in such proportion as is appropriate to reflect the relative fault of the indemnifying party or parties on the one hand and of the indemnified party on the other hand in connection with the statements or omissions which resulted in such losses, liabilities, claims, damages or expenses, as well as any other relevant equitable considerations. The relative fault of the Company on the one hand and the holders of the Registrable Securities or the Initial Purchasers on the other hand shall be determined by reference to, among other things, whether any such untrue or alleged untrue statement of a material fact or omission or alleged omission to state a material fact relates to information supplied by the Company or by the Holder, including without limitation the Initial Purchasers and the parties' relative intent, knowledge, access to information and opportunity to correct or prevent such statement or omission. The parties hereto agree that it would not be just and equitable if contribution pursuant to this Section 6(e) were determined by pro rata allocation or by any other method of allocation which does not take account of the equitable considerations referred to above in this Section 6(e). The aggregate amount of losses, liabilities, claims, damages, and expenses incurred by an indemnified party and referred to above in this Section 6(e) shall be deemed to include any legal or other expenses reasonably incurred by such indemnified party in investigating, preparing or defending against any litigation, or any investigation or proceeding by any governmental agency or body, commenced or threatened, or any claim whatsoever based upon any such untrue or alleged untrue statement or omission or alleged omission. Notwithstanding the provisions of this Section 6, neither the Holders nor the Initial Purchasers, shall be required to indemnify or contribute any amount in excess of the amount by which the total price at which the Registrable Securities sold by such Holder or 15

underwritten by the Initial Purchasers, as the case may be, and distributed to the public were offered to the public exceeds the amount of any damages that such Holder or the Initial Purchasers has otherwise been required to pay by reason of such untrue or alleged untrue statement or omission or alleged omission. No person guilty of fraudulent misrepresentation (within the meaning of Section 11(f) of the Securities Act) shall be entitled to contribution from any person who was not guilty of such fraudulent misrepresentation. For purposes of this Section 6(e), each person, if any, who controls the Initial Purchasers or any Holder within the meaning of Section 15 of the Securities Act or Section 20 of the Exchange Act shall have the same rights to contribution as the Initial Purchasers or such holder, and each person, if any, who controls the Company within the meaning of Section 15 of the Securities Act or Section 20 of the Exchange Act shall have the same rights to contribution as the Company. Section 7. Information Requirements. The Company covenants that, if at any time before the end of the Effectiveness Period the Company is not subject to the reporting requirements of the Exchange Act, it will cooperate with any Holder and take such further reasonable action as any Holder may reasonably request in writing (including, without limitation, making such reasonable representations as any such Holder may reasonably request), all to the extent required from time to time to enable such Holder to sell Registrable Securities without registration under the Securities Act within the limitation of the exemptions provided by Rule 144 and Rule 144A under the Securities Act and customarily taken in connection with sales pursuant to such exemptions. Upon the written request of any Holder, the Company shall deliver to such Holder a written statement as to whether it has complied with such filing requirements, unless such a statement has been included in the Company's most recent report required to be filed and filed pursuant to Section 13 or Section 15(d) of Exchange Act. Section 8. Miscellaneous. (a) No Conflicting Agreements. The Company is not, as of the date hereof, a party to, nor shall it, on or after the date of this Agreement, enter into, any agreement with respect to its securities that conflicts with the rights granted to the Holders of Registrable Securities in this Agreement. The Company represents and warrants that the rights granted to the Holders of Registrable Securities hereunder do not in any way conflict with the rights granted to the holders of the Company's securities under any other agreements. (b) Amendments and Waivers. The provisions of this Agreement, including the provisions of this sentence, may not be amended, modified or supplemented, and waivers or consents to departures from the provisions hereof may not be given, unless the Company has obtained the written consent of Holders of a majority of the then outstanding Underlying Common Stock constituting Registrable Securities (with Holders of Securities deemed to be the Holders, for purposes of this Section, of the number of outstanding shares of Underlying Common Stock into which such Securities are or would be convertible or exchangeable as of the date on which such consent is requested). Notwithstanding the foregoing, a waiver or consent to depart from the provisions hereof with respect to a matter that relates exclusively to the rights of 16

