<PAGE>   1
                       SECURITIES AND EXCHANGE COMMISSION

                             Washington, D.C. 20549

                                _______________


                                    FORM 8-A



                FOR REGISTRATION OF CERTAIN CLASSES OF SECURITIES
                     PURSUANT TO SECTION 12(b) OR (g) OF THE
                         SECURITIES EXCHANGE ACT OF 1934



                        IDEC PHARMACEUTICALS CORPORATION
- --------------------------------------------------------------------------------
               (Exact name of registrant as specified in charter)


             DELAWARE                        0-19311            33-0112644
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(State of incorporation or organization)  (Commission         (IRS Employer
                                           File Number)     Identification No.)

11011 TORREYANA ROAD, SAN DIEGO, CALIFORNIA                      92121
- --------------------------------------------------------------------------------
(Address of principal executive offices)


Registrant's telephone number, including area code      (619) 550-8500

Securities to be registered pursuant to Section 12(b) of the Act:

                        PREFERRED SHARE PURCHASE RIGHTS
- --------------------------------------------------------------------------------
                                (Title of Class)


Securities to be registered pursuant to Section 12(g) of the Act:


                                      NONE
- --------------------------------------------------------------------------------
                                (Title of Class)








<PAGE>   2
Item 1.  Description of Registrant's Securities to be Registered

                 On July 22, 1997, the Board of Directors of IDEC
Pharmaceuticals Corporation (the "Company") declared a dividend of one preferred
share purchase right (a "Right") for each outstanding share of common stock,
$0.001 par value (the "Common Shares"), of the Company.  The dividend is payable
on August 11, 1997 (the "Record Date") to the stockholders of record on that
date.  Each Right entitles the registered holder to purchase from the Company
one one-thousandth of a share of Series X Junior Participating Preferred Stock,
$0.001 par value (the "Preferred Shares"), of the Company at a price of $200.00
per one one-thousandth of a Preferred Share (the "Purchase Price"), subject to
adjustment.  The description and terms of the Rights are set forth in a Rights
Agreement (the "Rights Agreement") between the Company and ChaseMellon
Shareholder Services LLC, as Rights Agent (the "Rights Agent").

                 Until the earlier to occur of (i) ten (10) business days
following a public announcement that a person or group of affiliated or
associated persons (an "Acquiring Person") have acquired beneficial ownership
of 15% or more of the outstanding Common Shares or (ii) ten (10) business days
(or such later date as may be determined by action of the Board of Directors
prior to such time as any Person becomes an Acquiring Person) following either
the commencement of, or announcement of an intention to make, a tender offer or
exchange offer, the consummation of which would result in the beneficial
ownership by a person or group of 15% or more of such outstanding Common Shares
(the earlier of such dates 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 Agreement provides that, until the Distribution
Date, 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 Record Date, upon
transfer or new issuance of Common Shares, will contain a notation
incorporating the Rights Agreement by reference.  Until the Distribution Date
(or earlier redemption or expiration of the Rights), the surrender for transfer
of any certificates for Common Shares outstanding as of the Record Date 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 ("Rights
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 Rights
Certificates alone will evidence the Rights.

                 The Rights are not exercisable until the Distribution Date.
The Rights will expire at the close of business on July 22, 2007 (the "Final
Expiration Date"), unless the Final Expiration Date is extended or unless the
Rights are earlier redeemed by the Company, in each case as described below.

                 The Purchase Price payable, and the number of Preferred Shares
or other securities or property issuable, upon exercise of the 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 at a
price, or securities convertible into Preferred Shares with a conversion price,
less than the then-current market price of the Preferred Shares; or (iii) upon
the distribution to holders of the Preferred Shares of evidences of
indebtedness or assets (excluding regular periodic cash dividends paid out of
earnings or retained earnings or dividends payable in Preferred Shares) or of
subscription rights or warrants (other than those referred to above).

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





                                       2.

<PAGE>   3
                 Preferred Shares purchasable upon exercise of the Rights will
not be redeemable.  Each Preferred Share will be entitled to an aggregate
dividend of 1000 times the dividend declared per Common Share.  In the event of
liquidation, the holders of the Preferred Shares will be entitled to an
aggregate payment of 1000 times the payment made per Common Share.  Each
Preferred Share will have 1000 votes, voting together with the Common Shares.
Finally, in the event of any merger, consolidation or other transaction in
which Common Shares are exchanged, each Preferred Share will be entitled to
receive 1000 times the amount received per Common Share.  These rights are
protected by customary antidilution provisions.

                 Because of the nature of the Preferred Shares' dividend,
liquidation and voting rights, the value of the one one-thousandth interest in
a Preferred Share purchasable upon exercise of each Right should approximate
the value of one Common Share.

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

                 In the event that any person or group of affiliated or
associated persons becomes the beneficial owner of 15% or more of the
outstanding Common Shares (except pursuant to a tender offer for all of the
Common Shares at a price and on terms determined by a majority of the
Continuing Directors to be fair to and otherwise in the best interests of the
Company and its stockholders), each holder of a Right, other than Rights
beneficially owned by the Acquiring Person (which will thereafter be void),
will thereafter have the right to receive, upon exercise, that number of Common
Shares (or cash, other securities or property) having a market value of two
times the exercise price of the Right.

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

                 At any time prior to the tenth (10th) business day after the
Distribution Date (unless the Board of Directors extends such ten (10) day
period), the Board of Directors of the Company may redeem the Rights in whole,
but not in part, at a price of $0.001 per Right (the "Redemption Price").  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.  The Rights are also redeemable under
other circumstances as specified in the Rights Agreement.

                 The terms of the Rights may be amended by the Board of
Directors of the Company without the consent of the holders of the Rights,
including an amendment to lower certain thresholds described above to not less
than the greater of (i) any percentage greater than the largest percentage of
the outstanding Common Shares then known to the Company to be beneficially
owned by any person or group of affiliated or associated persons and (ii) 10%,
except that, from and after the Distribution Date, no such amendment may
adversely affect the interests of the holders of the Rights.

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





                                       3.

<PAGE>   4
                 The Rights have certain anti-takeover effects.  The Rights
will cause substantial dilution to a person or group that attempts to acquire
the Company on terms not approved by the Company's Board of Directors, except
pursuant to an offer conditioned on a substantial number of Rights being
acquired.  The Rights should not interfere with any merger or other business
combination approved by the Board of Directors, since the Rights may be
redeemed by the Company at the Redemption Price prior to the  occurrence of a
Distribution Date.

                 The Rights Agreement, dated as of July 22, 1997, between the
Company and the Rights Agent, specifying the terms of the Rights, is attached
hereto as an exhibit and is incorporated herein by reference.  The foregoing
description of the Rights is qualified in its entirety by reference to such
exhibit.


Item 2.  Exhibits.

1.       Form of Rights Certificate is included as Exhibit B to Exhibit 2
         below.

2.       Rights Agreement, dated as of July 22, 1997, between the Company and
         ChaseMellon Shareholder Services LLC, which includes the form of
         Certificate of Designation for the Series X Junior Participating 
         Preferred Stock as Exhibit A, the form of Rights Certificate as 
         Exhibit B and the Summary of Rights to Purchase Preferred Shares as 
         Exhibit C.  Pursuant to the Rights Agreement, printed Rights 
         Certificates will not be mailed until as soon as practicable after 
         the earlier of the tenth (10th) business day after public announcement
         that a person or group has acquired beneficial ownership of 15% or 
         more of the Common Shares or the tenth (10th) business day (or such 
         later date as may be determined by action of the Board of Directors) 
         after a person commences, or announces its intention to commence, a 
         tender offer or exchange offer, the consummation of which would result
         in the beneficial ownership by a person or group of 15% or more of 
         the Common Shares
















                                       4.





<PAGE>   5
                                   SIGNATURE

     Pursuant to the requirements of Section 12 of the Securities Exchange Act
of 1934, the registrant has duly caused this registration statement to be
signed on its behalf by the undersigned, thereto duly authorized.



                                          IDEC PHARMACEUTICALS CORPORATION



DATE:  July 31, 1997                      By:  /s/ William H. Rastetter, Ph.D.
- ---------------------------                  ---------------------------------
                                          Name:    William H. Rastetter, Ph.D.
                                          Title:   Chairman, President and
                                                   Chief Executive Officer


















<PAGE>   6
                                 EXHIBIT INDEX


EXHIBIT
NUMBER                            DOCUMENT DESCRIPTION


1.       Form of Rights Certificate is included as Exhibit B to Exhibit 2
         below.

2.       Rights Agreement, dated as of July 22, 1997, between the Company and
         ChaseMellon Shareholder Services LLC, which includes the form of
         Certificate of Designation for the Series X Junior Participating
         Preferred Stock as Exhibit A, the form of Rights Certificate as
         Exhibit B and the Summary of Rights to Purchase Preferred Shares as
         Exhibit C.  Pursuant to the Rights Agreement, printed Rights
         Certificates will not be mailed until as soon as practicable after the
         earlier of the tenth (10th) business day after public announcement
         that a person or group has acquired beneficial ownership of 15% or
         more of the Common Shares or the tenth (10th) business day (or such
         later date as may be determined by action of the Board of Directors)
         after a person commences, or announces its intention to commence, a
         tender offer or exchange offer the consummation of which would result
         in the beneficial ownership by a person or group of 15% or more of the
         Common Shares
























                                       6.







