BIOGEN INC
8-K, 1999-04-27
BIOLOGICAL PRODUCTS, (NO DIAGNOSTIC SUBSTANCES)
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<PAGE>   1
                       SECURITIES AND EXCHANGE COMMISSION

                             Washington, D.C. 20549

                                    FORM 8-K

                                 CURRENT REPORT

                         PURSUANT TO SECTION 13 OR 15(d)

                     OF THE SECURITIES EXCHANGE ACT OF 1934

                                 DATE OF REPORT
                (Date of earliest event reported): April 16, 1999

                                  BIOGEN, INC.

             (Exact name of registrant as specified in its charter)

     Massachusetts                      0-12042             04-3002117
    (State or other                   (Commission        (IRS Employer
    jurisdiction of                   File Number)       Identification No.)
    incorporation)

                               14 Cambridge Center
                               Cambridge, MA 02142
               (Address of principal executive offices) (Zip Code)

Registrant's telephone number, including area code:  (617) 679-2000

                                       N/A

         (Former name or former address, if changed since last report.)
<PAGE>   2
ITEM 5.  OTHER EVENTS.

I.       ADOPTION OF RIGHTS AGREEMENT

Expiration of Old Rights and Dividend of New Rights

         In 1989, the Board of Directors of Biogen, Inc. (the "Company")
declared a dividend to holders of the Company's Common Stock, $.01 par value per
share ("Common Shares"), of rights (the "Old Rights") to purchase shares of
Series A Junior Participating Preferred Stock (the "Old Preferred Stock"). Each
Old Right entitled the registered holder to purchase from the Company one
one-hundredth of a share of Old Preferred Stock upon the terms and subject to
the conditions set forth in a Rights Agreement dated as of May 8, 1989, between
Biogen, Inc. and The First National Bank of Boston (the "Old Plan"). The Old
Plan and Old Rights expire on May 8, 1999. Accordingly, on April 16, 1999, the
Board of Directors declared a dividend of one new preferred share purchase right
(a "New Right") for each outstanding Common Share of the Company, which shall be
made to the stockholders of record on May 8, 1999 (the "Record Date"). Each New
Right entitles the registered holder to purchase from the Company one
one-thousandth of a share of a new series of preferred stock (the Series A-1
Junior Participating Preferred Stock, referred to herein as the "Preferred
Shares"), at a price of $850 per one one-thousandth of a Preferred Share (the
"Purchase Price"), subject to adjustment. Each one one-thousandth of a Preferred
Share has rights, privileges and preferences which make its value approximately
equal to the value of one Common Share. A full description of the terms of the
New Rights is set forth in a new shareholder rights agreement dated as of May 8,
1999 (the "New Rights Agreement"), between the Company and State Street Bank and
Trust Company, as Rights Agent (the "Rights Agent").

Terms and Conditions of New Rights and New Rights Agreement

         Initially, the New Rights will be evidenced by the stock certificates
representing the Common Shares then outstanding, and no separate Right
Certificates, as defined, will be distributed. Until the earlier of (i) the
close of business on the tenth day following the day on which there is a public
announcement or public disclosure of facts indicating that a person, entity or
group of affiliated or associated persons (an "Acquiring Person") have acquired,
beneficial ownership of 20% or more of the outstanding Common Shares (other than
certain excluded persons) or (ii) the tenth business day (or such later date as
may be determined by action of the Board of Directors prior to such time as any
person or entity becomes an Acquiring Person) following the commencement of, or
announcement of an intention to make, a tender offer or exchange offer the
consummation of which would result in the beneficial ownership by a person or
group of 20% or more of such outstanding Common Shares (the earlier of such
dates being called the "Distribution Date"), the New Rights will be evidenced,
with respect to any of the Common Share certificates outstanding as of May 8,
1999, by such Common Share certificates.

         The New Rights Agreement provides that, until the Distribution Date,
the New Rights will be transferred with and only with the Common Shares. Until
the Distribution Date (or earlier redemption or expiration of the New Rights),
new Common Share certificates issued after May 8, 1999, upon transfer or new
issuance of Common Shares, will contain a notation incorporating


                                       1
<PAGE>   3
the New Rights Agreement by reference. Until the Distribution Date (or earlier
redemption or expiration of the New Rights), the surrender or transfer of any
certificates for Common Shares outstanding as of May 8, 1999, even without such
notation or a copy of the Summary of Rights being attached thereto, will also
constitute the transfer of the New Rights associated with the Common Shares
represented by such certificate. As soon as practicable following the
Distribution Date, separate certificates evidencing the New Rights ("Right
Certificates") will be mailed to holders of record of the Common Shares as of
the close of business on the Distribution Date and such separate Right
Certificates alone will evidence the New Rights.

         The New Rights are not exercisable until the Distribution Date. The New
Rights will expire on May 8, 2009 (the "Final Expiration Date"), unless the
Final Expiration Date is extended or unless the New Rights are earlier redeemed
or exchanged by the Company, in each case, as described below.

         The Purchase Price payable, and the number of Preferred Shares or other
securities or property issuable, upon exercise of the New Rights are subject to
adjustment from time to time to prevent dilution (i) in the event of a stock
dividend on, or a subdivision, combination or reclassification of, the Preferred
Shares, (ii) upon the grant to holders of the Preferred Shares of certain
rights, options or warrants to subscribe for or purchase Preferred Shares at a
price, or securities convertible into Preferred Shares with a conversion price,
less than the then current market price of the Preferred Shares or (iii) upon
the distribution to holders of the Preferred Shares of evidences of indebtedness
or assets (excluding regular periodic cash dividends or dividends payable in
Preferred Shares) or of subscription rights or warrants (other than those
referred to above).

         The number of outstanding New Rights and the number of one
one-thousandths of a Preferred Share issuable upon exercise of each New Right
are also subject to adjustment in the event of a stock split of the Common
Shares or a stock dividend on the Common Shares payable in Common Shares or
subdivisions, consolidation or combinations of the Common Shares occurring, in
any case, prior to the Distribution Date.

         Preferred Shares purchasable upon exercise of the New Rights will not
be redeemable. Each Preferred Share will be entitled to receive when, as and if
approved by the Board of Directors out of funds legally available for the
purpose, a minimum preferential quarterly dividend payment of $1.00 but will be
entitled to an aggregate dividend of 1,000 times the dividend declared per
Common Share. In the event of liquidation, the holders of the Preferred Shares
will be entitled to a minimum preferential liquidation payment of $1,000 but
will be entitled to an aggregate payment of 1,000 times the payment made per
Common Share. Each Preferred Share will have 1,000 votes, voting together with
the Common Shares. Finally, in the event of any merger, consolidation or other
transaction in which Common Shares are exchanged, each Preferred Share will be
entitled to receive 1,000 times the amount of consideration received per Common
Share. These rights are protected by customary anti-dilution provisions. Because
of the nature of the Preferred Shares' dividend and liquidation rights, the
value of one one-thousandth of a Preferred Share should approximate the value of
one Common Share.


                                       2
<PAGE>   4
         In the event that any person becomes an Acquiring Person, proper
provision shall be made so that each holder of a New Right, other than New
Rights beneficially owned by the Acquiring Person or an Associate or Affiliate
of such Acquiring Person or certain of their transferees (which Rights will
thereafter be void), will have the right to receive upon exercise that number of
Common Shares having a market value of two times the purchase price of the New
Right (or, if such number of shares is not and cannot be authorized, the Company
may issue Preferred Stock, cash, debt, stock or a combination thereof in
exchange for the New Rights).

         In the event that the Company is acquired in a merger or other business
combination transaction or 50% or more of its consolidated assets or earning
power are sold, proper provision will be made so that each holder of a New Right
will thereafter have the right to receive, upon the exercise thereof at the then
current exercise price of the New Right, that number of shares of common stock
of the acquiring company which at the time of such transaction will have a
market value of two times the exercise price of the New Right.

         At any time after the acquisition by a person or group of affiliated or
associated persons of beneficial ownership of 20% or more of the outstanding
Common Shares and prior to the acquisition by such person or group of 50% or
more of the outstanding Common Shares, the Board of Directors of the Company may
exchange the New Rights (other than New Rights owned by such person or group
which have become void), in whole or in part, at an exchange ratio of one Common
Share, or one one-thousandth of a Preferred Share, per New Right (or, if the
number of shares is not and cannot be authorized, the Company may issue cash,
debt, stock or a combination thereof in exchange for the New Rights), subject to
adjustment.

         With certain exceptions, no adjustment in the Purchase Price will be
required until cumulative adjustments require an adjustment of at least 1% in
such Purchase Price. No fractional Preferred Shares will be issued (other than
fractions which are integral multiples of the number of one one-thousandths of a
Preferred Share issuable upon the exercise of one New Right, which may, at the
option of the Company, be evidenced by depository receipts), and in lieu
thereof, an adjustment in cash will be made based on the market price of the
Preferred Shares on the last trading day prior to the date of exercise.

         At any time prior to the earlier of (i) the time that any person
becomes an Acquiring Person, or (ii) the Final Expiration Date, the Board of
Directors of the Company may redeem the New Rights in whole, but not in part, at
a price of $.001 per New Right (the "Redemption Price"). Following the
expiration of the above periods, the New Rights become nonredeemable.
Immediately upon any redemption of the New Rights, the right to exercise the New
Rights will terminate and the only right of the holders of New Rights will be to
receive the Redemption Price.

         The Company may from time to time, and the Rights Agent will, if the
Company so directs, supplement or amend the New Rights Agreement without the
approval of any holders of Right Certificates in order to cure any ambiguity, to
correct or supplement any provision contained therein which may be defective or
inconsistent with any other provisions therein, or to make any change to or
delete any provision thereof or to adopt any other provisions with respect to
the Rights which the Company may deem necessary or desirable; provided, however,
that from and after such time as


                                       3
<PAGE>   5
any Person becomes an Acquiring Person, the New Rights Agreement may not be
amended or supplemented in any manner which would adversely affect the interests
of the holders of Rights (other than an Acquiring Person and its Affiliates and
Associates).

         Until a New Right is exercised, the holder thereof, as such, will have
no rights as a stockholder of the Company, including, without limitation, the
right to vote or to receive dividends.

         The New Rights have certain anti-takeover effects. The New Rights will
cause substantial dilution to a person or group that attempts to acquire the
Company on terms not approved by the Company's Board of Directors. The New
Rights should not interfere with any merger or other business combination
approved by the Board of Directors since the New Rights may be redeemed by the
Company at $.001 per New Right prior to the earlier of (i) such time as any
person has become an Acquiring Person, or (ii) the Final Expiration Date.

         The foregoing description of the New Rights Agreement and New Rights,
as well as the other matters discussed herein, is qualified in its entirety by
reference to the New Rights Agreement and the Exhibits thereto and the Press
Release, each of which is attached hereto as an Exhibit and is incorporated
herein by reference.

II.      STOCK SPLIT OF COMMON STOCK

         On April 16, 1999, the Board of Directors of Biogen, Inc. (the
"Company") conditionally approved a two-for-one stock split of the Company's
common stock ("Common Stock") to be effected in the form of a stock dividend of
one share of Common Stock for each share of Common Stock outstanding. If
approved, the dividend will be payable on June 25, 1999 to all stockholders of
record as of June 11, 1999. The stock split is subject to the approval of an
increase in the Company's authorized Common Stock by the stockholders of the
Company at its Annual Meeting on June 11, 1999.



                                       4
<PAGE>   6
ITEM 7.  FINANCIAL STATEMENTS AND EXHIBITS.

         (c)      Exhibits.

                  4.1 Rights Agreement, dated as of May 8, 1999, between Biogen,
Inc. and State Street Bank and Trust Company, which includes the Certificate of
Vote of Directors Establishing a Class or Series of Stock as Exhibit A, the Form
of Rights Certificate as Exhibit B and the Summary of Rights as Exhibit C.

                  99.1     The Registrant's Press Release dated April 16, 1999.



                                       5
<PAGE>   7
                                   SIGNATURES

         Pursuant to the requirements of the Securities Exchange Act of 1934,
the Registrant has duly caused this report to be signed on its behalf by the
undersigned hereunto duly authorized.

Date:  April 23, 1999                   By: /s/ Michael J. Astrue
                                            -------------------------------
                                            Michael J. Astrue
                                            Vice President -General Counsel


                                       6

<PAGE>   1
                                   EXHIBIT 4.1

            ---------------------------------------------------------

                                  BIOGEN, INC.

                                       AND

                       STATE STREET BANK AND TRUST COMPANY

                                 AS RIGHTS AGENT

                                RIGHTS AGREEMENT

                             DATED AS OF MAY 8, 1999

           -----------------------------------------------------------
<PAGE>   2
                                TABLE OF CONTENTS

<TABLE>
<CAPTION>
                                                                                                                   Page
<S>         <C>                                                                                                    <C>
SECTION 1.   CERTAIN DEFINITIONS...................................................................................   1
                                                                                                                      
SECTION 2.   APPOINTMENT OF RIGHTS AGENT...........................................................................   4
                                                                                                                     
SECTION 3.   ISSUE OF RIGHT CERTIFICATES...........................................................................   4
                                                                                                                     
SECTION 4.   FORM OF RIGHT CERTIFICATES............................................................................   5
                                                                                                                     
SECTION 5.   COUNTERSIGNATURE AND REGISTRATION.....................................................................   6
                                                                                                                     
SECTION 6.   TRANSFER, SPLIT UP, COMBINATION AND EXCHANGE OF RIGHT CERTIFICATES; MUTILATED,                           
             DESTROYED, LOST OR STOLEN RIGHT CERTIFICATES..........................................................   6
                                                                                                                     
SECTION 7.   EXERCISE OF RIGHTS; PURCHASE PRICE; EXPIRATION DATE OF RIGHTS.........................................   7
                                                                                                                     
                                                                                                                     
SECTION 8.   CANCELLATION AND DESTRUCTION OF RIGHT CERTIFICATES....................................................   8
                                                                                                                     
SECTION 9.   AVAILABILITY OF PREFERRED SHARES......................................................................   8
                                                                                                                     
SECTION 10.  PREFERRED SHARES RECORD DATE..........................................................................   9
                                                                                                                  
SECTION 11.  ADJUSTMENT OF PURCHASE PRICE, NUMBER OF SHARES OR NUMBER OF RIGHTS....................................  10
                                                                                                                    
                                                                                                                    
SECTION 12.  CERTIFICATE OF ADJUSTED PURCHASE PRICE OR NUMBER OF SHARES............................................  16
                                                                                                                    
                                                                                                                    
SECTION 13.  CONSOLIDATION, MERGER OR SALE OR TRANSFER OF ASSETS OR EARNING POWER..................................  16
                                                                                                                    
                                                                                                                    
SECTION 14.  FRACTIONAL RIGHTS AND FRACTIONAL SHARES...............................................................  19
                                                                                                                    
SECTION 15.  RIGHTS OF ACTION......................................................................................  20
                                                                                                                    
SECTION 16.  AGREEMENT OF RIGHT HOLDERS............................................................................  20
                                                                                                                    
SECTION 17.  RIGHT CERTIFICATE HOLDER NOT DEEMED A STOCKHOLDER.....................................................  21
                                                                                                                    
SECTION 18.  CONCERNING THE RIGHTS AGENT...........................................................................  21
                                                                                                                    
SECTION 19.  MERGER OR CONSOLIDATION OR CHANGE OF NAME OF RIGHTS AGENT.............................................  21
                                                                                                                    
                                                                                                                    
SECTION 20.  DUTIES OF RIGHTS AGENT................................................................................  22
                                                                                                                    
SECTION 21.  CHANGE OF RIGHTS AGENT................................................................................  24
                                                                                                                    
SECTION 22.  ISSUANCE OF NEW RIGHT CERTIFICATES....................................................................  25
</TABLE>
<PAGE>   3
<TABLE>
<S>          <C>                                                                                                    <C>
SECTION 23.  REDEMPTION..........................................................................................   25
                                                                                                                    
SECTION 24.  EXCHANGE............................................................................................   26
                                                                                                                    
SECTION 25.  NOTICE OF CERTAIN EVENTS............................................................................   27
                                                                                                                    
SECTION 26.  NOTICES.............................................................................................   28
                                                                                                                    
SECTION 27.  SUPPLEMENTS AND AMENDMENTS..........................................................................   28
                                                                                                                    
SECTION 28.  DETERMINATION AND ACTIONS BY THE BOARD OF DIRECTORS, ETC............................................   29
                                                                                                                    
                                                                                                                    
SECTION 29.  SUCCESSORS..........................................................................................   29
                                                                                                                    
SECTION 30.  BENEFITS OF THIS AGREEMENT..........................................................................   29
                                                                                                                    
SECTION 31.  SEVERABILITY........................................................................................   29
                                                                                                                    
SECTION 32.  GOVERNING LAW.......................................................................................   29
                                                                                                                    
SECTION 33.  COUNTERPARTS........................................................................................   29
                                                                                                                    
SECTION 34.  DESCRIPTIVE HEADINGS................................................................................   29
</TABLE>

Exhibit A - Certificate of Vote of Directors Establishing a Class or Series of
            Stock

Exhibit B -  Form of Right Certificate

Exhibit C - Summary Of Rights To Purchase Series A-1 Junior Participating
            Preferred Shares
<PAGE>   4
                                             RIGHTS AGREEMENT

         RIGHTS AGREEMENT (THE "AGREEMENT"), dated as of May 8, 1999, between
BIOGEN, INC., a Massachusetts corporation (the "Company"), and STATE STREET BANK
AND TRUST COMPANY, a Massachusetts Trust Company ("Rights Agent").

         The Board of Directors of the Company has authorized and declared a
dividend of one preferred share purchase right (a "Right") for each Common Share
(as hereinafter defined) of the Company outstanding at the close of business on
May 8, 1999 (the "Record Date"), each Right representing the right to purchase
one one-thousandth of a Preferred Share (as hereinafter defined), upon the terms
and subject to the conditions herein set forth, and has further authorized and
directed the issuance of one Right with respect to each Common Share that shall
become outstanding between the Record Date and the earliest of the Distribution
Date, the Redemption Date and the Final Expiration Date (as such terms are
hereinafter defined).