Holders of Registrable Securities whose securities are being sold pursuant to a Registration Statement and that does not directly or indirectly affect the rights of other Holders of Registrable Securities may be given by Holders of at least a majority of the Registrable Securities being sold by such Holders pursuant to such Registration Statement; provided, that the provisions of this sentence may not be amended, modified, or supplemented except in accordance with the provisions of the immediately preceding sentence. Each Holder shall be bound by any such amendment, modification, supplement, waiver or consent effected pursuant to this Section 8(b), whether or not any notice, writing or marking indicating such amendment, modification, supplement, waiver or consent appears on the Registrable Securities or is delivered to such Holder. (c) Notices. All notices and other communications provided for or permitted hereunder shall be made in writing by hand delivery, by telecopier, by courier guaranteeing overnight delivery or by first-class mail, return receipt requested, and shall be deemed given (i) when made, if made by hand delivery, (ii) upon confirmation, if made by telecopier, (iii) one (1) Business Day after being deposited with such courier, if made by overnight courier or (iv) on the date indicated on the notice of receipt, if made by first-class mail, to the parties as follows: (w) if to a Holder, at the most current address given by such Holder to the Company in a Notice and Questionnaire or any amendment thereto; (x) if to the Company, to: Regeneron Pharmaceuticals, Inc. 777 Old Saw Mill River Road Tarrytown, New York 10591-607 Attention: General Counsel Telecopy No.: (914) 345-7721 with a copy to: Skadden, Arps, Slate, Meagher & Flom LLP 4 Times Square New York, NY10036-6522 Attention: David J. Goldschmidt and (y) if to the Initial Purchasers, to: Merrill Lynch & Co., Merrill Lynch, Pierce, Fenner & Smith Incorporated World Financial Center North Tower 250 Vesey Street New York, New York 10281 Attention: Syndicate Department Telecopy No.: (212) 738-1069 17

or to such other address as such person may have furnished to the other persons identified in this Section 8(c) in writing in accordance herewith. (d) Approval of Holders. Whenever the consent or approval of Holders of a specified percentage of Registrable Securities is required hereunder, the Registrable Securities held by the Company or its Affiliates (other than the Initial Purchasers or subsequent Holders of Registrable Securities if such subsequent Holders are deemed to be such affiliates solely by reason of their holdings of such Registrable Securities) shall not be counted in determining whether such consent or approval was given by the Holders of such required percentage. (e) Successors and Assigns. Any person who purchases any Registrable Securities from the Initial Purchasers shall be deemed, for purposes of this Agreement, to be an assignee of the Initial Purchasers. This Agreement shall inure to the benefit of and be binding upon the successors and assigns of each of the parties and shall inure to the benefit of and be binding upon each Holder. (f) Counterparts. This Agreement may be executed in any number of counterparts and by the parties hereto in separate counterparts, each of which when so executed shall be deemed to be original and all of which taken together shall constitute one and the same agreement. (g) Headings. The headings in this Agreement are for convenience of reference only and shall not limit or otherwise affect the meaning hereof. (h) Governing Law. THIS AGREEMENT SHALL BE GOVERNED BY AND CONSTRUED IN ACCORDANCE WITH THE LAWS OF THE STATE OF NEW YORK. (i) Severability. If any term, provision, covenant or restriction of this Agreement is held to be invalid, illegal, void or unenforceable, the remainder of the terms, provisions, covenants and restrictions set forth herein shall remain in full force and effect and shall in no way be affected, impaired or invalidated thereby, and the parties hereto shall use their best efforts to find and employ an alternative means to achieve the same or substantially the same result as that contemplated by such term, provision, covenant or restriction, it being intended that all of the rights and privileges of the parties shall be enforceable to the fullest extent permitted by law. (j) Entire Agreement. This Agreement is intended by the parties as a final expression of their agreement and is intended to be a complete and exclusive statement of the agreement and understanding of the parties hereto in respect of the subject matter contained herein and the registration rights granted by the Company with respect to the Registrable Securities. Except as provided in the Purchase Agreement, there are no restrictions, promises, warranties or undertakings, other than those set forth or referred to herein, with respect to the registration rights granted by the Company with respect to the Registrable Securities. This Agreement supersedes all prior agreements and undertakings among the parties with respect to such registration rights. 18