<PAGE>   1

                                                                     


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




                        IDEC PHARMACEUTICALS CORPORATION




                                      and




                      CHASEMELLON SHAREHOLDER SERVICES LLC



                                  Rights Agent




                                Rights Agreement

                           Dated as of July 22, 1997




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





<PAGE>   2
                               TABLE OF CONTENTS



<TABLE>
<CAPTION>
                                                                                                                          PAGE
                                                                                                                          ----
<S>              <C>                                                                                                       <C>
Section 1.       Certain Definitions  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .   1

Section 2.       Appointment of Rights Agent  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .   6

Section 3.       Issue of Rights Certificates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .   6

Section 4.       Form of Rights Certificates  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .   8

Section 5.       Countersignature and Registration  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .   8

Section 6.       Transfer, Split-Up, Combination and Exchange of Rights Certificates; Mutilated, Destroyed, Lost or
                 Stolen Rights Certificates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .   8

Section 7.       Exercise of Rights; Purchase Price; Expiration Date of Rights  . . . . . . . . . . . . . . . . . . . . .   9

Section 8.       Cancellation and Destruction of Rights Certificates  . . . . . . . . . . . . . . . . . . . . . . . . . .  10

Section 9.       Availability of Preferred Shares . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  11

Section 10.      Preferred Shares Record Date . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  12

Section 11.      Adjustment of Purchase Price, Number of Shares or Number of Rights . . . . . . . . . . . . . . . . . . .  13

Section 12.      Certificate of Adjusted Purchase Price or Number of Shares . . . . . . . . . . . . . . . . . . . . . . .  21

Section 13.      Consolidation, Merger or Sale or Transfer of Assets or Earning Power . . . . . . . . . . . . . . . . . .  21

Section 14.      Fractional Rights and Fractional Shares  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  23

Section 15.      Rights of Action . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  24

Section 16.      Agreement of Rights Holders  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  24

Section 17.      Rights Certificate Holder Not Deemed a Stockholder . . . . . . . . . . . . . . . . . . . . . . . . . . .  25

Section 18.      Concerning
 the Rights Agent  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  25
</TABLE>






                                       i.



<PAGE>   3


<TABLE>
<S>              <C>                                                                                                       <C>
Section 19.      Merger or Consolidation or Change of Name of Rights Agent  . . . . . . . . . . . . . . . . . . . . . . .  26

Section 20.      Duties of Rights Agent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  27

Section 21.      Change of Rights Agent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  29

Section 22.      Issuance of New Rights Certificates  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  30

Section 23.      Redemption . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  30

Section 24.      Exchange . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  31

Section 25.      Notice of Certain Events . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  33

Section 26.      Notices  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  34

Section 27.      Supplements and Amendments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  35

Section 28.      Successors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  35

Section 29.      Determinations and Actions by the Board of Directors . . . . . . . . . . . . . . . . . . . . . . . . . .  35

Section 30.      Benefits of this Agreement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  36

Section 31.      Severability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  36

Section 32.      Governing Law  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  36

Section 33.      Counterparts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  37

Section 34.      Descriptive Headings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  37
</TABLE>



EXHIBIT A        Form of Certificate of Designation of Series X Junior
                 Participating Preferred Stock of IDEC Pharmaceuticals 
                 Corporation
EXHIBIT B        Form of Rights Certificate
EXHIBIT C        Summary of Rights To Purchase Preferred Shares







                                      ii.


<PAGE>   4
                                RIGHTS AGREEMENT



                 Rights Agreement, dated as of July 22, 1997 between IDEC
Pharmaceuticals Corporation, a Delaware corporation (the "Company"), and
ChaseMellon Shareholder Services LLC, a national banking association (the
"Rights Agent").

                 The Board of Directors of the Company has authorized and
declared a dividend of one preferred share purchase right (a "Right") for each
Common Share (as hereinafter defined) of the Company outstanding as of the Close
of Business (as hereinafter defined) on August 11, 1997 (the "Record Date"),
each Right representing the right to purchase one one-thousandth (1/1000th) of a
Preferred Share (as hereinafter defined) upon the terms and subject to the
conditions herein set forth, and has further authorized and directed the
issuance of one Right with respect to each Common Share that shall become
outstanding between the Record Date and the earliest of the Distribution Date,
the Redemption Date or the Final Expiration Date (as such terms are hereinafter
defined).

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

                 Section 1.       Certain Definitions.  For purposes of this
Agreement, the following terms have the meanings indicated:

                 (a)      "Acquiring Person" shall mean any Person (as such
term is hereinafter defined) who or which, together with all Affiliates and
Associates (as such terms are hereinafter defined) of such Person, shall be the
Beneficial Owner (as such term is hereinafter defined) of 15% or more of the
Common Shares of the Company then outstanding, but shall not include the
Company, any Subsidiary (as such term is hereinafter defined) of the Company,
any employee benefit plan of the Company or any Subsidiary of the Company, or
any entity holding Common Shares for or pursuant to the terms of any such plan.
Notwithstanding the foregoing:

                      (i)         No Person 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
         15% or more of the Common Shares of the Company then outstanding;
         provided, however, that if a Person shall become the Beneficial Owner
         of 15% or more of the Common Shares of the Company then outstanding 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";

<PAGE>   5

                      (ii)        If the Board of Directors of the Company
         determines (upon approval by a majority of the Continuing Directors
         (as such term is hereinafter defined)), in good faith, that a Person
         who would otherwise be an Acquiring Person, as defined pursuant to the
         foregoing provisions of this paragraph (a), is eligible to file and
         did file a Schedule 13G, and such Person divests as promptly as
         practicable a sufficient number of Common Shares so that such Person
         would no longer be an Acquiring Person, as defined pursuant to the
         foregoing provisions of this paragraph (a), then such Person shall not
         be deemed to be an "Acquiring Person" for any purpose of this
         Agreement; and

                    (iii)         No Person shall become an "Acquiring Person"
         if the transaction or series of related transactions in which such
         Person (together with all Affiliates or Associates of such Person)
         became the Beneficial Owner of 15% or more of the Common Shares of the
         Company then outstanding had received prior approval of a majority of
         the Continuing Directors; provided, however, that in the event a
         Person is not an Acquiring Person by reason of this clause (iii) of
         this Section 1(a), such Person shall become an Acquiring Person, in
         the event such Person thereafter acquires Beneficial Ownership of any
         additional Common Shares, unless such acquisition of such additional
         Common Shares would not result in such Person becoming an Acquiring
         Person by reason of any provision of this Agreement, including,
         without limitation, this clause (iii) of this Section 1(a).

                 (b)      "Affiliate" and "Associate" shall have the respective
meanings ascribed to such terms in Rule 12b-2 of the General Rules and
Regulations under the Exchange Act (as such term is hereinafter defined).

                 (c)      A Person shall be deemed the "Beneficial Owner" of
and shall be deemed to "beneficially own" any securities:

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

                      (ii)        Which such Person or any of such Person's
Affiliates or Associates has:

                          (A)     the right to acquire (whether such right is
         exercisable immediately or only after the passage of time) pursuant to
         any agreement, arrangement or understanding (other than customary
         agreements with and between underwriters and selling group members
         with respect to a bona fide public offering of securities), or upon
         the exercise of conversion rights, exchange rights, rights (other than
         these Rights), warrants or options, or otherwise; provided, however,
         that a Person shall not be deemed the Beneficial Owner of, or to
         beneficially own: (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





                                       2.

<PAGE>   6
         securities are accepted for purchase or exchange or (2) securities
         which a Person or any Person's Affiliates or Associates 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 such Person's Affiliates or Associates) if such agreement has
         been approved by the Board of Directors of the Company, upon the
         affirmative vote of a majority of the Continuing Directors, prior to
         there being an Acquiring Person; or

                          (B)     The right to vote pursuant to any agreement,
         arrangement or understanding; provided, however, that a Person shall
         not be deemed the Beneficial Owner of, or to beneficially own, any
         security if the agreement, arrangement or understanding to vote such
         security (1) arises solely from a revocable proxy or consent given to
         such Person in response to a public proxy or consent solicitation made
         pursuant to, and in accordance with, the applicable rules and
         regulations promulgated under the Exchange Act and (2) is not also
         then reportable on Schedule 13D under the Exchange Act (or any
         comparable or successor report);

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

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

                 (d)      "Business Day" shall mean any day other than a
Saturday, a Sunday, or a day on which banking institutions in the State of
California or the state in which the principal office of the Rights Agent is
located are authorized or obligated by law or executive order to close.

                 (e)      "Company" shall have the meaning set forth in the
first paragraph at the beginning of this Agreement.

                 (f)      "Close of Business" on any given date shall mean 
5:00 P.M., Eastern time, on such date; provided, however, that if such date is
not a Business Day it shall mean 5:00 P.M., Eastern time, on the next succeeding
Business Day.





                                       3.

<PAGE>   7
                 (g)      "Common Shares" when used with reference to the
Company shall mean the shares of common stock of the Company.  "Common Shares"
when used with reference to any Person other than the Company shall mean the
capital stock (or other equity interest) with the greatest voting power of such
other Person or, if such other Person is a Subsidiary of another Person, the
Person or Persons which ultimately control such first-mentioned Person.

                 (h)      "Common Stock Equivalents" shall have the meaning set
forth in Section 11(a)(iv) hereof.

                 (i)      "Continuing Director" shall mean (i) any person who
is, while a member of the Board of Directors of the Company, not an Acquiring
Person, or an Affiliate or Associate of an Acquiring Person, or a
representative or agent of an Acquiring Person or of any such Affiliate or
Associate, and who was a member of the Board of Directors prior to the date of
this Agreement, or (ii) any person who subsequently becomes a member of the
Board of Directors and who, is a member of the Board of Directors, is not an
Acquiring Person or an Affiliate or Associate of an Acquiring Person, or a
representative or agent of an Acquiring Person or of any such Affiliate or
Associate, if such Person's nomination for election or such Person's election
to the Board of Directors is recommended or approved by a majority of the
Continuing Directors then on the Board of Directors.

                 (j)      "Current Per-Share Market Price" shall have the
meaning set forth in Section 11(d)(i) hereof.

                 (k)      "Current Value" shall have the respective meanings
set forth in Section 11(a)(iv) hereof and Section 24 hereof.

                 (l)      "Distribution Date" shall have the meaning set forth
in Section 3 hereof.

                 (m)      "Equivalent Preferred Shares" shall have the meaning
set forth in Section 11(b) hereof.

                 (n)      "Exchange Act" shall mean the Securities Exchange Act
of 1934, as amended, as in effect on the date of this Agreement.

                 (o)      "Exchange Ratio" shall have the meaning set forth in
Section 24 hereof.

                 (p)      "Final Expiration Date" shall have the meaning set
forth in Section 7 hereof.

                 (q)      "Issuer" shall have the meaning set forth in Section
13 hereof

                 (r)      "Person" shall mean any individual, firm, corporation
or other entity, and shall include any successor (by merger or otherwise) of
such entity.









                                       4.



<PAGE>   8

                 (s)      "Preferred Shares" shall mean shares of Series X
Junior Participating Preferred Shares, par value .001, of the Company having
the rights and preferences set forth in the Form of Certificate of Designations
attached to this Agreement as Exhibit A.