         Accordingly, in consideration of the premises and the mutual agreements
herein set forth, the parties hereby agree as follows:

         SECTION 1. CERTAIN DEFINITIONS. For purposes of this Agreement, the
following terms have the meanings indicated:

         (a) "ACQUIRING PERSON" shall mean any Person (as such term is
hereinafter defined) who or which, together with all Affiliates and Associates
(as such terms are hereinafter defined) of such Person, shall be the Beneficial
Owner (as such term is hereinafter defined) of 20% or more of the Common Shares
of the Company then outstanding. Notwithstanding the foregoing, (A) the term
Acquiring Person shall not include (i) the Company, (ii) any Subsidiary (as such
term is hereinafter defined) of the Company, (iii) any employee benefit plan of
the Company or any Subsidiary of the Company, (iv) or any entity holding Common
Shares for or pursuant to the terms of any such employee benefit plan and (B) no
Person shall become an "Acquiring Person" either (x) as the result of an
acquisition of Common Shares by the Company which, by reducing the number of
shares outstanding, increases the proportionate number of shares beneficially
owned by such Person to 20% or more of the Common Shares of the Company then
outstanding; provided, however, that, if a Person shall become the Beneficial
Owner of 20% or more of the Common Shares of the Company then outstanding by
reason of share acquisitions by the Company and shall, after such share
acquisitions by the Company, become the Beneficial Owner of any additional
Common Shares of the Company, then such Person shall be deemed to be an
"Acquiring Person" or (y) if the Board of Directors determines in good faith
that a Person who would otherwise be an "Acquiring Person," as defined pursuant
to the foregoing provisions of this paragraph (a), has become such
inadvertently, and such Person divests as promptly as practicable a sufficient
number of Common Shares so that such Person would no longer be an Acquiring
Person, as defined pursuant to the foregoing provisions of this paragraph (a),
then such Person shall not be deemed to be an "Acquiring Person" for any
purposes of this Agreement.

         (b) "AFFILIATE" and "ASSOCIATE" shall have the respective meanings
ascribed to such terms in Rule 12b-2 of the General Rules and Regulations under
the Securities Exchange Act of 1934, as amended (the "Exchange Act"), as in
effect on the date of this Agreement.


                                       1
<PAGE>   5
         (c) A Person shall be deemed the "BENEFICIAL OWNER" of and shall be
deemed to "beneficially own" any securities:

                  (i) which such Person or any of such Person's Affiliates or
         Associates beneficially owns, directly or indirectly;

                  (ii) which such Person or any of such Person's Affiliates or
         Associates has (A) the right to acquire (whether such right is
         exercisable immediately or only after the passage of time) pursuant to
         any agreement, arrangement or understanding (other than customary
         agreements with and between underwriters and selling group members with
         respect to a bona fide public offering of securities) written or
         otherwise, or upon the exercise of conversion rights, exchange rights,
         rights (other than these Rights), warrants or options, or otherwise;
         provided, however, that a Person shall not be deemed the Beneficial
         Owner of, or to beneficially own, securities tendered pursuant to a
         Tender Offer made by or on behalf of such Person or any of such
         Person's Affiliates or Associates until such tendered securities are
         accepted for purchase or exchange; or (B) the right to vote pursuant to
         any agreement, arrangement or understanding; provided, however, that a
         Person shall not be deemed the Beneficial Owner of, or to beneficially
         own, any security if the agreement, arrangement or understanding to
         vote such security (1) arises solely from a revocable proxy or consent
         given to such Person in response to a public proxy or consent
         solicitation made pursuant to, and in accordance with, the applicable
         rules and regulations promulgated under the Exchange Act and (2) is not
         also then reportable on Schedule 13D under the Exchange Act (or any
         comparable or successor report); or

                  (iii) which are beneficially owned, directly or indirectly, by
         any other Person with which such Person or any of such Person's
         Affiliates or Associates has any agreement, arrangement or
         understanding (other than customary agreements with and between
         underwriters and selling group members with respect to a bona fide
         public offering of securities) written or otherwise for the purpose of
         acquiring, holding, voting (except to the extent contemplated by the
         proviso to Section 1(c)(ii)(B) hereof) or disposing of any securities
         of the Company.

Notwithstanding anything in this definition of Beneficial Ownership to the
contrary, the phrase, "then outstanding," when used with reference to a Person's
Beneficial Ownership of securities of the Company, shall mean the number of such
securities then issued and outstanding together with the number of such
securities not then actually issued and outstanding which such Person would be
deemed to own beneficially hereunder.

         (d) "BOARD OF DIRECTORS OR THE BOARD" shall mean the Board of Directors
of the Company.

         (e) "BUSINESS DAY" shall mean any day other than a Saturday, a Sunday,
or a day on which banking institutions in the Commonwealth of Massachusetts or
the State of New York are authorized or obligated by law or executive order to
close.


                                       2
<PAGE>   6
         (f) "CLOSE OF BUSINESS" on any given date shall mean 5:00 p.m., Eastern
Standard time, on such date; provided, however, that if such date is not a
Business Day it shall mean 5:00 p.m., Eastern Standard time, on the next
succeeding Business Day.

         (g) "COMMON SHARES" when used with reference to the Company shall mean
the shares of common stock, par value $.01 per share, of the Company. "Common
Shares" when used with reference to any Person other than the Company shall mean
the capital stock (or equity interest) with the greatest voting power of such
other Person or, if such other Person is a Subsidiary of another Person, the
Person or Persons which ultimately control such first-mentioned Person.

         (h) "DISTRIBUTION DATE" shall have the meaning set forth in Section
3(a) hereof.

         (i) "FINAL EXPIRATION DATE" shall have the meaning set forth in Section
7(a) hereof.

         (j) "PERSON" shall mean any individual, firm, corporation, partnership,
limited partnership, limited liability company, business trust, unincorporated
association or other entity, and shall include any successor (by merger or
otherwise) of such entity.

         (k) "PREFERRED SHARES" shall mean shares of Series A-1 Junior
Participating Preferred Stock, par value $.01 per share, of the Company having
the designations and the powers, preferences and rights, and the qualifications,
limitations and restrictions set forth in the Certificate of Designation
attached to this Agreement as Exhibit A.

         (l) "PURCHASE PRICE" shall have the meaning set forth in Section 7(b)
hereof.

         (m) "REDEMPTION DATE" shall have the meaning set forth in Section 7(a)
hereof.

         (n) "RECORD DATE" shall mean May 8, 1998.

         (o) "SHARES ACQUISITION DATE" shall mean the earlier of the first date
of (i) the public announcement by the Company or an Acquiring Person that an
Acquiring Person has become such or (ii) the public disclosure of facts by the
Company or an Acquiring Person indicating that an Acquiring Person has become
such, provided, however, that if such Person is determined not to have become an
Acquiring Person pursuant to (y) of the last sentence of Section 1(a) hereof,
then no Shares Acquisition Date shall be deemed to have occurred.

         (p) "SUBSIDIARY" of any Person shall mean any Person of which a
majority of the voting power of the voting equity securities or equity interest
is owned, directly or indirectly, by such Person.

         (q) "TENDER OFFER" shall mean a tender or exchange offer made in
accordance with the provisions of the Exchange Act and the rules and regulations
promulgated thereunder (the "Rules and Regulations"), including the payment of
applicable fees, announcement of a tender offer and the dissemination of tender
offer materials (as those terms are defined respectively in the Rules and
Regulations) which the Board of Directors or a committee of the Board of
Directors authorized by the Board shall have determined to not be frivolous or
to be made in good faith; any such 


                                       3
<PAGE>   7
determination made promptly and in good faith to be conclusive for the purposes
of this Agreement.

         SECTION 2. APPOINTMENT OF RIGHTS AGENT. The Company hereby appoints the
Rights Agent to act as agent for the Company and the holders of the Rights (who,
in accordance with Section 3 hereof, shall prior to the Distribution Date also
be the holders of Common Shares) in accordance with the terms and conditions
hereof, and the Rights Agent hereby accepts such appointment. The Company may
from time to time appoint such co-Rights Agents as it may deem necessary or
desirable, upon ten (10) days' prior written notice to the Rights Agent. The
Rights Agent shall have no duty to supervise, and in no event be liable for, the
acts or omissions of any such co-Rights Agent.

         SECTION 3.  ISSUE OF RIGHT CERTIFICATES.

         (a) Until the earlier of the Close of Business on (i) the tenth day
following the Shares Acquisition Date or (ii) the tenth business day (or such
later date as may be determined by action of the Board of Directors prior to
such time as any Person becomes an Acquiring Person) after the date of the
commencement (determined in accordance with Rule 14d-2 under the Exchange Act)
by any Person (other than the Company, any Subsidiary of the Company, any
employee benefit plan of the Company or of any Subsidiary of the Company or any
entity holding Common Shares for or pursuant to the terms of any such plan) of,
or of the first public announcement of the intention of any Person (other than
the Company, any Subsidiary of the Company, any employee benefit plan of the
Company or of any Subsidiary of the Company or any entity holding Common Shares
for or pursuant to the terms of any such plan) to commence, a tender or exchange
offer (which intention to commence remains in effect for five Business Days
after such announcement), the consummation of which would result in any Person
becoming an Acquiring Person (including any such date which is after the date of
this Agreement and prior to the issuance of the Rights, the earlier of such
dates being herein referred to as the "Distribution Date"), (x) the Rights will
be evidenced by (subject to the provisions of Section 3(b) hereof) the
certificates for Common Shares registered in the names of the holders thereof
(which certificates shall also be deemed to be Right Certificates) and not by
separate Right Certificates (as hereafter defined), and (y) the Rights (and the
right to receive Right Certificates therefor) will be transferable only in
connection with the transfer of Common Shares. As soon as practicable after the
Distribution Date, the Company will prepare and execute, the Rights Agent will
countersign, and the Company will send or cause to be sent (and the Rights Agent
will, if requested, send) by first-class, insured, postage-prepaid mail, to each
record holder of Common Shares as of the Close of Business on the Distribution
Date, at the address of such holder shown on the records of the Company, a Right
Certificate in substantially the form of Exhibit B hereto (a "Right
Certificate"), evidencing one Right for each Common Share so held. As of the
Close of Business on the Distribution Date, the Rights will be evidenced solely
by such Right Certificates.

         (b) On the Record Date, or as soon as practicable thereafter, the
Company will send a summary of the Rights and the Agreement (the "Summary of
Rights") by first-class, postage-prepaid mail, to each record holder of Common
Shares as of the Close of Business on the Record Date, at the address of such
holder shown on the records of the Company. With respect to certificates for
Common Shares outstanding as of the Record Date, until the Distribution Date,
the Rights will be evidenced by such certificates registered in the names of the
holders thereof together 


                                       4
<PAGE>   8
with a copy of the Summary of Rights attached thereto. Until the Distribution
Date (or the earlier of the Redemption Date or the Final Expiration Date), the
surrender for transfer of any certificate for Common Shares outstanding on the
Record Date, with or without a copy of the Summary of Rights attached thereto,
shall also constitute the transfer of the Rights associated with the Common
Shares evidenced thereby.

         (c) Certificates for Common Shares which become outstanding (including,
without limitation, reacquired Common Shares referred to in the last sentence of
this paragraph (b)) after the Record Date but prior to the earliest of the
Distribution Date, the Redemption Date or the Final Expiration Date shall have
impressed on, printed on, written on or otherwise affixed to them the following
legend:

                  This certificate also evidences and entitles the holder hereof
                  to certain rights (the "Rights") as set forth in a Rights
                  Agreement between Biogen, Inc. and State Street Bank and Trust
                  Company, dated as of May 8, 1999, as it may, from time to
                  time, be amended (the "Rights Agreement"), the terms of which
                  are hereby incorporated herein by reference and a copy of
                  which is on file at the principal executive offices of Biogen,
                  Inc. Under certain circumstances, as set forth in the Rights
                  Agreement, such Rights will be evidenced by separate
                  certificates and will no longer be evidenced by this
                  certificate. Biogen, Inc. will mail to the holder of this
                  certificate a copy of the Rights Agreement without charge
                  after receipt of a written request therefor. Under certain
                  circumstances, Rights that are or were acquired or
                  beneficially owned by an Acquiring Person or Associates or
                  Affiliates thereof (as defined in the Rights Agreement) may
                  become null and void.

With respect to such certificates containing the foregoing legend, until the
Distribution Date, the Rights associated with the Common Shares represented by
such certificates shall be evidenced by such certificates alone, and the
surrender for transfer of any such certificate shall also constitute the
transfer of the Rights associated with the Common Shares represented thereby. In
the event that the Company purchases or acquires any Common Shares after the
Record Date but prior to the Distribution Date, any Rights associated with such
Common Shares shall be deemed canceled and retired so that the Company shall not
be entitled to exercise any Rights associated with the Common Shares which are
no longer outstanding.

         SECTION 4. FORM OF RIGHT CERTIFICATES. The Right Certificates (and the
form of election to purchase Preferred Shares, the form of assignment and the
form of certification to be printed on the reverse thereof) shall be
substantially the same as Exhibit B hereto and may have such marks of
identification or designation and such legends, summaries or endorsements
printed thereon as the Company may deem appropriate and as are not inconsistent
with the provisions of this Agreement, or as may be required to comply with any
applicable law or with any rule or regulation made pursuant thereto or with any
rule or regulation of any stock exchange on which the Rights may from time to
time be listed, or to conform to usage. Subject to the other provisions of this
Agreement, the Right Certificates shall entitle the holders thereof to purchase
such number of one one-thousandths of a Preferred Share as shall be set forth
therein at the Purchase Price, but the number 


                                       5
<PAGE>   9
of such one one-thousandths of a Preferred Share and the Purchase Price shall be
subject to adjustment as provided herein.

         SECTION 5. COUNTERSIGNATURE AND REGISTRATION. The Right Certificates
shall be executed on behalf of the Company by its Chairman of the Board, its
Chief Executive Officer, its President, its Chief Financial Officer or any of
its Vice Presidents, either manually or by facsimile signature, shall have
affixed thereto the Company's seal or a facsimile thereof, and shall be attested
by the Secretary or an Assistant Secretary of the Company, either manually or by
facsimile signature. The Right Certificates shall be manually countersigned by
the Rights Agent and shall not be valid for any purpose unless countersigned. In
case any officer of the Company who shall have signed any of the Right
Certificates shall cease to be such officer of the Company before
countersignature by the Rights Agent and issuance and delivery by the Company,
such Right Certificates, nevertheless, may be countersigned by the Rights Agent
and issued and delivered by the Company with the same force and effect as though
the person who signed such Right Certificates had not ceased to be such officer
of the Company; and any Right Certificate may be signed on behalf of the Company
by any person who, at the actual date of the execution of such Right
Certificate, shall be a proper officer of the Company to sign such Right
Certificate, although at the date of the execution of this Rights Agreement any
such person was not such an officer.

         Following the Distribution Date, the Rights Agent will keep or cause to
be kept, at its office designated for such purpose, books for registration and
transfer of the Right Certificates issued hereunder. Such books shall show the
names and addresses of the respective holders of the Right Certificates, the
number of Rights evidenced on its face by each of the Right Certificates and the
date of each of the Right Certificates.

         SECTION 6. TRANSFER, SPLIT UP, COMBINATION AND EXCHANGE OF RIGHT
CERTIFICATES; MUTILATED, DESTROYED, LOST OR STOLEN RIGHT CERTIFICATES. Subject
to the provisions of Section 4, Section 11(a)(ii), Section 14 and Section 24
hereof, at any time after the Close of Business on the Distribution Date, and
prior to the Close of Business on the earlier of the Redemption Date or the
Final Expiration Date, any Right Certificate or Right Certificates may be
transferred, split up, combined or exchanged for another Right Certificate or
Right Certificates, entitling the registered holder to purchase a like number of
one one-thousandths of a Preferred Share as the Right Certificate or Right
Certificates surrendered then entitled such holder to purchase. Any registered
holder desiring to transfer, split up, combine or exchange any Right Certificate
or Right Certificates shall make such request in writing delivered to the Rights
Agent, and shall surrender the Right Certificate or Right Certificates to be
transferred, split up, combined or exchanged at the office of the Rights Agent
designated for such purpose. Neither the Rights Agent nor the Company shall be
obligated to take any action whatsoever with respect to the transfer of any such
surrendered Right Certificate until the registered holder shall have completed
and signed the certificate contained in the form of assignment on the reverse
side of such Right Certificate and shall have provided such additional evidence
of the identity of the Beneficial Owner (or former Beneficial Owner) or
Affiliates or Associates thereof as the Company shall reasonably request.
Thereupon the Rights Agent shall, subject to Section 4, Section 11(a)(ii),
Section 14 and Section 24 hereof, countersign and deliver to the person entitled
thereto a Right Certificate or Right Certificates, as the case may be, as so
requested. The Company may require payment of a sum sufficient to cover any tax
or governmental charge that may be imposed in connection with any transfer,
split up, combination or exchange of Right Certificates.


                                       6
<PAGE>   10
         Upon receipt by the Company and the Rights Agent of evidence reasonably
satisfactory to them of the loss, theft, destruction or mutilation of a Right
Certificate, and, in case of loss, theft or destruction, of indemnity or
security reasonably satisfactory to them, and, at the Company's request,
reimbursement to the Company and the Rights Agent of all reasonable expenses
incidental thereto, and upon surrender to the Rights Agent and cancellation of
the Right Certificate if mutilated, the Company will issue, execute and deliver
a new Right Certificate of like tenor to the Rights Agent for countersignature
and delivery to the registered holder in lieu of the Right Certificate so lost,
stolen, destroyed or mutilated.

         SECTION 7. EXERCISE OF RIGHTS; PURCHASE PRICE; EXPIRATION DATE OF
RIGHTS.

         (a) The registered holder of any Right Certificate may exercise the
Rights evidenced thereby (except as otherwise provided herein) in whole or in
part at any time after the Distribution Date upon surrender of the Right
Certificate, with the form of election to purchase on the reverse side thereof
duly executed, to the Rights Agent at the office of the Rights Agent designated
for such purpose, together with payment of the Purchase Price for each one
one-thousandth of a Preferred Share (or such other number of shares or other
securities) as to which the Rights are exercised, at or prior to the earliest of
(i) the Close of Business on May 8, 2009 (the "Final Expiration Date"), (ii) the
time at which the right to exercise the Rights terminates pursuant to Section 23
hereof (the "Redemption Date"), or (iii) the time at which such right to
exercise the Rights terminates pursuant to Section 24 hereof.

