AMGEN INC
8-K, 1997-02-28
BIOLOGICAL PRODUCTS, (NO DIAGNOSTIC SUBSTANCES)
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<PAGE>
 
                      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):    February 18, 1997



                                  AMGEN INC.
          -----------------------------------------------------------
            (Exact name of registrant as specified in its charter)


      Delaware                    0-12477                        95-3540776
  ----------------        ------------------------              ------------
  (State of               (Commission File Number)           (IRS Employer
  Incorporation)                                             Identification No.)


       1840 DeHavilland Drive, Thousand Oaks, California     91320-1789
 ----------------------------------------------------------------------------
            (Address of principal executive offices)         (Zip Code)

                                (805) 447-1000
      ------------------------------------------------------------------
             (Registrant's telephone number, including area code)

   ------------------------------------------------------------------------
         (former name or former address, if changed since last report)
<PAGE>
 
Item 5.   Other Events.
          ------------ 

          On February 18, 1997 the Board of Directors of Amgen Inc. (the
"Company") adopted a new Stockholder Rights Plan, effective as of March 21, 1997
(the "Rights Plan"), to replace the Company's existing plan (the "Existing
Plan").

          On February 18, 1997, the Board of Directors redeemed the Company's
Existing Plan effective March 21, 1997.  As a result of the redemption,
shareholders of record on March 21, 1997 will receive $.0008 per right.  In
connection with the redemption, the Board of Directors and the Rights Agent
entered into the Fourth Amendment to the Existing Plan.  A copy of the Fourth
Amendment to the Existing Plan is filed herewith as Exhibit 4.1 and incorporated
herein by reference.

          In connection with the Rights Plan, the Board of Directors of the
Company declared a dividend of one preferred share purchase right (the "Rights")
for each outstanding share of common stock, par value $.0001 per share (the
"Common Shares"), of the Company outstanding at the close of business on March
21, 1997 (the "Record Date").  Each Right will entitle the registered holder
thereof, after the Rights become exercisable and until March 21, 2007 (or the
earlier redemption, exchange or termination of the Rights), to purchase from the
Company one one-thousandth (1/1000th) of a share of Series A Junior
Participating Preferred Stock, par value $.0001 per share (the "Preferred
Shares"), at a price of $225.00 per one one-thousandth (1/1000th) of a Preferred
Share, subject to certain anti-dilution adjustments (the "Purchase Price").
Until the earlier to occur of (i) ten (10) days following a public announcement
that a person or group of affiliated or associated persons has acquired, or
obtained the right to acquire, beneficial ownership of 10% or more of the Common
Shares (or in the case of an Approved Stockholder (as defined below), 20% or
more of the Common Shares) (an "Acquiring Person") or (ii) ten business days
following the commencement 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 10% or more of the Common Shares (the earlier
of (i) and (ii) being called the "Distribution Date"), the Rights will be
evidenced, with respect to any of the Common Share certificates outstanding as
of the Record Date, by such Common Share certificate.  The Rights will be
transferred with and only with the Common Shares until the Distribution Date or
earlier redemption or expiration of the Rights.  As soon as practicable
following the Distribution Date, separate certificates evidencing the 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 Rights.  The Rights will at no time have
any voting rights.

          An "Approved Stockholder" means any person who is approved by a
majority of the directors who are neither officers or employees of the Company
or representatives of an Acquiring Person or an Approved Stockholder ("Outside
Directors") and who enters into a standstill agreement with the Company, so long
as such person owns less than 20% of the outstanding Common Shares.  The
provisions in the Rights Agreement relating to "Approved Stockholder"
automatically terminate on March 12, 2004.

          Each Preferred Share purchasable upon exercise of the Rights will be
entitled to a minimum preferential quarterly dividend payment of $1.00 per share
but will be entitled to an aggregate dividend of 1,000 times the dividend, if
any, declared per Common Share.  In the event of liquidation, the holders of the
Preferred Shares will be entitled to a preferential liquidation payment of
$1,000 per 

                                       2
<PAGE>
 
share 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 and will vote
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 received per
Common Share. These Rights are protected by customary anti-dilution provisions.
Because of the nature of the Preferred Share's dividend, liquidation and voting
rights, the value of one one-thousandth of a Preferred Share purchasable upon
exercise of each Right should approximate the value of one Common Share.

          In the event that a Person becomes an Acquiring Person or if the
Company were the surviving corporation in a merger with an Acquiring Person or
any affiliate or associate of an Acquiring Person and the Common Shares were not
changed or exchanged, each holder of a Right, other than Rights that are or were
acquired or beneficially owned by the Acquiring Person (which Rights will
thereafter be void), will thereafter have the right to receive upon exercise
that number of Common Shares having a market value of two times the then current
Purchase Price of one Right.  With certain exceptions, in the event that, the
Company were acquired in a merger or other business combination transaction or
more than 50% of its assets or earning power were sold, proper provision shall
be made so that each holder of a Right shall thereafter have the right to
receive, upon the exercise thereof at the then current Purchase Price of the
Right, that number of shares of common stock of the acquiring company which at
the time of such transaction would have a market value of two times the then
current Purchase Price of one Right.

          At any time after a Person becomes an Acquiring Person and prior to
the acquisition by such Acquiring Person of 50% or more of the then outstanding
Common Shares, the Board of Directors may cause the Company to acquire the
Rights (other than Rights owned by an Acquiring Person which have become void),
in whole or in part, in exchange for one Common Share per Right (subject to
adjustment).

          The Rights may be redeemed in whole, but not in part, at a price of
$.001 per Right (the "Redemption Price") by the Board of Directors at any time
prior to the time that an Acquiring Person has become such.  The redemption of
the Rights may be made effective at such time, on such basis and with such
conditions as the Board of Directors in its sole discretion may establish.  The
Company may, at its option, pay the Redemption Price in cash, Common Shares
(based on the current per share market price at the time of the redemption) or
any other form of consideration deemed appropriate by the Board of Directors.
Immediately upon any redemption of the Rights, the right to exercise the Rights
will terminate and the only right of the holders of Rights will be to receive
the Redemption Price.

          The Rights will expire on March 21, 2007 (the "Final Expiration Date")
(unless earlier redeemed, exchanged or terminated).  American Stock Transfer &
Trust Company is the Rights Agent.

          The Purchase Price payable, and the number of one one-thousandths of a
Preferred Share or other securities or property issuable, upon exercise of the
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 or warrants to subscribe for or purchase
Preferred Shares or convertible securities at less than the current market price
of the Preferred Shares or (iii) upon the distribution to holders of the
Preferred Shares of evidences of indebtedness, cash, securities or assets
(excluding regular periodic cash dividends 

                                       3
<PAGE>
 
at a rate not in excess of 125% of the rate of the last regular periodic cash
dividend theretofore paid or, in case regular periodic cash dividends have not
theretofore been paid, at a rate not in excess of 50% of the average net income
per share of the Company for the four quarters ended immediately prior to the
payment of such dividend, or dividends payable in Preferred Shares (which
dividends will be subject to the adjustment described in clause (i) above)) or
of subscription rights or warrants (other than those referred to above).

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

          Subject to the last sentence of this paragraph, any of the provisions
of the Rights Agreement dated as of March 21, 1997 between the Company and the
Rights Agent (the "Rights Agreement") may be amended by the Board of Directors
of the Company for so long as the Rights are then redeemable, and after the
Rights are no longer redeemable, the Company may amend or supplement the Rights
Agreement in any manner that does not adversely affect the interests of the
holder of the Rights.  Notwithstanding anything herein to the contrary, any
supplement or amendment to the Rights Agreement will require the affirmative
vote of a majority of the Outside Directors, and any extension of the Final
Expiration Date will require the affirmative vote of three-quarters of the
Outside Directors.

          One Right will be distributed to stockholders of the Company for each
Common Share owned of record by them on March 21, 1997.  As long as the Rights
are attached to the Common Shares, the Company will issue one Right with each
new Common Share so that all such shares will have attached Rights.  The Company
has agreed that, from and after the Distribution Date, the Company will reserve
750,000 Preferred Shares initially for issuance upon exercise of the Rights.

          The Rights Plan is essentially the same in purpose and effect as the
Existing Plan being redeemed.  The new rights, like the existing rights, are
designed to assure that all of the Company's stockholders receive fair and equal
treatment in the event of any proposed takeover of the Company and to guard
against partial tender offers, open market accumulations and other abusive
tactics to gain control of the Company without paying all stockholders a control
premium.  The Rights will cause substantial dilution to a person or group that
acquires 10% or more of the Company's stock on terms not approved by the
Company's Board of Directors.  The Rights should not interfere with any merger
or other business combination approved by the Board of Directors at any time
prior to the first date that a Person or group has become an Acquiring Person.

          The amendment to the Existing Plan describing the redemption of the
rights issued under the Existing Plan, the Rights Agreement specifying the terms
of the Rights, and the text of the press release announcing the declaration of
the Rights, are incorporated herein by reference as exhibits to this Current
Report.  The foregoing description of the Rights is qualified in its entirety by
reference to such exhibits.

                                       4
<PAGE>
 
Item 7.   Exhibits.
          -------- 

     4.1  Fourth Amendment, dated as of February 18, 1997, to the Rights
          Agreement, dated as of January 24, 1989, as amended, between Amgen
          Inc. and American Stock Transfer & Trust Company.

     4.2  Rights Agreement, dated as of February 18, 1997, between Amgen Inc.
          and American Stock Transfer & Trust Company, which includes the form
          of Certificate of Designations of the Series A Junior Participating
          Preferred Stock of Amgen Inc. as Exhibit A, the form of Right
          Certificate as Exhibit B and the Summary of Rights to Purchase
          Preferred Shares as Exhibit C.

     99.  Text of Press Release, dated February 19, 1997.

                                       5
<PAGE>
 
                                   SIGNATURE

          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.


Dated:  February 28, 1997

                                      AMGEN INC.



                                      By: /s/ ROBERT S. ATTIYEH
                                         -------------------------
                                         Name: Robert S. Attiyeh
                                         Title: Senior Vice President, Finance
                                                and Corporate Development


                                       6
<PAGE>
 
                                 EXHIBIT INDEX


 
     4.1  Fourth Amendment, dated as of February 18, 1997, to the Rights
          Agreement, dated as of January 24, 1989, between Amgen Inc. and
          American Stock Transfer & Trust Company, as amended.

     4.2  Rights Agreement, dated as of February 18, 1997, between Amgen Inc.
          and American Stock Transfer & Trust Company, which includes the form
          of Certificate of Designations of the Series A Junior Participating
          Preferred Stock of Amgen Inc. as Exhibit A, the form of Right
          Certificate as Exhibit B and the Summary of Rights to Purchase
          Preferred Shares as Exhibit C.

     99.  Text of Press Release, dated February 19, 1997.

                                       7

<PAGE>
 
                                                                     EXHIBIT 4.1

                     FOURTH AMENDMENT TO RIGHTS AGREEMENT
                     ------------------------------------

     AMENDMENT, dated as of February 18, 1997, to the Rights Agreement, dated as
of January 24, 1989, between Amgen, Inc., a Delaware corporation (the
"Company"), American Stock Transfer & Trust Company, as Rights Agent (the
"Rights Agent"), as amended by the First Amendment to Rights Agreement, dated as
of January 22, 1991, between the Company and the Rights Agent, the Second
Amendment to Rights Agreement, dated as of April 2, 1991, between the Company
and the Rights Agent and the Third Amendment to Rights Agreement, dated as of
February 21, 1995, between the Company and the Rights Agent (as so amended, the
"Rights Agreement").

                                   RECITALS
                                   --------

     The Company and the Rights Agent have heretofore executed and entered into
the Rights Agreement. Pursuant to Section 27 of the Rights Agreement, the
Company and the Rights Agent may from time to time supplement or amend the
Rights Agreement. Any acts and things necessary to make this Amendment a valid
agreement, enforceable according to its terms, have been done and performed, and
the execution and delivery of this Amendment by the Company and the Rights Agent
have been in all respects duly authorized by the Company and the Rights Agent.

                                   AGREEMENT
                                   ---------

     In consideration of the foregoing and the mutual agreements set forth
herein, the parties hereto agree as follows:

     1.  Section 23(c) of the Rights Agreement is hereby modified and amended by
amending the first sentence thereof to read in its entirety as follows:

               "Immediately upon the action of the Board of Directors of the
          Company ordering the redemption of the Rights (or at such later time
          as the Board of Directors may establish for the effectiveness of such
          redemption) pursuant to subsection (b) of this Section 23, 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."

                                       1
<PAGE>
 
     2.  If any term, provision, covenant or restriction of this Amendment 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 Amendment, and the Rights Agreement, shall remain in full
force and effect and shall in no way be affected, impaired or invalidated.