                 (t)      "Purchase Price" shall have the meaning set forth in
Section 4 hereof.

                 (u)      "Record Date" shall have the meaning set forth in the
second paragraph at the beginning of this Agreement.

                 (v)      "Redemption Date" shall have the meaning set forth in
Section 7 hereof.

                 (w)      "Redemption Price" shall have the meaning set forth
in Section 23 hereof.

                 (x)      "Right" shall have the meaning set forth in the
second paragraph at the beginning of this Agreement.

                 (y)      "Rights Certificate" shall have the meaning set forth
in Section 3 hereof.

                 (z)      "Rights Agent" shall have the meaning set forth in
the first paragraph at the beginning of this Agreement.

                 (aa)     "Securities Act" shall have the meaning set forth in
Section 9 hereof.

                 (ab)     "Security" shall have the meaning set forth in
Section 11(d)(i) hereof.

                 (ac)     "Shares Acquisition Date" shall mean the first date
of public announcement (which, for purposes of this definition, shall include,
without limitation, a report filed pursuant to Section 13(d) of the Exchange
Act) by the Company or an Acquiring Person that an Acquiring Person has become
such.

                 (ad)     "Spread" shall have the meaning set forth in Section
11(a)(iv) hereof.

                 (ae)     "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 interest is owned, directly or indirectly, by such Person.

                 (af)     "Substitution Period" shall have the meaning set
forth in Section 11(a)(iv) hereof.

                 (ag)     "Summary of Rights" shall have the meaning set forth
in Section 3 hereof.





                                       5.

<PAGE>   9

                 (ah)     "Trading Day" shall have the meaning set forth in
Section 11(d)(i) hereof.

                 Section 2. Appointment of Rights Agent.  The Company hereby
appoints the Rights Agent to act as agent for the Company in accordance with
the terms and conditions hereof, and the Rights Agent hereby accepts such
appointment.  The Company may from time to time appoint such co-Rights Agents
as it may deem necessary or desirable upon ten (10) days prior written notice
to the Rights Agent.  The Rights Agent shall have no duty to supervise and
shall in no event be liable for the acts or omissions of any such co-Rights
Agent.

                 Section 3. Issue of Rights Certificates. (a)  Until the
earlier of (i) the tenth day after the Shares Acquisition Date or (ii) the
tenth business day (or such later date as may be determined by action of the
Board of Directors (upon approval by a majority of the Continuing Directors)
prior to such time as any Person becomes an Acquiring Person) after the date of
the commencement by any Person (other than the Company, any Subsidiary of the
Company, any employee benefit plan of the Company or of any Subsidiary of the
Company or any entity holding Common Shares for or pursuant to the terms of any
such plan) of, or of the first public announcement of the intention of any
Person (other than the Company, any Subsidiary of the Company, any employee
benefit plan of the Company or of any Subsidiary of the Company or any entity
holding Common Shares for or pursuant to the terms of any such plan) to
commence a tender or exchange offer, the consummation of which would result in
any Person becoming the Beneficial Owner of Common Shares aggregating 15% or
more of the then-outstanding Common Shares (including any such date which is
after the date of this Agreement and prior to the issuance of the Rights; the
earlier of such dates being herein referred to as the "Distribution Date"), (x)
the Rights will be evidenced (subject to the provisions of Section 3(b) hereof)
by the certificates for Common Shares registered in the names of the holders
thereof (which certificates shall also be deemed to be Rights Certificates) and
not by separate Rights Certificates, and (y) the right to receive Rights
Certificates will be transferable only in connection with the transfer of
Common Shares.  As soon as practicable after the Distribution Date, the Company
will notify the Rights Agent thereof and the Company will prepare and execute,
the Rights Agent will countersign, and the Company will send or cause to be
sent (and the Rights Agent will, if requested, send) by first-class, insured,
postage-prepaid mail, to each record holder of Common Shares as of the Close of
Business on the Distribution Date, at the address of such holder shown on the
records of the Company, a Rights Certificate, in substantially the form of
Exhibit B hereto (a "Rights Certificate"), evidencing one Right for each Common
Share so held.  As of the Distribution Date, the Rights will be evidenced
solely by such Rights Certificates.

                 (b)      On the Record Date, or as soon as practicable
thereafter, the Company will send a copy of a Summary of Rights to Purchase
Preferred Shares, in substantially the form of Exhibit C hereto (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





                                       6.

<PAGE>   10
the address of such holder shown on the records of the Company.  With respect
to certificates for Common Shares outstanding as of the Record Date, until the
Distribution Date, the Rights will be evidenced by such certificates registered
in the names of the holders thereof together with a copy of the Summary of
Rights attached thereto.  Until the Distribution Date (or the earlier of the
Redemption Date or the Final Expiration Date), the surrender for transfer of
any certificate for Common Shares outstanding on the Record Date, with or
without a copy of the Summary of Rights attached thereto, shall also constitute
the transfer of the Rights associated with the Common Shares represented
thereby.

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

          This  certificate  also  evidences  and  entitles the holder
          hereof to certain rights as set forth in a Rights  Agreement
          between IDEC  Pharmaceuticals  Corporation  and  ChaseMellon
          Shareholder  Services  LLC,  dated as of July 22,  1997 (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   IDEC
          Pharmaceuticals Corporation 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.   IDEC   Pharmaceuticals
          Corporation  will mail to the holder of this  certificate  a
          copy of the Rights Agreement without charge after receipt of
          a written request therefor. Under certain circumstances,  as
          set  forth in the  Rights  Agreement,  Rights  issued to any
          Person who  becomes an  Acquiring  Person (as defined in the
          Rights Agreement) may become null and void.

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





                                       7.

<PAGE>   11
                 Section 4.       Form of Rights Certificates.  The Rights
Certificates (and the forms of election to purchase Preferred Shares and of
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 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 transaction reporting system on which the Rights may from
time to time be listed, or to conform to usage.  Subject to the provisions of
Section 22 hereof, the Rights Certificates shall entitle the holders thereof to
purchase such number of one one-thousandths of a Preferred Share as shall be
set forth therein at the 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
Rights Certificates shall be executed on behalf of the Company by its Chairman
of the Board, its President, any of its Vice Presidents, or its Treasurer or
Chief Financial Officer, either manually or by facsimile signature; shall have
affixed thereto the Company's seal or a facsimile thereof; and shall be
attested by the Secretary or an Assistant Secretary of the Company, either
manually or by facsimile signature.  The Rights Certificates shall be manually
countersigned by the Rights Agent and shall not be valid for any purpose unless
countersigned.  In case any officer of the Company who shall have signed any of
the Rights Certificates shall cease to be such officer of the Company before
countersignature by the Rights Agent and issuance and delivery by the Company,
such Rights Certificates, nevertheless, may be countersigned by the Rights
Agent and issued and delivered by the Company with the same force and effect as
though the person who signed such Rights Certificates had not ceased to be such
officer of the Company; and any Rights Certificate may be signed on behalf of
the Company by any person who, at the actual date of the execution of such
Rights Certificate, shall be a proper officer of the Company to sign such
Rights Certificate, although at the date of the execution of this Rights
Agreement any such person was not such an officer.

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

                 Section 6.       Transfer, Split-Up, Combination and Exchange
of Rights Certificates; Mutilated, Destroyed, Lost or Stolen Rights
Certificates.  Subject to the provisions of Section 14 hereof, 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 Rights Certificate or Rights Certificates (other than Rights
Certificates representing Rights that have become void pursuant to Section
11(a)(ii) hereof





                                       8.

<PAGE>   12
or that have been exchanged pursuant to Section 24 hereof) may be transferred,
split up, combined or exchanged for another Rights Certificate or Rights
Certificates, entitling the registered holder to purchase a like number of one
one-thousandths of a Preferred Share (or other securities or property) as the
Rights Certificate or Rights Certificates surrendered then entitled such holder
to purchase.  Any registered holder desiring to transfer, split up, combine or
exchange any Rights Certificate or Rights Certificates shall make such request
in writing delivered to the Rights Agent, and shall surrender the Rights
Certificate or Rights Certificates to be transferred, split up, combined or
exchanged at the office of the Rights Agent designated for such purpose.
Thereupon the Rights Agent shall countersign and deliver to the person entitled
thereto a Rights Certificate or Rights Certificates, as the case may be, as so
requested.  The Company may require payment of a sum sufficient to cover any
tax or governmental charge that may be imposed in connection with any transfer,
splitup, combination or exchange of Rights 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 Rights Certificate, and, in case of loss, theft or destruction, of
indemnity or security reasonably satisfactory to them, and, at the Company's
request, reimbursement to the Company and the Rights Agent of all reasonable
expenses incidental thereto, and upon surrender to the Rights Agent and
cancellation of the Rights Certificate if mutilated, the Company will make and
deliver a new Rights Certificate of like tenor to the Rights Agent for delivery
to the registered holder in lieu of the Rights Certificate so lost, stolen,
destroyed or mutilated.

                 Section 7.       Exercise of Rights; Purchase Price;
Expiration Date of Rights. (a)  Except as provided in Section 23(c), the
registered holder of any Rights Certificate may exercise the Rights evidenced
thereby (except as otherwise provided herein) in whole or in part at any time
after the Distribution Date upon surrender of the Rights 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 July 21, 2007, (the
"Final Expiration Date"), (ii) the time at which the Rights are redeemed as
provided in Section 23 hereof (the "Redemption Date"), (iii) the time at which
such Rights are exchanged as provided in Section 24 hereof, or (iv) the
consummation of any merger or other acquisition involving the Company pursuant
to an agreement described in Section l(c)(ii)(A)(2) hereof

                 (b)      The Purchase Price for each one one-thousandth of a
Preferred Share pursuant to the exercise of a Right shall initially be $200.00,
shall be subject to adjustment from time to time as provided in Sections 11 and
13 hereof and shall be payable in lawful money of the United States of America
in accordance with paragraph (c) below.

                 (c)      Upon receipt of a Rights Certificate representing
exercisable Rights, with the form of election to purchase duly executed,
accompanied by payment of the





                                       9.