(k) Termination. This Agreement and the obligations of the parties hereunder shall terminate upon the expiration of the Effectiveness Period, except for any liabilities or obligations under Sections 4, 5 or 6 hereof and the obligations to make payments of and provide for liquidated damages under Section 2(e) hereof to the extent such damages accrue prior to the end of the Effectiveness Period, each of which shall remain in effect in accordance with its terms. * * * * * * * * 19

IN WITNESS WHEREOF, the parties have executed this Registration Rights Agreement as of the date first written above. REGENERON PHARMACEUTICALS, INC. By: __________________________________ Name: Title: Confirmed and accepted as of the date first above written: MERRILL LYNCH & CO. MERRILL LYNCH, PIERCE, FENNER & SMITH INCORPORATED ROBERTSON STEPHENS, INC. By: MERRILL LYNCH & CO. MERRILL LYNCH, PIERCE, FENNER & SMITH INCORPORATED By: _________________________________ Name: Title:

LETTERHEAD OF SKADDEN, ARPS, SLATE MEAGHER & FLOM LLP EXHIBIT 5 December 3, 2001 Regeneron Pharmaceuticals, Inc. 777 Old Saw Mill River Road Tarrytown, New York 10591-6707 Re: Registration Statement of Regeneron Pharmaceuticals, Inc. on Form S-3 Ladies and Gentlemen: We have acted as special counsel to Regeneron Pharmaceuticals, Inc., a New York corporation (the "Company"), in connection with its filing with the Securities and Exchange Commission (the "Commission") of a registration statement on Form S-3 on December 3, 2001 (the "Registration Statement") with respect to the registration under the Securities Act of 1933, as amended (the "Securities Act"), of $200,000,000 aggregate principal amount at maturity of its 5.50% Convertible Subordinated Notes due 2008 (the "Securities"), and shares of the Company's common stock (the "Common Stock"), par value $0.001 per share (the "Shares"), issuable upon conversion of the Securities, as contemplated by the registration rights agreement, dated as of October 17, 2001 (the "Registration Rights Agreement"), by and among the Company, Merrill Lynch, Pierce, Fenner & Smith Incorporated, J.P. Morgan Securities Inc., and Robertson Stephens, Inc. (collectively, the "Initial Purchasers"). The Company issued the Securities pursuant to the Purchase Agreement, dated as of October 12, 2001, by and among the Company and the Initial Purchasers (the "Purchase Agreement").

Regeneron Pharmaceuticals, Inc. December 3, 2001 This opinion is being furnished in accordance with the requirements of Item 601(b)(5) of Regulation S-K under the Securities Act. In connection with this opinion, we have examined originals or copies, certified or otherwise identified to our satisfaction, of (i) the Registration Statement filed on December 3, 2001; (ii) an executed copy of the Registration Rights Agreement; (iii) an executed copy of the Indenture, dated as of October 17, 2001 (the "Indenture"), between the Company and American Stock Transfer & Trust Company, as trustee (the "Trustee"); (iv) the closing documents delivered in connection with the sale of the Securities, including the executed global note representing the Securities authenticated by the Trustee; (v) the Restated Certificate of Incorporation of the Company, as amended to date; (vi) the By-laws of the Company, as amended to date; (vii) certain resolutions of the Company's Board of Directors adopted by unanimous written consent on Wednesday, October 10, 2001 relating to the issuance and sale of the Securities, the execution of the Registration Rights Agreement and filing of the Registration Statement; (viii) the Form T-1 of the Trustee filed as an exhibit to the Registration Statement; and (ix) a specimen certificate representing the Common Stock. We have also examined originals or copies, certified or otherwise identified to our satisfaction, of such records of the Company and such agreements, certificates of public officials, certificates of officers or other representatives of the Company and others, and such other documents, certificates and records as we have deemed necessary or appropriate as a basis for the opinions set forth herein. In our examination, we have assumed the legal capacity of all natural persons, the genuineness of all signatures, the authenticity of all documents submitted to us as originals, the conformity to original documents of all documents submitted to us as certified, conformed or photostatic copies and the authenticity of the originals of such latter documents. In making our examination of executed documents, we have assumed that the parties thereto, other than the Company, had or will have the power, corporate or other, to enter into and perform all obligations thereunder and have also assumed the due authorization by all requisite action, corporate or other, and execution and delivery by such parties of such documents and the validity and binding effect on such parties. In rendering the opinion set forth in Paragraph 1 below, we have also assumed that the global note representing the Securities was duly authenticated by the Trustee.