         (b) The Purchase Price for each one one-thousandth of a Preferred Share
pursuant to the exercise of a Right shall initially be $850 (the "Purchase
Price"), shall be subject to adjustment from time to time as provided in
Sections 11 and 13 hereof and shall be payable in lawful money of the United
States of America in accordance with Section 7 (c) hereof.

         (c) Upon receipt of a Right Certificate representing exercisable
Rights, with the form of election to purchase duly executed, accompanied by
payment of the Purchase Price for the shares to be purchased and an amount equal
to any applicable transfer tax required to be paid by the holder of such Right
Certificate in accordance with Section 9 hereof by certified check, cashier's
check, bank draft or money order payable to the order of the Company, the Rights
Agent shall thereupon promptly (i) (A) requisition from any transfer agent for
the Preferred Shares certificates for the number of one one-thousandths of a
Preferred Share to be purchased and the Company hereby irrevocably authorizes
its transfer agent to comply with all such requests, or (B) if the Company, in
its sole discretion, shall have elected to deposit the Preferred Shares issuable
upon exercise of the Rights hereunder into a depository, requisition from the
depository agent depository receipts representing such number of one
one-thousandths of a Preferred Share as are to be purchased (in which case
certificates for the Preferred Shares represented by such receipts shall be
deposited by the transfer agent with the depository agent) and the Company
hereby directs the depository agent to comply with such request, (ii) when
appropriate, requisition from the Company the amount of cash to be paid in lieu
of issuance of fractional shares in accordance with Section 14 hereof, (iii)
after receipt of such certificates or depository receipts, cause the same to be
delivered to or upon the order of the registered holder of such Right
Certificate, registered in such name or names as may be designated by such
holder and (iv) when appropriate, after receipt, deliver such cash to or upon
the order of the registered holder of such Right Certificate. In the event that
the Company is 


                                       7
<PAGE>   11
obligated to issue securities of the Company other than Preferred Shares
(including Common Shares) of the Company pursuant to Section 11(a) hereof, the
Company will make all arrangements necessary so that such other securities are
available for distribution by the Rights Agent, if and when appropriate.

         (d) In case the registered holder of any Right Certificate shall
exercise fewer than all the Rights evidenced thereby, a new Right Certificate
evidencing Rights equivalent to the Rights remaining unexercised shall be issued
by the Rights Agent to the registered holder of such Right Certificate or to his
duly authorized assigns, subject to the provisions of Section 14 hereof.

         (e) The Company covenants and agrees that it will cause to be reserved
and kept available out of its authorized and unissued Preferred Shares or any
Preferred Shares held in its treasury, the number of Preferred Shares that will
be sufficient to permit the exercise in full of all outstanding Rights in
accordance with this Section 7.

         (f) Notwithstanding anything in this Agreement to the contrary, neither
the Rights Agent nor the Company shall be obligated to undertake any action with
respect to a registered holder upon the occurrence of any purported exercise as
set forth in this Section 7 unless such registered holder shall have (i)
completed and signed the certification following the form of election to
purchase set forth on the reverse side of the Rights Certificate surrendered for
such exercise and (ii) provided such additional evidence of the identity of the
Beneficial Owner (or former Beneficial Owner) or Affiliates or Associates
thereof as the Company shall reasonably request.

         SECTION 8. CANCELLATION AND DESTRUCTION OF RIGHT CERTIFICATES. All
Right Certificates surrendered for the purpose of exercise, transfer, split up,
combination or exchange shall, if surrendered to the Company or to any of its
agents, be delivered to the Rights Agent for cancellation or in canceled form,
or, if delivered or surrendered to the Rights Agent, shall be canceled by it,
and no Right Certificates shall be issued in lieu thereof except as expressly
permitted by any of the provisions of this Rights Agreement. The Company shall
deliver to the Rights Agent for cancellation and retirement, and the Rights
Agent shall so cancel and retire, any other Right Certificate purchased or
acquired by the Company otherwise than upon the exercise thereof. The Rights
Agent shall deliver all canceled Right Certificates to the Company, or shall, at
the written request of the Company, destroy such canceled Right Certificates,
and in such case shall deliver a certificate of destruction thereof to the
Company.

         SECTION 9.  AVAILABILITY OF PREFERRED SHARES.

         (a) The Company covenants and agrees that so long as the Preferred
Shares (and, after the time a person becomes an Acquiring Person, Common Shares
or any other securities) issuable upon the exercise of the Rights may be listed
on any national securities exchange or quotation system, the Company shall use
its best efforts to cause, from and after such time as the Rights become
exercisable, all shares reserved for such issuance to be listed on such exchange
or quotation system upon official notice of issuance upon such exercise.

         (b) The Company covenants and agrees that it will take all such action
as may be necessary to ensure that all Preferred Shares (or Common Shares and
other securities, as the case may be) delivered upon exercise of Rights shall,
at the time of delivery of the certificates for such 


                                       8
<PAGE>   12
Preferred Shares (subject to payment of the Purchase Price), be duly and validly
authorized and issued and fully paid and nonassessable shares or other
securities.

         (c) The Company further covenants and agrees that it will pay when due
and payable any and all federal and state transfer taxes and charges which may
be payable in respect of the issuance or delivery of the Right Certificates or
of any Preferred Shares upon the exercise of Rights. The Company shall not,
however, be required to pay any transfer tax which may be payable in respect of
any transfer or delivery of Right Certificates to a person other than, or the
issuance or delivery of certificates or depository receipts for the Preferred
Shares in a name other than that of, the registered holder of the Right
Certificate evidencing Rights surrendered for exercise or to issue or to deliver
any certificates or depository receipts for Preferred Shares upon the exercise
of any Rights until any such tax shall have been paid (any such tax being
payable by the holder of such Right Certificate at the time of surrender) or
until it has been established to the Company's reasonable satisfaction that no
such tax is due.

         (d) As soon as practicable after the Shares Acquisition Date, the
Company shall use its best efforts to:

                  (i) prepare and file a registration statement under the
         Securities Act of 1933, as amended (the "Act"), with respect to the
         securities purchasable upon exercise of the Rights on an appropriate
         form, will use its best efforts to cause such registration statement to
         become effective as soon as practicable after such filing and will use
         its best efforts to cause such registration statement to remain
         effective (with a prospectus at all times meeting the requirements of
         the Act) until the Final Expiration Date; and

                  (ii) use its best efforts to qualify or register the Rights
         and the securities purchasable upon exercise of the Rights under the
         blue sky laws of such jurisdictions as may be necessary or appropriate.

         SECTION 10. PREFERRED SHARES RECORD DATE. Each person in whose name any
certificate for Preferred Shares or other securities is issued upon the exercise
of Rights shall for all purposes be deemed to have become the holder of record
of the Preferred Shares or other securities represented thereby on, and such
certificate shall be dated, the date upon which the Right Certificate evidencing
such Rights was duly surrendered with the forms of election and certification
duly executed and payment of the Purchase Price (and any applicable transfer
taxes) was made; provided, however, that if the date of such surrender and
payment is a date upon which the Preferred Shares or other securities transfer
books of the Company are closed, such person shall be deemed to have become the
record holder of such shares on, and such certificate shall be dated, the next
succeeding Business Day on which the Preferred Shares or other securities
transfer books of the Company are open. Prior to the exercise of the Rights
evidenced thereby, the holder of a Right Certificate, as such, shall not be
entitled to any rights of a holder of Preferred Shares for which the Rights
shall be exercisable, including, without limitation, the right to vote, to
receive dividends or other distributions or to exercise any preemptive rights,
and shall not be entitled to receive any notice of any proceedings of the
Company, except as provided herein.


                                       9
<PAGE>   13
         SECTION 11. ADJUSTMENT OF PURCHASE PRICE, NUMBER OF SHARES OR NUMBER OF
RIGHTS. The Purchase Price, the number of Preferred Shares covered by each Right
and the number of Rights outstanding are subject to adjustment from time to time
as provided in this Section 11.

         (a) (i) In the event the Company shall at any time after the date of
this Agreement (A) declare a dividend on the Preferred Shares payable in
Preferred Shares, (B) subdivide the outstanding Preferred Shares, (C) combine
the outstanding Preferred Shares into a smaller number of Preferred Shares or
(D) issue any shares of its capital stock in a reclassification of the Preferred
Shares (including any such reclassification in connection with a consolidation
or merger in which the Company is the continuing or surviving corporation),
except as otherwise provided in this Section 11(a), the Purchase Price in effect
at the time of the record date for such dividend or of the effective date of
such subdivision, combination or reclassification, and the number and kind of
shares of capital stock issuable on such date, shall be proportionately adjusted
so that the holder of any Right exercised after such time shall be entitled to
receive the aggregate number and kind of shares of capital stock which, if such
Right had been exercised immediately prior to such date and at a time when the
Preferred Shares transfer books of the Company were open, such holder would have
owned upon such exercise and been entitled to receive by virtue of such
dividend, subdivision, combination or reclassification; provided, however, that
in no event shall the consideration to be paid upon the exercise of one Right be
less than the aggregate par value of the shares of capital stock of the Company
issuable upon exercise of one Right. If an event occurs which would require an
adjustment under both Section 11(a)(i) and Section 11(a)(ii) hereof, the
adjustment provided for in this Section 11(a)(i) shall be in addition to, and
shall be made prior to any adjustment required pursuant to Section 11(a)(ii)
hereof.

                  (ii) Subject to Section 24 hereof, in the event any Person
shall become an Acquiring Person, each holder of a Right shall thereafter have a
right to receive, upon exercise of each Right at a price equal to the then
current Purchase Price multiplied by the number of one one-thousandths of a
Preferred Share for which a Right is then exercisable, in accordance with the
terms of this Agreement and in lieu of Preferred Shares, such number of Common
Shares of the Company as shall equal the result obtained by (A) multiplying the
then current Purchase Price by the number of one one-thousandths of a Preferred
Share for which a Right is then exercisable and dividing that product by (B) 50%
of the then current per share market price of the Common Shares (determined
pursuant to Section 11(d) hereof) on the date such Person became an Acquiring
Person. In the event that any Person shall become an Acquiring Person and the
Rights shall then be outstanding, the Company shall not take any action which
would eliminate or diminish the benefits intended to be afforded by the Rights.

         Notwithstanding anything in this Agreement to the contrary, from and
after the time any Person becomes an Acquiring Person, any Rights beneficially
owned by (i) such Acquiring Person or an Associate or Affiliate of such
Acquiring Person, (ii) a transferee of such Acquiring Person (or of any such
Associate or Affiliate) who becomes a transferee after the Acquiring Person
became such, or (iii) a transferee of such Acquiring Person (or of any such
Associate or Affiliate) who becomes a transferee prior to or concurrently with
the Acquiring Person's becoming such and receives such Rights pursuant to either
(A) a transfer (whether or not for consideration) from the Acquiring Person to
holders of equity interests in such Acquiring Person or to any Person with whom
the Acquiring Person has any continuing agreement, arrangement or understanding
regarding the transferred Rights or (B) a transfer which the Board of Directors
of the Company has 


                                       10
<PAGE>   14
determined is part of a plan, arrangement or understanding which has as a
primary purpose or effect the avoidance of this Section 11(a)(ii), shall become
null and void without any further action and no holder of such Rights shall have
any rights whatsoever with respect to such Rights, whether under any provision
of this Agreement or otherwise. The Company shall use all reasonable efforts to
insure that the provisions of this Section 11(a)(ii) and Section 4 hereof are
complied with, but shall have no liability to any holder of Right Certificates
or other Person as a result of its failure to make any determinations with
respect to an Acquiring Person or its Affiliates, Associates or transferees
hereunder. No Right Certificate shall be issued at any time upon the transfer of
any Rights to an Acquiring Person or transferee whose Rights would be void
pursuant to the preceding sentence or any Associate or Affiliate thereof or to
any nominee of such Acquiring Person, Associate or Affiliate; and any Right
Certificate delivered to the Rights Agent for transfer to an Acquiring Person
whose Rights would be void pursuant to the preceding sentence shall be canceled.

                  (iii) In the event that the number of Common Shares which are
authorized by the Company's Articles of Organization and not outstanding or
subscribed for, or reserved or otherwise committed for issuance for purposes
other than upon exercise of the Rights, are not sufficient to permit the holder
of each Right to purchase the number of Common Shares to which he would be
entitled upon the exercise in full of the Rights in accordance with the
foregoing subparagraph (ii) of paragraph (a) of this Section 11, or should the
Board of Directors so elect, the Company shall: (A) determine the excess of (1)
the value of the Common Shares issuable upon exercise of a Right (calculated as
provided in the last sentence of this subparagraph (iii)) pursuant to Section
11(a)(ii) hereof (the "Current Value") over (2) the Purchase Price (such excess,
the "Spread"), and (B) with respect to each Right, make adequate provision to
substitute for such Common Shares, upon payment of the applicable Purchase
Price, any one or more of the following having an aggregate value determined by
the Board of Directors to be equal to the Current Value: (1) cash, (2) a
reduction in the Purchase Price, (3) Common Shares or other equity securities of
the Company (including, without limitation, shares, or units of shares, of
preferred stock which the Board of Directors of the Company has determined to
have the same value as shares of Common Stock (such shares of preferred stock,
"common stock equivalents")), (4) debt securities of the Company, or (5) other
assets; provided, however, if the Company shall not have made adequate provision
to deliver value pursuant to clause (B) above within thirty (30) days following
the first occurrence of an event triggering the rights to purchase Common Shares
described in Section 11(a)(ii) (the "Section 11(a)(ii) Trigger Date"), then the
Company shall be obligated to deliver, upon the surrender for exercise of a
Right and without requiring payment of the Purchase Price, shares of Common
Stock (to the extent available) and then, if necessary, cash, which shares and
cash have an aggregate value equal to the Spread. If the Board of Directors of
the Company shall determine in good faith that it is likely that sufficient
additional Common Shares could be authorized for issuance upon exercise in full
of the Rights, the thirty (30) day period set forth above may be extended to the
extent necessary, but not more than ninety (90) days after the Section 11(a)(ii)
Trigger Date, in order that the Company may seek stockholder approval for the
authorization of such additional shares (such period, as it may be extended, the
"Substitution Period"). To the extent that the Company determines that some
action need be taken pursuant to the first and/or second sentences of this
Section 11(a)(iii), the Company (x) shall provide, subject to Section 7(f)
hereof and the last paragraph of Section 11(a)(ii) hereof, that such action
shall apply uniformly to all outstanding Rights, and (y) may suspend the
exercisability of the Rights until the expiration of the Substitution Period in
order to seek any authorization of additional shares and/or to decide the
appropriate form of distribution to be made pursuant to such first sentence and
to determine the value thereof. In the 


                                       11
<PAGE>   15
event of any such suspension, the Company shall make a public announcement, and
shall deliver to the Rights Agent a statement, stating that the exercisability
of the Rights has been temporarily suspended. At such time as the suspension is
no longer in effect, the Company shall make another public announcement, and
deliver to the Rights Agent a statement, so stating. For purposes of this
Section 11(a)(iii), the value of the Common Shares shall be the current per
share market price (as determined pursuant to Section 11(d)(i) hereof) of the
Common Shares on the Section 11(a)(ii) Trigger Date and the value of any common
stock equivalent shall be deemed to have the same value as the Common Shares on
such date.

         (b) In case the Company shall fix a record date for the issuance of
rights, options or warrants to all holders of Preferred Shares entitling them
(for a period expiring within 45 calendar days after such record date) to
subscribe for or purchase Preferred Shares (or shares having the same
designations and the powers, preferences and rights, and the qualifications,
limitations and restrictions as the Preferred Shares ("equivalent preferred
shares")) or securities convertible into Preferred Shares or equivalent
preferred shares at a price per Preferred Share or equivalent preferred share
(or having a conversion price per share, if a security convertible into
Preferred Shares or equivalent preferred shares) less than the then current per
share market price of the Preferred Shares (as defined in Section 11(d) hereof)
on such record date, the Purchase Price to be in effect after such record date
shall be determined by multiplying the Purchase Price in effect immediately
prior to such record date by a fraction, the numerator of which shall be the
number of Preferred Shares outstanding on such record date plus the number of
Preferred Shares which the aggregate offering price of the total number of
Preferred Shares and/or equivalent preferred shares so to be offered (and/or the
aggregate initial conversion price of the convertible securities so to be
offered) would purchase at such current market price and the denominator of
which shall be the number of Preferred Shares outstanding on such record date
plus the number of additional Preferred Shares and/or equivalent preferred
shares to be offered for subscription or purchase (or into which the convertible
securities so to be offered are initially convertible); provided, however, that
in no event shall the consideration to be paid upon the exercise of one Right be
less than the aggregate par value of the shares of capital stock of the Company
issuable upon exercise of one Right. In case such subscription price may be paid
in a consideration part or all of which shall be in a form other than cash, the
value of such consideration shall be as determined in good faith by the Board of
Directors of the Company, whose determination shall be described in a statement
filed with the Rights Agent. Preferred Shares owned by or held for the account
of the Company shall not be deemed outstanding for the purpose of any such
computation. Such adjustment shall be made successively whenever such a record
date is fixed; and in the event that such rights, options or warrants are not so
issued, the Purchase Price shall be adjusted to be the Purchase Price which
would then be in effect if such record date had not been fixed.

         (c) In case the Company shall fix a record date for the making of a
distribution to all holders of the Preferred Shares (including any such
distribution made in connection with a consolidation or merger in which the
Company is the continuing or surviving corporation) of evidences of indebtedness
or assets (other than a regular quarterly cash dividend or a dividend payable in
Preferred Shares) or subscription rights or warrants (excluding those referred
to in Section 11(b) hereof), the Purchase Price to be in effect after such
record date shall be determined by multiplying the Purchase Price in effect
immediately prior to such record date by a fraction, the numerator of which
shall be the then current per share market price of the Preferred Shares (as
defined in Section 11(d) hereof) on such record date, less the fair market value
(as determined in


                                       12
<PAGE>   16
good faith by the Board of Directors of the Company, whose determination shall
be described in a statement filed with the Rights Agent) of the portion of the
assets or evidences of indebtedness so to be distributed or of such subscription
rights or warrants applicable to one Preferred Share and the denominator of
which shall be such current per share market price of the Preferred Shares;
provided, however, that in no event shall the consideration to be paid upon the
exercise of one Right be less than the aggregate par value of the shares of
capital stock of the Company to be issued upon exercise of one Right. Such
adjustments shall be made successively whenever such a record date is fixed; and
in the event that such distribution is not so made, the Purchase Price shall
again be adjusted to be the Purchase Price which would then be in effect if such
record date had not been fixed.