<PAGE>   13

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 Rights
Certificate in accordance with Section 9 hereof by certified check, 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 (if such transfer agent is an entity other than the Rights
Agent) certificates for the number of Preferred Shares to be purchased and the
Company hereby irrevocably authorizes such transfer agent to comply with all
such requests, or (B) requisition, from a depositary agent properly appointed
by the Company, depositary receipts representing such number of 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 such request; (ii) when appropriate,
requisition from the Company the amount of cash to be paid in lieu of issuance
of fractional shares in accordance with Section 14 hereof; (iii) after receipt
of such certificates or depositary receipts, cause the same to be delivered to
or upon the order of the registered holder of such Rights Certificate,
registered in such name or names as may be designated by such holder; and (iv)
when appropriate, after receipt, deliver such cash to or upon the order of the
registered holder of such Rights Certificate.

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

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

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

                 Section 8.       Cancellation and Destruction of Rights
Certificates.  All Rights 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 cancelled form, or, if surrendered to the Rights Agent,
shall be cancelled by it, and no Rights Certificates shall be issued in lieu
thereof except as





                                      10.

<PAGE>   14
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 Rights Certificate
purchased or acquired by the Company otherwise than upon the exercise thereof.
The Rights Agent shall deliver all cancelled Rights Certificates to the
Company, or shall, at the written request of the Company, destroy such
cancelled Rights Certificates, and in such case shall deliver a certificate of
destruction thereof to the Company.

                 Section 9.       Availability of Preferred Shares.  (a)  The
company covenants and agrees that it will use its best efforts to cause to be
reserved and kept available out of and to the extent of its authorized and
unissued shares of Preferred Stock not reserved for another purpose (and,
following the occurrence of an event described in Section 11(a)(ii) or Section
13(a), out of its authorized and unissued shares of Common Stock and/or other
securities), the number of Preferred Shares (and, following the occurrence of
any such event, Common Stock and/or other securities) that will be sufficient
to permit the exercise in full of all outstanding Rights.

                 (b)      If the Preferred Shares (or, following the occurrence
of an event described in Section 11(a)(ii) or Section 13(a), the Common Shares
and/or other securities) are at any time listed on a national securities
exchange or included for quotation on any transaction reporting system, then so
long as the Preferred Shares (and, following the occurrence of any such event,
Common Shares and/or other securities) issuable and deliverable upon exercise
of the Rights may be listed on such exchange or included for quotation on any
such transaction reporting system, the Company shall use its best efforts to
cause, from and after such time as the Rights become exercisable (but only to
the extent that it is reasonably likely that the Rights will be exercised), all
shares reserved for such issuance to be listed on such exchange or included for
quotation on any such transaction reporting system upon official notice of
issuance upon such exercise.

                 (c)      The Company shall use its best efforts to: (i) file,
as soon as practicable following the earliest date after the first occurrence
of an event described in Section 11(a)(ii) in which the consideration to be
delivered by the Company upon exercise of the Rights has been determined in
accordance with Section 11(a)(iv) hereof, or as soon as is required by law
following the Distribution Date, as the case may be, a registration statement
under the Securities Act of 1933, as amended (the "Securities Act"), with
respect to the securities purchasable upon exercise of the Rights on an
appropriate form; (ii) cause such registration statement to become effective as
soon as practicable after such filing; and (iii) cause such registration
statement to remain effective (with a prospectus at all times meeting the
requirements of the Securities Act) until the earlier of (A) the date as of
which the Rights are no longer exercisable for such securities or (B) the date
of expiration of the Rights.  The Company may temporarily suspend, for a period
not to exceed ninety (90) days after the date set forth in clause (i) of the
first sentence of this Section 9(c), the exercisability of the Rights in order
to prepare and file such registration statement and permit it to become
effective.  Upon any such suspension, the Company shall issue a public





                                      11.

<PAGE>   15
announcement stating, and notify the Rights Agent, that the exercisability of
the Rights has been temporarily suspended, as well as a public announcement and
notification to the Rights Agent at such time as the suspension is no longer in
effect.  The Company will also take such action as may be appropriate under, or
to ensure compliance with, the securities or "blue sky" laws of the various
states in connection with the exercisability of the Rights.  Notwithstanding
any provision of this Agreement to the contrary, the Rights shall not be
exercisable in any jurisdiction, unless the requisite qualification in such
jurisdiction shall have been obtained, or an exemption therefrom shall be
available and until a registration statement has been declared effective.

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

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

                 Section 10.      Preferred Shares Record Date.  Each person in
whose name any certificate for Preferred Shares is issued upon the exercise of
Rights shall, for all purposes, be deemed to have become the holder of record
of the Preferred Shares represented thereby on, and such certificate shall be
dated, the date upon which the Rights 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 transfer books of the Company
are closed, such person shall be deemed to have become the record holder of
such shares on, and such certificate shall be dated, the next succeeding
Business Day on which the Preferred Shares transfer books of the Company are
open.  Prior to the exercise of the Rights evidenced thereby, the holder of a
Rights Certificate shall not be entitled to any rights of a holder of Preferred
Shares for which the Rights shall be exercisable, including, the right to vote,
to receive dividends or other distributions or to exercise any preemptive
rights, and shall not be entitled to receive any notice of any proceedings of
the Company, except as provided herein.





                                      12.

<PAGE>   16

                 Section 11.      Adjustment of Purchase Price, Number of
Shares or Number of Rights.  The Purchase Price, the number of Preferred Shares
covered by each Right and the number of Rights outstanding are subject to
adjustment from time to time as provided in this Section 11.

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

                      (ii)        Subject to Section 24 of this Agreement, in
         the event that any Person becomes an Acquiring Person, each holder of
         a Right shall thereafter have a right to receive, upon exercise
         thereof, at a price equal to the then-current Purchase Price
         multiplied by the number of one-thousandths of a Preferred Share for
         which a Right is then exercisable, in accordance with the terms of
         this Agreement and in lieu of Preferred Shares, such number of Common
         Shares of the Company as shall equal the result obtained by (x)
         multiplying the then-current Purchase Price by the number of one
         one-thousandths of a Preferred Share for which a Right is then
         exercisable and dividing that product by (y) 50% of the then-current
         per-share market price of the Company's Common Shares (determined
         pursuant to Section 11(d) hereof) on the date of the occurrence of
         such event.  Except as provided in Section 23(C), in the event that
         any Person shall become an Acquiring Person and the Rights shall then
         be outstanding, the Company shall not take any action which would
         eliminate or diminish the benefits intended to be afforded by the
         Rights.

                 Notwithstanding anything in this Agreement to the contrary,
from and after the first occurrence of an event in which any Person shall
become an Acquiring Person, any Rights beneficially owned by (A) an Acquiring
Person or an Associate or Affiliate of an





                                      13.

<PAGE>   17

Acquiring Person, (B) a transferee of an Acquiring Person (or of any such
Associate or Affiliate) who becomes a transferee after the Acquiring Person
becomes such, or (C) 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
(1) 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 (2) a transfer which the Board of
Directors, upon approval by a majority of the Continuing Directors, has
determined is part of a plan, arrangement or understanding which has as a
primary purpose or effect the avoidance of this Section 11(a)(ii), shall become
null and void without any further action and no holder of such Rights shall
have any rights whatsoever with respect to such Rights, whether under any
provision of this Agreement or otherwise.  No Rights Certificate shall be
issued pursuant to Section 3 that represents Rights beneficially owned by an
Acquiring Person whose Rights would be void pursuant to the preceding sentence
or any Associate or Affiliate thereof; no Rights Certificate shall be issued at
any time upon the transfer of any Rights to an Acquiring Person whose Rights
would be void pursuant to the preceding sentence or any Associate or Affiliate
thereof or to any nominee of such Acquiring Person, Associate or Affiliate; and
any Rights Certificate delivered to the Rights Agent for transfer to an
Acquiring Person whose Rights would be void pursuant to the preceding sentence
shall be cancelled.  The Company shall use all reasonable efforts to ensure
that the provisions of this Section 11(a)(ii) are complied with, but shall have
no liability to any holder of Rights Certificates or other Person as a result
of its failure to make any determinations with respect to an Acquiring person
or its Affiliates, Associates or transferees hereunder.

                    (iii)         The right to buy Common Shares of the Company
         pursuant to subparagraph (ii) of this paragraph (a) shall not arise if
         the event causing such Person to become an Acquiring Person (A) is a
         consolidation, merger, sale, transfer or similar transaction subject
         to Section 13 hereof, or (B) is an acquisition of shares of Common
         Stock pursuant to a tender offer or an exchange offer for all
         outstanding Common Shares at a price and on terms determined by at
         least a majority of the Continuing Directors, and after receiving
         advice from one or more investment banking firms, to be (1) at a price
         which is fair to stockholders (taking into account all factors which
         such members of the Board of Directors deem relevant including, but
         without limitation, prices which could reasonably be achieved if the
         Company or its assets were sold in an orderly basis designed to
         realize maximum value) and (2) otherwise in the best interests of the
         Company and its stockholders.

                      (iv)        In lieu of issuing Common Shares in
         accordance with Section 11(a)(ii) hereof, the Company may, if the
         Board of Directors of the Company, upon approval by a majority of the
         Continuing Directors, determines that such action is necessary or
         appropriate and not contrary to the interest of holders of Rights
         (and, in the event that the number of Common Shares which are
         authorized by the Company's Certificate of Incorporation but not
         outstanding or reserved for issuance





                                      14.