Regeneron Pharmaceuticals, Inc. December 3, 2001 As to any facts material to the opinions expressed herein which we have not independently established or verified, we have relied upon oral or written statements and representations of officers and other representatives of the Company and others. In rendering the opinion set forth in paragraph 2 below, we have assumed that the certificates evidencing the Shares issuable upon conversion of the Securities will be manually signed by one of the authorized officers of the transfer agent and registrar for the Common Stock and registered by such transfer agent and registrar and will conform to the specimen certificate examined by us evidencing the Common Stock. Our opinions set forth herein are limited to the laws of the State of New York which, in our experience, are normally applicable to transactions of the type contemplated by the Registration Statement and Registration Rights Agreement and to the extent that judicial or regulatory orders or decrees or consents, approvals, licenses, authorizations, validations, filings, recordings or registrations with governmental authorities are relevant, to those required under such laws (all of the foregoing being referred to as "Opined on Law"). We do not express any opinion with respect to the law of any jurisdiction other than Opined on Law or as to the effect of any such non opined on law on the opinions herein stated. Based upon and subject to the foregoing and the limitations, qualifications, exceptions and assumptions set forth herein, we are of the opinion that: 1. The Securities have been duly authorized and are valid and binding obligations of the Company, enforceable against the Company in accordance with their terms, except to the extent that enforcement thereof may be limited by (i) bankruptcy, insolvency, reorganization, moratorium, fraudulent conveyance or other similar laws now or hereafter in effect relating to creditors' rights generally, and (ii) general principles of equity (regardless of whether enforceability is considered in a proceeding at law or equity). 2. The Shares initially issuable upon conversion of the Securities have been duly authorized and reserved for issuance and, when issued and delivered upon such conversion pursuant to the terms of the Indenture, will be validly issued, fully paid and, except as provided in section 630 of the New York Business Corporation Law (the "BCL"), non-assessable.

Regeneron Pharmaceuticals, Inc. December 3, 2001 In rendering the opinion set forth above in paragraph 1, we have assumed that the execution and delivery by the Company of the Indenture and the Securities and the performance by the Company of its obligations thereunder do not violate, conflict with or constitute a default under any agreement or instrument to which the Company or its properties is subject, except for those agreements and instruments which have been identified to us by the Company as being material to it and which are listed in Part 2 of the Registration Statement or the Company's Annual Report on Form 10-K. We hereby consent to the filing of this opinion with the Commission as an exhibit to the Registration Statement. We also consent to the reference to our firm under the caption "Legal Matters" in the Registration Statement. In giving this consent, we do not thereby admit that we are included in the category of persons whose consent is required under Section 7 of the Securities Act or the rules and regulations of the Commission. Very truly yours, /s/ SKADDEN, ARPS, SLATE, MEAGHER & FLOM LLP

EXHIBIT 12 REGENERON PHARMACEUTICALS, INC. COMPUTATION OF RATIO OF EARNINGS TO FIXED CHARGES

NINE MONTHS YEARS ENDED DECEMBER 31, ENDED -------------------------------------------------- SEPTEMBER 30, 2000 1999 1998 1997 1996 2001 -------- -------- ------- ------- -------- ------------- (AMOUNTS IN THOUSANDS OF DOLLARS) Loss from continuing operations before loss from equity investee............ $(17,077) $(18,911) $(6,141) $(8,176) $(18,174) $(46,746) ======== ======== ======= ======= ======== ======== Fixed charges: Interest expense............. $ 281 $ 284 $ 428 $ 735 $ 940 $ 130 Interest portion of rent expense.................... 1,028 994 887 1,057 1,136 890 -------- -------- ------- ------- -------- -------- Total fixed charges.......... $ 1,309 $ 1,278 $ 1,315 $ 1,792 $ 2,076 $ 1,020 ======== ======== ======= ======= ======== ======== Loss from continuing operations before loss from equity investee plus fixed charges.................... $(15,768) $(17,633) $(4,826) $(6,384) $(16,098) $(45,726) ======== ======== ======= ======= ======== ======== Ratio of earnings to fixed charges(A)................. -- -- -- -- -- --
- --------------- (A) Due to the registrant's losses for the years ended December 31, 2000, 1999, 1998, 1997 and 1996 and for the nine months ended September 30, 2001, the ratio coverage was less than 1:1. The registrant must generate additional earnings of $17,077, $18,911, $6,141, $8,176, $18,174 and $46,746 for the years ended December 31, 2000, 1999, 1998, 1997 and 1996 and for the nine months ended September 30, 2001, respectively, to achieve a coverage ratio of 1:1.