     3.  This Amendment shall be deemed to be a contract made under the laws of
the State of Delaware and for all purposes shall be governed by and construed in
accordance with the laws of such State applicable to contracts to be made and
performed entirely within such State.

     4.  This Amendment 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.

     5.  In all respects not inconsistent with the terms and provisions of this
Amendment, the Rights Agreement is hereby ratified, adopted, approved and
confirmed.  In executing and delivering this Amendment, the Rights Agent shall
be entitled to all the privileges and immunities afforded to the Rights Agent
under the terms and conditions of the Rights Agreement.

     IN WITNESS WHEREOF, the parties hereto have caused this Amendment to be
duly executed, all as of the date and year first above written.

                                     AMGEN, INC.



                                     /s/ ROBERT S. ATTIYEH           
                                     ---------------------           
                                     Robert S. Attiyeh               
                                     Senior Vice President, Finance  
                                     and Corporate Development       
                                                                     
                                                                     
                                     AMERICAN STOCK TRANSFER & TRUST 
                                     COMPANY                         
                                                                     
                                                                     
                                                                     
                                     /s/ HERBERT J. LEMMER           
                                     ---------------------           
                                     Name:   Herbert J. Lemmer       
                                     Title:   Vice President          

                                       2

<PAGE>
 
                                                                     EXHIBIT 4.2



================================================================================


                                  Amgen Inc.
 

                                      and

 
                    American Stock Transfer & Trust Company
 
                                as Rights Agent



 
                               Rights Agreement

                         Dated as of February 18, 1997



================================================================================
<PAGE>
 
                               RIGHTS AGREEMENT
                               ----------------

     Agreement, dated as of February 18, 1997, between Amgen Inc., a Delaware
corporation (the "Company"), and American Stock Transfer & Trust Company, a New
York corporation, as Rights Agent (the "Rights Agent").

                                   RECITALS
                                   --------

     WHEREAS, the Board of Directors of the Company previously approved a Rights
Agreement dated January 24, 1989, between the Company and the Rights Agent, as
amended (the "Existing Agreement");

     WHEREAS, on February 18, 1997, the Board of Directors of the Company
reedemed the rights issued under the Existing Agreement effective as of March
21, 1997; and

     WHEREAS, on February 18, 1997, the Board of Directors of the Company
adopted a new Rights Agreement to be effective as of March 21, 1997, and has
authorized and declared a dividend of one right (a "Right") for each Common
Share (as defined in Section 1.6) of the Company outstanding at the close of
business on March 21, 1997 (the "Record Date") and has authorized the issuance
of one Right (subject to adjustment as provided herein) 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 defined in Sections 3.1 and 7.1), each Right initially
representing the right to purchase one one-thousandth of a share of Series A
Junior Participating Preferred Stock (the "Preferred Shares") of the Company
having the rights, powers and preferences set forth in the form of Certificate
of Designations attached hereto as Exhibit A, upon the terms and subject to the
conditions hereinafter set forth.

     NOW, THEREFORE, 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 Rights Agreement, 
                 -------------------
the following terms have the meanings indicated:

     1.1  (a)  Subject to Section 1.1(b), "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
10% or more of the Common Shares of the Company then outstanding but shall not
include the Company, any Subsidiary of the Company or any employee benefit plan
of the Company or of any Subsidiary of the Company or any entity holding shares
of capital stock of the Company for or pursuant to the terms of any such plan,
in its capacity as an agent or trustee for any such plan. Notwithstanding the
foregoing, no Person shall become an "Acquiring Person" as the result of an
acquisition of Common Shares by the 

                                       1
<PAGE>
 
Company which, by reducing the number of shares outstanding, increases the
proportionate number of shares beneficially owned by such Person to 10% or more
of the Common Shares of the Company then outstanding; provided, however, that if
a Person shall become the Beneficial Owner of 10% or more of the Common Shares
of the Company then outstanding solely by reason of share purchases by the
Company and shall, after such share purchases 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." Notwithstanding the
foregoing, if the Board of Directors of the Company determines in good faith
that a Person who would otherwise be an "Acquiring Person," as defined pursuant
to the foregoing provisions of this Section 1.1, 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 Section 1.1, then such Person shall
not be deemed to be an "Acquiring Person" at any time for any purposes of this
Agreement.

     (b)  Subject to Section 26(b), notwithstanding anything in this Rights
Agreement to the contrary, "Acquiring Person" shall not include any Person that
is an Approved Stockholder (so long as such Person remains an Approved
Stockholder), and no Approved Stockholder shall become an "Acquiring Person" 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 more than 20% of the Common Shares of the
Company then outstanding; provided, however, that if a Person shall become the
Beneficial Owner of more than 20% of the Common Shares of the Company then
outstanding solely by reason of share purchases by the Company and shall, after
such share purchases 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."

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

     1.3  (a)  Subject to Section 26(b), "Approved Stockholder" shall mean any
Person (as such term is hereinafter defined) who or which enters into a
Standstill Agreement (as such term is hereinafter defined) approved by a
majority of the Outside Directors and with respect to whom or which the Outside
Directors determine that beneficial ownership of the Common Shares by such
Person is in the best interests of the Company and is not reasonably likely to
cause a material adverse impact on the business or prospects of the Company;
provided, however, that such Person shall cease to be an Approved Stockholder if
(i) such Person, together with all Affiliates and Associates, shall be the
Beneficial Owner (as such term is hereinafter defined) of more than 20% of the
Common Shares of the Company then outstanding or (ii) such Person is not in
compliance with the terms of the Standstill Agreement. Upon the expiration or
termination of the Standstill Agreement, such Person shall cease to be an
Approved Stockholder.

                                       2
<PAGE>
 
     (b)  If, at the time of such expiration or termination, such Person,
together with all Affiliates or Associates, is the Beneficial Owner of 10% or
more, but less than 20%, of the Common Shares of the Company then outstanding,
then, notwithstanding any other provision of this Agreement, such Person shall
not be an Acquiring Person; provided, however, that thereafter such Person shall
become an Acquiring Person if (i) such Person, or any Affiliate or Associate of
such Person, shall acquire Beneficial Ownership of one or more additional Common
Shares (other than pursuant to a stock split, stock dividend or similar
transaction approved by a majority of the Outside Directors), and (ii) after
such acquisition such Person is the Beneficial Owner of 10% or more of the
Common Shares then outstanding.

     1.4  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 (as determined
     pursuant to Rule 13d-3 of the General Rules and Regulations under the
     Exchange Act as in effect on the date of this Agreement);

          (ii) which such Person or any of such Person's Affiliates or
     Associates, directly or indirectly, has (A) the right to acquire (whether
     such right is exercisable immediately, or only after the passage of time,
     compliance with regulatory requirements, fulfillment of a condition or
     otherwise) pursuant to any agreement, arrangement or understanding, whether
     or not in writing (other than customary agreements with and between
     underwriters and selling group members with respect to a bona fide public
     offering of securities), or upon the exercise of conversion rights,
     exchange rights, rights (other than the Rights), warrants or options, or
     otherwise; provided, however, that a Person shall not be deemed the
     Beneficial Owner of, or to beneficially own, (1) securities tendered
     pursuant to a tender or exchange 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 (2) securities which
     such Person or any of such Person's Affiliates or Associates may acquire,
     does or do acquire or may be deemed to have the right to acquire, pursuant
     to any merger or other acquisition agreement between the Company and such
     Person (or one or more of his Affiliates or Associates) if such agreement
     has been approved by the Board of Directors of the Company prior to such
     Person's becoming an Acquiring Person; or (B) the right to vote pursuant to
     any agreement, arrangement or understanding (whether or not in writing);
     provided, however, that a Person shall not be deemed the Beneficial Owner
     of, or to beneficially own, any security under this clause (B) 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 of the Exchange Act
     and (2) is not also then 

                                       3
<PAGE>
 
     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 (or any Affiliate or Associate thereof) 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), whether or not in writing, for the purpose
     of acquiring, holding, voting (except pursuant to a revocable proxy as
     described in the proviso to Section 1.3(ii)(B)) or disposing of any
     securities of the Company.

     1.5  "Business Day" shall mean any day other than a Saturday, Sunday, or a
day on which banking institutions in the State of New York are authorized or
obligated by law or executive order to close.

     1.6  "close of business" on any given date shall mean 5:00 p.m., California
time, on such date; provided, however, that if such date is not a Business Day
it shall mean 5:00 p.m., California time, on the next succeeding Business Day.

     1.7  "Common Shares" when used with reference to the Company shall mean the
shares of common stock, par value $.0001 per share, of the Company. "Common
Shares" when used with reference to any Person other than the Company shall mean
the capital stock with the greatest voting power, or the equity securities or
other equity interest having power to control or direct the management, of such
other Person or, if such Person is a Subsidiary of another Person, the Person or
Persons which ultimately control such first-mentioned Person, and which has
issued and outstanding such capital stock, equity securities or equity interest.

     1.8  "Outside Director" shall mean a member of the Board of Directors of
the Company who is not an officer or employee of the Company, who is not an
Acquiring Person or an Approved Stockholder or an Affiliate or Associate of an
Acquiring Person or an Approved Stockholder, or a representative or nominee of
an Acquiring Person or an Approved Stockholder or of any such Affiliate or
Associate, and who either (i) was a member of the Board of Directors of the
Company prior to the time that Person becomes an Acquiring Person or an Approved
Stockholder or (ii) subsequently becomes a director of the Company, and whose
election or nomination for election is approved or recommended by a vote of a
majority of the Board of Directors of the Company, which majority includes a
majority of the Outside Directors then on the Board of Directors.

     1.9  "Person" shall mean any individual, partnership, joint venture,
limited liability company, firm, corporation, unallocated association, trust or
other entity, and shall include any successor (by merger or otherwise) of such
entity.

                                       4
<PAGE>
 
     1.10  "Shares Acquisition Date" shall mean the first date of public
announcement (which, for purposes of this definition, shall include, without
limitation, the filing of a report pursuant to Section 13(d) of the Exchange Act
or pursuant to a comparable successor statute) by the Company or an Acquiring
Person that an Acquiring Person has become such or that discloses information
which reveals the existence of an Acquiring Person.

     1.11  Subject to Section 26(b), "Standstill Agreement" shall mean an
agreement entered into between the Company (upon the approval of a majority of
the Outside Directors) and a Person which restricts or prohibits such Person
from taking certain actions with respect to the Company and its equity
securities, including, but not limited to, acquiring or offering to acquire
Common Shares, engaging in a tender or exchange offer or proxy contest with
respect to the Common Shares, taking actions to directly or indirectly acquire
control of the Company or the Common Shares or other actions that the Board
determines would not be in the best interests of the Company and its
shareholders ("Restricted Actions"). Any Standstill Agreement entered into prior
to March 12, 2002 shall provide that the term during which such Person is
restricted or prohibited from taking such Restricted Actions shall be no more
than two (2) years. The Standstill Agreement shall provide that in the event
that any Person signing the Standstill Agreement shall sell, in compliance with
the Standstill Agreement, a sufficient number of Common Shares so that such
Person is then the Beneficial Owner of less than 10% of the Common Shares then
outstanding, then all restrictions under the Standstill Agreement shall
automatically be removed (except as the Company and such Person shall otherwise
agree in writing) and the Standstill Agreement shall be automatically
terminated.

     1.12  "Subsidiary" of any Person shall mean any corporation or other entity
of which a majority of the voting power of the voting equity securities or
equity interests is owned, of record or beneficially, directly or indirectly, by
such Person.

     1.13  A "Trigger Event" shall be deemed to have occurred upon any Person
becoming an Acquiring Person.

     1.14  The following terms shall have the meanings defined for such terms in
the Sections set forth below:

<TABLE>
<CAPTION>
 
            Term                                Section
            ----                                --------
            <S>                                 <C> 
            Adjustment Shares                     11.1.2
            common stock equivalent               11.1.3
            Company                             Recitals
            current per share market price          11.4
            Current Value                         11.1.3
            Distribution Date                        3.1
            equivalent preferred stock              11.2
            Exchange Act                             1.2
            Exchange Consideration                    27
</TABLE> 

                                       5
<PAGE>
 
<TABLE> 
            <S>                                 <C> 
            Final Expiration Date                    7.1
            NASDAQ                                     9
            Preferred Shares                    Recitals
            Purchase Price                             4
            Record Date                         Recitals
            Redemption Date                          7.1
            Redemption Price                        23.1
            Right                               Recitals
            Right Certificate                        3.1
            Rights Agent                        Recitals
            Security                                11.4
            Spread                                11.1.3
            Substitution Period                   11.1.3
            Summary of Rights                        3.2
            Trading Day                             11.4
</TABLE>

          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, shall prior to the Distribution Date also be
the holders of the 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.  In the event the Company appoints one or more co-Rights Agents, the
respective duties of the Rights Agent and any co-Rights Agent shall be as the
Company shall determine.  Contemporaneously with such appointment, if any, the
Company shall notify the Rights Agent thereof.