<PAGE>   18
         for purposes other than upon exercise of the Rights are not sufficient
         to permit the exercise in full of the Rights, or if any necessary
         regulatory approval for such issuance has not been obtained by the
         Company), the Company shall: (A) determine the excess of (1) the value
         of the Common Shares issuable upon the exercise of a Right (the
         "Current Value") over (2) the Purchase Price (such excess being
         referred to as the "Spread") and (B) with respect to each Right, make
         adequate provision to substitute for such Common Shares, upon exercise
         of the Rights: (1) cash, (2) a reduction in the Purchase Price, (3)
         other equity securities of the Company (including, but without
         limitation, shares or units of shares of any series of preferred stock
         which the Board of Directors of the Company, upon approval by a
         majority of the Continuing Directors, has deemed to have the same
         value as Common Shares (such shares or units of shares of preferred
         stock are herein called "common stock equivalents")), except to the
         extent that the Company has not obtained any necessary regulatory
         approval for such issuance, (4) debt securities of the Company, except
         to the extent that the Company has not obtained any necessary
         regulatory approval for such issuance, (5) other assets or (6) any
         combination of the foregoing, having an aggregate value equal to the
         Current Value, based upon the advice of a nationally recognized
         investment banking firm selected by the Board of Directors of the
         Company and approved by a majority of the Continuing Directors, the
         Board of Directors of the Company, subject to approval by a majority
         of the Continuing Directors, shall determine such aggregate value;
         provided, however, if the Company shall not have made adequate
         provision to deliver value pursuant to clause (B) above within thirty
         (30) days following the occurrence of an event described in Section
         11(a)(ii), 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), except to the
         extent that the Company has not obtained any necessary regulatory
         approval for such issuance, and then, if necessary, cash, which shares
         and/or cash have an aggregate value equal to the Spread.  If the Board
         of Directors, upon approval by a majority of the Continuing Directors,
         shall determine in good faith that it is likely that sufficient
         additional Common Shares could be authorized for issuance upon
         exercise in full of the Rights or that any necessary regulatory
         approval for such issuance will be obtained, the thirty (30) day
         period set forth above may be extended to the extent necessary, but
         not more than ninety (90) days after the occurrence of an event
         described in Section 11(a)(ii), in order that the Company may seek
         stockholder approval for the authorization of such additional shares
         or take action to obtain such regulatory approval (such period, as it
         may be extended, the "Substitution Period").  To the extent that the
         Company determines that some action need be taken pursuant to the
         first and/or second sentences of this Section 11(a)(iv), the Company
         (x) shall provide that such action shall apply uniformly to all
         outstanding Rights held by holders entitled to receive Common Shares
         or other securities or property upon exercise of such 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, to take any action to obtain any required
         regulatory approval and/or to decide the appropriate form of





                                      15.

<PAGE>   19
         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 and shall promptly notify the Rights Agent of such
         suspension.  For purposes of this Section 11(a)(iv), the value of the
         Common Shares shall be the Current Per-Share Market price (as
         determined pursuant to Section 11(d) hereof) of the Common Shares at
         the Close of Business on the date of the occurrence of one of the
         events described in Section 11(a)(ii) and the value of any "Common
         Stock Equivalent" shall be deemed to have the same value as the Common
         Shares on such date.

                 (b)      In the event that the Company shall fix a record date
for the issuance of rights, options or warrants to all holders of Preferred
Shares entitling them (for a period expiring within 45 calendar days after such
record date) to subscribe for or purchase Preferred Shares (or shares having
the same rights, privileges and preferences as the Preferred Shares
("Equivalent Preferred Shares")) or securities convertible into Preferred
Shares or equivalent preferred shares at a price per Preferred Share or
Equivalent Preferred Share (or having a conversion price per share, if a
security convertible into Preferred Shares or Equivalent Preferred Shares) less
than the then-Current Per-Share Market Price of the Preferred Shares (as
defined in Section 11(d)) on such record date, the Purchase Price to be in
effect after such record date shall be determined by multiplying the Purchase
Price in effect immediately prior to such record date by a fraction, the
numerator of which shall be the number of Preferred Shares outstanding on such
record date plus the number of Preferred Shares which the aggregate offering
price of the total number of Preferred Shares and/or equivalent preferred
shares so to be offered (and/or the aggregate initial conversion price of the
convertible securities so to be offered) would purchase at such current market
price and the denominator of which shall be the number of Preferred Shares
outstanding on such record date plus the number of additional Preferred Shares
and/or Equivalent Preferred Shares to be offered for subscription or purchase
(or into which the convertible securities so to be offered are initially
convertible).  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, upon approval by a majority of the Continuing Directors, 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 shall not be deemed
outstanding for the purpose of any such computation.  Such adjustment shall be
made successively whenever such a record date is fixed; and in the event that
such rights, options or warrants are not so issued, the Purchase Price shall be
adjusted to be the Purchase Price which would then be in effect if such record
date had not been fixed.

                 (c)      In case the Company shall fix a record date for the
making of a distribution to all holders of the Preferred Shares (including any
such distribution made in





                                      16.

<PAGE>   20

connection with a consolidation or merger in which the Company is the
continuing or surviving corporation) of evidences of indebtedness or assets
(other than a regular quarterly cash dividend or a dividend payable in
Preferred Shares) or subscription rights or warrants (excluding those referred
to in Section 11(b) hereof), the Purchase Price to be in effect after such
record date shall be determined by multiplying the Purchase Price in effect
immediately prior to such record date by a fraction, the numerator of which
shall be the then current per share market price of the Preferred Shares on
such record date, less the fair market value (as determined in good faith by
the Board of Directors of the Company, upon approval by a majority of the
Continuing Directors, whose determination shall be described in a statement
filed with the Rights Agent) of the portion of the assets or evidences of
indebtedness so to be distributed or of such subscription rights or warrants
applicable to one Preferred Share and the denominator of which shall be such
Current Per Share market price of the Preferred Shares.  Such adjustments shall
be made successively whenever such a record date is fixed; and in the event
that such distribution is not so made, the Purchase Price shall again be
adjusted to be the Purchase Price which would then be in effect if such record
date had not been fixed.

                 (d)      (i)  For the purpose of any computation hereunder,
the "Current Per-Share Market Price" of any security (a "Security" for the
purpose of this Section 11(d)(i)) on any date shall be deemed to be the average
of the daily closing prices per share of such Security for the 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 a period following
the announcement by the issuer of such Security of (A) a dividend or
distribution on such Security payable in shares of such Security or securities
convertible into such shares, or (B) any subdivision, combination or
reclassification of such Security 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,
or, in case no such sale takes place on such day, the average of the closing
bid and asked prices, in either case as reported in the principal consolidated
transaction reporting system with respect to securities listed or admitted to
trading on the Nasdaq National Market ("Nasdaq") or, if the Security is not
listed or admitted to trading on the Nasdaq, 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 the 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, upon approval by a majority of the Continuing Directors.  If on any
such date no market maker is making a market in the Security, the "Current
Per-Share





                                      17.

<PAGE>   21

Market Price" of such Security on such date as determined in good faith by the
Board of Directors of the Company, as provided for above, 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.

                      (ii)        For the purpose of any computation hereunder,
         the "Current Per-Share Market Price" of the Preferred Shares shall be
         determined in accordance with the method set forth in Section
         11(d)(i).  If the Preferred Shares are not publicly traded, the
         "Current Per-Share Market Price" of the Preferred Shares shall be
         conclusively deemed to be the current per-share market price of the
         Common Shares as determined pursuant to Section 11(d)(i)
         (appropriately adjusted to reflect any stock split, stock dividend or
         similar transaction occurring after the date hereof), multiplied by
         one one-thousandth.  If neither the Common Shares nor the Preferred
         Shares are publicly held or so listed or traded, "Current Per-Share
         Market Price" shall mean the fair value per share as determined in
         good faith by the Board of Directors of the Company, upon approval by
         a majority of the Continuing Directors, whose determination shall be
         described in a statement filed with the Rights Agent.

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

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

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





                                      18.

<PAGE>   22
                 (h)      Unless the Company shall have exercised its election
as provided in Section 11(i), upon each adjustment of the Purchase Price as a
result of the calculations made in Sections 11(b) and (c), 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
one-millionth of a Preferred Share) obtained by (i) multiplying (x) the number
of one one-thousandths of a share covered by a Right immediately prior to this
adjustment by (y) the Purchase Price in effect immediately prior to such
adjustment of the Purchase Price and (ii) dividing the product so obtained by
the Purchase Price in effect immediately after such adjustment of the Purchase
Price.

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

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





                                      19.

<PAGE>   23
                 (k)      Before taking any action that would cause an
adjustment reducing the Purchase Price below one one-thousandth of the then-par
value, if any, of the Preferred Shares issuable upon exercise of the Rights,
the Company shall take any corporate action which may, in the opinion of its
counsel, be necessary in order that the Company may validly and legally issue
fully paid and nonassessable Preferred Shares at such adjusted Purchase Price.

                 (l)      In any case in which this Section 11 shall require
that an adjustment in the Purchase Price be made effective as of a record date
for a specified event, the Company may elect to defer until the occurrence of
such event the issuing to the holder of any Right exercised after such record
date of the Preferred Shares and other capital stock or securities of the
Company, if any, issuable upon such exercise 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.

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

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





                                      20.

<PAGE>   24

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 hereof, the Company shall promptly (a) prepare a certificate setting
forth such adjustment, and a brief statement of the facts accounting for such
adjustment, (b) file with the Rights Agent and with each transfer agent for the
Common Shares or the Preferred Shares (if such transfer agent is an entity
other than the Rights Agent) a copy of such certificate and (c) mail a brief
summary thereof to each holder of a Rights Certificate in accordance with
Section 25 hereof.  Notwithstanding the foregoing sentence, the failure by the
Company to make such certification or give such notice shall not affect the
validity of or the force or effect of the requirement for such adjustment.  The
Rights Agent shall be fully protected in relying on any such certificate and on
any adjustment contained therein and shall not be deemed to have knowledge of
such adjustment unless and until it shall have received such certificate.

                 Section 13.      Consolidation, Merger or Sale or Transfer of
Assets or Earning Power.  (a)  Except as provided in Section 13(b) hereof, in
the event that after the Rights become exercisable, (1) the Company shall
consolidate with, or merge with and into, any other Person, (2) 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 consolidation or merger
and, in connection with such consolidation or merger, all or part of the Common
Shares shall be changed into or exchanged for stock or other securities of any
other Person (or the Company) or cash or any other property, or (3) the Company
shall sell or otherwise transfer (or one or more of its Subsidiaries shall sell
or otherwise transfer), in one or more transactions, directly or indirectly,
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 other
than the Company or one or more of its wholly-owned Subsidiaries.  Then, and in
each such case, proper provision shall be made so that (i) each holder of a
Right (except as otherwise provided herein) shall thereafter have the right to
receive, upon the exercise thereof at a price equal to the then-current Purchase
Price multiplied by the number of one one-thousandths of a Preferred Share for
which a Right is then exercisable, in accordance with the terms of this
Agreement and in lieu of Preferred Shares, such number of Common Shares of such
other Person (including the Company as successor thereto or as the surviving
corporation) as shall equal the result obtained by (A) multiplying the
then-Current Purchase Price by the number of one one-thousandths of a Preferred
Share for which a Right is then exercisable and dividing that product by (B) 50%
of the then-Current Per-Share Market Price of the Common Shares of such other
Person (determined pursuant to Section 11(d) hereof) on the date of consummation
of such consolidation, merger, sale or transfer; (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 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





                                      21.