         (d) (i) For the purpose of any computation hereunder, the "current per
share market price" of any security (a "Security") for the purpose of this
Section 11(d)(i)) on any date shall be deemed to be the average of the daily
closing prices per share of such Security for the 30 consecutive Trading Days
(as such term is hereinafter defined) immediately prior to such date; provided,
however, that in the event that the current per share market price of the
Security is determined during a period following the announcement by the issuer
of such Security of (A) a dividend or distribution on such Security payable in
shares of such Security or securities convertible into such shares, or (B) any
subdivision, combination or reclassification of such Security or securities
convertible into such shares, or (C) any subdivision, combination or
reclassification of such Security and prior to the expiration of 30 Trading Days
after the ex-dividend date for such dividend or distribution, or the record date
for such subdivision, combination or reclassification, then, and in each such
case, the current per share market price shall be appropriately adjusted to
reflect the current market price per share equivalent of such Security. The
closing price for each day shall be the last sale price, regular way, or, in
case no such sale takes place on such day, the average of the closing bid and
asked prices, regular way, in either case as reported in the principal
consolidated transaction reporting system with respect to securities listed or
admitted to trading on the New York Stock Exchange or, if the Security is not
listed or admitted to trading on the New York Stock Exchange, as reported in the
principal consolidated transaction reporting system with respect to securities
listed on the principal national securities exchange on which the Security is
listed or admitted to trading or as reported on the Nasdaq National Market or,
if the Security is not listed or admitted to trading on any national securities
exchange or reported on the Nasdaq National Market, the last quoted price or, if
not so quoted, the average of the high bid and low asked prices in the
over-the-counter market, as reported by the National Association of Securities
Dealers, Inc. Automated Quotations System ("Nasdaq") or such other system then
in use, or, if on any such date the Security is not quoted by any such
organization, the average of the closing bid and asked prices as furnished by a
professional market maker making a market in the Security selected by the Board
of Directors of the Company. The term "Trading Day" shall mean a day on which
the principal national securities exchange on which the Security is listed or
admitted to trading is open for the transaction of business or, if the Security
is not listed or admitted to trading on any national securities exchange, a
Business Day.

                  (ii) For the purpose of any computation hereunder, the
"current per share market price" of the Preferred Shares shall be determined in
accordance with the method set forth in Section 11(d)(i) hereof. If the
Preferred Shares are not publicly traded, the "current per share market price"
of the Preferred Shares shall be conclusively deemed to be the current per share
market price of the Common Shares as determined pursuant to Section 11(d)(i)
hereof 


                                       13
<PAGE>   17
(appropriately adjusted to reflect any stock split, stock dividend or similar
transaction occurring after the date hereof) multiplied by one thousand. If
neither the Common Shares nor the Preferred Shares are publicly held or so
listed or traded, "current per share market price" shall mean the fair value per
share as determined in good faith by the Board of Directors or a committee of
the Board of Directors authorized by the Board, whose determination shall be
described in a statement filed with the Rights Agent.

         (e) No adjustment in the Purchase Price shall be required unless such
adjustment would require an increase or decrease of at least 1% in the Purchase
Price; provided, however, that any adjustments which by reason of this Section
11(e) are not required to be made shall be carried forward and taken into
account in any subsequent adjustment. All calculations under this Section 11
shall be made to the nearest cent or to the nearest one ten-millionth of a
Preferred Share or one ten-thousandth of any other share or security as the case
may be. Notwithstanding the first sentence of this Section 11(e), any adjustment
required by this Section 11 shall be made no later than the earlier of (i) three
years from the date of the transaction which requires such adjustment or (ii)
the date of the expiration of the right to exercise any Rights.

         (f) If as a result of an adjustment made pursuant to Section 11(a)
hereof, the holder of any Right thereafter exercised shall become entitled to
receive any shares of capital stock of the Company other than Preferred Shares,
thereafter the number of such other shares so receivable upon exercise of any
Right shall be subject to adjustment from time to time in a manner and on terms
as nearly equivalent as practicable to the provisions with respect to the
Preferred Shares contained in Section 11(a) through (c) hereof, inclusive, and
the provisions of Sections 7, 9, 10, 13 and 14 hereof with respect to the
Preferred Shares shall apply on like terms to any such other shares.

         (g) All Rights originally issued by the Company subsequent to any
adjustment made to the Purchase Price hereunder shall evidence the right to
purchase, at the adjusted Purchase Price, the number of one one-thousandths of a
Preferred Share purchasable from time to time hereunder upon exercise of the
Rights, all subject to further adjustment as provided herein.

         (h) Unless the Company shall have exercised its election as provided in
Section 11(i) hereof, upon each adjustment of the Purchase Price as a result of
the calculations made in Section 11(b) and (c) hereof, each Right outstanding
immediately prior to the making of such adjustment shall thereafter evidence the
right to purchase, at the adjusted Purchase Price, that number of one
one-thousandths of a Preferred Share (calculated to the nearest one
ten-millionth of a Preferred Share) obtained by (i) multiplying (x) the number
of one one-thousandths of a Preferred Share covered by a Right immediately prior
to this adjustment by (y) the Purchase Price in effect immediately prior to such
adjustment of the Purchase Price and (ii) dividing the product so obtained by
the Purchase Price in effect immediately after such adjustment of the Purchase
Price.

         (i) The Company may elect on or after the date of any adjustment of the
Purchase Price to adjust the number of Rights, in substitution for any
adjustment in the number of one one-thousandths of a Preferred Share purchasable
upon the exercise of a Right. Each of the Rights outstanding after such
adjustment of the number of Rights shall be exercisable for the number of one
one-thousandths of a Preferred Share for which a Right was exercisable
immediately prior to such adjustment. Each Right held of record prior to such
adjustment of the number of Rights shall 


                                       14
<PAGE>   18
become that number of Rights (calculated to the nearest one ten-thousandth)
obtained by dividing the Purchase Price in effect immediately prior to
adjustment of the Purchase Price by the Purchase Price in effect immediately
after adjustment of the Purchase Price. The Company shall make a public
announcement of its election to adjust the number of Rights, indicating the
record date for the adjustment, and, if known at the time, the amount of the
adjustment to be made. This record date may be the date on which the Purchase
Price is adjusted or any day thereafter, but, if the Right Certificates have
been issued, shall be at least 10 days later than the date of the public
announcement. If Right Certificates have been issued, upon each adjustment of
the number of Rights pursuant to this Section 11(i), the Company shall, as
promptly as practicable, cause to be distributed to holders of record of Right
Certificates on such record date Right Certificates evidencing, subject to
Section 14 hereof, the additional Rights to which such holders shall be entitled
as a result of such adjustment, or, at the option of the Company, shall cause to
be distributed to such holders of record in substitution and replacement for the
Right Certificates held by such holders prior to the date of adjustment, and
upon surrender thereof, if required by the Company, new Right Certificates
evidencing all the Rights to which such holders shall be entitled after such
adjustment. Right Certificates so to be distributed shall be issued, executed
and countersigned in the manner provided for herein and shall be registered in
the names of the holders of record of Right Certificates on the record date
specified in the public announcement.

         (j) Irrespective of any adjustment or change in the Purchase Price or
the number of one one-thousandths of a Preferred Share issuable upon the
exercise of the Rights, the Right Certificates theretofore and thereafter issued
may continue to express the Purchase Price and the number of one one-thousandths
of a Preferred Share which were expressed in the initial Right Certificates
issued hereunder.

         (k) Before taking any action that would cause an adjustment reducing
the Purchase Price below one one-thousandth of the then par value, if any, of
the Preferred Shares issuable upon exercise of the Rights, the Company shall
take any corporate action which may, in the opinion of its counsel, be necessary
in order that the Company may validly and legally issue fully paid and
nonassessable Preferred Shares at such adjusted Purchase Price.

         (l) In any case in which this Section 11 shall require that an
adjustment in the Purchase Price be made effective as of a record date for a
specified event, the Company may elect to defer until the occurrence of such
event the issuing to the holder of any Right exercised after such record date of
the Preferred Shares and other capital stock or securities of the Company, if
any, issuable upon such exercise on the basis of the Purchase Price in effect
prior to such adjustment; provided, however, that the Company shall deliver to
such holder a due bill or other appropriate instrument evidencing such holder's
right to receive such additional shares upon the occurrence of the event
requiring such adjustment.

         (m) The Company covenants and agrees that, after the Distribution Date,
it will not, except as permitted by Section 23, Section 24 or Section 27 hereof,
take (or permit any Subsidiary to take) any action the purpose of which is to,
or if at the time such action is taken it is reasonably foreseeable that the
effect of such action is to, materially diminish or eliminate the benefits
intended to be afforded by the Rights.


                                       15
<PAGE>   19
         (n) Anything in this Section 11 to the contrary notwithstanding, the
Company shall be entitled to make such reductions in the Purchase Price, in
addition to those adjustments expressly required by this Section 11, as and to
the extent that it in its sole discretion shall determine to be advisable in
order that any consolidation or subdivision of the Preferred Shares, issuance
wholly for cash of any Preferred Shares at less than the current market price,
issuance wholly for cash of Preferred Shares or securities which by their terms
are convertible into or exchangeable for Preferred Shares, dividends on
Preferred Shares payable in Preferred Shares or issuance of rights, options or
warrants referred to hereinabove in Section 11(b) hereof, hereafter made by the
Company to holders of its Preferred Shares shall not be taxable to such
stockholders.

         (o) In the event that at any time after the date of this Agreement and
prior to the Distribution Date, the Company shall (i) declare or pay any
dividend on the Common Shares payable in Common Shares or (ii) effect a
subdivision, combination or consolidation of the Common Shares (by
reclassification or otherwise than by payment of dividends in Common Shares)
into a greater or lesser number of Common Shares, then in any such case (A) the
number of one one-thousandths of a Preferred Share purchasable after such event
upon proper exercise of each Right shall be determined by multiplying the number
of one one-thousandths of a Preferred Share so purchasable immediately prior to
such event by a fraction, the numerator of which is the number of Common Shares
outstanding immediately before such event and the denominator of which is the
number of Common Shares outstanding immediately after such event, and (B) each
Common Share outstanding immediately after such event shall have issued with
respect to it that number of Rights which each Common Share outstanding
immediately prior to such event had issued with respect to it. The adjustments
provided for in this Section 11(o) shall be made successively whenever such a
dividend is declared or paid or such a subdivision, combination or consolidation
is effected.

         (p) The exercise of Rights under Section 11(a)(ii) hereof shall only
result in the loss of rights under Section 11(a)(ii) hereof to the extent so
exercised and shall not otherwise affect the rights represented by the Rights
under this Rights Agreement, including the rights represented by Section 13
hereof.

         SECTION 12. CERTIFICATE OF ADJUSTED PURCHASE PRICE OR NUMBER OF SHARES.
Whenever an adjustment is made as provided in Sections 11 and 13 hereof, the
Company shall promptly (a) prepare a certificate setting forth such adjustment,
and a brief statement of the facts accounting for such adjustment, (b) file with
the Rights Agent and with each transfer agent for the Common Shares or the
Preferred Shares a copy of such certificate and (c) mail a brief summary thereof
to each holder of a Right Certificate in accordance with Section 25 hereof. The
Rights Agent shall be fully protected in relying on any such certificate and on
any adjustment therein contained and shall not be deemed to have knowledge of
any adjustment unless and until it shall have received such certificate.

         SECTION 13. CONSOLIDATION, MERGER OR SALE OR TRANSFER OF ASSETS OR
EARNING POWER.

         (a) In the event that, following the Shares Acquisition Date, directly
or indirectly (x) the Company shall consolidate with, or merge with and into,
any other Person, (y) any Person shall consolidate with the Company, or merge
with and into the Company, and the Company shall be the continuing or surviving
corporation of such merger (other than, in the case of either transaction
described in (x) or (y), a merger or consolidation which would result in all of
the voting power 


                                       16
<PAGE>   20
represented by the securities of the Company outstanding immediately prior
thereto continuing to represent (either by remaining outstanding or by being
converted into securities of the surviving entity) all of the voting power
represented by the securities of the Company or such surviving entity
outstanding immediately after such merger or consolidation and the holders of
such securities not having changed as a result of such merger or consolidation),
or (z) the Company shall sell, mortgage or otherwise transfer (or one or more of
its Subsidiaries shall sell, mortgage or otherwise transfer), in one or more
transactions, assets or earning power aggregating more than 50% of the assets or
earning power of the Company and its Subsidiaries (taken as a whole) to any
other Person, (other than the Company or any Subsidiary of the Company in one or
more transactions each of which individually and the aggregate does not violate
Section 13(d) hereof) then, and in each such case, proper provision shall be
made so that (i) following the Distribution Date, each holder of a Right,
subject to Section 11(a)(ii) hereof, shall have the right to receive, upon the
exercise thereof at a price equal to the then current Purchase Price multiplied
by the number of one one-thousandths of a Preferred Share for which a Right is
then exercisable in accordance with the terms of this Agreement and in lieu of
Preferred Shares, such number of shares of freely tradeable Common Shares of the
Principal Party (as hereinafter defined), free and clear of liens, rights of
call or first refusal, encumbrances or other adverse claims, as shall be equal
to the result obtained by (A) multiplying the then current Purchase Price by the
number of one one-thousandths of a Preferred Share for which a Right is then
exercisable (without taking into account any adjustment previously made pursuant
to Section 11(a)(ii) hereof) and dividing that product by (B) 50% of the then
current per share market price of the Common Shares of such Principal Party
(determined pursuant to Section 11(d) hereof) on the date of consummation of
such consolidation, merger, sale or transfer; (ii) such Principal Party shall
thereafter be liable for, and shall assume, by virtue of such consolidation,
merger, sale or transfer, all the obligations and duties of the Company pursuant
to this Agreement; (iii) the term "Company" shall thereafter be deemed to refer
to such Principal Party, it being specifically intended that the provisions of
Section 11 hereof shall apply to such Principal Party; and (iv) such Principal
Party shall take such steps in connection with such consummation as may be
necessary to assure that the provisions hereof shall thereafter be applicable,
as nearly as reasonably may be, in relation to its Common Shares thereafter
deliverable upon the exercise of the Rights.

         (b) "Principal Party" shall mean:

                  (i) in the case of any transaction described in (x) or (y) of
         the first sentence of Section 13(a) hereof, the Person that is the
         issuer of any securities into which Common Shares of the Company are
         converted in such merger or consolidation, and if no securities are so
         issued, the Person that is the other party to the merger or
         consolidation (including, if applicable, the Company, if it is the
         surviving corporation); and

                  (ii) in the case of any transaction described in (z) of the
         first sentence in Section 13(a) hereof, the Person that is the party
         receiving the greatest portion of the assets or earning power
         transferred pursuant to such transaction or transactions;

provided, however, that in any case, (1) if the Common Shares of such Person are
not at such time and have not been continuously over the preceding 12-month
period registered under Section 12 of the Exchange Act, and such Person is a
direct or indirect Subsidiary or Affiliate of another Person the Common Shares
of which are and have been so registered, "Principal Party" shall refer to such


                                       17
<PAGE>   21
other Person; (2) in case such Person is a Subsidiary, directly or indirectly,
or Affiliate of more than one Person, the Common Shares of two or more of which
are and have been so registered, "Principal Party" shall refer to whichever of
such Persons is the issuer of the Common Shares having the greatest aggregate
market value; and (3) in case such Person is owned, directly or indirectly, by a
joint venture formed by two or more Persons that are not owned, directly or
indirectly, by the same Person, the rules set forth in (1) and (2) above shall
apply to each of the chains of ownership having an interest in such joint
venture as if such party were a "Subsidiary" of both or all of such joint
venturers and the Principal Parties in each such chain shall bear the
obligations set forth in this Section 13 in the same ratio as their direct or
indirect interests in such Person bear to the total of such interests.

         (c) The Company shall not consummate any such consolidation, merger,
sale or transfer unless the Principal Party shall have a sufficient number of
authorized shares of its Common Shares that have not been issued or reserved for
issuance to permit the exercise in full of the Rights in accordance with this
Section 13 and unless prior thereto the Company and each Principal Party and
each other Person who may become a Principal Party as a result of such
consolidation, merger, sale or transfer shall have executed and delivered to the
Rights Agent a supplemental agreement providing for the terms set forth in
paragraphs (a) and (b) of this Section 13 and further providing that, as soon as
practicable after the date of any consolidation, merger, sale or transfer of
assets mentioned in paragraph (a) of this Section 13, the Principal Party at its
own expense will:

                  (i) prepare and file a registration statement under the Act
         with respect to the securities purchasable upon exercise of the Rights
         on an appropriate form, will use its best efforts to cause such
         registration statement to become effective as soon as practicable after
         such filing and will use its best efforts to cause such registration
         statement to remain effective (with a prospectus at all times meeting
         the requirements of the Act) until the Final Expiration Date;

                  (ii) use its best efforts to qualify or register the Rights
         and the securities purchasable upon exercise of the Rights under the
         blue sky laws of such jurisdictions as may be necessary or appropriate;
         and

                  (iii) deliver to holders of the Rights historical financial
         statements for the Principal Party and each of its Affiliates which
         comply in all material respects with the requirements for registration
         on Form 10 under the Exchange Act.

The provisions of this Section 13 shall similarly apply to successive mergers or
consolidations or sales or other transfers.