          Section 3.  Issuance of Right Certificates.
                      ------------------------------

          3.1  Rights Evidenced by Share Certificates.  Until the earlier of (i)
               --------------------------------------
the tenth day after the Shares Acquisition Date or (ii) the tenth business day
after the date of the commencement of, or first public announcement of the
intent 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 shares of capital stock of the Company for or pursuant to the
terms of any such plan, in its capacity as an agent or trustee for any such
plan) to commence, a tender or exchange offer the consummation of which would
result in any Person becoming the Beneficial Owner of Common Shares aggregating
10% or more of the then outstanding Common Shares of the Company (the earlier of
(i) and (ii) being herein referred to as the "Distribution Date"), (x) the
Rights (unless earlier expired, redeemed or terminated) will be evidenced
(subject to the provisions of Section 3.2) by the certificates for Common Shares
registered in the names of the holders thereof (which certificates for Common
Shares shall also be deemed to be Right Certificates) and not by separate
certificates, and (y) the Rights (and the right to receive certificates
therefor) will be transferable only in connection with the transfer of the
underlying Common Shares.  The preceding sentence notwithstanding, prior to the

                                       6
<PAGE>
 
occurrence of a Distribution Date specified as a result of an event described in
clause (ii) (or such later Distribution Date as the Board of Directors of the
Company may select pursuant to this sentence), the Outside Directors may
postpone, one or more times, the Distribution Date which would occur as a result
of an event described in clause (ii) beyond the earlier of the date set forth in
such clause (ii).  Nothing herein shall permit such a postponement of a
Distribution Date following the occurrence of an event described in clause (i)
above.  As soon as practicable after the Distribution Date, the Rights Agent
will send, by first-class, 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, one or more certificates for
Rights, in substantially the form of Exhibit B hereto (a "Right Certificate"),
evidencing one Right (subject to adjustment as provided herein) for each Common
Share so held.  As of the Distribution Date, the Rights will be evidenced solely
by such Right Certificates.

          3.2  Summary of Rights.  On the Record Date or as soon as practicable
               -----------------
thereafter, the Company will send or cause to be sent a copy of a Summary of
Rights to Purchase Preferred Shares, in substantially the form attached hereto
as Exhibit C (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 close of
business on the Record Date, until the Distribution Date (or the earlier
Redemption Date or Final Expiration Date), the Rights will be evidenced by such
certificates for Common Shares registered in the names of the holders thereof
together with a copy of the Summary of Rights and the registered holders of the
Common Shares shall also be registered holders of the associated Rights.  Until
the Distribution Date (or the earlier Redemption Date or Final Expiration Date),
the surrender for transfer of any certificate for Common Shares outstanding at
the close of business on the Record Date, with or without a copy of the Summary
of Rights, shall also constitute the transfer of the Rights associated with the
Common Shares represented thereby.

          3.3  New Certificates After Record Date.  Certificates for Common
               ----------------------------------
Shares which become outstanding (whether upon issuance out of authorized but
unissued Common Shares, issuance out of treasury or transfer or exchange of
outstanding Common Shares) after the Record Date but prior to the earliest of
the Distribution Date, the Redemption Date or the Final Expiration Date, shall
be deemed also to be certificates for Rights, and shall have impressed, printed,
stamped, written or otherwise affixed onto them the following legend:

     This certificate also evidences and entitles the holder hereof to certain
     Rights as set forth in a Rights Agreement between Amgen Inc. and American
     Stock Transfer & Trust Company, dated as of February 18, 1997, as the same
     may be amended from time to time (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 Amgen 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.  Amgen Inc. will 

                                       7
<PAGE>
 
     mail to the holder of this certificate a copy of the Rights Agreement
     without charge after receipt of a written request therefor. As described in
     the Rights Agreement, Rights which are held by or have been held by
     Acquiring Persons or Associates or Affiliates thereof (as defined in the
     Rights Agreement) shall become null and void.

With respect to such certificates containing the foregoing legend, until the
Distribution Date (or the earlier Redemption Date or Final Expiration Date), the
Rights associated with the Common Shares represented by such certificates shall
be evidenced by such certificates (together with a copy of the Summary of
Rights), and the surrender for transfer of any such certificates 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 forms of election to purchase Preferred Shares, certification and assignment
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 Rights
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 or trading system on which the Rights may from time to time be
listed or quoted, or to conform to usage.  Subject to the terms and conditions
hereof, the Right Certificates, whenever issued, shall be dated as of the Record
Date, and shall show the date of countersignature by the Rights Agent, and on
their face 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 price per
one one-thousandth of a Preferred Share set forth therein (the "Purchase
Price"), but the number 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 of
Directors, the Chief Executive Officer, President or any Vice President, either
manually or by facsimile signature, and shall have affixed thereto the Company's
seal or a facsimile thereof which shall be attested by the Secretary or any
Assistant Secretary of the Company, either manually or by facsimile signature.
The Right Certificates shall be manually countersigned by an authorized
signatory of the Rights Agent, but it shall not be necessary for the same
signatory to countersign all of the Right Certificates hereunder.  No Right
Certificate shall be valid for any purpose unless so 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 

                                       8
<PAGE>
 
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 principal office, 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, the certificate
number of 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 11.1.2 and Section 14, at any time after the close
of business on the Distribution Date, and at or prior to the close of business
on the earlier of the Redemption Date or the Final Expiration Date, any Right
Certificate or Right Certificates (other than Right Certificates representing
Rights that have become void pursuant to Section 11.1.2 or that have been
exchanged pursuant to Section 27) may be transferred, split up or 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 or combine or exchange any Right Certificate shall make such request in
writing delivered to the Rights Agent, and shall surrender, together with any
required form of assignment and certificate duly completed, the Right
Certificate or Right Certificates to be transferred, split up or 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 or Right Certificates 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 or Right Certificates 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 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 from the holders of Right Certificates of a sum sufficient to cover any
tax or governmental charge that may be imposed in connection with any transfer,
split up or combination or exchange of such Right Certificates.

          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 

                                       9
<PAGE>
 
expenses incidental thereto, and upon surrender to the Rights Agent and
cancellation of the Right Certificate if mutilated, the Company will make and
deliver a new Right Certificate of like tenor to the Rights Agent for
countersignature and delivery to the registered owner in lieu of the Right
Certificate so lost, stolen, destroyed or mutilated.

          Section 7.  Exercise of Rights; Purchase Price; Expiration Date of
                      ------------------------------------------------------
Rights.
- ------

          7.1  Exercise of Rights.  Subject to Section 11.1.3 and except as
               ------------------
otherwise provided herein, the registered holder of any Right Certificate may
exercise the Rights evidenced thereby 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 and certification 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 as to which the Rights are exercised, at or
prior to the earliest of (i) the close of business on March 21, 2007 (the "Final
Expiration Date"), (ii) the time at which the Rights are redeemed as provided in
Section 23 (the "Redemption Date"), (iii) the closing of any merger or other
acquisition transaction involving the Company pursuant to an agreement of the
type described in Sections 1.4(ii)(A)(2) and 13.2, at which time the Rights are
deemed terminated, or (iv) the time at which the Rights are exchanged as
provided in Section 27.

          7.2  Purchase.  The Purchase Price for each one one-thousandth of a
               --------
Preferred Share pursuant to the exercise of a Right shall initially be $225.00,
shall be subject to adjustment from time to time as provided in Sections 11, 13
and 26 and shall be payable in lawful money of the United States of America in
accordance with paragraph 7.3.

          7.3  Payment Procedures.  Upon receipt of a Right Certificate
               ------------------
representing exercisable Rights, with the form of election to purchase and
certification 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, by certified or cashier's check or money order payable to the order
of the Company, the Rights Agent shall thereupon promptly (i)(A) requisition
from any transfer agent of the Preferred Shares (or make available, if the
Rights Agent is the transfer agent) certificates for the number of Preferred
Shares to be purchased and the Company hereby irrevocably authorizes its
transfer agent to comply with all such requests, or (B) if the Company shall
have elected to deposit the total number of Preferred Shares issuable upon
exercise of the Rights hereunder with a depositary agent, requisition from the
depositary agent depositary 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 depositary agent) and the Company
hereby directs the depositary agent to comply with all such requests, (ii) when
appropriate, requisition from the Company the amount of cash to be paid in lieu
of the issuance of fractional shares in accordance with Section 14, (iii)
promptly after receipt of such certificates or depositary receipts, cause the
same to be delivered to or upon the order of the registered holder of such Right
Certificate, 

                                       10
<PAGE>
 
registered in such name or names as may be designated by such holder and (iv)
when appropriate, after receipt, promptly deliver such cash to or upon the order
of the registered holder of such Right Certificate. In the event that the
Company is obligated to issue other securities of the Company, pay cash and/or
distribute other property pursuant to Section 11.1.3, the Company will make all
arrangements necessary so that such other securities, cash and/or other property
are available for distribution by the Rights Agent, if and when appropriate.

          7.4  Partial Exercise.  In case the registered holder of any Right
               ----------------
Certificate shall exercise less 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 and delivered to the registered
holder of such Right Certificate or to his duly authorized assigns, subject to
the provisions of Section 14.

          7.5  Full Information Concerning Ownership.  Notwithstanding anything
               -------------------------------------
in this Rights Agreement to the contrary, neither the Rights Agent nor the
Company shall be obligated to undertake any action with respect to a registered
holder of Rights upon the occurrence of any purported exercise as set forth in
this Section 7 unless the certificate contained in the form of election to
purchase set forth on the reverse side of the Right Certificate surrendered for
such exercise shall have been duly completed and signed by the registered holder
thereof and the Company shall have been provided with 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 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.  Reservation and Availability of Capital Stock.  The
                      ---------------------------------------------
Company covenants and agrees that from and after the Distribution Date it will
cause to be reserved and kept available out of its authorized and unissued
Preferred Shares (and, following the occurrence of a Trigger Event, out of its
authorized and unissued Common Shares or other securities or out of its shares
held in its treasury) the number of Preferred Shares (and, following the
occurrence of a Trigger Event, Common Shares and/or other securities) that will
be sufficient to permit the exercise in full of all outstanding Rights.

                                       11
<PAGE>
 
          So long as the Preferred Shares (and, following the occurrence of a
Trigger Event, Common Shares and/or other securities) issuable upon the exercise
of Rights may be listed on any national securities exchange or traded in the
over-the-counter market and quoted on the National Association of Securities
Dealers, Inc. Automated Quotation System ("Nasdaq"), (including the National
Market or Small Cap Market) 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 so traded in such over-the-
counter market, upon official notice of issuance upon such exercise.

          The Company covenants and agrees that it will take all such action as
may be necessary to ensure that all Preferred Shares (and, following the
occurrence of a Trigger Event, Common Shares  and/or other securities) delivered
upon exercise of Rights shall, at the time of delivery of the certificates for
such shares (subject to payment of the Purchase Price), be duly and validly
authorized and issued and fully paid and nonassessable shares.

          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 (or Common Shares and/or other securities, as the case may
be) 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 for the Preferred Shares (or Common Shares and/or other securities,
as the case may be) in a name other than that of, the registered holder of the
Right Certificate evidencing Rights surrendered for exercise or to issue or
deliver any certificates for Preferred Shares (or Common Shares and/or other
securities, as the case may be) in a name other than that of the registered
holder 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 satisfaction
that no such tax is due.

          Section 10.  Preferred Shares Record Date.  Each person in whose name
                       ----------------------------
any certificate for Preferred Shares (or Common Shares and/or other securities,
as the case may be) 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 Common
Shares and/or other securities, as the case may be) represented thereby on, and
such certificate shall be dated, the date upon which the Right Certificate
evidencing such Rights was duly surrendered 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
Common Shares and/or other securities, as the case may be) transfer books of the
Company are closed, such person shall be deemed to have become the record holder
of such shares (fractional or otherwise) on, and such certificate shall be
dated, the next succeeding Business Day on which the Preferred Shares (or Common
Shares and/or other securities, as the case may be) transfer books of the
Company are open.

                                       12
<PAGE>
 
          Section 11.  Adjustment of Purchase Price, Number of Shares or Number
                       --------------------------------------------------------
of Rights.  The Purchase Price, the number of 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.