<PAGE>   25

hereof) 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 the Common Shares thereafter deliverable upon the
exercise of 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 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 provisions of this Section
13 shall similarly apply to successive mergers or consolidations or sales or
other transfers.

                 The supplemental agreement referred to above in this Section
13(a) to be entered into by the Company and the Rights Agent shall also provide
that, as soon as practicable after the date of any of the events described in
this Section 13(a), such Issuer shall:

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

                      (ii)        Use its best efforts to list (or continue the
         listing of) the Rights and the securities purchasable upon exercise of
         the Rights on a national securities exchange or to meet the
         eligibility requirements for quotation on Nasdaq; and

                    (iii)         Deliver to holders of the Rights historical
         financial statements for such issuer which comply in all respects with
         the requirements for registration on Form 10 (or any successor form)
         under the Exchange Act.

                 (b)      In the event of any merger or other acquisition
transaction involving the Company pursuant to an agreement described in Section
1(c)(ii)(A)(2), the provisions of Section 13(a) hereof shall not be applicable
to such transaction and this Rights Agreement and the rights of holders of
Rights hereunder shall be terminated in accordance with Section 7(a) hereof.

                 (c)      The term "Issuer," for purposes of this Section 13,
shall refer to the Person (or Affiliate or Associate) referred to in Section
13(a); provided, however, that (i) if such Person (or Affiliate or Associate)
is a direct or indirect Subsidiary of another Person, Issuer shall refer to
such other Person, and (ii) in case such Person is a Subsidiary, directly





                                      22.

<PAGE>   26

or indirectly, of more than one Person, Issuer shall refer to whichever of such
Persons is the Issuer of such Common Shares having the greatest aggregate
value.

                 (d)      If, for any reason, the Rights cannot be exercised
for Common Shares of such issuer as provided in Section 13(a), then each holder
of Rights shall have the right to exchange its Rights for cash from such issuer
in an amount equal to the number of Common Shares that it would otherwise be
entitled to purchase multiplied by 50% of the Current Per-Share Market Price,
as determined pursuant to Section 11(d) hereof, of such Common Shares of such
issuer.  If, for any reason, the foregoing provision cannot be applied to
determine the cash amount into which the Rights are exchangeable, then the
Board of Directors of the Company, upon approval by a majority of the
Continuing Directors, based upon the advice of one or more nationally
recognized investment banking firms, shall determine such amount reasonably and
with good faith to the holders of Rights.  Any such determination shall be
final and binding on the Rights Agent and the holders of Rights.

                 Section 14.      Fractional Rights and Fractional Shares. (a)
The Company shall not be required to issue fractions of Rights or to distribute
Rights Certificates which evidence fractional Rights.  In lieu of such
fractional Rights, there shall be paid to the registered holders of the Rights
Certificates, with regard to which such fractional Rights would otherwise be
issuable, an amount in cash equal to the same fraction of the current market
value of a whole Right.  For the purposes of this Section 14(a), the current
market value of a whole Right shall be the closing price of the Rights for the
Trading Day immediately prior to the date on which such fractional Rights would
have been otherwise issuable.  The closing price for any day shall be the last
sale price, regular way, or, in case no such sale takes place on such day, the
average of the closing bid and asked prices, regular way, in either case as
reported in the principal consolidated transaction reporting system with
respect to securities listed or admitted to trading on the Nasdaq or, if the
Rights are not listed or admitted to trading on the Nasdaq, 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, upon approval by a majority of the Continuing Directors.  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, upon approval by a majority of the Continuing
Directors, shall be used.  If the Rights are not publicly traded, the current
market value of a whole Right shall equal the difference between the closing
price of a Common Share (as determined pursuant to the second sentence of
Section 11(d)(i) hereof) less the current Purchase Price, multiplied by 1000.





                                      23.

<PAGE>   27

                 (b)      The Company shall not be required to issue fractions
of Preferred Shares (other than fractions which are integral multiples of one
one-thousandth of a Preferred Share) upon exercise of the Rights or to
distribute certificates which evidence fractional Preferred Shares (other than
fractions which are integral multiples of one one-thousandth of a Preferred
Share).  Fractions of Preferred Shares in integral multiples of one
one-thousandth of a Preferred Share may, at the election of the Company, be
evidenced by depositary receipts, pursuant to an appropriate agreement between
the Company and a depositary 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 Rights Certificates at the time such Rights are exercised as herein
provided an amount in cash equal to the same fraction of the current market
value of one Preferred Share.  For the purposes of this Section 14(b), the
current market value of a Preferred Share shall be the closing price of a
Preferred Share (as determined pursuant to the second sentence of Section
11(d)(i) hereof) for the Trading Day immediately prior to the date of such
exercise.  If the Preferred Shares are not publicly traded, the current market
value shall be determined in accordance with Section 11(d)(ii) hereof.

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

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

                 Section 16.      Agreement of Rights 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:





                                      24.

<PAGE>   28

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

                 (b)      After the Distribution Date, the Rights 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;

                 (c)      Subject to Sections 6 and 7(f) hereof, the Company
and the Rights Agent may deem and treat the person in whose name the Rights
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
Rights 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;

                 (d)      Notwithstanding anything in this Agreement to the
contrary, neither the Company nor the Rights Agent shall have any liability to
any holder of a Right or other Person as a result of its inability to perform
any of its obligations under this Agreement by reason of any preliminary or
permanent injunction or other order, decree or ruling issued by a court of
competent jurisdiction or by a governmental, regulatory or administrative
agency or commission, or any statute, rule, regulation or executive order
promulgated or enacted by any governmental authority, prohibiting or otherwise
restraining performance of such obligation; provided, however, the Company must
use its best efforts to have any such order, decree or ruling lifted or
otherwise overturned as soon as possible.

                 Section 17.      Rights Certificate Holder Not Deemed a
Stockholder.  No holder, as such, of any Rights 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 Rights Certificate be construed to confer
upon the holder of any Rights Certificate, as such, any of the rights of a
stockholder of the Company or any right to vote for the election of directors
or upon any matter submitted to stockholders at any meeting thereof, or to give
or withhold consent to any corporate action, or to receive notice of meetings
or other actions affecting stockholders (except as provided in Section 25
hereof), or to receive dividends or subscription rights, or otherwise, until
the Right or Rights evidenced by such Rights Certificate shall have been
exercised in accordance with the provisions hereof.

                 Section 18.      Concerning the Rights Agent.  The Company
agrees to pay to the Rights Agent reasonable compensation for all services
rendered by it hereunder and, from time to time, on demand of the Rights Agent,
its reasonable expenses and counsel fees and other disbursements incurred in
the administration and execution of this Agreement and





                                      25.

<PAGE>   29

the exercise and performance of its duties hereunder.  The Company also agrees
to indemnify the Rights Agent for, and to hold it harmless against, any loss,
liability, or expense, incurred without gross negligence, bad faith or willful
misconduct on the part of the Rights Agent, for any action taken, suffered or
omitted by the Rights Agent in connection with the execution, acceptance and
administration of this Agreement and the exercise and performance hereunder of
its duties, including the costs and expenses of defending against and appealing
any claim of liability in the premises.  The indemnity provided herein shall
survive the termination of this Agreement and the expiration of the Rights.  In
no case will the Rights Agent be liable for special, indirect, incidental or
consequential loss or damage of any kind whatsoever (including but not limited
to lost profits), even if the Rights Agent has been advised of the possibility
of such loss or damage.

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

                 Section 19.      Merger or Consolidation or Change of Name of
Rights Agent.  Any corporation 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 which the Rights
Agent or any successor Rights Agent shall be a party, or any corporation
succeeding to the stock transfer or corporate trust business of the Rights
Agent or any successor Rights Agent, shall be the successor to the Rights Agent
under this Agreement without the execution or filing of any paper or any
further act on the part of any of the parties hereto, provided that such
corporation would be eligible for appointment as a successor Rights Agent under
the provisions of Section 21 hereof.  In case at the time such successor Rights
Agent shall succeed to the agency created by this Agreement any of the Rights
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 Rights Certificates so countersigned; and in case at
that time any of the Rights Certificates shall not have been countersigned, any
successor Rights Agent may countersign such Rights 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 Rights Certificates shall have the fall force
provided in the Rights Certificates and in this Agreement.

                 In case at any time the name of the Rights Agent shall be
changed and at such time any of the Rights Certificates shall have been
countersigned but not delivered, the Rights Agent may adopt the
countersignature under its prior name and deliver Rights Certificates so
countersigned; and in case at that time any of the Rights Certificates shall





                                      26.

<PAGE>   30

not have been countersigned, the Rights Agent may countersign such Rights
Certificates either in its prior name or in its changed name; and in all such
cases such Rights Certificates shall have the full force provided in the Rights
Certificates and in this Agreement.

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

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

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

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

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

                 (e)      The Rights Agent shall not be under any liability or
responsibility in respect to the legality, validity or enforceability of this
Agreement or the execution and delivery hereof (except the due execution hereof
by the Rights Agent) or in respect to the legality, validity or enforceability
or the execution of any Rights Certificate (except its countersignature
thereof); nor shall it be liable or responsible for any breach by the Company
of any covenant or condition contained in this Agreement or in any Rights
Certificate; nor shall it be responsible for any change in the exercisability
of the Rights (including the Rights becoming void pursuant to Section 11(a)(ii)
hereof) or any adjustment in the terms of the Rights (including the manner,
method or amount thereof) provided for in Section 3, 11, 13, 23 or 24, or the
ascertaining of the existence of facts that would require





                                      27.