         (d) After the Distribution Date, the Company covenants and agrees that
it shall not (i) consolidate with, (ii) merge with or into, or (iii) sell or
transfer to, in one or more transactions, assets or earning power aggregating
more than 50% of the assets or earning power of the Company and its Subsidiaries
taken as a whole, any other Person (other than a Subsidiary of the Company in a
transaction which does not violate Section 11(m) hereof), if (x) at the time of
or after such consolidation, merger or sale there are any charter or bylaw
provisions or any rights, warrants or other instruments or securities
outstanding, agreements in effect or any other action taken which would diminish
or otherwise eliminate the benefits intended to be afforded by the Rights or (y)


                                       18
<PAGE>   22
prior to, simultaneously with or immediately after such consolidation, merger or
sale, the stockholders of the Person who constitutes, or would constitute, the
Principal Party for purposes of Section 13(a) hereof shall have received a
distribution of Rights previously owned by such Person or any of its Affiliates
and Associates. The Corporation shall not consummate any such consolidation,
merger, sale or transfer unless prior thereto the Company and such other Person
shall have executed and delivered to the Rights Agent a supplemental agreement
evidencing compliance with this Section 13(d).

         SECTION 14.  FRACTIONAL RIGHTS AND FRACTIONAL SHARES.

         (a) The Company shall not be required to issue fractions of Rights or
to distribute Right Certificates which evidence fractional Rights. In lieu of
such fractional Rights, there shall be paid to the registered holders of the
Right Certificates with regard to which such fractional Rights would otherwise
be issuable, an amount in cash equal to the same fraction of the current market
value of a whole Right. For the purposes of this Section 14(a), the current
market value of a whole Right shall be the closing price of the Rights for the
Trading Day immediately prior to the date on which such fractional Rights would
have been otherwise issuable. The closing price for any day shall be the last
sale price, regular way, or, in case no such sale takes place on such day, the
average of the closing bid and asked prices, regular way, in either case as
reported in the principal consolidated transaction reporting system with respect
to securities listed or admitted to trading on the New York Stock Exchange or,
if the Rights are not listed or admitted to trading on the New York Stock
Exchange, as reported in the principal consolidated transaction reporting system
with respect to securities listed on the principal national securities exchange
on which the Rights are listed or admitted to trading or as reported on the
Nasdaq National Market or, if the Rights are not listed or admitted to trading
on any national securities exchange or reported on the Nasdaq National Market,
the last quoted price or, if not so quoted, the average of the high bid and low
asked prices in the over-the-counter market, as reported by Nasdaq or such other
system then in use or, if on any such date the Rights are not quoted by any such
organization, the average of the closing bid and asked prices as furnished by a
professional market maker making a market in the Rights selected by the Board of
Directors of the Company or a committee of the Board of Directors authorized by
the Board. If on any such date no such market maker is making a market in the
Rights, the fair value of the Rights on such date as determined in good faith by
the Board of Directors of the Company shall be used.

         (b) The Company shall not be required to issue fractions of Preferred
Shares (other than fractions which are integral multiples of one one-thousandth
of a Preferred Share) upon exercise of the Rights or to distribute certificates
which evidence fractional Preferred Shares (other than fractions which are
integral multiples of one one-thousandth of a Preferred Share). Fractions of
Preferred Shares in integral multiples of one one-thousandth of a Preferred
Share may, at the election of the Company, be evidenced by depository receipts;
provided, however, that holders of such depository receipts shall have all of
the designations and the powers, preferences and rights, and the qualifications,
limitations and restrictions to which they are entitled as beneficial owners of
the Preferred Shares represented by such depository receipts. In lieu of
fractional Preferred Shares that are not integral multiples of one
one-thousandth of a Preferred Share, the Company shall pay to the registered
holders of Right Certificates at the time such Rights are exercised as herein
provided an amount in cash equal to the same fraction of the current market
value of one Preferred Share. For the purposes of this Section 14(b), the
current market value of a Preferred Share shall be the 


                                       19
<PAGE>   23
current per share market price of the Preferred Shares (as determined pursuant
to the second sentence of Section 11(d)(i) hereof) for the Trading Day
immediately prior to the date of such exercise (or, if not publicly traded, in
accordance with Section 11(d)(ii) hereof).

         (c) Following the occurrence of one of the transactions or events
specified in Section 11 giving rise to the right to receive Common Shares,
common stock equivalents (other than Preferred Shares) or other securities upon
the exercise of a Right, the Company shall not be required to issue fractions of
Common Shares or units of such Common Shares, capital stock equivalents or other
securities upon exercise of the Rights or to distribute certificates which
evidence fractional Common Shares, capital stock equivalents or other
securities. In lieu of fractional Common Shares, capital stock equivalents or
other securities, the Company shall pay to the registered holders of Right
Certificates at the time such Rights are exercised as herein provided an amount
in cash equal to the same fraction of the current market value of one Common
Share or unit of such Common Shares, capital stock equivalents or other
securities. For purposes of this Section 14(c), the current market value shall
be the current per share market price (as determined pursuant to Section
11(d)(i) hereof) for the Trading Day immediately prior to the date of such
exercise and, if such capital stock equivalent is not traded, each such capital
stock equivalent shall have the value of one one-thousandth of a Preferred
Share.

         (d) The holder of a Right by the acceptance of the Right expressly
waives his right to receive any fractional Rights or any fractional shares upon
exercise of a Right (except as provided above).

         SECTION 15. RIGHTS OF ACTION. All rights of action in respect of this
Agreement, excepting the rights of action given to the Rights Agent under
Sections 18 and 20 hereof, are vested in the respective registered holders of
the Right Certificates (and, prior to the Distribution Date, the registered
holders of the Common Shares) and any registered holder of any Right Certificate
(or, prior to the Distribution Date, of the Common Shares), without the consent
of the Rights Agent or of the holder of any other Right Certificate (or, prior
to the Distribution Date, of the Common Shares), may, in his own behalf and for
his own benefit, enforce, and may institute and maintain any suit, action or
proceeding against the Company to enforce, or otherwise act in respect of, his
right to exercise the Rights evidenced by such Right Certificate in the manner
provided in such Right Certificate and in this Agreement. Without limiting the
foregoing or any remedies available to the holders of Rights, it is specifically
acknowledged that the holders of Rights would not have an adequate remedy at law
for any breach of this Agreement and will be entitled to specific performance of
the obligations under, and injunctive relief against actual or threatened
violations of the obligations of any Person subject to, this Agreement.

         SECTION 16. AGREEMENT OF RIGHT HOLDERS. Every holder of a Right, by
accepting the same, consents and agrees with the Company and the Rights Agent
and with every other holder of a Right that:

                  (a) prior to the Distribution Date, the Rights will be
transferable only in connection with the transfer of the Common Shares;


                                       20
<PAGE>   24
                  (b) after the Distribution Date, the Right Certificates are
transferable only on the registry books of the Rights Agent if surrendered at
the principal office of the Rights Agent, duly endorsed or accompanied by a
proper instrument of transfer; and

                  (c) the Company and the Rights Agent may deem and treat the
person in whose name the Right Certificate (or, prior to the Distribution Date,
the associated Common Shares certificate) is registered as the absolute owner
thereof and of the Rights evidenced thereby (notwithstanding any notations of
ownership or writing on the Right Certificates or the associated certificate
representing Common Shares of the Company made by anyone other than the Company
or the Rights Agent) for all purposes whatsoever, and neither the Company nor
the Rights Agent shall be affected by any notice to the contrary.

         SECTION 17. RIGHT CERTIFICATE HOLDER NOT DEEMED A STOCKHOLDER. No
holder, as such, of any Right Certificate shall be entitled to vote, receive
dividends or be deemed for any purpose the holder of the Preferred Shares or any
other securities of the Company which may at any time be issuable on the
exercise of the Rights represented thereby, nor shall anything contained herein
or in any Right Certificate be construed to confer upon the holder of any Right
Certificate, as such, any of the rights of a stockholder of the Company or any
right to vote for the election of directors or upon any matter submitted to
stockholders at any meeting thereof, or to give or withhold consent to any
corporate action, or to receive notice of meetings or other actions affecting
stockholders (except as provided in Section 25 hereof), or to receive dividends
or subscription rights, or otherwise, until the Right or Rights evidenced by
such Right Certificate shall have been exercised in accordance with the
provisions hereof.

         SECTION 18. CONCERNING THE RIGHTS AGENT. The Company agrees to pay to
the Rights Agent reasonable compensation for all services rendered by it
hereunder and, from time to time, on demand of the Rights Agent, its reasonable
expenses and counsel fees and other disbursements incurred in the administration
and execution of this Agreement and the exercise and performance of its duties
hereunder. The Company also agrees to indemnify the Rights Agent for, and to
hold it harmless against, any loss, liability, or expense, incurred without
gross negligence, bad faith or willful misconduct on the part of the Rights
Agent, for anything done or omitted by the Rights Agent in connection with the
acceptance and administration of this Agreement, including the costs and
expenses of defending against any claim of liability in the premises. The
indemnity provided herein shall survive the expiration of the Rights and the
termination of this Agreement.

         The Rights Agent shall be protected and shall incur no liability for,
or in respect of any action taken, suffered or omitted by it in connection with,
its administration of this Agreement in reliance upon any Right Certificate or
certificate for the Preferred Shares or Common Shares or for other securities of
the Company, instrument of assignment or transfer, power of attorney,
endorsement, affidavit, letter, notice, direction, consent, certificate,
statement, or other paper or document believed by it to be genuine and to be
signed, executed and, where necessary, verified or acknowledged, by the proper
person or persons, or otherwise upon the advice of counsel as set forth in
Section 20 hereof.

         SECTION 19. MERGER OR CONSOLIDATION OR CHANGE OF NAME OF RIGHTS AGENT.
Any corporation or other entity into which the Rights Agent or any successor
Rights Agent may be merged or with which it may be consolidated, or any
corporation resulting from any merger or 


                                       21
<PAGE>   25
consolidation to which the Rights Agent or any successor Rights Agent shall be a
party, or any corporation succeeding to the shareholder services or corporate
trust business of the Rights Agent or any successor Rights Agent, shall be the
successor to the Rights Agent under this Agreement without the execution or
filing of any paper or any further act on the part of any of the parties hereto,
provided, however that such corporation or other entity would be eligible for
appointment as a successor Rights Agent under the provisions of Section 21
hereof. In case at the time such successor Rights Agent shall succeed to the
agency created by this Agreement any of the Right Certificates shall have been
countersigned but not delivered, any such successor Rights Agent may adopt the
countersignature of the predecessor Rights Agent and deliver such Right
Certificates so countersigned; and in case at that time any of the Right
Certificates shall not have been countersigned, any successor Rights Agent may
countersign such Right Certificates either in the name of the predecessor Rights
Agent or in the name of the successor Rights Agent; and in all such cases such
Right Certificates shall have the full force provided in the Right Certificates
and in this Agreement.

         In case at any time the name of the Rights Agent shall be changed and
at such time any of the Right Certificates shall have been countersigned but not
delivered, the Rights Agent may adopt the countersignature under its prior name
and deliver Right Certificates so countersigned; and in case at that time any of
the Right Certificates shall not have been countersigned, the Rights Agent may
countersign such Right Certificates either in its prior name or in its changed
name; and in all such cases such Right Certificates shall have the full force
provided in the Right Certificates and in this Agreement.

         SECTION 20. DUTIES OF RIGHTS AGENT. The Rights Agent undertakes the
duties and obligations imposed by this Agreement upon the following terms and
conditions, by all of which the Company and the holders of Right Certificates,
by their acceptance thereof, shall be bound:

         (a) The Rights Agent may consult with legal counsel of its choice (who
may be legal counsel for the Company), and the opinion of such counsel shall be
full and complete authorization and protection to the Rights Agent as to any
action taken or omitted by it in good faith and in accordance with such opinion.

         (b) Whenever in the performance of its duties under this Agreement the
Rights Agent shall deem it necessary or desirable that any fact or matter be
proved or established by the Company prior to taking or suffering any action
hereunder, such fact or matter (unless other evidence in respect thereof be
herein specifically prescribed) may be deemed to be conclusively proved and
established by a certificate signed by any one of the Chairman of the Board, the
Chief Executive Officer, the President, the Chief Financial Officer, any Vice
President, the Treasurer or the Secretary of the Company and delivered to the
Rights Agent; and such certificate shall be full authorization to the Rights
Agent for any action taken or suffered in good faith by it under the provisions
of this Agreement in reliance upon such certificate.

         (c) The Rights Agent shall be liable hereunder to the Company and any
other Person only for its own gross negligence, bad faith or willful misconduct.

         (d) The Rights Agent shall not be liable for or by reason of any of the
statements of fact or recitals contained in this Agreement or in the Right
Certificates (except its countersignature 


                                       22
<PAGE>   26
thereof) or be required to verify the same, but all such statements and recitals
are and shall be deemed to have been made by the Company only.

         (e) The Rights Agent shall not be under any responsibility in respect
of the validity of this Agreement or the execution and delivery hereof (except
the due execution hereof by the Rights Agent) or in respect of the validity or
execution of any Right Certificate (except its countersignature thereof); nor
shall it be responsible for any breach by the Company of any covenant or
condition contained in this Agreement or in any Right Certificate; nor shall it
be responsible for any change in the exercisability of the Rights (including the
Rights becoming void pursuant to Section 11(a)(ii) hereof) or any adjustment in
the terms of the Rights (including the manner, method or amount thereof)
provided for in Section 3, 11, 13, 23 or 24 hereof, or the ascertaining of the
existence of facts that would require any such change or adjustment (except with
respect to the exercise of Rights evidenced by Right Certificates after receipt
of a certificate pursuant to Section 12 hereof describing such change or
adjustment); nor shall it by any act hereunder be deemed to make any
representation or warranty as to the authorization or reservation of any
Preferred Shares to be issued pursuant to this Agreement or any Right
Certificate or as to whether any Preferred Shares will, when issued, be validly
authorized and issued, fully paid and nonassessable.

         (f) The Company agrees that it will perform, execute, acknowledge and
deliver or cause to be performed, executed, acknowledged and delivered all such
further and other acts, instruments and assurances as may reasonably be required
by the Rights Agent for the carrying out or performing by the Rights Agent of
the provisions of this Agreement.

         (g) The Rights Agent is hereby authorized and directed to accept
instructions with respect to the performance of its duties hereunder from any
one of the Chairman of the Board, the Chief Executive Officer, the President,
the Chief Financial Officer, any Vice President, the Secretary or the Treasurer
of the Company, and to apply to such officers for advice or instructions in
connection with its duties, and it shall not be liable for any action taken or
suffered by it in good faith in accordance with instructions of any such officer
or for any delay in acting while waiting for those instructions. Any application
by the Rights Agent for written instructions from the Company may, at the option
of the Rights Agent, set forth in writing any action proposed to be taken or
omitted by the Rights Agent with respect to its duties or obligations under this
Rights Agreement and the date on and/or after which such action shall be taken
or omitted and the Rights Agent shall not be liable for any action taken or
omitted in accordance with a proposal included in any such application on or
after the date specified therein (which date shall not be less than three
business days after the date indicated in such application unless any such
officer shall have consented in writing to an earlier date) unless, prior to
taking or omitting any such action, the Rights Agent has received written
instructions in response to such application specifying the action to be taken
or omitted.

         (h) The Rights Agent and any stockholder, director, officer or employee
of the Rights Agent may buy, sell or deal in any of the Rights or other
securities of the Company or become pecuniarily interested in any transaction in
which the Company may be interested, or contract with or lend money to the
Company or otherwise act as fully and freely as though it were not Rights Agent
under this Agreement. Nothing herein shall preclude the Rights Agent from acting
in any other capacity for the Company or for any other legal entity.


                                       23
<PAGE>   27
         (i) The Rights Agent may execute and exercise any of the rights or
powers hereby vested in it or perform any duty hereunder either itself or by or
through its attorneys or agents, and the Rights Agent shall not be answerable or
accountable for any act, default, neglect or misconduct of any such attorneys or
agents or for any loss to the Company resulting from any such act, default,
neglect or misconduct, provided reasonable care was exercised in the selection
and continued employment thereof.

         (j) No provision of this Agreement shall require the Rights Agent to
expend or risk its own funds or otherwise incur any financial liability in the
performance of any of its duties hereunder or in the exercise of its rights if
there shall be reasonable grounds for believing that repayment of such funds or
adequate indemnification against such risk or liability is not reasonably
assured to it.

         (k) If, with respect to any Right Certificate surrendered to the Rights
Agent for exercise or transfer, the certificate attached to the form of
assignment or form of election to purchase, as the case may be, has not been
executed, the Rights Agent shall not take any further action with respect to
such requested exercise of transfer without first consulting with the Company.

         SECTION 21. CHANGE OF RIGHTS AGENT. The Rights Agent or any successor
Rights Agent may resign and be discharged from its duties under this Agreement
upon 30 days' notice in writing mailed to the Company and to each transfer agent
for the Common Shares or Preferred Shares by registered or certified mail, and
to the holders of the Right Certificates by first-class mail. The Company may
remove the Rights Agent or any successor Rights Agent upon 30 days' notice in
writing, mailed to the Rights Agent or successor Rights Agent, as the case may
be, and to each transfer agent for the Common Shares or Preferred Shares by
registered or certified mail, and to the holders of the Right Certificates by
first-class mail. If the Rights Agent shall resign or be removed or shall
otherwise become incapable of acting, the Company shall appoint a successor to
the Rights Agent. If the Company shall fail to make such appointment within a
period of 30 days after giving notice of such removal or after it has been
notified in writing of such resignation or incapacity by the resigning or
incapacitated Rights Agent or by the holder of a Right Certificate (who shall,
with such notice, submit his Right Certificate for inspection by the Company),
then the registered holder of any Right Certificate may apply to any court of
competent jurisdiction for the appointment of a new Rights Agent. Any successor
Rights Agent, whether appointed by the Company or by such a court, shall be a
corporation organized and doing business under the laws of the United States or
of any other state of the United States which is authorized under such laws to
exercise corporate trust or stock transfer powers and is subject to supervision
or examination by federal or state authority and which has at the time of its
appointment as Rights Agent a combined capital and surplus of at least $1
billion. After appointment, the successor Rights Agent shall be vested with the
same powers, rights, duties and responsibilities as if it had been originally
named as Rights Agent without further act or deed; but the predecessor Rights
Agent shall deliver and transfer to the successor Rights Agent any property at
the time held by it hereunder, and execute and deliver any further assurance,
conveyance, act or deed necessary for the purpose. Not later than the effective
date of any such appointment the Company shall file notice thereof in writing
with the predecessor Rights Agent and each transfer agent for the Common Shares
or Preferred Shares, and mail a notice thereof in writing to the registered
holders of the Right Certificates. Failure to give any notice provided for in
this Section 21, however, or any defect therein, shall not affect the legality
or 


                                       24
<PAGE>   28
validity of the resignation or removal of the Rights Agent or the appointment of
the successor Rights Agent, as the case may be.