          11.1  Post Execution Events.
                ----------------------

          11.1.1  Corporate Dividends, Reclassifications, Etc.  In the event the
                  -------------------------------------------
Company shall at any time after the date of this Rights 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 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 11.1,
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, he would have owned upon such exercise and been entitled to receive by
virtue of such dividend, subdivision, combination or reclassification.  If an
event occurs which would require an adjustment under both Section 11.1.1 and
Section 11.1.2, the adjustment provided for in this Section 11.1.1 shall be in
addition to, and shall be made prior to, the adjustment required pursuant to,
Section 11.1.2.

          11.1.2  Acquiring Person Events; Triggering Events.  Subject to
                  ------------------------------------------
Sections 23.1 and 27 of this Agreement, in the event

               (A) that any Acquiring Person or any Associate or Affiliate of
     any Acquiring Person, at any time after the date of this Rights Agreement,
     directly or indirectly, shall merge into the Company or otherwise combine
     with the Company and the Company shall be the continuing or surviving
     corporation of such merger or combination and the Common Shares of the
     Company shall remain outstanding and not changed into or exchanged for
     stock or other securities of any other Person or the Company or cash or any
     other property, or

               (B)  that a Trigger Event occurs,

then, from and after the first occurrence of such event, each holder of a Right,
except as provided below, shall thereafter have a right to receive, upon
exercise thereof at a price per Right 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 (without giving effect to this Section 11.1.2), in
accordance with the terms of this Rights Agreement, such number of Common Shares
as shall equal the result obtained by (x) multiplying the then current Purchase
Price by the then 

                                       13
<PAGE>
 
number of one one-thousandths of a Preferred Share for which a Right is then
exercisable (without giving effect to this Section 11.1.2) and (y) dividing that
product by 50% of the current per share market price of the Common Shares
(determined pursuant to Section 11.4) on the first of the date of the occurrence
of, or the date of the first public announcement of, one of the events listed
above in this Section 11.1.2 (the "Adjustment Shares"); provided, however, that
if the transaction that would otherwise give rise to the foregoing adjustment is
also subject to the provisions of Section 13, then only the provisions of
Section 13 shall apply and no adjustment shall be made pursuant to this Section
11.1.2; provided, further, that nothing contained in this Section 11.1.2 shall
limit or otherwise diminish the power of the Outside Directors to postpone the
Distribution Date pursuant to Section 3.1; provided, further, that the Purchase
Price and the number of Adjustment Shares shall thereafter be subject to further
adjustment pursuant to Section 11.1.1 hereof. Notwithstanding the foregoing,
upon the occurrence of either of the events listed above in this Section 11.1.2,
any Rights that are or were acquired or beneficially owned by (1) an Acquiring
Person or any Associate or Affiliate thereof, (2) a transferee of an Acquiring
Person (or of any such Associate or Affiliate) who becomes a transferee after
the Acquiring Person becomes such, or (3) a transferee of an Acquiring Person
(or of any such Associate or Affiliate) who becomes a transferee prior to or
concurrently with the Acquiring Person 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 determined is part of a plan,
arrangement or understanding which has as a primary purpose or effect avoidance
of this Section 11.1.2, shall become void, and any holder (whether or not such
holder is an Acquiring Person or an Associate or Affiliate of an Acquiring
Person) of such Rights shall thereafter have no right to exercise such Rights
under any provision of this Rights Agreement or otherwise. The Company shall not
enter into any transaction of the type described in this Section 11.1.2 if at
the time of such transaction there are any rights, warrants, instruments or
securities outstanding or any arrangements which, as a result of the
consummation of such transaction, would eliminate or substantially diminish the
benefits intended to be afforded by the Rights. Any Right Certificate issued
pursuant to Section 3 or Section 22 that represents Rights beneficially owned
by: (1) an Acquiring Person or any Associate or Affiliate thereof, (2) a
transferee of an Acquiring Person (or of any such Associate or Affiliate) who
becomes a transferee after the Acquiring Person becomes such, or (3) a
transferee of an Acquiring Person (or of any such Associate or Affiliate) who
becomes a transferee prior to or concurrently with the Acquiring Person 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
determined is part of a plan, arrangement or understanding which has as a
primary purpose or effect avoidance of this Section 11.1.2, and any Right
Certificate issued pursuant to Section 6, 7.4 or 22 or this Section 11 upon
transfer, exchange, replacement or adjustment of any other Right Certificate
referred to in this sentence, shall contain the following legend (provided,
however, 

                                       14
<PAGE>
 
that the Rights Agent shall not be responsible for affixing such legend unless
it has actual knowledge as to the foregoing circumstances or the Company has
notified the Rights Agent in writing thereof):

          THE RIGHTS REPRESENTED BY THIS RIGHT CERTIFICATE ARE HELD OR HAVE BEEN
          HELD BY A PERSON WHO IS OR WAS AN ACQUIRING PERSON OR AN AFFILIATE OR
          AN ASSOCIATE OF AN ACQUIRING PERSON OR A NOMINEE THEREOF. THIS RIGHT
          CERTIFICATE AND THE RIGHTS REPRESENTED HEREBY HAVE BECOME NULL AND
          VOID AS SPECIFIED IN SECTION 11.1.2 OF THE RIGHTS AGREEMENT.

          The Company shall use all reasonable efforts to insure that the
provisions of this Section 11.1.2 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 any Acquiring Person or its
Affiliates, Associates or transferees hereunder.

          11.1.3  Insufficient Shares.  In the event that upon the occurrence of
                  -------------------
one or more of the events listed in Section 11.1.2 above there shall not be
sufficient Common Shares authorized but unissued, or held by the Company as
treasury shares, to permit the exercise in full of the Rights in accordance with
the foregoing Section 11.1.2, the Company shall take all such action as may be
necessary to authorize additional Common Shares for issuance upon exercise of
the Rights, provided, however, that if the Company determines that it is unable
to cause the authorization of a sufficient number of additional Common Shares,
then, in the event the Rights become exercisable, the Company, with respect to
each Right and to the extent necessary and permitted by applicable law and any
agreements or instruments in effect on the date hereof to which it is a party,
shall:  (A)  determine the excess of (1) the value of the Adjustment Shares
issuable upon the exercise of a Right (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 the Adjustment Shares, upon payment of
the applicable Purchase Price, (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 deemed to have the same value as Common Shares)
(each such share of preferred stock constituting a "common stock equivalent")),
(4) debt securities of the Company, (5) other assets or (6) any combination of
the foregoing having an aggregate value equal to the Current Value, where such
aggregate value has been determined by the Board of Directors of the Company
based upon the advice of a nationally recognized investment banking firm
selected by the Board of Directors of the Company; provided, however, that 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 one
of the events listed in Section 11.1.2 above, then the Company shall be
obligated to deliver, upon the surrender for exercise of a Right and without
requiring payment of the Purchase Price, Common Shares (to the extent available)
and then, if necessary, cash, which in the aggregate are equal to the Spread.
If the Board of Directors of the Company shall determine in good faith that it
is unlikely that sufficient additional Common Shares could be authorized for
issuance upon exercise in full of the Rights, 

                                       15
<PAGE>
 
the thirty (30) day period set forth above may be extended and re-extended to
the extent necessary, but not more than ninety (90) days following the first
occurrence of one of the events listed in Section 11.1.2 above, in order that
the Company may seek stockholder approval for the authorization of such
additional shares (such period as 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 11.1.3, the
Company (x) shall provide 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
event of any such suspension, the Company shall issue a public announcement
stating that the exercisability of the rights has been temporarily suspended as
well as a public announcement at such time as the suspension is no longer in
effect. For purposes of this Section 11.1.3, the value of a Common Share shall
be the current per share market price (as determined pursuant to Section 11.4)
on the date of the first occurrence of one of the events listed in Section
11.1.2 above and the value of any "common stock equivalent" shall be deemed to
have the same value as the Common Shares on such date.

          11.2  Dilutive Rights Offering.  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
securities having the same rights, privileges and preferences as the Preferred
Shares ("equivalent preferred stock")) or securities convertible into Preferred
Shares or equivalent preferred stock at a price per share of Preferred Shares or
per share of equivalent preferred stock (or having a conversion or exercise
price per share, if a security convertible into or exercisable for Preferred
Shares or equivalent preferred stock) less than the current per share market
price of the Preferred Shares (as defined in Section 11.4) 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 stock to be offered (and/or the aggregate initial
conversion price of the convertible securities so to be offered) would purchase
at such current per share 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 stock to be offered for
subscription or purchase (or into which the convertible securities so to be
offered are initially convertible).  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 and shall be binding on the Rights Agent and the
holders of the Rights.  Preferred Shares owned by or held for the account of the
Company or any Subsidiary of the Company shall not be deemed outstanding for the
purpose of any such computation.  Such adjustments shall be made successively
whenever such a record date is fixed; and in the event that such rights or
warrants are not so issued, the Purchase Price 

                                       16
<PAGE>
 
shall be adjusted to be the Purchase Price which would then be in effect if such
record date had not been fixed.

          11.3  Distributions.  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, cash, securities or assets (other than a regular periodic cash
dividend at a rate not in excess of 125% of the rate of the last regular
periodic cash dividend theretofore paid or, in case regular periodic cash
dividends have not theretofore been paid, at a rate not in excess of 50% of the
average net income per share of the Company for the four quarters ended
immediately prior to the payment of such dividend, or a dividend payable in
Preferred Shares (which dividend, for purposes of this Agreement, shall be
subject to the provisions of Section 11.1.1(A) hereof)) or convertible
securities, or subscription rights or warrants (excluding those referred to in
Section 11.2), 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 current per
share market price of the Preferred Shares (as defined in Section 11.4) on such
record date, less the fair market value (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) of the portion of the cash, assets,
securities 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.  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.

          11.4  Current Per Share Market Value.
                ------------------------------

          11.4.1  General.  For the purpose of any computation hereunder, the
                  -------
"current per share market price" of any security (a "Security" for the purpose
of this Section 11.4.1) on any date shall be deemed to be the average of the
daily closing prices per share of such Security for the thirty (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 any period following the announcement
by the issuer of such Security of (i) a dividend or distribution on such
Security payable in shares of such Security or securities convertible into such
shares or (ii) any subdivision, combination or reclassification of such
Security, and prior to the expiration of thirty (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 

                                       17
<PAGE>
 
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, if the Security is
not listed or admitted to trading on any national securities exchange, 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 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. If on any such date no such market maker is
making a market in the Security, the fair value of the Security on such date as
determined in good faith by the Board of Directors of the Company shall be used.
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. If the
Security is not publicly held or not 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 of the Company or, if at the time of such determination
there is an Acquiring Person, by a majority of the Outside Directors then in
office, or if there are no Outside Directors, by a nationally recognized
investment banking firm selected by the Board of Directors, which shall have the
duty to make such determination in a reasonable and objective manner, whose
determination shall be described in a statement filed with the Rights Agent and
shall be conclusive for all purposes.

          11.4.2  Preferred Shares.  Notwithstanding Section 11.4.1, for the
                  ----------------
purpose of any computation hereunder, the "current per share market price" of
the Preferred Shares shall be determined in the same manner as set forth above
in Section 11.4.1 (other than the last sentence thereof).  If the current per
share market price of the Preferred Shares cannot be determined in the manner
described in Section 11.4.1, the "current per share market price" of the
Preferred Shares shall be conclusively deemed to be an amount equal to 1,000 (as
such number may be appropriately adjusted for such events as stock splits, stock
dividends and recapitalizations with respect to the Common Shares occurring
after the date of this Agreement) multiplied by the current per share market
price of the Common Shares.  If neither the Common Shares nor the Preferred
Shares is publicly held or so listed or traded, "current per share market price"
of the Preferred Shares shall mean the fair value per share as determined in
good faith by the Board of Directors of the Company, or, if at the time of such
determination there is an Acquiring Person, by a majority of the Outside
Directors then in office, or if there are no Outside Directors, by a nationally
recognized investment banking firm selected by the Board of Directors of the
Company, which shall have the duty to make such determination in a reasonable
and objective manner, which determination shall be described in a statement
filed with the Rights Agent and shall be conclusive for all purposes.  For
purposes of this Agreement, the "current per share market price" of one one-
thousandth of a Preferred Share shall be equal to the "current per share market
price" of one Preferred Share divided by 1,000.

                                       18
<PAGE>
 
          11.5  Insignificant Changes.  No adjustment in the Purchase Price
                ---------------------
shall be required unless such adjustment would require an increase or decrease
of at least 1% in such price.  Any adjustments which by reason of this Section
11.5 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-millionth of a Preferred Share or
the nearest ten-thousandth of a Common Share, as the case may be.

          11.6  Shares Other Than Preferred Shares.  If as a result of an
                ----------------------------------
adjustment made pursuant to Section 11.1, 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 Sections 11.1
through 11.3, inclusive, and the provisions of Sections 7, 9, 10 and 13 with
respect to the Preferred Shares shall apply on like terms to any such other
shares.

