Document:

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                                                                     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
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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

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         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

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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.

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                  (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.

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                  (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.

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                  (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.

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                  (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.

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                  (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

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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
<PAGE>
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
<PAGE>
         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.

<PAGE>

         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
<PAGE>
         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
<PAGE>
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
<PAGE>
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
<PAGE>
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
<PAGE>
            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:
<PAGE>
                                   SCHEDULE I

                            Pledged Financial Assets

<TABLE>
<CAPTION>
        Security                Coupon Date                  CUSIP No.
        --------                -----------                  ---------
<S>                             <C>                          <C>
       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
</TABLE>
<PAGE>
                                                                         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.
<PAGE>
         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),
<PAGE>
(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.
<PAGE>
         (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
<PAGE>
         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
<PAGE>
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
<PAGE>
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.
<PAGE>
            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
<PAGE>
                                   SCHEDULE I

                            Pledged Financial Assets

<TABLE>
<CAPTION>
        Security                Coupon Date                  CUSIP No.
        --------                -----------                  ---------
<S>                             <C>                          <C>
       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
</TABLE><PAGE>
                                                                     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.
<PAGE>
            "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
<PAGE>
            "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
<PAGE>
            "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
<PAGE>
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
<PAGE>
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
<PAGE>
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
<PAGE>
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
<PAGE>
         (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
<PAGE>
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
<PAGE>
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
<PAGE>
         (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
<PAGE>
         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
<PAGE>
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
<PAGE>
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
<PAGE>
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
<PAGE>
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
<PAGE>
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
<PAGE>
         (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
<PAGE>
            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:

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