         SECTION 22. ISSUANCE OF NEW RIGHT CERTIFICATES. Notwithstanding any of
the provisions of this Agreement or of the Rights to the contrary, the Company
may, at its option, issue new Right Certificates evidencing Rights in such form
as may be approved by its Board of Directors to reflect any adjustment or change
in the Purchase Price and the number or kind or class of shares or other
securities or property purchasable under the Right Certificates made in
accordance with the provisions of this Agreement. In addition, in connection
with the issuance or sale of Common Shares following the Distribution Date and
prior to the earlier of the Redemption Date and the Final Expiration Date, the
Company (a) shall with respect to Common Shares so issued or sold pursuant to
the exercise of stock options or under any employee plan or arrangement, or upon
the exercise, conversion or exchange of securities, notes or debentures issued
by the Company (other than the Rights), and (b) may, in any other case, if
deemed necessary or appropriate by the Board of Directors of the Company, issue
Right Certificates representing the appropriate number of Rights in connection
with such issuance or sale; provided, however, that (i) the Company shall not be
obligated to issue any such Right Certificates if, and to the extent that, the
Company shall be advised by counsel that such issuance would create a
significant risk of material adverse tax consequences to the Company or the
Person to whom such Right Certificate would be issued, and (ii) no Right
Certificate shall be issued if, and to the extent that, appropriate adjustment
shall otherwise have been made in lieu of the issuance thereof.

         SECTION 23.  REDEMPTION.

         (a) The Rights may be redeemed by action of the Board of Directors
pursuant to subsection (b) of this Section 23 and shall not be redeemed in any
other manner.

         (b) The Board of Directors of the Company may, at its option, at any
time prior to the earlier of (i) the time that any Person becomes an Acquiring
Person; or (ii) the Final Expiration Date, redeem all but not less than all of
the then outstanding Rights at a redemption price of $.001 per Right,
appropriately adjusted to reflect any stock split, stock dividend or similar
transaction occurring after the date hereof (such redemption price being
hereinafter referred to as the "Redemption Price"). The redemption of the Rights
by the Board of Directors may be made effective at such time, on such basis and
subject to such conditions as the Board of Directors in its sole discretion may
establish.

         (c) In case of a redemption permitted under Section 23(b) hereof,
immediately upon the time of the effectiveness of the redemption of the Rights
pursuant to paragraph (b) of this Section 23 or such earlier time as has been
determined by the Board of Directors of the Company in the action ordering such
redemption (although not earlier than the time of such action), and without any
further action and without any notice, the right to exercise the Rights will
terminate and the only right thereafter of the holders of Rights shall be to
receive the Redemption Price. The Company shall promptly give public notice of
any such redemption; provided, however, that the failure to give, or any defect
in, any such notice shall not affect the validity of such redemption. Within 10
days after such action of the Board of Directors or such later date as is
determined by the Board of Directors ordering the redemption of the Rights
pursuant to subsection (b) the Company shall mail a notice of redemption to all
the holders of the then outstanding Rights at their last addresses as they


                                       25
<PAGE>   29
appear upon the registry books of the Rights Agent or, prior to the Distribution
Date, on the registry books of the transfer agent for the Common Shares. Any
notice which is mailed in the manner herein provided shall be deemed given,
whether or not the holder receives the notice. Each such notice of redemption
will state the method by which the payment of the Redemption Price will be made.
Neither the Company nor any of its Affiliates or Associates may redeem, acquire
or purchase for value any Rights at any time in any manner other than that
specifically set forth in this Section 23 or in Section 24 hereof, and other
than in connection with the purchase of Common Shares prior to the Distribution
Date.

         (d) The Company may, at its option, at any time that the Rights may
otherwise be redeemed pursuant to subsection (b) hereof discharge all of its
obligations with respect to the Rights by (i) issuing a press release announcing
the manner of redemption of the Rights and (ii) mailing payment of the
Redemption Price to the registered holders of the Rights at their last addresses
as they appear on the registry books of the Rights Agent or, prior to the
Distribution Date, on the registry books of the transfer agent for the Common
Shares, and upon such action, all outstanding Right Certificates shall be null
and void without any further action by the Company.

         SECTION 24.  EXCHANGE.

         (a) The Board of Directors of the Company may, at its option, at any
time after any Person becomes an Acquiring Person, exchange all or part of the
then outstanding and exercisable Rights (which shall not include Rights that
have become void pursuant to the provisions of Section 11(a)(ii) hereof) for
Common Shares at an exchange ratio of one Common Share per Right, appropriately
adjusted to reflect any stock split, stock dividend or similar transaction
occurring after the date hereof (such exchange ratio being hereinafter referred
to as the "Exchange Ratio"). Notwithstanding the foregoing, the Board of
Directors shall not be empowered to effect such exchange at any time after any
Person (other than the Company, any Subsidiary of the Company, any employee
benefit plan of the Company or any such Subsidiary, or any entity holding Common
Shares for or pursuant to the terms of any such plan), together with all
Affiliates and Associates of such Person, becomes the Beneficial Owner of 50% or
more of the Common Shares then outstanding.

         (b) Immediately upon the action of the Board of Directors of the
Company ordering the exchange of any Rights pursuant to subsection (a) of this
Section 24 and without any further action and without any notice, the right to
exercise such Rights shall terminate and the only right thereafter of a holder
of such Rights shall be to receive that number of Common Shares equal to the
number of such Rights held by such holder multiplied by the Exchange Ratio. The
Company shall promptly give public notice of any such exchange; provided,
however, that the failure to give, or any defect in, such notice shall not
affect the validity of such exchange. The Company promptly shall mail a notice
of any such exchange to all of the holders of such Rights at their last
addresses as they appear upon the registry books of the Rights Agent. Any notice
which is mailed in the manner herein provided shall be deemed given, whether or
not the holder receives the notice. Each such notice of exchange will state the
method by which the exchange of the Common Shares for Rights will be effected
and, in the event of any partial exchange, the number of Rights which will be
exchanged. Any partial exchange shall be effected pro rata based on the number
of Rights (other than Rights which have become void pursuant to the provisions
of Section 11(a)(ii) hereof) held by each holder of Rights.


                                       26
<PAGE>   30
         (c) In any exchange pursuant to this Section 24, the Company, at its
option, may substitute Preferred Shares or common stock equivalents for Common
Shares exchangeable for Rights, at the initial rate of one one-thousandth of a
Preferred Share (or an appropriate number of common stock equivalents) for each
Common Share, as appropriately adjusted to reflect adjustments in the voting
rights of the Preferred Shares pursuant to the terms thereof, so that the
fraction of a Preferred Share delivered in lieu of each Common Share shall have
the same voting rights as one Common Share.

         (d) In the event that there shall not be sufficient Common Shares,
Preferred Shares or common stock equivalents authorized by the Company's
Articles of Organization and not outstanding or subscribed for, or reserved or
otherwise committed for issuance for purposes other than upon exercise of
Rights, to permit any exchange of Rights as contemplated in accordance with this
Section 24, the Company shall take all such action as may be necessary to
authorize additional Common Shares, Preferred Shares or common stock equivalents
for issuance upon exchange of the Rights.

         (e) The Company shall not be required to issue fractions of Common
Shares or to distribute certificates which evidence fractional Common Shares. In
lieu of such fractional Common Shares, the Company shall pay to the registered
holders of the Right Certificates with regard to which such fractional Common
Shares would otherwise be issuable an amount in cash equal to the same fraction
of the current per share market value of a whole Common Share. For the purposes
of this paragraph (e), the current per share market value of a whole Common
Share shall be the closing price of a Common Share (as determined pursuant to
the second sentence of Section 11(d)(i) hereof) for the Trading Day immediately
prior to the date of exchange pursuant to this Section 24.

         SECTION 25.  NOTICE OF CERTAIN EVENTS.

         (a) In case the Company shall after the Distribution Date propose (i)
to pay any dividend payable in stock of any class to the holders of its
Preferred Shares or to make any other distribution to the holders of its
Preferred Shares (other than a regular quarterly cash dividend), (ii) to offer
to the holders of its Preferred Shares rights or warrants to subscribe for or to
purchase any additional Preferred Shares or shares of stock of any class or any
other securities, rights or options, (iii) to effect any reclassification of its
Preferred Shares (other than a reclassification involving only the subdivision
of outstanding Preferred Shares), (iv) to effect any consolidation or merger
into or with, or to effect any sale or other transfer (or to permit one or more
of its Subsidiaries to effect any sale or other transfer), in one or more
transactions, of 50% or more of the assets or earning power of the Company and
its Subsidiaries, taken as a whole, to any other Person, (v) to effect the
liquidation, dissolution or winding up of the Company, or (vi) to declare or pay
any dividend on the Common Shares payable in Common Shares or to effect a
subdivision, combination or consolidation of the Common Shares (by
reclassification or otherwise than by payment of dividends in Common Shares),
then, in each such case, the Company shall give to each holder of a Right
Certificate, in accordance with Section 26 hereof, a notice of such proposed
action, which shall specify the record date for the purpose of such stock
dividend, or distribution of rights or warrants, or the date on which such
reclassification, consolidation, merger, sale, transfer, liquidation,
dissolution, or winding up is to take place and the date of participation
therein by the 


                                       27
<PAGE>   31
holders of the Common Shares and/or the Preferred Shares, if any such date is to
be fixed, and such notice shall be so given in the case of any action covered by
clause (i) or (ii) above at least 10 days prior to the record date for
determining holders of the Preferred Shares for purposes of such action, and in
the case of any such other action, at least 10 days prior to the date of the
taking of such proposed action or the date of participation therein by the
holders of the Common Shares and/or the Preferred Shares, whichever shall be the
earlier.

         (b) In case the event set forth in Section 11(a)(ii) hereof shall
occur, then the Company shall as soon as practicable thereafter give to each
holder of a Right Certificate, in accordance with Section 26 hereof, a notice of
the occurrence of such event, which notice shall describe the event and the
consequences of the event to holders of Rights under Section 11(a)(ii) hereof.

         SECTION 26. NOTICES. Notices or demands authorized by this Agreement to
be given or made by the Rights Agent or by the holder of any Right Certificate
to or on the Company shall be sufficiently given or made if sent by first-class
mail, postage prepaid, addressed (until another address is filed in writing with
the Rights Agent) as follows:

                           BIOGEN, INC.
                           14 Cambridge Center
                           Cambridge, MA 02142
                           Attention: General Counsel

Subject to the provisions of Section 21 hereof, any notice or demand authorized
by this Agreement to be given or made by the Company or by the holder of any
Right Certificate to or on the Rights Agent shall be sufficiently given or made
if sent by first-class mail, postage prepaid, addressed (until another address
is filed in writing with the Company) as follows:

                           STATE STREET BANK AND TRUST COMPANY
                           c/o EquiServe Limited Partnership
                           150 Royall Street
                           Canton, Massachusetts  02021
                           Attention:  Client Administration

Notices or demands authorized by this Agreement to be given or made by the
Company or the Rights Agent to the holder of any Right Certificate shall be
sufficiently given or made if sent by first-class mail, postage prepaid,
addressed to such holder at the address of such holder as shown on the registry
books of the Company.

         SECTION 27. SUPPLEMENTS AND AMENDMENTS. The Company may from time to
time, and the Rights Agent shall, if the Company so directs, supplement or amend
this Agreement without the approval of any holders of Right Certificates in
order to cure any ambiguity, to correct or supplement any provision contained
herein which may be defective or inconsistent with any other provisions herein,
or to make any change to or delete any provision hereof or to adopt any other
provisions with respect to the Rights which the Company may deem necessary or
desirable; provided, however, that from and after such time that any Person
becomes an Acquiring Person, this Agreement shall not be amended or supplemented
in any manner which would adversely affect the interests of the holders of
Rights (other than an Acquiring Person and its Affiliates and 


                                       28
<PAGE>   32
Associates). Any supplement or amendment authorized by this Section 27 will be
evidenced by a writing signed by the Company and the Rights Agent.

         SECTION 28. DETERMINATION AND ACTIONS BY THE BOARD OF DIRECTORS, ETC.
The Board of Directors of the Company shall have the exclusive power and
authority to administer this Agreement and to exercise all rights and powers
specifically granted to the Board, or the Company, or as may be necessary or
advisable in the administration of this Agreement, including without limitation,
the right and power to (i) interpret the provisions of this Agreement, and (ii)
make all determinations and calculations deemed necessary or advisable for the
administration of this Agreement (including a determination to redeem or not
redeem the Rights or to amend the Agreement). All such actions, calculations,
interpretations and determinations (including, for purposes of clause (y) below,
all omissions with respect to the foregoing) which are done or made by the Board
in good faith, shall (x) be final, conclusive and binding on the Rights Agent
and the holders of the Right Certificates, and (y) not subject the Board to any
liability to the holders of the Right Certificates.

         SECTION 29. SUCCESSORS. All the covenants and provisions of this
Agreement by or for the benefit of the Company or the Rights Agent shall bind
and inure to the benefit of their respective successors and assigns hereunder.

         SECTION 30. BENEFITS OF THIS AGREEMENT. Nothing in this Agreement shall
be construed to give to any person or corporation other than the Company, the
Rights Agent and the registered holders of the Right Certificates (and, prior to
the Distribution Date, the Common Shares) any legal or equitable right, remedy
or claim under this Agreement; but this Agreement shall be for the sole and
exclusive benefit of the Company, the Rights Agent and the registered holders of
the Right Certificates (and, prior to the Distribution Date, the Common Shares).

         SECTION 31. SEVERABILITY. If any term, provision, covenant or
restriction of this Agreement is held by a court of competent jurisdiction or
other authority to be invalid, void or unenforceable, the remainder of the
terms, provisions, covenants and restrictions of this Agreement shall remain in
full force and effect and shall in no way be affected, impaired or invalidated.

         SECTION 32. GOVERNING LAW. This Agreement and each Right Certificate
issued hereunder shall be deemed to be a contract made under the laws of the
Commonwealth of Massachusetts and for all purposes shall be governed by and
construed in accordance with the law of such State applicable to contracts to be
made and performed entirely within such State without regard to its conflict of
laws principles.

         SECTION 33. COUNTERPARTS. This Agreement may be executed in any number
of counterparts and each of such counterparts shall for all purposes be deemed
to be an original, and all such counterparts shall together constitute but one
and the same instrument.

         SECTION 34. DESCRIPTIVE HEADINGS. Descriptive headings of the several
Sections of this Agreement are inserted for convenience only and shall not
control or affect the meaning or construction of any of the provisions hereof.


                                       29
<PAGE>   33
         IN WITNESS WHEREOF, the parties hereto have caused this Agreement to be
duly executed and their seals attested, all as of the day and year first above
written.

ATTEST:                                      BIOGEN, INC.

By: /s/ Michael J. Astrue                    By: /s/ James L. Vincent
    -------------------------------              -------------------------------
Title: Vice President-General                    Chairman and Chief Executive
       Counsel                                   Officer


ATTEST:                                      STATE STREET BANK AND TRUST COMPANY
                                             AS RIGHTS AGENT

By: /s/ Michael Peltier                      By: /s/ Margaret Prentice
    --------------------------------             -------------------------------
Title: Account Manager                           Director of Administration


                                       30
<PAGE>   34
                                    Exhibit A

                           CERTIFICATE OF ELIMINATION

                                       of

                  SERIES A JUNIOR PARTICIPATING PREFERRED STOCK

                                       of
                                  BIOGEN, INC.

                                       and

               CERTIFICATE OF DESIGNATION, PREFERENCES AND RIGHTS

                                       of

                 SERIES A-1 JUNIOR PARTICIPATING PREFERRED STOCK

                                       of
                                  BIOGEN, INC.

         Biogen, Inc., a corporation organized and existing under the Business
Corporation Law of the Commonwealth of Massachusetts (hereinafter called the
"Company"),

         DOES HEREBY CERTIFY THAT:

         1. The voting powers, designations, preferences, and the relative,
participating, optional, or other rights, and the qualifications, limitations,
and restrictions of the Series A Junior Participating Preferred Stock of the
Company (the "Old Series A") were provided for in resolutions adopted by the
Board of Directors of the Company (the "Board of Directors") dated May 8, 1989.
A certificate setting forth such resolutions has been heretofore filed with the
Secretary of State of the Commonwealth of Massachusetts pursuant to the
provisions of Section 26 of the Business Corporation Law of the Commonwealth of
Massachusetts.

         2. No shares of the Old Series A have ever been issued.

         3. This Certificate is being filed to eliminate the Old Series A and
replace it with the Series A-1 Junior Participating Preferred Stock of the
Company as set forth below.

         4. Pursuant to authority conferred upon the Board of Directors of the
Company by the Articles of Organization of the Company, and pursuant to the
provisions of Section 26 of the Business Corporation Law, the Board of
Directors, at a meeting of its members held on April 16, 1999, adopted votes
providing for the elimination of the Old Series A, which votes are as follows:

VOTED:   That none of the authorized shares of the original Series A Junior
         Participating Preferred Stock of the Company are outstanding and none
         of such shares will be issued and that the officers of the Company be,
         and each hereby is, authorized and


                                       1
<PAGE>   35
         directed to file a Certificate of Vote of Directors Establishing a
         Class or Series of Stock providing for the elimination of such Series A
         Junior Participating Preferred Stock setting forth the text of this
         vote with the Secretary of State of the Commonwealth of Massachusetts
         for the purpose of eliminating from the Articles of Organization of the
         Company the original Series A Junior Participating Preferred Stock of
         the Company.

VOTED:   That the proper officers of the Company be, and each of them hereby is,
         authorized, in the name and on behalf of the Company, to take all such
         actions and to execute all such documents as they may deem necessary or
         appropriate in connection with the elimination of the original Series A
         Junior Participating Preferred Stock.