<PAGE>   31

any such change or adjustment (except with respect to the exercise of Rights
evidenced by Rights Certificates after receipt of the certificate described in
Section 12 hereof); nor shall it by any act hereunder be deemed to make any
representation or warranty as to the authorization or reservation of any
Preferred Shares to be issued pursuant to this Agreement or any Rights
Certificate or as to whether any Preferred Shares will, when issued, be validly
authorized and issued, fully paid and nonassessable;

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

                 (g)      The Rights Agent is hereby authorized and directed to
accept instructions with respect to the administration, exercise and
performance of its duties hereunder from any one of the Chairman of the Board,
the Chief Executive Officer, the President, any Vice President, the Secretary
or the Treasurer of the Company, and to apply to such officers for advice or
instructions in connection with its duties, and it shall not be responsible or
liable for any action taken, suffered or omitted by it in good faith in
accordance with instructions of any such officer or for any delay in acting
while waiting for those instructions.  Any application by the Rights Agent for
written instructions from the Company may, at the option of the Rights Agent,
set forth in writing any action proposed to be taken or omitted by the Rights
Agent under this Rights Agreement and the date on and/or after which such
action shall be taken or such omission shall be effective.  The Rights Agent
shall not be liable for any action taken by, or omission of, the Rights Agent
in accordance with a proposal included in any such application on or after the
date specified in such application (which date shall not be less than five (5)
Business Days after the date any officer of the Company actually received such
application, unless any such officer shall have consented in writing to an
earlier date) unless, prior to taking any such action (or the effective date in
the case of an omission), the Rights Agent shall have received written
instructions in response to such application specifying the action to be taken
or omitted;

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

                 (i)      The Rights Agent may execute and exercise any of the
rights or powers hereby vested in it or perform any duty hereunder either by
itself or by or through its attorneys or agents, and the Rights Agent shall not
be answerable or accountable for any act, default, neglect or misconduct of any
such attorneys or agents or for any loss to the





                                      28.

<PAGE>   32

Company resulting from any such act, default, neglect or misconduct, provided
reasonable care was exercised in the selection and continued employment
thereof;

                 (j)      No provision of this Agreement shall require the
Rights Agent to expend or risk its own funds or otherwise incur any financial
liability in the performance of any of its duties hereunder or in the exercise
of its rights if the Rights Agent in good faith believes that repayment of such
funds or adequate indemnification against such risk or liability is not
reasonably assured;

                 (k)      If, in the case of any Rights Certificate surrendered
to the Rights Agent for exercise, transfer, split up, combination or exchange,
where the form of assignment or the form of election to purchase (either of
which may be appropriate under the circumstances) certifies that the Rights
evidenced by the Rights Certificate are not owned by an Acquiring Person, or an
Affiliate or Associate thereof, has either not been completed or in any manner
indicates any other response thereto, the Rights Agent shall not take any
further action with respect to such requested exercise, transfer, split up,
combination or exchange, without first consulting with the Company.

                 Section 21.      Change of Rights Agent.  The Rights Agent or
any successor Rights Agent may resign and be discharged from its duties under
this Agreement upon thirty (30) days' written notice mailed to the Company and
to each other transfer agent of the Common Shares or Preferred Shares (if any)
(as to which the Rights Agent has received prior written notice) by registered
or certified mail.  The Company shall also mail notice thereof to the holders
of the Rights Certificates by first-class mail.  The Company may remove the
Rights Agent or any successor Rights Agent upon thirty (30) days' written
notice, mailed to the Rights Agent or successor Rights Agent, as appropriate,
and to each other transfer agent of the Common Shares or Preferred Shares (if
any) (as to which the Rights Agent has received prior written notice) by
registered or certified mail, and to the holders of the Rights Certificates by
first-class mail.  If the Rights Agent shall resign or be removed or shall
otherwise become incapable of acting, the Company shall appoint a successor to
the Rights Agent.  If the Company shall fail to make such appointment within a
period of 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 Rights Certificate (who shall,
with such notice, submit such holder's Rights Certificate for inspection by the
Company), then the registered holder of any Rights 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 either (A) a corporation organized and doing business under the laws
of the United States or of any state of the United States, in good standing,
authorized under such laws to exercise corporate trust or stock transfer
powers, and 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 $50 million or (B) an affiliate of such a corporation.
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





                                      29.

<PAGE>   33

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 written notice
thereof with the predecessor Rights Agent and each other transfer agent of the
Common Shares or Preferred Shares (if any), and mail a notice thereof in
writing to the registered holders of the Rights 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 Rights Certificates.
Notwithstanding any of the provisions of this Agreement or of the Rights to the
contrary, the Company may, at its option, issue new Rights Certificates
evidencing Rights in such form as may be approved by its Board of Directors,
upon approval by a majority of the Continuing 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 Rights
Certificates made in accordance with the provisions of this Agreement.  In
addition, in connection with the issuance or sale of Common Shares following
the Distribution Date and prior to the redemption 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 benefit plan or
arrangement or upon the exercise, conversion or exchange of securities of the
Company currently outstanding or issued at any time in the future by the
Company and (b) may, in any other case, if deemed necessary or appropriate by
the Board of Directors of the Company, upon approval by a majority of the
Continuing Directors, issue Rights Certificates representing the appropriate
number of Rights in connection with such issuance or sale; provided, however,
that (i) no such Rights Certificate shall be issued and this sentence shall be
null and void ab initio if, and to the extent that, such issuance or this
sentence would create a significant risk of or result in material adverse tax
consequences to the Company or the Person to whom such Rights Certificate would
be issued or would create a significant risk of or result in such options' or
employee plans' or arrangements' failing to qualify for otherwise available
special tax treatment and (ii) no such Rights Certificate shall be issued if,
and to the extent that, appropriate adjustment shall otherwise have been made
in lieu of the issuance thereof.

                 Section 23.      Redemption. (a)  The Company may, at its
option, upon approval by a majority of the Continuing Directors, at any time
prior to the earlier of (i) the tenth business day following the Shares
Acquisition Date, or (ii) such date or dates on or after the tenth business day
following the Shares Acquisition Date to which such option may be extended by a
majority of the Continuing Directors (for one or more successive 10-day
periods) by vote(s) first taken or written consent(s) first given prior to the
tenth business day following the Shares Acquisition Date and, thereafter, prior
to the completion of any such 10-day extension or extensions (or, if the Shares
Acquisition Date shall have occurred prior to the Record Date, prior to (A) the
tenth business day following the Record Date or (B)





                                      30.

<PAGE>   34
such date or dates on or after the tenth business day after the Record Date to
which such option may be extended by a majority of the Continuing Directors
(for one or more successive 10 day periods) by vote(s) first taken or written
consent(s) first given prior to the tenth business day following the Record
Date and, thereafter, prior to the completion of any such 10 day extension or
extensions), redeem all (but not less than all) the then-outstanding Rights at
a redemption price of $.001 per Right, appropriately adjusted to reflect any
stock split, stock dividend or similar transaction occurring after the date
hereof (such redemption price being hereinafter referred to as the "Redemption
Price"), and the Company may, at its option, pay the Redemption Price either in
cash, Common Shares (based on the current per-share market price thereof (as
determined pursuant to Section 11(d) hereof) at the time of redemption), 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 and on such basis and with such conditions as the Board of Directors
in its sole discretion may establish, upon approval by a majority of the
Continuing Directors.

                 (b)      Immediately upon the action of the Board of Directors
of the Company ordering the redemption of the Rights pursuant to paragraph (a)
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.  The Company
shall promptly give public notice of any such redemption; provided, however,
that the failure to give or any defect in any such notice shall not affect the
validity of such redemption.  Within 10 days after such action of the Board of
Directors ordering the redemption of the Rights, the Company shall give notice
of such redemption to the Rights Agent and shall mail a notice of redemption to
all the holders of the then outstanding Rights 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, regardless of whether 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.  In connection with the purchase of Common
Shares prior to the Distribution Date, neither the Company nor any of its
Affiliates or Associates may redeem, acquire or purchase for value any Rights
at any time nor in any manner other than that specifically set forth in this
Section 23 or in Section 24 hereof, and other than

                 (c)      Notwithstanding anything contained in this Agreement
to the contrary, the Rights shall not be exercisable pursuant to Section 7(a)
at any time when the Rights are redeemable hereunder.

                 Section 24.      Exchange. (a)  The Company, at its option and
upon approval by a majority of the Continuing Directors, at any time after any
Person becomes an Acquiring Person, may exchange all or part of the
then-outstanding and exercisable Rights (which shall not include Rights that
have become void pursuant to the provisions of Section 11(a)(ii) hereof) for
Common Shares at an exchange ratio of one Common Share per Right, appropriately
adjusted to reflect any stock split, stock dividend or similar transaction





                                      31.

<PAGE>   35

occurring after the date hereof (such exchange ratio being hereinafter referred
to as the "Exchange Ratio").  Notwithstanding the foregoing, the Board of
Directors shall not be empowered to effect such exchange at any time after any
Person (other than the Company, any Subsidiary of the Company, any employee
benefit plan of the Company or any such Subsidiary, or any entity holding
Common Shares for or pursuant to the terms of any such plan), together with all
Affiliates and Associates of such Person, becomes the Beneficial Owner of 50%
or more of the Common Shares then outstanding.

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

                 (c)      In any exchange pursuant to this Section 24, the
Company, at its option, may substitute Preferred Shares (or Equivalent
Preferred Shares, as such term is defined in Section 11(b) hereof) for Common
Shares exchangeable for Rights, at the initial rate of one one-thousandth of a
Preferred Share (or Equivalent Preferred Share) for each Common Share, as
appropriately adjusted to reflect adjustments in the voting rights of the
Preferred Shares pursuant to the terms thereof, so that the fraction of a
Preferred Share delivered in lieu of each Common Share shall have the same
voting rights as one Common Share.

                 (d)      In the event that there shall not be sufficient
Common Shares or Preferred Shares, either because such shares are issued but
not outstanding or authorized but unissued, to permit any exchange of Rights as
contemplated in accordance with Section 24(a), the Company shall either take
such action as may be necessary to authorize additional Common Shares or
Preferred Shares for issuance upon exchange of the Rights or, alternatively, at
the option of the Board of Directors and upon approval by a majority of the
Continuing Directors, the Company, with respect to each Right, shall (i) pay
cash in an amount equal to the Purchase Price, in lieu of issuing Common Shares
or Preferred Shares in exchange therefor, or (ii) issue debt or equity
securities, or a combination thereof, having a value equal to the Current Value
(as hereinafter defined) of the Common Shares or Preferred Shares exchangeable
for each such Right, where the value of such securities shall





                                      32.