          11.7  Rights Issued Prior to Adjustment.  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.

          11.8  Effect of Adjustments.  Unless the Company shall have exercised
                ---------------------
its election as provided in Section 11.9, upon each adjustment of the Purchase
Price as a result of the calculations made in Sections 11.2 and 11.3, 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-
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.

          11.9  Adjustment in Number of Rights.  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 issuable 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 become that number of
Rights (calculated to the nearest 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 

                                       19
<PAGE>
 
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 ten (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
11.9, 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, 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 may
bear, at the option of the Company, the adjusted Purchase Price) and shall be
registered in the names of the holders of record of Right Certificates on the
record date specified in the public announcement.

          11.10  Right Certificates Unchanged.  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 per
share and the number of one one-thousandths of a Preferred Share which were
expressed in the initial Right Certificates issued hereunder.

          11.11  Par Value Limitations.  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.

          11.12  Deferred Issuance.  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 over and above 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.

          11.13  Reduction in Purchase Price.  Anything in this Section 11 to
                 ---------------------------
the contrary notwithstanding, the Company shall be entitled to make such
reductions in the Purchase Price, in 

                                       20
<PAGE>
 
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 of the 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 this Section 11, hereafter made by the
Company to holders of its Preferred Shares shall not be taxable to such
stockholders.

          11.14  The Company covenants and agrees that after the Distribution
Date it will not, except as permitted by Section 23 or Section 26, take (or
permit any Subsidiary to take) any action if at the time such action is taken it
is reasonably foreseeable that such action will substantially diminish or
otherwise eliminate the benefits intended to be afforded by the Rights.

          11.15  Notwithstanding anything contained in this Agreement to the
contrary, in the event that the Company shall at any time after the date hereof
and prior to the Distribution Date (i) declare or pay any dividend on the
outstanding Common Shares payable in Common Shares, (ii) effect a subdivision or
consolidation of the outstanding Common Shares (by reclassification or otherwise
than by the payment of dividends payable in Common Shares), or (iii) combine the
outstanding Common Shares into a greater or lesser number of Common Shares, then
in any such case, the number of Rights associated with each Common Share then
outstanding, or issued or delivered thereafter but prior to the Distribution
Date, shall be proportionately adjusted so that the number of Rights thereafter
associated with each Common Share following any such event shall equal the
result obtained by multiplying the number of Rights associated with each Common
Share immediately prior to such event by a fraction, the numerator of which
shall be the total number of Common Shares outstanding immediately prior to the
occurrence of the event and the denominator of which shall be the total number
of Common Shares outstanding immediately following the occurrence of such event.
The adjustments provided for in this Section 11.15 shall be made successively
whenever such a dividend is declared or paid or such a subdivision, combination
or consolidation is effected.

          Section 12.  Certificate of Adjusted Purchase Price or Number of
                       ---------------------------------------------------
Shares.  Whenever an adjustment is made as provided in Sections 11 and 13, the
- ------
Company shall (a) promptly prepare a certificate setting forth such adjustment,
and a brief statement of the facts accounting for such adjustment, (b) promptly
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.
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 such adjustment unless and until it shall have received such certificate.

          Section 13.  Consolidation, Merger or Sale or Transfer of Assets or
                       ------------------------------------------------------
Earning Power.
- -------------

                                       21
<PAGE>
 
          13.1  General.  In the event that, from and after the first occurrence
                -------
of a Trigger Event, directly or indirectly, (A) the Company shall consolidate
with, or merge with and into, any other Person and the Company shall not be the
continuing or surviving corporation, (B) 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 and, in connection with such
merger, all or part of the Common Shares shall be changed into or exchanged for
stock or other securities of the Company or any other Person or cash or any
other property, or (C) the Company shall sell, exchange, mortgage or otherwise
transfer (or one or more of its Subsidiaries shall sell, exchange, mortgage or
otherwise transfer), in one or more transactions, assets or earning power
aggregating 50% or more of the assets or earning power of the Company and its
Subsidiaries (taken as a whole) to any other Person or Persons, then, and in
each such case, proper provision shall be made so that (i) each holder of a
Right (except as provided in Section 11.1.2 and as otherwise provided herein)
shall thereafter have the right to receive, upon the exercise thereof at a price
per Right equal to the then current Purchase Price multiplied by the number of
one one-thousandths of a Preferred Share for which a Right was exercisable
immediately prior to the first occurrence of a Trigger Event (as subsequently
adjusted pursuant to Sections 11.1.1, 11.2, 11.3, 11.8, 11.9 and 11.12), in
accordance with the terms of this Rights Agreement and in lieu of Preferred
Shares, such number of Common Shares of such other Person (including the Company
as successor thereto or as the surviving corporation) as shall be equal to the
result obtained by (x) multiplying the then current Purchase Price by the number
of one one-thousandths of a Preferred Share for which a Right was exercisable
immediately prior to the first occurrence of a Trigger Event (as subsequently
adjusted pursuant to Sections 11.1.1, 11.2, 11.3, 11.8, 11.9 and 11.12) and (y)
dividing that product by 50% of the then current per share market price of the
Common Shares of such other Person (determined pursuant to Section 11.4) on the
date of consummation of such consolidation, merger, sale or transfer; provided,
that the price per Right so payable and the number of Common Shares of such
Person so purchasable shall thereafter be adjusted in accordance with Sections
11.1.1, 11.2, 11.3, 11.8, 11.9 and 11.12 by reason of such subsequent events
covered thereby occurring in respect of such Person; (ii) the issuer of such
Common Shares 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 rights agreement; (iii) the term "Company" shall
thereafter be deemed to refer to such issuer; and (iv) such issuer shall take
such steps (including, but not limited to, the reservation of a sufficient
number of its Common Shares in accordance with Section 9) 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.  The
Company shall not enter into any transaction of the kind referred to in this
Section 13 if at the time of such transaction there are any rights, warrants,
instruments or securities outstanding or any agreements or arrangements which,
as a result of the consummation of such transaction, would eliminate or
substantially diminish the benefits intended to be afforded by the Rights.  The
Company shall not consummate any such consolidation, merger, sale or transfer
unless prior thereto the Company and such issuer shall have executed and
delivered to the Rights Agent a supplemental agreement so providing.  The

                                       22
<PAGE>
 
provisions of this Section 13 shall similarly apply to successive mergers or
consolidations or sales or other transfers.

          13.2  Approved Acquisitions.  Notwithstanding anything contained
                ---------------------
herein to the contrary, in the event of any merger or other acquisition
transaction involving the Company pursuant to a merger or other acquisition
agreement between the Company and any Person (or one or more of such Person's
Affiliates or Associates) which agreement has been approved by the Board of
Directors of the Company prior to any Person becoming an Acquiring Person, this
Rights Agreement and the rights of holders of Rights hereunder shall be
terminated in accordance with Section 7.1.

          Section 14.  Fractional Rights and Fractional Shares.
                       ---------------------------------------

          14.1  Cash in Lieu of Fractional Rights.  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 14.1, 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, if the Rights are not listed or admitted to trading on
any national securities exchange, 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.  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.

          14.2  Cash in Lieu of Fractional Shares.  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 depositary receipts, pursuant to an appropriate agreement between
the Company and a depositary 

                                       23
<PAGE>
 
selected by it; provided, that such agreement shall provide that the holders of
such depositary receipts shall have all the rights, privileges and preferences
to which they are entitled as beneficial owners of the Preferred Shares
represented by such depositary 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 per share market price of one Preferred Share. For
purposes of this Section 14.2, the current per share market price of a Preferred
Share shall be the closing price of a Preferred Share (as determined pursuant to
the second sentence of Section 11.4.2) for the Trading Day immediately prior to
the date of such exercise.

          14.3  Waiver of Right to Receive Fractional Rights or Shares.  The
                ------------------------------------------------------
holder of a Right by the acceptance of the Rights expressly waives his right to
receive any fractional Rights or any fractional shares upon exercise of a Right,
except as permitted by this Section 14.

          Section 15.  Rights of Action.  All rights of action in respect of
                       ----------------
this Rights Agreement, except the rights of action given to the Rights Agent
under Section 18, 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 this Rights Agreement, and may institute and maintain any suit,
action or proceeding against the Company to enforce this Rights Agreement, or
otherwise enforce or 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 Rights 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 Rights Agreement and shall be entitled to specific performance of
the obligations under, and injunctive relief against actual or threatened
violations of, the obligations of any Person (including, without limitation, the
Company) subject to this Rights 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;

               (b) as of and after the Distribution Date, the Right Certificates
     are transferable only on the registry books of the Rights Agent if
     surrendered at the office of the Rights Agent designated for such purpose,
     duly endorsed or accompanied by a proper instrument of transfer with all
     required certifications completed; and

                                       24
<PAGE>
 
               (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 Common Shares certificate 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 24), 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 in accordance with a fee schedule to be mutually agreed upon 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 Rights 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 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 Rights Agreement, including the costs and expenses of
defending against any claim of liability in the premises.

          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 Rights Agreement in reliance upon any Right
Certificate or certificate for the Preferred Shares or the Common Shares or for
other securities of the Company, instrument of assignment or transfer, power of
attorney, endorsement, affidavit, letter, notice, instruction, 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.

          Section 19.  Merger or Consolidation or Change of Name of Rights
                       ---------------------------------------------------
Agent.  Any corporation 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 consolidation to 

                                       25
<PAGE>
 
which the Rights Agent or any successor Rights Agent shall be a party, or any
corporation succeeding to the corporate trust or stock transfer business of the
Rights Agent or any successor Rights Agent, shall be the successor to the Rights
Agent under this Rights Agreement without the execution or filing of any paper
or any further act on the part of any of the parties hereto, provided that such
corporation would be eligible for appointment as a successor Rights Agent under
the provisions of Section 21. In case at the time such successor Rights Agent
shall succeed to the agency created by this Rights 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 Rights 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 Rights Agreement.

          Section 20.  Duties of Rights Agent.  The Rights Agent undertakes the
                       ----------------------
duties and obligations imposed by this Rights 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:

          20.1  Legal Counsel.  The Rights Agent may consult with legal counsel
                -------------
selected by it (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.

          20.2  Certificates as to Facts or Matters.  Whenever in the
                -----------------------------------
performance of its duties under this Rights 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 of Directors, the
Chief Executive Officer, the President, the Chief Financial Officer, any Vice
President, the Treasurer, the Secretary or any Assistant Treasurer or Assistant
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 Rights Agreement in reliance
upon such certificate.

                                       26
<PAGE>
 
          20.3  Standard of Care.  The Rights Agent shall be liable hereunder
                ----------------
only for its own negligence, bad faith or willful misconduct.

          20.4  Reliance on Rights Agreement and Right Certificates.  The Rights
                ---------------------------------------------------
Agent shall not be liable for or by reason of any of the statements of fact or
recitals contained in this Rights Agreement or in the Right Certificates (except
as to its countersignature 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.

          20.5  No Responsibility as to Certain Matters.  The Rights Agent shall
                ---------------------------------------
not be under any responsibility in respect of the validity of this Rights
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
Rights 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 11.1.2) or any adjustment required under the provisions
of Sections 3, 11, 13, 23 or 27 or responsible for the manner, method or amount
of any such adjustment or the ascertaining of the existence of facts that would
require any such adjustment (except with respect to the exercise of Rights
evidenced by Right Certificates after actual notice of any such 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 Rights Agreement or any Right Certificate or as to whether any
Preferred Shares will, when so issued, be validly authorized and issued, fully
paid and nonassessable.

          20.6  Further Assurance by Company.  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 Rights
Agreement.

          20.7  Authorized Company Officers.  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 of Directors,
the Chief Executive Officer, the President, the Chief Financial Officer, any
Vice President, the Treasurer, the Secretary or any Assistant Treasurer or
Assistant Secretary of the Company, and to apply to such officers for advice or
instructions in connection with its duties under this Rights Agreement, and it
shall not be liable for any action taken or suffered to be taken by it in good
faith in accordance with instructions of any such officer or for any delay in
acting while waiting for these 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 

                                       27
<PAGE>
 
which such action shall be taken or omitted. The Rights Agent shall not be
liable to the Company 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 any such
officer actually receives such application, unless any such officer shall have
consented in writing to an earlier date) unless, prior to taking of any such
action (or the effective date in the case of omission), the Rights Agent shall
have received written instructions in response to such application specifying
the action to be taken or omitted.

          20.8  Freedom to Trade in Company Securities.  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 Rights Agreement.
Nothing herein shall preclude the Rights Agent from acting in any other capacity
for the Company or for any other legal entity.