         5. That, pursuant to authority conferred upon the Board of Directors by
the Articles of Organization of this Company, and pursuant to the provisions of
Section 26 of the Business Corporation Law, the Board of Directors, at a meeting
of its members held on April 16, 1999, adopted a vote providing for the
designations, preferences and relative, participating, optional or other rights,
and the qualifications, limitations or restrictions thereof, of two hundred
fifty thousand (250,000) shares of the Company's Preferred Stock, par value one
cent ($.01) per share, which vote is as follows:

VOTED:   That pursuant to the authority granted to and vested in the Board of
         Directors of the Company in accordance with the provisions of its
         Articles of Organization, the Board of Directors of the Company hereby
         creates a new series of Preferred Stock, par value $.01 per share, of
         the Company and hereby fixes the designation and number of shares, and
         the relative rights, preferences and limitations thereof (in addition
         to the provisions set forth in the Articles of Organization of the
         Company which are applicable to the Preferred Stock of all classes and
         series), as follows.

Series A-1 Junior Participating Preferred Stock. The preferences, privileges and
restrictions granted to or imposed on the Company's Series A-1 Junior
Participating Preferred Stock, par value $.01 per share, or the holders thereof,
are as follows:

         Section 1. Designation and Amount. The shares of such series shall be
designated as "Series A-1 Junior Participating Preferred Stock" (the "Series A-1
Preferred Stock") and the number of shares constituting the Series A-1 Preferred
Stock shall be two hundred fifty thousand (250,000). Such number of shares may
be increased or decreased by resolution of the Board of Directors; provided,
that no decrease shall reduce the number of shares of Series A-1 Preferred Stock
to a number less than the number of shares then outstanding plus the number of
shares reserved for issuance upon the exercise of outstanding options, rights or
warrants or upon the conversion of any outstanding securities issued by the
Company convertible into Series A-1 Preferred Stock.

         Section 2. Dividends and Distributions.

                  (A) Subject to the rights of the holders of any shares of any
         series of Preferred Stock (or any similar stock) ranking prior and
         superior to the Series A-1 Preferred Stock 


                                       2
<PAGE>   36
         with respect to dividends, the holders of shares of Series A-1
         Preferred Stock, in preference to the holders of Common Stock, $.01 par
         value (the "Common Stock"), of the Company, and of any other junior
         stock, shall be entitled to receive, when, as and if declared by the
         Board of Directors out of funds legally available for the purpose,
         quarterly dividends payable in cash on the first day of March, June,
         September and December in each year (each such date being referred to
         herein as a "Quarterly Dividend Payment Date"), commencing on the first
         Quarterly Dividend Payment Date after the first issuance of a share or
         fraction of a share of Series A-1 Preferred Stock, in an amount per
         share (rounded to the nearest cent) equal to the greater of (a) $1 or
         (b) subject to the provision for adjustment hereinafter set forth, 1000
         times the aggregate per share amount of all cash dividends, and 1000
         times the aggregate per share amount (payable in kind) of all non-cash
         dividends or other distributions, other than a dividend payable in
         shares of Common Stock or a subdivision of the outstanding shares of
         Common Stock (by reclassification or otherwise), declared on the Common
         Stock since the immediately preceding Quarterly Dividend Payment Date
         or, with respect to the first Quarterly Dividend Payment Date, since
         the first issuance of any share or fraction of a share of Series A-1
         Preferred Stock. In the event the Company shall at any time declare or
         pay any dividend on the Common Stock payable in shares of Common Stock,
         or effect a subdivision or combination or consolidation of the
         outstanding shares of Common Stock (by reclassification or otherwise
         than by payment of a dividend in shares of Common Stock) into a greater
         or lesser number of shares of Common Stock, then in each such case the
         amount to which holders of shares of Series A-1 Preferred Stock were
         entitled immediately prior to such event under clause (b) of the
         preceding sentence shall be adjusted by multiplying such amount by a
         fraction, the numerator of which is the number of shares of Common
         Stock outstanding immediately after such event and the denominator of
         which is the number of shares of Common Stock that were outstanding
         immediately prior to such event.

                  (B) The Company shall declare a dividend or distribution on
         the Series A-1 Preferred Stock as provided in paragraph (A) of this
         Section immediately after it declares a dividend or distribution on the
         Common Stock (other than a dividend payable in shares of Common Stock);
         provided that, in the event no dividend or distribution shall have been
         declared on the Common Stock during the period between any Quarterly
         Dividend Payment Date and the next subsequent Quarterly Dividend
         Payment Date, a dividend of $1 per share on the Series A-1 Preferred
         Stock shall nevertheless be payable on such subsequent Quarterly
         Dividend Payment Date.

                  (C) Dividends shall begin to accrue and be cumulative on
         outstanding shares of Series A-1 Preferred Stock from the Quarterly
         Dividend Payment Date next preceding the date of issue of such shares,
         unless the date of issue of such shares is prior to the record date for
         the first Quarterly Dividend Payment Date, in which case dividends on
         such shares shall begin to accrue from the date of issue of such
         shares, or unless the date of issue is a Quarterly Dividend Payment
         Date or is a date after the record date for the determination of
         holders of shares of Series A-1 Preferred Stock entitled to receive a
         quarterly dividend and before such Quarterly Dividend Payment Date, in
         either of which events such dividends shall begin to accrue and be
         cumulative from such Quarterly Dividend Payment Date. Accrued but
         unpaid dividends shall not bear interest. 



                                       3
<PAGE>   37
         Dividends paid on the shares of Series A-1 Preferred Stock in an amount
         less than the total amount of such dividends at the time accrued and
         payable on such shares shall be allocated pro rata on a share-by-share
         basis among all such shares at the time outstanding. The Board of
         Directors may fix a record date for the determination of holders of
         shares of Series A-1 Preferred Stock entitled to receive payment of a
         dividend or distribution declared thereon, which record date shall be
         not more than 60 days prior to the date fixed for the payment thereof.

         Section 3. Voting Rights. The holders of shares of Series A-1 Preferred
Stock shall have the following voting rights:

                  (A) Subject to the provision for adjustment hereinafter set
         forth, each share of Series A-1 Preferred Stock shall entitle the
         holder thereof to 1000 votes on all matters submitted to a vote of the
         stockholders of the Company. In the event the Company shall at any time
         declare or pay any dividend on the Common Stock payable in shares of
         Common Stock, or effect a subdivision or combination or consolidation
         of the outstanding shares of Common Stock (by reclassification or
         otherwise than by payment of a dividend in shares of Common Stock) into
         a greater or lesser number of shares of Common Stock, then in each such
         case the number of votes per share to which holders of shares of Series
         A-1 Preferred Stock were entitled immediately prior to such event shall
         be adjusted by multiplying such number by a fraction, the numerator of
         which is the number of shares of Common Stock outstanding immediately
         after such event and the denominator of which is the number of shares
         of Common Stock that were outstanding immediately prior to such event.

                  (B) Except as otherwise provided herein, in any other
         Certificate of Designation creating a series of Preferred Stock or any
         similar stock, or by law, the holders of shares of Series A-1 Preferred
         Stock and the holders of shares of Common Stock and any other capital
         stock of the Company having general voting rights shall vote together
         as one class on all matters submitted to a vote of stockholders of the
         Company.

                  (C) Except as set forth herein, or as otherwise provided by
         law, holders of Series A-1 Preferred Stock shall have no special voting
         rights and their consent shall not be required (except to the extent
         they are entitled to vote with holders of Common Stock as set forth
         herein) for taking any corporate action.

         Section 4. Certain Restrictions.

                  (A) Whenever quarterly dividends or other dividends or
         distributions payable on the Series A-1 Preferred Stock as provided in
         Section 2 are in arrears, thereafter and until all accrued and unpaid
         dividends and distributions, whether or not declared, on shares of
         Series A-1 Preferred Stock outstanding shall have been paid in full,
         the Company shall not:

                  (i) declare or pay dividends, or make any other distributions,
                  on any shares of stock ranking junior (either as to dividends
                  or upon liquidation, dissolution or winding up) to the Series
                  A-1 Preferred Stock;


                                       4
<PAGE>   38
                  (ii) declare or pay dividends, or make any other
                  distributions, on any shares of stock ranking on a parity
                  (either as to dividends or upon liquidation, dissolution or
                  winding up) with the Series A-1 Preferred Stock, except
                  dividends paid ratably on the Series A-1 Preferred Stock and
                  all such parity stock on which dividends are payable or in
                  arrears in proportion to the total amounts to which the
                  holders of all such shares are then entitled;

                  (iii) redeem or purchase or otherwise acquire for
                  consideration shares of any stock ranking junior (either as to
                  dividends or upon liquidation, dissolution or winding up) to
                  the Series A-1 Preferred Stock, provided that the Company may
                  at any time redeem, purchase or otherwise acquire shares of
                  any such junior stock in exchange for shares of any stock of
                  the Company ranking junior (either as to dividends or upon
                  dissolution, liquidation or winding up) to the Series A-1
                  Preferred Stock; or

                  (iv) redeem or purchase or otherwise acquire for consideration
                  any shares of Series A-1 Preferred Stock, or any shares of
                  stock ranking on a parity with the Series A-1 Preferred Stock,
                  except in accordance with a purchase offer made in writing or
                  by publication (as determined by the Board of Directors) to
                  all holders of such shares upon such terms as the Board of
                  Directors, after consideration of the respective annual
                  dividend rates and other relative rights and preferences of
                  the respective series and classes, shall determine in good
                  faith will result in fair and equitable treatment among the
                  respective series or classes.

                  (B) The Company shall not permit any subsidiary of the Company
         to purchase or otherwise acquire for consideration any shares of stock
         of the Company unless the Company could, under paragraph (A) of this
         Section 4, purchase or otherwise acquire such shares at such time and
         in such manner.

         Section 5. Reacquired Shares. Any shares of Series A-1 Preferred Stock
purchased or otherwise acquired by the Company in any manner whatsoever shall be
retired and canceled promptly after the acquisition thereof. All such shares
shall upon their cancellation become authorized but unissued shares of Preferred
Stock and may be reissued as part of a new series of Preferred Stock subject to
the conditions and restrictions on issuance set forth herein, in the Articles of
Organization, or in any other Certificate of Designation creating a series of
Preferred Stock or any similar stock or as otherwise required by law.

         Section 6. Liquidation, Dissolution or Winding Up. Upon any
liquidation, dissolution or winding up of the Company, no distribution shall be
made (1) to the holders of shares of stock ranking junior (either as to
dividends or upon liquidation, dissolution or winding up) to the Series A-1
Preferred Stock unless, prior thereto, the holders of shares of Series A-1
Preferred Stock shall have received $1000 per share, plus an amount equal to
accrued and unpaid dividends and distributions thereon, whether or not declared,
to the date of such payment, provided that the holders of shares of Series A-1
Preferred Stock shall be entitled to receive an aggregate amount per share,
subject to the provision for adjustment hereinafter set forth, equal to 1000
times the aggregate amount to be distributed per share to holders of shares of
Common 


                                       5
<PAGE>   39
Stock, or (2) to the holders of shares of stock ranking on a parity (either as
to dividends or upon liquidation, dissolution or winding up) with the Series A-1
Preferred Stock, except distributions made ratably on the Series A-1 Preferred
Stock and all such parity stock in proportion to the total amounts to which the
holders of all such shares are entitled upon such liquidation, dissolution or
winding up. In the event the Company shall at any time declare or pay any
dividend on the Common Stock payable in shares of Common Stock, or effect a
subdivision or combination or consolidation of the outstanding shares of Common
Stock (by reclassification or otherwise than by payment of a dividend in shares
of Common Stock) into a greater or lesser number of shares of Common Stock, then
in each such case the aggregate amount to which holders of shares of Series A-1
Preferred Stock were entitled immediately prior to such event under the proviso
in clause (1) of the preceding sentence shall be adjusted by multiplying such
amount by a fraction the numerator of which is the number of shares of Common
Stock outstanding immediately after such event and the denominator of which is
the number of shares of Common Stock that were outstanding immediately prior to
such event.

         Section 7. Consolidation, Merger, etc. In case the Company shall enter
into any consolidation, merger, combination or other transaction in which the
shares of Common Stock are exchanged for or changed into other stock or
securities, cash and/or any other property, then in any such case each share of
Series A-1 Preferred Stock shall at the same time be similarly exchanged or
changed into an amount per share, subject to the provision for adjustment
hereinafter set forth, equal to 1000 times the aggregate amount of stock,
securities, cash and/or any other property (payable in kind), as the case may
be, into which or for which each share of Common Stock is changed or exchanged.
In the event the Company at any time declares or pays any dividend on the Common
Stock payable in shares of Common Stock, or effects a subdivision or combination
or consolidation of the outstanding shares of Common Stock (by reclassification
or otherwise than by payment of a dividend in shares of Common Stock) into a
greater or lesser number of shares of Common Stock, then in each such case the
amount set forth in the preceding sentence with respect to the exchange or
change of shares of Series A-1 Preferred Stock shall be adjusted by multiplying
such amount by a fraction, the numerator of which is the number of shares of
Common Stock outstanding immediately after such event and the denominator of
which is the number of shares of Common Stock that were outstanding immediately
prior to such event.

         Section 8. No Redemption. The shares of Series A-1 Preferred Stock
shall not be redeemable.

         Section 9. Rank. The Series A-1 Preferred Stock shall rank junior with
respect to the payment of dividends and the distribution of assets to all other
series of the Company's Preferred Stock.

         Section 10. Amendment. The Articles of Organization of the Company
shall not be amended in any manner which would materially alter or change the
powers, preferences or special rights of the Series A-1 Preferred Stock so as to
affect them adversely without the affirmative vote of the holders of at least
two-thirds of the outstanding shares of Series A-1 Preferred Stock, voting
together as a single class.


                                       6
<PAGE>   40
         IN WITNESS WHEREOF, Biogen, Inc. has caused this certificate to be
executed by its President this ____th day of May, 1999.

                                                      __________________________
                                                      President


                                       7
<PAGE>   41
                                    Exhibit B

                            FORM OF RIGHT CERTIFICATE

CERTIFICATE NO. R-                                                 _____ RIGHTS

         NOT EXERCISABLE AFTER MAY 8, 2009 OR EARLIER IF REDEMPTION OR EXCHANGE
         OCCURS. THE RIGHTS ARE SUBJECT TO REDEMPTION AT $.001 PER RIGHT AND TO
         EXCHANGE ON THE TERMS SET FORTH IN THE RIGHTS AGREEMENT.

                                RIGHT CERTIFICATE

                                  BIOGEN, INC.

         This certifies that ___________________ or registered assigns, is the
registered owner of the number of Rights set forth above, each of which entitles
the owner thereof, subject to the terms, provisions and conditions of the Rights
Agreement, dated as of May 8, 1999 (the "Rights Agreement"), between Biogen,
Inc., a Massachusetts corporation (the "Company"), and State Street Bank and
Trust Company (the "Rights Agent"), to purchase from the Company at any time
after the Distribution Date (as such term is defined in the Rights Agreement)
and prior to 5:00 P.M., Eastern Standard Time, on May 8, 2009 at the office of
the Rights Agent designated for such purpose, or at the office of its successor
as Rights Agent, one one-thousandth of a fully paid non-assessable share of
Series A-1 Junior Participating Preferred Stock, par value $.01 per share (the
"Preferred Shares"), of the Company, at a purchase price of $ per one
one-thousandth of a Preferred Share (the "Purchase Price"), upon presentation
and surrender of this Right Certificate with the Form of Election to Purchase
duly executed. The number of Rights evidenced by this Right Certificate (and the
number of one one-thousandths of a Preferred Share which may be purchased upon
exercise hereof) set forth above, and the Purchase Price set forth above, are
the number and Purchase Price as of May 8, 1999 based on the Preferred Shares as
constituted at such date.

         From and after the time any Person becomes an Acquiring Person, (as
such terms are defined in the Rights Agreement), if the Rights evidenced by this
Right Certificate are beneficially owned by (i) an Acquiring Person or an
Affiliate or Associate of any such Acquiring Person (as such terms are defined
in the Rights Agreement), (ii) a transferee of any such Acquiring Person,
Associate or Affiliate who becomes a transferee after the Acquiring Person
becomes such, or (iii) under certain circumstances specified in the Rights
Agreement, a transferee of any such Acquiring Person, Associate or Affiliate who
becomes a transferee prior to or concurrently with the Acquiring Person becoming
such, such Rights shall become null and void and no holder hereof shall have any
right with respect to such Rights from and after the time any Person becomes an
Acquiring Person.

         As provided in the Rights Agreement, the Purchase Price and the number
of one one-thousandths of a Preferred Share which may be purchased upon the
exercise of the Rights 



                                       1
<PAGE>   42
evidenced by this Right Certificate are subject to modification and adjustment
upon the happening of certain events.

                                       2
<PAGE>   43
         This Right Certificate is subject to all of the terms, provisions and
conditions of the Rights Agreement, as amended from time to time, which terms,
provisions and conditions are hereby incorporated herein by reference and made a
part hereof and to which Rights Agreement reference is hereby made for a full
description of the rights, limitations of rights, obligations, duties and
immunities hereunder of the Rights Agent, the Company and the holders of the
Right Certificates. Copies of the Rights Agreement are on file at the principal
executive offices of the Company and the above-mentioned offices of the Rights
Agent.

         This Right Certificate, with or without other Right Certificates, upon
surrender at the office of the Rights Agent designated for such purpose, may be
exchanged for another Right Certificate or Right Certificates of like tenor and
date evidencing Rights entitling the holder to purchase a like aggregate number
of Preferred Shares as the Rights evidenced by the Right Certificate or Right
Certificates surrendered shall have entitled such holder to purchase. If this
Right Certificate shall be exercised in part, the holder shall be entitled to
receive upon surrender hereof another Right Certificate or Right Certificates
for the number of whole Rights not exercised.

         Subject to the provisions of the Rights Agreement, the Rights evidenced
by this Certificate (i) may be redeemed by the Company at a redemption price of
$.001 per Right or (ii) may be exchanged in whole or in part for shares of the
Company's Common Stock, par value $.01 per share, or other consideration as set
forth in the Rights Agreement.

         No fractional Preferred Shares will be issued upon the exercise of any
Right or Rights evidenced hereby (other than fractions which are integral
multiples of one one-thousandth of a Preferred Share, which may, at the election
of the Company, be evidenced by depository receipts) but in lieu thereof a cash
payment will be made, as provided in the Rights Agreement.