EXHIBIT 23.1 CONSENT OF INDEPENDENT ACCOUNTANTS We hereby consent to the incorporation by reference in this Registration Statement on Form S-3 of our report, which is based in part on the report of other auditors, dated February 7, 2001 relating to the financial statements, which appears in Regeneron Pharmaceuticals, Inc.'s Annual Report on Form 10-K for the year ended December 31, 2000. We also consent to the reference to us under the heading "Experts" in such Registration Statement. PRICEWATERHOUSECOOPERS LLP New York, New York November 29, 2001

EXHIBIT 23.2 CONSENT OF ERNST & YOUNG LLP, INDEPENDENT AUDITORS We consent to the reference to our firm under the caption "Experts" in the Registration Statement (Form S-3) and related Prospectus of Regeneron Pharmaceuticals, Inc. for the registration of $200,000,000 aggregate principal amount of Regeneron's 5 1/2% Convertible Senior Subordinated Notes due 2008 and the shares of its common stock issuable upon conversion of the notes and to the incorporation by reference therein of our report dated February 2, 2001, with respect to the financial statements of Amgen Regeneron Partners included in Regeneron Pharmaceuticals, Inc.'s Annual Report (Form 10-K) for the year ended December 31, 2000, filed with the Securities and Exchange Commission. ERNST & YOUNG LLP Los Angeles, California November 29, 2001

Exhibit 25 SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM T-1 STATEMENT OF ELIGIBILITY AND QUALIFICATION UNDER THE TRUST INDENTURE ACT OF 1939 OF A CORPORATION DESIGNATED TO ACT AS TRUSTEE AMERICAN STOCK TRANSFER & TRUST COMPANY (Exact name of trustee as specified in its charter) New York 13-3439945 (State of incorporation (I.R.S. employer if not a national bank) identification No.) 59 Maiden Lane 10038 New York, New York (Zip Code) (Address of trustee's principal executive offices) REGENERON PHARMACEUTICALS, INC. (Exact name of obligor as specified in its charter) New York 13-3444607 (State or other jurisdiction of (I.R.S. employee incorporation or organization) identification. No.) 777 Old Saw Mill Road 10591 Tarrytown, New York (Zip Code) (Address of principal executive offices) 5-1/2 % CONVERTIBLE SENIOR SUBORDINATED NOTES DUE 2008 (Title of the indenture Securities)

-2- GENERAL 1. General Information. Furnish the following information as to the trustee: a. Name and address of each examining or supervising authority to which it is subject. New York State Banking Department, Albany, New York b. Whether it is authorized to exercise corporate trust powers. The Trustee is authorized to exercise corporate trust powers. 2. Affiliations with Obligor and Underwriters. If the obligor or any underwriter for the obligor is an affiliate of the trustee, describe each such affiliation. None. 3. Voting Securities of the Trustee. Furnish the following information as to each class of voting securities of the trustee: As of November 8, 2001 COL. A COL. B Title of Class Amount Outstanding Common Shares - par value $600 per share. 1,000 shares 4. Trusteeships under Other Indentures. None.

-3- 5. Interlocking Directorates and Similar Relationships with the Obligor or Underwriters. None. 6. Voting Securities of the Trustee Owned by the Obligor or its Officials. None. 7. Voting Securities of the Trustee Owned by Underwriters or their Officials. None. 8. Securities of the Obligor Owned or Held by the Trustee. None. 9. Securities of Underwriters Owned or Held by the Trustee. None. 10. Ownership or Holdings by the Trustee of Voting Securities of Certain Affiliates or Security Holders of the Obligor. None. 11. Ownership or Holdings by the Trustee of any Securities of a Person Owning 50 Percent or More of the Voting Securities of the Obligor. None. 12. Indebtedness of the Obligor to the Trustee. None. 13. Defaults by the Obligor. None. 14. Affiliations with the Underwriters. None. 15. Foreign Trustee. Not applicable.