          20.9  Reliance on Attorneys and Agents.  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, omission, default,
neglect or misconduct of any such attorneys or agents or for any loss to the
Company resulting from any such act, omission, default, neglect or misconduct,
provided that reasonable care was exercised in the selection and continued
employment thereof.

          20.10  Rights Holders List.  At any time and from time to time after
                 -------------------
the Distribution Date, upon the request of the Company, the Rights Agent shall
promptly deliver to the Company a list, as of the most recent practicable date
(or as of such earlier date as may be specified by the Company), of the holders
of record of Rights.

          Section 21.  Change of Rights Agent.  The Rights Agent or any
                       ----------------------
successor Rights Agent may resign and be discharged from its duties under this
Rights Agreement upon thirty (30) days' notice in writing mailed to the Company
and to each transfer agent of the Common Shares and/or Preferred Shares, as
applicable, by registered or certified mail.  The Company shall promptly notify
the holders of the Right Certificates by first-class mail of any such
resignation.  The Company may remove the Rights Agent or any successor Rights
Agent upon thirty (30) days' notice in writing, mailed to the Rights Agent or
successor Rights Agent, as the case may be, and to each transfer agent of the
Common Shares and/or Preferred Shares, as applicable, 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 resigning, removed, or incapacitated Rights Agent shall remit to the
Company, or to any successor Rights Agent designated by the Company, all books,
records, funds, certificates or other documents or instruments of any kind then
in its possession which were acquired by such resigning, removed or
incapacitated Rights Agent in connection with its services as Rights Agent

                                       28
<PAGE>
 
hereunder, and shall thereafter be discharged from all duties and obligations
hereunder.  Following notice of such removal, resignation or incapacity, the
Company shall appoint a successor to such Rights Agent.  If the Company shall
fail to make such appointment within a period of thirty (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 the State of New
York or the State of California (or any other state of the United States so long
as such corporation is authorized to do business as a banking institution in the
State of New York or California) in good standing, having an office in the State
of New York or the State of California, which is authorized under such laws to
exercise stock transfer or corporate trust 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 $10
million.  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 of the Common Shares
and/or Preferred Shares, as applicable, 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 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 Rights 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 Rights Agreement.  In addition, in
connection with the issuance or sale of Common Shares following the Distribution
Date and prior to the redemption, exchange, termination or expiration of the
Rights, 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, granted or awarded as of the Distribution Date, or upon exercise,
conversion or exchange of securities hereinafter issued by the Company, 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) no such Right Certificate shall be issued if, and to the extent that,
the Company shall be advised by counsel that such issuance would create a

                                       29
<PAGE>
 
significant risk of material adverse tax consequences to the Company or the
Person to whom such Right Certificate would be issued, (ii) no such right
certificate shall be issued if, and to the extent that, appropriate adjustment
shall otherwise have been made in lieu of the issuance thereof and (iii) at the
time of a determination by the Board of Directors to cause the Company to issue
a Right Certificate under clause (b) above, there must be Outside Directors then
in office and any such determination shall require the approval of at least a
majority of such Outside Directors.

          Section 23.  Redemption.
                       ----------

          23.1  Right to Redeem.  The Board of Directors of the Company may, at
                ---------------
its option, at any time prior to a Trigger Event, 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,
recapitalization or similar transaction occurring after the date hereof (such
redemption price being hereinafter referred to as the "Redemption Price"), and
the Company may, at its option, pay the Redemption Price in Common Shares (based
on the "current per share market price," as defined in Section 11.4 hereof, of
the Common Shares at the time of redemption), cash or any other form of
consideration deemed appropriate by the Board of Directors.  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.  Notwithstanding anything contained in this Rights
Agreement to the contrary notwithstanding, the Rights shall not be exercisable
following a transaction or event described in Section 11.1.2 prior to the
expiration or termination of the Company's right of redemption hereunder.

          23.2  Redemption Procedures.  Immediately upon the action of the Board
                ---------------------
of Directors of the Company ordering the redemption of the Rights (or at such
later time as the Board of Directors may establish for the effectiveness of such
redemption), 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 for each Right so held.  The
Company shall promptly give public notice of such redemption; provided, however,
that the failure to give, or any defect in, any such notice shall not affect the
validity of such redemption.  The Company shall promptly give, or cause the
Rights Agent to give, notice of such redemption to the holders of the then
outstanding Rights by mailing such notice to all such holders at their last
addresses as they 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 27, and other than in connection with the purchase, acquisition or
redemption of Common Shares prior to the Distribution Date.

                                       30
<PAGE>
 
          Section 24.  Notice of Certain Events.  In case the Company shall
                       ------------------------
propose at any time after the Distribution Date (a) to pay any dividend payable
in stock of any class to the holders of Preferred Shares or to make any other
distribution to the holders of Preferred Shares (other than a regular periodic
cash dividend at a rate not in excess of 125% of the rate of the last regular
periodic cash dividend theretofore paid or, in case regular periodic cash
dividends have not theretofore been paid, at a rate not in excess of 50% of the
average net income per share of the Company for the four quarters ended
immediately prior to the payment of such dividends, or a stock dividend on, or a
subdivision, combination or reclassification of the Common Shares), or (b) to
offer to the holders of 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, or (c) to effect any reclassification
of its Preferred Shares (other than a reclassification involving only the
subdivision of outstanding Preferred Shares), or (d) 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 (other than
pursuant to a merger or other acquisition agreement of the type described in
Section 1.3(ii)(A)(2)), or (e) to effect the liquidation, dissolution or winding
up of the Company, or (f) 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 the Rights Agent and to each holder of a Right Certificate, in
accordance with Section 25, a notice of such proposed action, which shall
specify the record date for the purposes of such stock dividend, 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 holders of the Preferred Shares
and/or Common 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 (a) or (b) above at least
ten (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 ten (10) days prior to the date of the taking of such proposed action or
the date of participation therein by the holders of the Preferred Shares and/or
Common Shares, whichever shall be the earlier.

          In case any event set forth in Section 11.1.2 of this Rights Agreement
shall occur, then, in any such case, (i) the Company shall as soon as
practicable thereafter give to the Rights Agent and to each holder of a Right
Certificate, in accordance with Section 25, 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 11.1.2, and (ii) all references in this
Section 24 to Preferred Shares shall be deemed thereafter to refer to Common
Shares and/or, if appropriate, other securities.

          Notwithstanding anything in this Rights Agreement to the contrary,
prior to the Distribution Date a filing by the Company with the Securities and
Exchange Commission shall 

                                       31
<PAGE>
 
constitute sufficient notice to the holders of securities of the Company,
including the Rights, for purposes of this Rights Agreement and no other notice
need be given.

          Section 25.  Notices.  Notices or demands authorized by this Rights
                       -------
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:

                 Amgen Inc.
                 1900 Oak Terrace Lane
                 Thousand Oaks, CA  91320
                 Attention:  Secretary

Subject to the provisions of Section 21, any notice or demand authorized by this
Rights 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:

                 American Stock Transfer & Trust Company
                 6201 Fifteenth Avenue
                 Brooklyn, NY  11219
                 Attention:  Shareholder Services Division

Notices or demands authorized by this Rights Agreement to be given or made by
the Company or the Rights Agent to the holder of any Right Certificate (or,
prior to the Distribution Date, to the holder of any certificate representing
Common Shares) 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 26.  (a)  Supplements and Amendments.  For so long as the
                            --------------------------
Rights are then redeemable and subject to the last two sentences of this Section
26(a), the Company may in its sole and absolute discretion, and the Rights Agent
shall, if the Company so directs, supplement or amend any provision of this
Rights Agreement in any respect without the approval of any holders of Rights or
Common Shares.  From and after the time that the Rights are no longer redeemable
and subject to the last two sentences of this Section 26(a), the Company may,
and the Rights Agent shall, if the Company so directs, from time to time
supplement or amend this Rights Agreement without the approval of any holders of
Right Certificates (i) to cure any ambiguity or to correct or supplement any
provision contained herein which may be defective or inconsistent with any other
provisions herein, (ii) to shorten or lengthen any time period hereunder or
(iii) to make any other changes or provisions in regard to matters or questions
arising hereunder which the Company may deem necessary or desirable, including
but not limited to extending the Final Expiration Date; provided, however, that
no such supplement or amendment shall adversely affect the interests of the
holders of Rights as such (other than an 

                                       32
<PAGE>
 
Acquiring Person or an Affiliate or Associate of an Acquiring Person) and no
such supplement or amendment may cause the Rights again to become redeemable or
cause this Rights Agreement again to become amendable other than in accordance
with this sentence; provided further, that the right of the Board of Directors
to extend the Distribution Date shall not require any amendment or supplement
hereunder. Upon the delivery of a certificate from an appropriate officer of the
Company which states that the proposed supplement or amendment is in compliance
with the terms of this Section 26(a), the Rights Agent shall execute such
supplement or amendment. Notwithstanding anything herein to the contrary, any
supplement or amendment to this Rights Agreement shall require the affirmative
vote of a majority of the Outside Directors, and any extension of the Final
Expiration Date shall require the affirmative vote of three-quarters of the
Outside Directors. In connection with any such vote, directors, other than
Outside Directors, shall vote in the same proportion as do the Outside
Directors, to the extent permitted under applicable law.

          (b) Notwithstanding anything in this Rights Agreement to the contrary,
on and after March 12 2004, the provisions of Section 1.1(b), 1.3(a), 1.11 and
the last two sentences of Section 26(a) shall terminate and such sections, and
any references to any such Section or sentences or to "Approved Stockholder" or
"Standstill Agreement" in this Rights Agreement (except in this Section 26(b))
shall be deemed deleted in their entirety.  In addition, upon such termination,
Exhibit C shall be deemed to be automatically amended in accordance with this
Section 26(b) without any action on the part of the Company.


          Section 27.  Exchange.
                       --------

          27.1  Exchange of Common Shares for Rights.  The Board of Directors of
                ------------------------------------
the Company may, at its option, at any time after the occurrence of a Trigger
Event, exchange Common Shares for 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 11.1.2) by exchanging one Common Share per
Right, appropriately adjusted to reflect any stock split, stock dividend or
similar transaction occurring after the date hereof (such amount per Right being
hereinafter referred to as the "Exchange Consideration").  Notwithstanding the
foregoing, (i) 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 and (ii)
the Board shall not be empowered to effect an exchange for more than that number
of Rights for which there are sufficient Common Shares authorized but unissued,
or held by the Company as treasury shares, to permit the exchange for Rights.

          27.2  Exchange Procedures.  Immediately upon the action of the Board
                -------------------
of Directors of the Company ordering the exchange for any Rights pursuant to
Section 27.1 and 

                                       33
<PAGE>
 
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 one Common Shares.  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
the Rights which have become void pursuant to the provisions of Section 11.1.2)
held by each holder of Rights.

          Section 28.  Successors.  All the covenants and provisions of this
                       ----------
Rights 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 29.  Benefits of this Rights Agreement.  Nothing in this
                       ---------------------------------
Rights 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 Rights Agreement; but this Rights
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 30.  Determinations and Actions by the Board of Directors.
                       ----------------------------------------------------
The Board of Directors of the Company shall have the exclusive power and
authority to administer this Agreement and to exercise the rights and powers
specifically granted to the Board of Directors of the Company or to 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 deemed necessary
or advisable for the administration of this Agreement (including, without
limitation, a determination to redeem or not redeem the Rights or amend this
Agreement).  All such actions, calculations, interpretations and determinations
(including, for purposes of clause (y) below, all omissions with respect to the
foregoing) that are done or made by the Board of Directors of the Company in
good faith, shall (x) be final, conclusive and binding on the Company, the
Rights Agent, the holders of the Rights, as such, and all other parties, and (y)
not subject the Board of Directors to any liability to the holders of the
Rights.

          Section 31.  Severability.  If any term, provision, covenant or
                       ------------
restriction of this Rights 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

                                       34
<PAGE>
 
Rights Agreement shall remain in full force and effect and shall in no way be
affected, impaired or invalidated.

          Section 32.  Governing Law.  This Rights Agreement and each Right
                       -------------
Certificate issued hereunder shall be deemed to be a contract made under the
laws of the State of Delaware and for all purposes shall be governed by and
construed in accordance with the laws of such State applicable to contracts to
be made and performed entirely within such State.

          Section 33.  Counterparts.  This Rights 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 Heading.  Descriptive headings of the several
                       -------------------
Sections of this Rights Agreement are inserted for convenience only and shall
not control or affect the meaning or construction of any of the provisions
hereof.

                                       35
<PAGE>
 
          IN WITNESS WHEREOF, the parties hereto have caused this Rights
Agreement to be duly executed and their respective corporate seals to be
hereunto affixed, all as of the day and year first above written.