         No holder of this Right Certificate shall be entitled to vote or
receive dividends or be deemed for any purpose the holder of the Preferred
Shares or of any other securities of the Company which may at any time be
issuable on the exercise hereof, nor shall anything contained in the Rights
Agreement or herein be construed to confer upon the holder hereof, as such, any
of the rights of a stockholder of the Company or any right to vote for the
election of directors or upon any matter submitted to stockholders at any
meeting thereof, or to give or withhold consent to any corporate action, or to
receive notice of meetings or other actions affecting stockholders (except as
provided in the Rights Agreement), or to receive dividends or subscription
rights, or otherwise, until the Right or Rights evidenced by this Right
Certificate shall have been exercised as provided in the Rights Agreement.

         This Right Certificate shall not be valid or obligatory for any purpose
until it shall have been countersigned by the Rights Agent.


                                       3
<PAGE>   44
         WITNESS the facsimile signature of the proper officers of the Company
and its corporate seal. Dated as of __________.

ATTEST:                                         BIOGEN, INC.

________________________________                By:_____________________________
                                                   _____________________________
                                                   _____________________________

COUNTERSIGNED:

STATE STREET BANK AND TRUST COMPANY
as Rights Agent

By:_____________________________ 
     Authorized Signature


                                       4
<PAGE>   45
                    Form of Reverse Side of Right Certificate

                               FORM OF ASSIGNMENT

                (To be executed by the registered holder if such
               holder desires to transfer the Right Certificate.)

         FOR VALUE RECEIVED ______________________________________ hereby sells,
assigns and transfers unto

_________________________________________________________________________
              (Please print name and address of transferee)

______________________________________________________________ this Right
Certificate, together with all right, title and interest therein, and does
hereby irrevocably constitute and appoint ________________________ Attorney, to
transfer the within Right Certificate on the books of the within-named Company,
with full power of substitution.

Dated:  ____________________


                                           ____________________________________
                                           Signature


                                       5
<PAGE>   46
             Form of Reverse Side of Right Certificate -- continued

Signature Guaranteed:

         Signatures must be guaranteed by an "eligible guarantor institution" as
defined in Rule 17Ad-15 promulgated under the Securities Exchange Act of 1934,
as amended.

______________________________________________

         The undersigned hereby certifies that (1) the Rights evidenced by this
Right Certificate are not being sold, assigned or transferred by or on behalf of
a Person who is or was an Acquiring Person or an Affiliate or Associate thereof
(as defined in the Rights Agreement); and (2) after due inquiry and to the best
of the knowledge of the undersigned, the undersigned did not acquire the Rights
evidenced by this Right Certificate from any Person who is or was an Acquiring
Person, or an Affiliate or Associate thereof (as such terms are defined in the
Rights Agreement).

                                                  ______________________________
                                                  Signature


                                       6
<PAGE>   47
                          FORM OF ELECTION TO PURCHASE

                  (To be executed if holder desires to exercise
                 Rights represented by the Right Certificate.)

TO BIOGEN, INC.

         The undersigned hereby irrevocably elects to exercise
___________________________ Rights represented by this Right Certificate to
purchase the Preferred Shares issuable upon the exercise of such Rights and
requests that certificates for such Preferred Shares be issued in the name of:

Please insert social security
or other identifying number: ______________

____________________________________________________________________
                   (Please print name and address)

____________________________________________________________________

If such number of Rights shall not be all the Rights evidenced by this Right
Certificate, a new Right Certificate for the balance remaining of such Rights
shall be registered in the name of and delivered to:

Please insert social security
or other identifying number: ______________

____________________________________________________________________
                   (Please print name and address)

____________________________________________________________________

Dated:  _________________

                                     ________________________________
                                     Signature

             Form of Reverse Side of Right Certificate -- continued



                                       7
<PAGE>   48
Signature Guaranteed:

         Signatures must be guaranteed by an "eligible guarantor institution" as
defined in Rule 17Ad-15 promulgated under the Securities Exchange Act of 1934,
as amended.

______________________________________

         The undersigned hereby certifies that the Rights evidenced by this
Right Certificate are not being beneficially owned by nor are they being
exercised on behalf of (1) an Acquiring Person or an Affiliate or Associate
thereof (as defined in the Rights Agreement); and (2) after due inquiry and to
the best of the knowledge of the undersigned, the undersigned did not acquire
the Rights evidenced by this Right Certificate from any Person who is or was an
Acquiring Person or an Affiliate or Associate thereof (as such terms are defined
in the Rights Agreement).

                                    ____________________________________________
                                    Signature

________________________________________

                                     NOTICE

         The signature in the Form of Assignment or Form of Election to
Purchase, as the case may be, must conform to the name as written upon the face
of this Right Certificate in every particular, without alteration or enlargement
or any change whatsoever.

         In the event the certification set forth above in the Form of
Assignment or the Form of Election to Purchase, as the case may be, is not
completed, the Company and the Rights Agent will deem the beneficial owner of
the Rights evidenced by this Right Certificate to be an Acquiring Person or an
Affiliate or Associate thereof (as defined in the Rights Agreement) and such
Assignment or Election to Purchase will not be honored.


                                       8
<PAGE>   49
                                    Exhibit C

                 SUMMARY OF RIGHTS TO PURCHASE SERIES A-1 JUNIOR
                         PARTICIPATING PREFERRED SHARES

Expiration of Old Rights and Dividend of New Rights

         In 1989, the Board of Directors of Biogen, Inc. (the "Company")
declared a dividend to holders of the Company's Common Stock, $.01 par value per
share ("Common Shares"), of rights (the "Old Rights") to purchase shares of
Series A Junior Participating Preferred Stock (the "Old Preferred Stock"). Each
Old Right entitled the registered holder to purchase from the Company one
one-hundredth of a share of Old Preferred Stock upon the terms and subject to
the conditions set forth in a Rights Agreement dated as of May 8, 1989, between
Biogen, Inc. and The First National Bank of Boston (the "Old Plan"). The Old
Plan and Old Rights expire on May 8, 1999. Accordingly, on April 16, 1999, the
Board of Directors declared a dividend of one new preferred share purchase right
(a "New Right") for each outstanding Common Share of the Company, which shall be
made to the stockholders of record on May 8, 1999 (the "Record Date"). Each New
Right entitles the registered holder to purchase from the Company one
one-thousandth of a share of a new series of the preferred stock (the Series A-1
Junior Participating Preferred Stock, referred to herein as "Preferred Shares"),
at a price of $850 per one one-thousandth of a Preferred Share (the "Purchase
Price"), subject to adjustment. Each one one-thousandth of a Preferred Share has
rights, privileges and preferences which make its value approximately equal to
the value of one Common Share. A full description of the terms of the New Rights
is set forth in a new shareholder rights agreement dated as of May 8, 1999 (the
"New Rights Agreement"), between the Company and State Street Bank and Trust
Company, as Rights Agent (the "Rights Agent").

Terms and Conditions of New Rights and New Rights Agreement

         Initially, the New Rights will be evidenced by the stock certificates
representing the Common Shares then outstanding, and no separate Right
Certificates, as defined, will be distributed. Until the earlier of (i) the
close of business on the tenth day following the day on which there is a public
announcement or public disclosure of facts indicating that a person, entity or
group of affiliated or associated persons (an "Acquiring Person") have acquired,
beneficial ownership of 20% or more of the outstanding Common Shares (other than
certain excluded persons) or (ii) the tenth business day (or such later date as
may be determined by action of the Board of Directors prior to such time as any
person or entity becomes an Acquiring Person) following the commencement of, or
announcement of an intention to make, a tender offer or exchange offer the
consummation of which would result in the beneficial ownership by a person or
group of 20% or more of such outstanding Common Shares (the earlier of such
dates being called the "Distribution Date"), the New Rights will be evidenced,
with respect to any of the Common Share certificates outstanding as of May 8,
1999, by such Common Share certificates.

         The New Rights Agreement provides that, until the Distribution Date,
the New Rights will be transferred with and only with the Common Shares. Until
the Distribution Date (or earlier redemption or expiration of the New Rights),
new Common Share certificates issued after May 8, 1999, upon transfer or new
issuance of Common Shares, will contain a notation incorporating 


                                       1
<PAGE>   50
the New Rights Agreement by reference. Until the Distribution Date (or earlier
redemption or expiration of the New Rights), the surrender or transfer of any
certificates for Common Shares outstanding as of May 8, 1999, even without such
notation or a copy of the Summary of Rights being attached thereto, will also
constitute the transfer of the New Rights associated with the Common Shares
represented by such certificate. As soon as practicable following the
Distribution Date, separate certificates evidencing the New Rights ("Right
Certificates") will be mailed to holders of record of the Common Shares as of
the close of business on the Distribution Date and such separate Right
Certificates alone will evidence the New Rights.

         The New Rights are not exercisable until the Distribution Date. The New
Rights will expire on May 8, 2009 (the "Final Expiration Date"), unless the
Final Expiration Date is extended or unless the New Rights are earlier redeemed
or exchanged by the Company, in each case, as described below.

         The Purchase Price payable, and the number of Preferred Shares or other
securities or property issuable, upon exercise of the New Rights are subject to
adjustment from time to time to prevent dilution (i) in the event of a stock
dividend on, or a subdivision, combination or reclassification of, the Preferred
Shares, (ii) upon the grant to holders of the Preferred Shares of certain
rights, options or warrants to subscribe for or purchase Preferred Shares at a
price, or securities convertible into Preferred Shares with a conversion price,
less than the then current market price of the Preferred Shares or (iii) upon
the distribution to holders of the Preferred Shares of evidences of indebtedness
or assets (excluding regular periodic cash dividends or dividends payable in
Preferred Shares) or of subscription rights or warrants (other than those
referred to above).

         The number of outstanding New Rights and the number of one
one-thousandths of a Preferred Share issuable upon exercise of each New Right
are also subject to adjustment in the event of a stock split of the Common
Shares or a stock dividend on the Common Shares payable in Common Shares or
subdivisions, consolidation or combinations of the Common Shares occurring, in
any case, prior to the Distribution Date.

         Preferred Shares purchasable upon exercise of the New Rights will not
be redeemable. Each Preferred Share will be entitled to receive when, as and if
approved by the Board of Directors out of funds legally available for the
purpose, a minimum preferential quarterly dividend payment of $1.00 but will be
entitled to an aggregate dividend of 1,000 times the dividend declared per
Common Share. In the event of liquidation, the holders of the Preferred Shares
will be entitled to a minimum preferential liquidation payment of $1,000 but
will be entitled to an aggregate payment of 1,000 times the payment made per
Common Share. Each Preferred Share will have 1,000 votes, voting together with
the Common Shares. Finally, in the event of any merger, consolidation or other
transaction in which Common Shares are exchanged, each Preferred Share will be
entitled to receive 1,000 times the amount of consideration received per Common
Share. These rights are protected by customary anti-dilution provisions. Because
of the nature of the Preferred Shares' dividend and liquidation rights, the
value of one one-thousandth of a Preferred Share should approximate the value of
one Common Share.

         In the event that any person becomes an Acquiring Person, proper
provision shall be made so that each holder of a New Right, other than New
Rights beneficially owned by the 


                                       2
<PAGE>   51
Acquiring Person or an Associate or Affiliate of such Acquiring Person or
certain of their transferees (which Rights will thereafter be void), will have
the right to receive upon exercise that number of Common Shares having a market
value of two times the purchase price of the New Right (or, if such number of
shares is not and cannot be authorized, the Company may issue Preferred Stock,
cash, debt, stock or a combination thereof in exchange for the New Rights).

         In the event that the Company is acquired in a merger or other business
combination transaction or 50% or more of its consolidated assets or earning
power are sold, proper provision will be made so that each holder of a New Right
will thereafter have the right to receive, upon the exercise thereof at the then
current exercise price of the New Right, that number of shares of common stock
of the acquiring company which at the time of such transaction will have a
market value of two times the exercise price of the New Right.

         At any time after the acquisition by a person or group of affiliated or
associated persons of beneficial ownership of 20% or more of the outstanding
Common Shares and prior to the acquisition by such person or group of 50% or
more of the outstanding Common Shares, the Board of Directors of the Company may
exchange the New Rights (other than New Rights owned by such person or group
which have become void), in whole or in part, at an exchange ratio of one Common
Share, or one one-thousandth of a Preferred Share, per New Right (or, if the
number of shares is not and cannot be authorized, the Company may issue cash,
debt, stock or a combination thereof in exchange for the New Rights), subject to
adjustment.

         With certain exceptions, no adjustment in the Purchase Price will be
required until cumulative adjustments require an adjustment of at least 1% in
such Purchase Price. No fractional Preferred Shares will be issued (other than
fractions which are integral multiples of the number of one one-thousandths of a
Preferred Share issuable upon the exercise of one New Right, which may, at the
option of the Company, be evidenced by depository receipts), and in lieu
thereof, an adjustment in cash will be made based on the market price of the
Preferred Shares on the last trading day prior to the date of exercise.

         At any time prior to the earlier of (i) the time that any person
becomes an Acquiring Person, or (ii) the Final Expiration Date, the Board of
Directors of the Company may redeem the New Rights in whole, but not in part, at
a price of $.001 per New Right (the "Redemption Price"). Following the
expiration of the above periods, the New Rights become nonredeemable.
Immediately upon any redemption of the New Rights, the right to exercise the New
Rights will terminate and the only right of the holders of New Rights will be to
receive the Redemption Price.

         The Company may from time to time, and the Rights Agent will, if the
Company so directs, supplement or amend the New Rights Agreement without the
approval of any holders of Right Certificates in order to cure any ambiguity, to
correct or supplement any provision contained therein which may be defective or
inconsistent with any other provisions therein, or to make any change to or
delete any provision thereof or to adopt any other provisions with respect to
the Rights which the Company may deem necessary or desirable; provided, however,
that from and after such time as any Person becomes an Acquiring Person, the New
Rights Agreement may not be amended or supplemented in any manner which would
adversely affect the interests of the holders of Rights (other than an Acquiring
Person and its Affiliates and Associates).


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<PAGE>   52
         Until a New Right is exercised, the holder thereof, as such, will have
no rights as a stockholder of the Company, including, without limitation, the
right to vote or to receive dividends.

         The New Rights have certain anti-takeover effects. The New Rights will
cause substantial dilution to a person or group that attempts to acquire the
Company on terms not approved by the Company's Board of Directors. The New
Rights should not interfere with any merger or other business combination
approved by the Board of Directors since the New Rights may be redeemed by the
Company at $.001 per New Right prior to the earlier of (i) such time as any
person has become an Acquiring Person, or (ii) the Final Expiration Date.

         The foregoing description of the New Rights Agreement and New Rights,
as well as the other matters discussed herein, is qualified in its entirety by
reference to the New Rights Agreement and the Exhibits thereto and the Press
Release, each of which is attached hereto as an Exhibit and is incorporated
herein by reference.


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<PAGE>   1
                                  EXHIBIT 99.1

Media Contact:
Kathryn R. Bloom
Director of Communications
Biogen, Inc.
Tel: (617) 679-2851

Investment Community Contact:
Elizabeth Woo
Manager, Investor Relations
Biogen, Inc.
Tel: (617) 679-2812

                                                           FOR IMMEDIATE RELEASE

                      BIOGEN ANNOUNCES 2-FOR-1 STOCK SPLIT
                         AND NEW SHAREHOLDER RIGHTS PLAN

CAMBRIDGE, MA (April 16, 1999) - Biogen, Inc. (NASDAQ/BGEN) today announced that
its Board of Directors has approved a two-for-one stock split of its Common
Stock, subject to the approval by Biogen shareholders of an amendment to the
Company's articles of organization to increase the Company's authorized common
stock. The proposed increase, which will be acted upon at the Company's annual
meeting to be held on June 11, 1999, is necessary to give the Company a
sufficient number of shares to consummate this split. If the proposed increase
is approved, the stock split will be effected through a stock dividend of one
additional common share for every share held, payable on June 25, 1999, to
stockholders of record at the close of business on June 11, 1999. As a result of
the stock split, the number of outstanding shares of the Company's Common Stock
will increase to approximately 150,435,916.

Jim Vincent, Biogen's Chairman and Chief Executive Officer, said, "The stock
split is in keeping with the Company's long-term strategy of broadening our
shareholder base and increasing the liquidity of the Company's shares. This
action reflects our commitment to our stockholders and expresses our enthusiasm
for the Company's opportunities for continued growth."

Biogen also announced that its Board of Directors has adopted a new shareholder
rights plan. The new shareholder rights plan replaces the Company's current
rights plan when it expires on May 8, 1999. In addition to certain other
modifications, the new rights plan increases the purchase price of each right to
$850.00, subject to adjustment. The rights will be exercisable only if a person
or group acquires or announces an intent to acquire 20 percent or more of the
Company's common stock. The new purchase price reflects the significant increase
in the Company's stock price and long-term value since the current rights plan
was adopted in 1989. The rights expire on May 8, 2009, or earlier under certain
circumstances, including redemption. In adopting the new plan, the Company
stated that it was not doing so in response to any known effort to acquire the
Company, and that the plan is designed to assure that all Biogen shareholders
will receive fair and equal treatment in the event of any unsolicited attempt to
<PAGE>   2
acquire the Company. A detailed summary of the rights will be mailed to
stockholders of record on May 8, 1999, and a complete copy of the plan will be
filed with the SEC.

Biogen, Inc., winner of the 1998 U.S. National Medal of Technology, is a
biopharmaceutical company principally engaged in discovering and developing
drugs for human healthcare through genetic engineering. Headquartered in
Cambridge, MA, the Company's revenues are generated from worldwide sales of
AVONEX(R) (Interferon beta-1a) for treatment of relapsing forms of multiple
sclerosis, and from the worldwide sales by licensees of a number of products,
including alpha interferon and hepatitis B vaccines and diagnostic products.
Biogen's research and development activities are focused on novel products for
multiple sclerosis, inflammatory, respiratory, kidney and cardiovascular
diseases and in developmental biology and gene therapy. For copies of press
releases and additional information about the Company, please consult Biogen's
Homepage on the World Wide Web at http://www.biogen.com.

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