-4- 16. List of Exhibits. T-1.1 - A copy of the Organization Certificate of American Stock Transfer & Trust Company, as amended to date including authority to commence business and exercise trust powers was filed in connection with the Registration Statement of Live Entertainment, Inc., File No. 33-54654, and is incorporated herein by reference. T-1.4 - A copy of the By-Laws of American Stock Transfer & Trust Company, as amended to date was filed in connection with the Registration Statement of Live Entertainment, Inc., File No. 33-54654, and is incorporated herein by reference. T-1.6 - The consent of the Trustee required by Section 312(b) of the Trust Indenture Act of 1939. Exhibit A. T-1.7 - A copy of the latest report of condition of the Trustee published pursuant to law or the requirements of its supervising or examining authority. - Exhibit B. SIGNATURE Pursuant to the requirements of the Trust Indenture Act of 1939 the Trustee, American Stock Transfer & Trust Company, a corporation organized and existing under the laws of the State of New York, has duly caused this statement of eligibility and qualification to be signed on its behalf by the undersigned, thereunto duly authorized, all in the City of New York, and State of New York, on the 8th day of November 2001. AMERICAN STOCK TRANSFER & TRUST COMPANY Trustee By: /s/ Herbert J. Lemmer ----------------------- Vice President

EXHIBIT A Securities and Exchange Commission Washington, DC 20549 Gentlemen: Pursuant to the provisions of Section 321(b) of the Trust Indenture Act of 1939, and subject to the limitations therein contained, American Stock Transfer & Trust Company hereby consents that reports of examinations of said corporation by Federal, State, Territorial or District authorities may be furnished by such authorities to you upon request therefor. Very truly yours, AMERICAN STOCK TRANSFER & TRUST COMPANY By /s/ Herbert J. Lemmer ----------------------------------- Vice President

EXHIBIT B AMERICAN STOCK TRANSFER & TRUST COMPANY 59 MAIDEN LANE NEW YORK, NY 10038 CONSOLIDATED REPORT OF CONDITION AND INCOME FOR A BANK WITH DOMESTIC OFFICES ONLY AND TOTAL ASSETS OF LESS THAN $100 MILLION REPORT AT CLOSE OF BUSINESS ON JUNE 30, 2001 All schedules are to be reported in thousands of dollars. Unless otherwise indicated, report the amount outstanding as of the last business day of the quarter. SCHEDULE RC - BALANCE SHEET DOLLAR AMOUNTS IN THOUSANDS ASSETS 1. Cash and balances due from depository institutions: a. Non-interest-bearing balances and currency and coin 582 b. Interest-bearing balances 2. Securities: a. Held-to-maturity securities (from Schedule RC-B, column A) b. Available-for-sale securities (from Schedule RC-B, column D) 7,477 3. Federal funds sold and securities purchased under agreements to resell 4. Loans and lease financing receivables. 5. Trading assets 6. Premises and fixed assets (including capitalized leases) 4,373 7. Other real estate owned (from Schedule RC-M) 8. Investments in unconsolidated subsidiaries and associated companies (from Schedule RC-M) 9. Customers' liability to this bank on acceptances outstanding 10. Intangible assets (from Schedule RC-M) 11. Other assets (from Schedule RC-F) 7,335 12. Total assets (sum of items 1 through 11) 19,767

SCHEDULE RC - CONTINUED DOLLAR AMOUNTS IN THOUSANDS LIABILITIES 13. Deposits. 14. Federal funds purchased and securities sold under agreements to repurchase 15. Trading liabilities 16. Other borrowed money (includes mortgage indebtedness and obligations under capitalized leases): 17. Not applicable 18. Bank's liability on acceptances executed and outstanding 19. Subordinated notes and debentures 20. Other liabilities (from Schedule RC-G) 21. Total liabilities (sum of items 13 through 20) 1,103 22. Not applicable 1,103 EQUITY CAPITAL 23. Perpetual preferred stock and related surplus 24. Common stock 600 25. Surplus (exclude all surplus related to preferred stock) 9,289 26. Retained Earnings 8,775 27. Other equity capital components 28. Total equity capital (sum of items 23 through 27) 18,664 29. Total liabilities and equity capital (sum of items 21 and 28) 19,767