                         AMGEN INC.



                         By /s/ GORDON M. BINDER
                            ____________________________
                            Name: Gordon M. Binder
                            Title: Chairman of the Board
                                   and Chief Executive Officer


[SEAL]


                         AMERICAN STOCK TRANSFER & TRUST COMPANY



                         By   /s/ HERBERT J. LEMMER
                            -----------------------------
                            Name:   Herbert J. Lemmer
                            Title:  Vice President


[SEAL]

                                      S-1
<PAGE>
 
                                                                       EXHIBIT A
                                                                       ---------


                                     FORM

                                      of

                          CERTIFICATE OF DESIGNATIONS

                                      of

                 SERIES A JUNIOR PARTICIPATING PREFERRED STOCK

                                      of

                                  AMGEN INC.

                        (Pursuant to Section 151 of the
                       Delaware General Corporation Law)

                         _____________________________


     Amgen Inc., a corporation organized and existing under the General
Corporation Law of the State of Delaware (hereinafter called the "Corporation"),
hereby certifies that the following resolution was adopted by the Board of
Directors of the Corporation as required by Section 151 of the General
Corporation Law at a meeting duly called and held on February 18, 1997.

     RESOLVED, that pursuant to the authority granted to and vested in the Board
of Directors of this Corporation (hereinafter called the "Board of Directors" or
the "Board") in accordance with the provisions of the Certificate of
Incorporation, the Board of Directors hereby creates a series of Preferred
Stock, par value $.0001 per share (the "Preferred Stock"), of the Corporation
and hereby states the designation and number of shares, and fixes the relative
rights, preferences, and limitations thereof as follows:

     Series A Junior Participating Preferred Stock:

     Section 1.  Designation and Amount.  The shares of such series shall be
                 ----------------------
designated as "Series A Junior Participating Preferred Stock" (the "Series A
Preferred Stock") and the number of shares constituting the Series A Preferred
Stock shall be 750,000.  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 Preferred Stock to a number less than the
number of shares then outstanding plus the number of shares reserved for
issuance upon the 

                                      A-1
<PAGE>
 
exercise of outstanding options, rights or warrants or upon the conversion of
any outstanding securities issued by the corporation convertible into series a
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 Preferred Stock with respect to dividends, the holders of shares
     of Series A Preferred Stock, in preference to the holders of Common Stock,
     par value $.0001 per share (the "Common Stock"), of the Corporation, 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 Preferred Stock, in an amount per share
     (rounded to the nearest cent) equal to the greater of (a) $1.00 or (b)
     subject to the provision for adjustment hereinafter set forth, 1,000 times
     the aggregate per share amount of all cash dividends, and 1,000 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 Preferred Stock. In the event the
     Corporation shall at any time declare or pay any dividend on the Common
     Stock payable in shares of Common Stock, or effect a subdivision,
     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
     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 Corporation shall declare a dividend or distribution on the
     Series A Preferred Stock as provided in paragraph (A) of this Section 2
     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
     $1.00 per share on the Series A Preferred Stock shall nevertheless be
     payable on such subsequent Quarterly Dividend Payment Date.

                                      A-2
<PAGE>
 
          (C)  Dividends shall begin to accrue and be cumulative on outstanding
     shares of Series A 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 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.  Dividends paid on the shares of Series
     A 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 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 Preferred
                 -------------
Stock shall have the following voting rights:

          (A)  Subject to the provision for adjustment hereinafter set forth,
     each share of Series A Preferred Stock shall entitle the holder thereof to
     1,000 votes on all matters submitted to a vote of the stockholders of the
     Corporation.  In the event the Corporation shall at any time declare or pay
     any dividend on the Common Stock payable in shares of Common Stock, or
     effect a subdivision, 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 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
     Designations creating a series of Preferred Stock or any similar stock, or
     by law, the holders of shares of Series A Preferred Stock and the holders
     of shares of Common Stock and any other capital stock of the Corporation
     having general voting rights shall vote together as one class on all
     matters submitted to a vote of stockholders of the Corporation.

          (C)  Except as set forth herein, or as otherwise provided by law,
     holders of Series A Preferred Stock shall have no special voting rights and
     their consent shall not be 

                                      A-3
<PAGE>
 
     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 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 Preferred
     Stock outstanding shall have been paid in full, the Corporation 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 Preferred
          Stock;

               (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
          Preferred Stock, except dividends paid ratably on the Series A
          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 Preferred
          Stock, provided that the Corporation may at any time redeem, purchase
          or otherwise acquire shares of any such junior stock in exchange for
          shares of any stock of the Corporation ranking junior (either as to
          dividends or upon dissolution, liquidation or winding up) to the
          Series A Preferred Stock; or

               (iv)  redeem or purchase or otherwise acquire for consideration
          any shares of Series A Preferred Stock, or any shares of stock ranking
          on a parity with the Series A 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 Corporation shall not permit any Subsidiary of the
     Corporation to purchase or otherwise acquire for consideration any shares
     of stock of the Corporation unless the Corporation could, under paragraph
     (A) of this Section 4, purchase or otherwise acquire such shares at such
     time and in such manner.

                                      A-4
<PAGE>
 
     Section 5.  Reacquired Shares.  Any shares of Series A Preferred Stock
                 -----------------
purchased or otherwise acquired by the Corporation 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
Certificate of Incorporation, or in any other Certificate of Designations
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 Corporation, 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 Preferred Stock unless,
prior thereto, the holders of shares of Series A Preferred Stock shall have
received $1,000 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 Preferred Stock shall be
entitled to receive an aggregate amount per share, subject to the provision for
adjustment hereinafter set forth, equal to 1,000 times the aggregate amount to
be distributed per share to holders of shares of Common 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 Preferred Stock,
except distributions made ratably on the Series A 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 Corporation shall at any time declare or pay any dividend on the
Common Stock payable in shares of Common Stock, or effect a subdivision,
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 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 are outstanding immediately prior to such
event.

                                      A-5
<PAGE>
 
     Section 7.  Consolidation, Merger, etc.  In case the Corporation 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 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 1,000 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 Corporation shall at any time declare or pay any dividend on
the Common Stock payable in shares of Common Stock, or effect a subdivision,
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 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 Preferred Stock shall
                 -------------
not be redeemable.

     Section 9.  Rank.  The Series A Preferred Stock shall rank, with respect to
                 ----
the payment of dividends and the distribution of assets, junior to all series of
any other class of the Corporation's Preferred Stock, except to the extent that
any such other series specifically provides that it shall rank on a parity with
or junior to the Series A Preferred Stock.

     Section 10.  Amendment.  The Certificate of Incorporation of the
                  ---------
Corporation shall not be amended in any manner which would materially alter or
change the powers, preferences or special rights of the Series A 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 Preferred Stock, voting
together as a single class.

                                      A-6
<PAGE>
 
     IN WITNESS WHEREOF, this Certificate of Designations is executed on behalf
of the Corporation by its Chairman of the Board and attested by its Secretary
this ___ day of February, 1997.



                         ______________________________
                         Chairman of the Board


Attest:


______________________
Secretary

                                      A-7
<PAGE>
 
                                                                       EXHIBIT B
                                                                       ---------

                          [Form of Right Certificate]

Certificate No. R-                                                _______ Rights



     NOT EXERCISABLE AFTER MARCH 21, 2007 OR EARLIER IF NOTICE OF REDEMPTION OR
     EXCHANGE IS GIVEN OR IF THE COMPANY IS MERGED OR ACQUIRED PURSUANT TO AN
     AGREEMENT OF THE TYPE DESCRIBED IN SECTION 1.3(ii)(A)(2) OF THE RIGHTS
     AGREEMENT.  THE RIGHTS ARE SUBJECT TO REDEMPTION, AT THE OPTION OF THE
     COMPANY, AT $.001 PER RIGHT ON THE TERMS SET FORTH IN THE RIGHTS AGREEMENT.
     UNDER CERTAIN CIRCUMSTANCES (SPECIFIED IN SECTION 11.1.2 OF THE RIGHTS
     ----------------------------------------------------------------------
     AGREEMENT), RIGHTS BENEFICIALLY OWNED BY AN ACQUIRING PERSON, OR ITS
     --------------------------------------------------------------------
     AFFILIATES OR ASSOCIATES, OR ANY SUBSEQUENT HOLDER OF SUCH RIGHTS MAY
     ---------------------------------------------------------------------
     BECOME NULL AND VOID.  [THE RIGHTS REPRESENTED BY THIS CERTIFICATE ARE HELD
     --------------------
     OR HAVE BEEN HELD BY A PERSON WHO IS OR WAS AN ACQUIRING PERSON OR AN
     ASSOCIATE OR AFFILIATE OF AN ACQUIRING PERSON OR A NOMINEE THEREOF.  THIS
     RIGHT CERTIFICATE AND THE RIGHTS REPRESENTED HEREBY HAVE BECOME NULL AND
     VOID AS SPECIFIED IN SECTION 11.1.2 OF THE RIGHTS AGREEMENT.]

                               Right Certificate

                                  Amgen 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 February 18, 1997, as the same may be amended
from time to time (the "Rights Agreement"), between Amgen Inc., a Delaware
corporation (the "Company"), and American Stock Transfer & Trust Company, a New
York corporation, as Rights Agent (the "Rights Agent"), to purchase from the
Company at any time after the Distribution Date and prior to 5:00 P.M.
(California time) on March 21, 2007, at the offices of the Rights Agent, or its
successors as Rights Agent, designated for such purpose, one one-thousandth of a
fully paid, nonassessable share of Series A Junior Participating Preferred
Stock, par value $.0001 per share (the "Preferred Shares") of the Company, at a
purchase price of $225.00 per one one-thousandth of a share, subject to
adjustment (the "Purchase Price"), upon presentation and surrender of this Right
Certificate with the Form of Election to Purchase and certification 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 

                                      B-1
<PAGE>
 
thereof) set forth above, and the Purchase Price set forth above, are the number
and Purchase Price as of March 21, 1997 based on the Preferred Shares as
constituted at such date. Capitalized terms used in this Right Certificate
without definition shall have the meanings ascribed to them in the Rights
Agreement. As provided in the Rights Agreement, the Purchase Price and the
number of Preferred Shares which may be purchased upon the exercise of the
Rights evidenced by this Right Certificate are subject to modification and
adjustment upon the happening of certain events.

          This Right Certificate is subject to all of the terms, provisions and
conditions of the Rights Agreement, 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 offices of the Company and the
Rights Agent.

          This Right Certificate, with or without other Right Certificates, upon
surrender at the offices 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 one one-thousandths of a Preferred Share 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 Board of
Directors may, at its option, (i) redeem the Rights evidenced by this Right
Certificate at a redemption price of $.001 per Right or (ii) exchange Common
Shares for the Rights evidenced by this Certificate, in whole or in part.

          No fractional Preferred Shares will be issued upon the exercise of any
Right or Rights evidenced hereby (other than fractions of Preferred Stock which
are integral multiples of one one-thousandth of a share of Preferred Stock,
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, as such, 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 

                                      B-2
<PAGE>
 
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.

          If any term, provision, covenant or restriction of the Rights
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 the Rights Agreement shall remain in full force
and effect and shall in no way be affected, impaired or invalidated.

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

          WITNESS the facsimile signature of the proper officers of the Company
and its corporate seal.  Dated as of _______________.

Attest:                         AMGEN INC.


By ______________________       By _________________________________
 Title:                                     Title:


Countersigned:

AMERICAN STOCK TRANSFER & TRUST COMPANY


By_____________________________
 Authorized Signature

                                      B-3
<PAGE>
 
                  [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 and the Rights evidenced thereby, 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
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.

                                      B-4
<PAGE>
 
- --------------------------------------------------------------------------------


The undersigned hereby certifies by checking the appropriate boxes that:

          (1) the Rights evidenced by this Right Certificate    [  ] are [  ]
are not beneficially owned by an Acquiring Person or an Affiliate or an
Associate thereof; and

          (2) after due inquiry and to the best knowledge of the undersigned,
the undersigned [  ] did [  ] did not acquire the Rights evidenced by this Right
Certificate from any person who is, was or subsequently became an Acquiring
Person or an Affiliate or Associate thereof.

Dated:  __________________



                                     ------------------------------
                                     Signature

                                      B-5
<PAGE>
 
                         FORM OF ELECTION TO PURCHASE
                         ----------------------------

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

To: Amgen 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 (or such other securities of the
Company or of any other Person which may be issuable upon the exercise of the
Rights) and requests that certificates for such 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

Signature Guaranteed:

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

                                      B-6
<PAGE>
 
       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.

                                      B-7
<PAGE>
 
The undersigned hereby certifies by checking the appropriate boxes that:

       (1) the Rights evidenced by this Right Certificate [  ] are [  ] are not
beneficially owned by an Acquiring Person or an Affiliate or an Associate
thereof; and

       (2) after due inquiry and to the best knowledge of the undersigned, the
undersigned
[  ] did [  ] did not acquire the Rights evidenced by this Right Certificate
from any person who is, was or subsequently became an Acquiring Person or an
Affiliate or Associate thereof.

Dated:_______________

                                ________________________
                                Signature


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

                                 NOTICE
                                 ------

       The signature in the foregoing Form of Assignment and Form of Election to
Purchase 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 Form of Election to Purchase is not completed, the Company will deem the
beneficial owner of the Rights evidenced by this Right Certificate to be an
Acquiring Person or an Affiliate or Associate hereof and, in the case of an
Assignment, will affix a legend to that effect on any Right Certificates issued
in exchange for this Right Certificate.

                                      B-8
<PAGE>
 
                                                                       EXHIBIT C
                                                                       ---------

        As described in the Rights Agreement, Rights which are held by
        --------------------------------------------------------------
      or have been held by Acquiring Persons or Associates or Affiliates
      ------------------------------------------------------------------
   thereof (as defined in the Rights Agreement) shall become null and void.
   ------------------------------------------------------------------------


                         SUMMARY OF RIGHTS TO PURCHASE
                               PREFERRED SHARES

       On February 18, 1997 the Board of Directors of Amgen Inc. (the "Company")
declared a dividend of one Right for each share of common stock, $.0001 par
value (the "Common Shares"), of the Company outstanding at the close of business
on March 21, 1997 (the "Record Date").  As long as the Rights are attached to
the Common Shares, the Company will issue one Right (subject to adjustment) with
each new Common Share so that all such shares will have attached Rights.  When
exercisable, each Right will entitle the registered holder to purchase from the
Company one one-thousandth of a share of Series A Junior Participating Preferred
Stock (the "Preferred Shares") at a price of $225.00 per one one-thousandth of a
Preferred Share, subject to adjustment (the "Purchase Price").  The description
and terms of the Rights are set forth in a Rights Agreement, dated as of
February 18, 1997, as the same may be amended from time to time (the "Rights
Agreement"), between the Company and American Stock Transfer & Trust Company, as
Rights Agent (the "Rights Agent").

       Until the earlier to occur of (i) ten (10) days following a public
announcement that a person or group of affiliated or associated persons has
acquired, or obtained the right to acquire, beneficial ownership of 10% or more
of the Common Shares (or in the case of an Approved Stockholder (as defined
below), 20% or more of the Common Shares) (an "Acquiring Person") or (ii) ten
business (10) days following the commencement 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 10% or more of the Common
Shares (the earlier of (i) and (ii) being called the "Distribution Date"), the
Rights will be evidenced, with respect to any of the Common Share certificates
outstanding as of the Record Date, by such Common Share certificate together
with a copy of this Summary of Rights.  An "Approved Stockholder" means any
stockholder who is approved by a majority of the directors who are neither
officers or employees of the Company or representatives of an Acquiring Person
or an Approved Stockholder ("Outside Directors") and who enters into a
standstill agreement with the Company so long as such person owns less than 20%
of the outstanding Common Shares.  All provisions in the Rights Agreement
relating to "Approved Stockholder" automatically terminate on March 12, 2004.

       The Rights Agreement provides that until the Distribution Date (or
earlier redemption or expiration of the Rights), the Rights will be transferred
with and only with the Common Shares.  Until the Distribution Date (or earlier
redemption or expiration of the Rights), new Common Share certificates issued
after the close of business on the Record Date upon transfer or new issuance of
the Common Shares will contain a notation incorporating the Rights Agreement by
reference.  Until the Distribution Date (or earlier redemption, exchange,
termination or expiration of the Rights), the surrender for transfer of any
certificates for Common Shares, with or without a copy of this Summary 

                                      C-1
<PAGE>
 
of Rights, will also constitute the transfer of the Rights associated with the
Common Shares represented by such certificate. As soon as practicable following
the Distribution Date, separate certificates evidencing the 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 Rights.

       The Rights are not exercisable until the Distribution Date.  The Rights
will expire on March 21, 2007, subject to the Company's right to extend such
date (the "Final Expiration Date"), unless earlier redeemed or exchanged by the
Company or terminated.

       Each Preferred Share purchasable upon exercise of the Rights will be
entitled to a minimum preferential quarterly dividend payment of $1.00 per share
but will be entitled to an aggregate dividend of 1,000 times the dividend, if
any, 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 per share 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
and will vote 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 received
per Common Share.  These rights are protected by customary antidilution
provisions.  Because of the nature of the Preferred Share's dividend,
liquidation and voting rights, the value of one one-thousandth of a Preferred
Share purchasable upon exercise of each Right should approximate the value of
one Common Share.

       The Purchase Price payable, and the number of Preferred Shares or other
securities or property issuable, upon exercise of the 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
or warrants to subscribe for or purchase Preferred Shares or convertible
securities at less than the current market price of the Preferred Shares or
(iii) upon the distribution to holders of the Preferred Shares of evidences of
indebtedness, cash, securities or assets (excluding regular periodic cash
dividends at a rate not in excess of 125% of the rate of the last regular
periodic cash dividend theretofore paid or, in case regular periodic cash
dividends have not theretofore been paid, at a rate not in excess of 50% of the
average net income per share of the Company for the four quarters ended
immediately prior to the payment of such dividend, or dividends payable in
Preferred Shares (which dividends will be subject to the adjustment described in
clause (i) above)) or of subscription rights or warrants (other than those
referred to above).

       In the event that a Person becomes an Acquiring Person or if the Company
were the surviving corporation in a merger with an Acquiring Person or any
affiliate or associate of an Acquiring Person and the Common Shares were not
changed or exchanged, each holder of a Right, other than Rights that are or were
acquired or beneficially owned by the Acquiring Person (which Rights will
thereafter be void), will thereafter have the right to receive upon exercise
that number of Common Shares having a market value of two times the then current
Purchase Price of the Right.  With certain exceptions, in the event that the
Company were acquired in a merger or other business combination transaction or
more than 50% of its assets or earning power were sold, proper provision 

                                      C-2
<PAGE>
 
shall be made so that each holder of a Right shall thereafter have the right to
receive, upon the exercise thereof at the then current Purchase Price of the
Right, that number of shares of common stock of the acquiring company which at
the time of such transaction would have a market value of two times the then
current Purchase Price of the Right.

       At any time after a Person becomes an Acquiring Person and prior to the
acquisition by such Acquiring Person of 50% or more of the outstanding Common
Shares, the Board of Directors may cause the Company to acquire the Rights
(other than Rights owned by an Acquiring Person which have become void), in
whole or in part, in exchange for one Common Share per Right (subject to
adjustment).

       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 shares will be issued and in lieu thereof, a payment in cash will be
made based on the market price of the Preferred Shares on the last trading date
prior to the date of exercise.

       The Rights may be redeemed in whole, but not in part, at a price of $.001
per Right (the "Redemption Price") by the Board of Directors at any time prior
to the time that an Acquiring Person has become such.  The redemption of the
Rights may be made effective at such time, on such basis and with such
conditions as the Board of Directors in its sole discretion may establish.
Immediately upon any redemption of the Rights, the right to exercise the Rights
will terminate and the only right of the holders of Rights will be to receive
the Redemption Price.

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

       Subject to the last sentence of this paragraph, any of the provisions of
the Rights Agreement may be amended by the Board of Directors of the Company for
so long as the Rights are then redeemable, and after the Rights are no longer
redeemable, the Company may amend or supplement the Rights Agreement in any
manner that does not adversely affect the interests of the holders of the
Rights.  Notwithstanding anything herein to the contrary, any supplement or
amendment to the Rights Agreement shall require the affirmative vote of a
majority of the Outside Directors, and any extension of the Final Expiration
Date shall require the affirmative vote of three-quarters of the Outside
Directors.

       A copy of the Rights Agreement has been filed with the Securities and
Exchange Commission as an Exhibit to a Current Report on Form 8-K.  A copy of
the Rights Agreement is available free of charge from the Company.  This summary
description of the Rights does not purport to be complete and is qualified in
its entirety by reference to the Rights Agreement, which is incorporated herein
by reference.

                                      C-3

<PAGE>
 
                                                                      EXHIBIT 99



                     AMGEN DECLARES DIVIDEND DISTRIBUTION
                      OF PREFERRED SHARE PURCHASE RIGHTS

         Board Adopts New Rights Plan to Replace Existing Rights Plan

FOR IMMEDIATE RELEASE

     THOUSAND OAKS, Calif., February 19, 1997 -- The Amgen (NASDAQ: AMGN) Board
of Directors has declared a dividend distribution of one Preferred Share
Purchase Right on each outstanding share of Amgen common stock. Each Right will
entitle stockholders to buy one one-thousandth of a share of newly created
Series A Junior Participating Preferred Stock of the Company at an exercise
price of $225.00. Subject to limited exceptions, the Rights will be exercisable
if a person or group acquires 10 percent or more of the Company's common stock
or announces a tender offer for 10 percent or more of the common stock. The
Amgen Board will be entitled to redeem the Rights at $.001 per Right at any time
before a person has acquired 10 percent or more of the outstanding common stock.

     The Rights will replace Amgen's existing shareholder rights plan which will
be redeemed effective March 21, 1997. In connection with the redemption,
shareholders of record on that date will receive $.0008 per right.

     "The new Rights, like the Company's existing rights, are intended to enable
all Amgen stockholders to realize the long-term value of their investment in the
Company. They do not prevent a takeover, but should encourage anyone seeking to
acquire the Company to negotiate with the Board of Directors prior to attempting
a takeover," said George A. Vandeman, senior 
<PAGE>
 
vice president, general counsel and secretary of Amgen. "The new Rights Plan,
while very similar to our existing plan, contains certain provisions that
improve the structure of the plan, many of which have become more prevalent
since our existing plan was adopted in 1989. The new Rights Plan will expire in
2007, whereas the existing plan was scheduled to expire in January 1999," Mr.
Vandeman added.

     The Rights are not being distributed in response to any specific effort to
acquire control of the Company. The new Rights, like the existing rights, are
designed to assure that all Amgen stockholders receive fair and equal treatment
in the event of any proposed takeover of the Company and to guard against
partial tender offers, open market accumulations and other abusive tactics to
gain control of Amgen without paying all stockholders a control premium.

     The key provisions of the new Rights Plan are essentially the same in
purpose and effect as the existing plan being redeemed. If a person becomes an
Acquiring Person, each Right will entitle its holder to purchase, at the Right's
then-current exercise price, a number of Amgen common shares having a market
value at that time of twice the Right's exercise price. Rights held by the
Acquiring Person will become void and will not be exercisable to purchase shares
at the bargain purchase price. An Acquiring Person is defined as a person who
acquires 10 percent or more of the outstanding common stock of Amgen; except
that in certain limited circumstances approved by the Amgen Board described
below, a person may acquire up to 20 percent of the outstanding common stock. If
Amgen is acquired in a merger or other business combination transaction which
has not been approved by the Board of Directors, each Right will entitle its

                                       2
<PAGE>
 
holder to purchase, at the Right's then-current exercise price, a number of the
acquiring company's common shares having a market value at that time of twice
the Right's exercise price.

     The new Rights Plan provides that under certain limited circumstances
approved by the outside directors of the Board, a stockholder who enters into an
acceptable standstill agreement may acquire up to 20 percent of the outstanding
shares without triggering the Rights, and provides that amendments to the Plan
will require approval of the Company's outside directors. The Company agreed to
include these provisions in the new Rights Plan in connection with the
settlement of a lawsuit brought in 1995 which challenged previous amendments to
the rights plan. The new Rights Plan will carry forward the substance of the
challenged amendments.

     The dividend distribution to establish the new Rights Plan will be payable
to stockholders of record on March 21, 1997. The Rights will expire in ten
years. The Rights distribution is not taxable to stockholders, however
distribution of the $.0008 cash per share redemption price generally should be
treated as a taxable dividend.

     Amgen is a global biotechnology company that discovers, develops,
manufactures and markets human therapeutics based on advances in cellular and
molecular biology.


CONTACT: Amgen Thousand Oaks
David Kaye, 805/447-6692 (media)
Denise Powell, 805/447-4346 (investors)

EDITOR'S NOTE:  An electronic version of this news release may be accessed via
our web site at www.Amgen.com. Visit the Corporate Center and click on Amgen
News. Journalists and media representatives may sign up to receive all news
releases electronically at time of announcement by filling out a short form in
the Amgen News section of the web site.

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