<PAGE>   36

be determined by a nationally recognized investment banking firm, selected by
the Board of Directors, and approved by a majority of the Continuing Directors,
or (iii) deliver any combination of cash, property, Common Shares, Preferred
Shares and/or other securities having a value equal to the Current Value in
exchange for each Right.  The term "Current Value," for the purposes of this
Section 24, shall mean the product of the Current Per-Share Market Price of
Common Shares (determined pursuant to Section 11(d) on the date of the
occurrence of the event described above in subparagraph (a)) multiplied by the
number of Common Shares for which the Right otherwise would be exchangeable if
there were sufficient shares available.  To the extent that the Company
determines that some action need be taken pursuant to clauses (i), (ii) or
(iii) of this Section 24(d), the Board of Directors, upon approval by a
majority of the Continuing Directors, may temporarily suspend the
exercisability of the Rights for a period of up to sixty (60) days following
the date on which the event described in Section 24(a) shall have occurred, in
order to seek any authorization of additional Common Shares or Preferred Shares
and/or to decide the appropriate form of distribution to be made pursuant to
the above provision 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.

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

                 Section 25.      Notice of Certain Events.  (a)  In case the
Company shall propose (i) to pay any dividend payable in stock of any class to
the holders of its Preferred Shares or to make any other distribution to the
holders of its Preferred Shares (other than a regular quarterly cash dividend),
(ii) to offer to the holders of its Preferred Shares rights or warrants to
subscribe for or to purchase any additional Preferred Shares or shares of stock
of any class or any other securities, rights or options, (iii) to effect any
reclassification of its Preferred Shares (other than a reclassification
involving only the subdivision of outstanding Preferred Shares), (iv) to effect
any consolidation or merger into or with, or to effect any sale or other
transfer (or to permit one or more of its Subsidiaries to effect any sale or
other transfer), in one or more transactions, of 50% or more of the assets or
earning power of the Company and its Subsidiaries (taken as a whole) to, any
other Person, (v) to effect the liquidation, dissolution or winding up of the
Company, or (vi) to declare or pay any dividend on the Common Shares payable in
Common Shares or to effect a subdivision, combination or consolidation of the
Common Shares (by reclassification or otherwise than by payment of dividends in
Common Shares), then, in each such case, the Company shall





                                      33.

<PAGE>   37

give to each holder of a Rights Certificate, in accordance with Section 26
hereof, a notice of such proposed action, which shall specify the record date
for the purposes of such stock dividend, or distribution of rights or warrants,
or the date on which such reclassification, consolidation, merger, sale,
transfer, liquidation, dissolution, or winding up is to take place and the date
of participation therein by the holders of the Common Shares and/or Preferred
Shares, if any such date is to be fixed, and such notice shall be so given in
the case of any action covered by clause (i) or (ii) above at least 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 Common Shares and/or
Preferred Shares, whichever shall be the earlier.

                 (b)      In case any of the events set forth in Section
11(a)(ii) hereof shall occur, then the Company shall, as soon as practicable
thereafter, give to each holder of a Rights Certificate, in accordance with
Section 26 hereof, a notice of the occurrence of such event, which notice shall
describe such event and the consequences of such event to holders of Rights
under Section 11(a)(ii) hereof. In the event any Person becomes an Acquiring
Person, the Company will promptly notify the Rights Agent thereof.

                 Section 26.      Notices.  Notices or demands authorized by
this Agreement to be given or made by the Rights Agent or by the holder of any
Rights 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:

                 IDEC Pharmaceuticals Corporation
                 11011 Torreyana Road
                 San Diego, CA 92121

                 Attention:       William H. Rastetter, Ph.D.
                                  Chairman, President and
                                  Chief Executive Officer

Subject to the provisions of Section 21 hereof, any notice or demand authorized
by this Agreement to be given or made by the Company or by the holder of any
Rights 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:

                 ChaseMellon Shareholder Services LLC
                 400 South Hope Street, 4th Floor
                 Los Angeles, CA 90071

                 Attention:       Shareholder Services Division





                                      34.

<PAGE>   38

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

                 Section 27.      Supplements and Amendments.  Prior to the
Distribution Date, the Company may supplement or amend this Agreement in any
respect, without the approval of any holders of Rights, by action of its Board
of Directors upon approval by a majority of the Continuing Directors, and the
Rights Agent shall, if the Company so directs, execute such supplement or
amendment.  From and after the Distribution Date, the Company may from time to
time supplement or amend this Agreement without the approval of any holders of
Rights, by action of its Board of Directors, and approval by a majority of the
Continuing Directors, in order to cure any ambiguity, to correct or supplement
any provision contained herein which may be defective or inconsistent with any
other provisions herein, or to make any other provisions with respect to the
Rights which the Company may deem necessary or desirable and which shall be
consistent with, and for the purpose of fulfilling, the objectives of the Board
of Directors in adopting this Agreement, including, but without limitation, to
change the Purchase Price, the Redemption Price, any time periods herein
specified, and any other term hereof, any such supplement or amendment to be
evidenced by a writing signed by the Company and the Rights Agent; provided,
however, that from and after such time as any Person becomes an Acquiring
Person, this Agreement shall not be amended in any manner which would adversely
affect the interests of the holders of Rights.  Upon receipt of a certificate
from an appropriate officer of the Company that the proposed supplement or
amendment is consistent with this Section 27 and, after such time as any Person
has become an Acquiring Person, that the proposed supplement or amendment does
not adversely affect the interests of the holders of Rights, the Rights Agent
shall execute such supplement or amendment.  Without limiting the foregoing,
the Company may at any time prior to such time as any Person becomes an
Acquiring Person, by action of its Board of Directors, and approval by a
majority of the Continuing Directors, amend this Agreement to lower the
thresholds set forth in Sections 1(a) and 3(a) to not less than the greater of
(i) any percentage greater than the largest percentage of the outstanding
Common Shares then known by the Company to be beneficially owned by any Person
(other than the Company, any Subsidiary of the Company, any employee benefit
plan of the Company or any Subsidiary of the Company, or any entity holding
Common Shares for or pursuant to the terms of any such plan) and (ii) 10%.

                 Section 28.      Successors.  All the covenants and provisions
of this Agreement by or for the benefit of the Company or the Rights Agent
shall bind and inure to the benefit of their respective successors and assigns
hereunder.

                 Section 29.      Determinations and Actions by the Board of
Directors.  For all purposes of this Agreement, any calculation of the number
of Common Shares outstanding at any particular time, including for purposes of
determining the particular percentage of such outstanding Common Shares of
which any Person is the Beneficial Owner, shall be





                                      35.

<PAGE>   39

made in accordance with the last sentence of Rule 13d-3(d)(1)(i) of the General
Rules and Regulations under the Exchange Act.  The Board of Directors of the
Company (and, where specifically provided for herein, only upon approval by a
majority of the Continuing Directors) shall have the exclusive power and
authority to administer this Agreement and to exercise all rights and powers
specifically granted to the Board, or the Company, or as may be necessary or
advisable in the administration of this Agreement, including, but 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 a determination to redeem or
not redeem the Rights or to amend the Agreement).  All such actions,
calculations, interpretations and determinations (including, for purposes of
clause (y) below, all omissions with respect to the foregoing), which are done
or made by the Board (or, where specifically provided for herein, upon approval
by a majority of the Continuing Directors) in good faith, shall (x) be final,
conclusive and binding on the Company, the Rights Agent, the holders of the
Rights Certificates and all other parties and (y) not subject the Board or the
Continuing Directors to any liability to the holders of the Rights.

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

                 Section 31.      Severability.  If any term, provision,
covenant or restriction of this Agreement is held by a court of competent
jurisdiction or other authority to be invalid, void or unenforceable, the
remainder of the terms, provisions, covenants and restrictions of this
Agreement shall remain in full force and effect and shall in no way be
affected, impaired or invalidated; provided, however, that notwithstanding
anything in this Agreement to the contrary, if any such term, provision,
covenant or restriction is held by such court or authority to be invalid, void
or unenforceable and the Board of Directors of the Company, upon approval by a
majority of the Continuing Directors, determines in its good faith judgment
that severing the invalid language from this Agreement would adversely affect
the purpose or effect of this Agreement, the right of redemption set forth in
Section 23 hereof shall be reinstated and shall not expire until the tenth
business day following the date of such determination by the Board of Directors
of the Company.

                 Section 32.      Governing Law.  This Agreement and each
Rights 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.





                                      36.

<PAGE>   40
                 Section 33.      Counterparts.  This Agreement may be executed
in any number of counterparts and each of such counterparts shall for all
purposes be deemed to be an original, and all such counterparts shall together
constitute but one and the same instrument.

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































                                      37.

<PAGE>   41
                 IN WITNESS WHEREOF, the parties hereto have caused this
Agreement to be duly executed and attested, all as of the day and year first
above written.

ATTEST:                                  IDEC PHARMACEUTICALS
                                         CORPORATION



By     /s/ Kenneth J. Woolcott             By   /s/ William H. Rastetter, Ph.D.
       -------------------------------          ------------------------------
Name:  Kenneth J. Woolcott               Name:  William H. Rastetter, Ph.D.
Title: Vice President, General Counsel   Title: Chairman, President and Chief
       and Licensing Executive                  Executive Officer


ATTEST:                                  CHASEMELLON SHAREHOLDER
                                         SERVICES LLC, as Rights Agent



By     /s/ Ronald Lug                      By     /s/ Rosa Maria Bautista
       -------------------------------          ------------------------------
Name:  Ronald Lug                          Name:  Rosa Maria Bautista
Title: Vice President and Deputy           Title: Relationship Manager
       Manager






















<PAGE>   42
                                   Exhibit A



                         CERTIFICATE OF DESIGNATION OF
                 SERIES X JUNIOR PARTICIPATING PREFERRED STOCK
                      OF IDEC PHARMACEUTICALS CORPORATION
























<PAGE>   43

                                                                     

                           CERTIFICATE OF DESIGNATION

                                       of

                 Series X JUNIOR PARTICIPATING PREFERRED STOCK

                                       of

                        IDEC PHARMACEUTICALS CORPORATION

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

                       __________________________________


                 IDEC Pharmaceuticals Corporation, 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 July 22, 1997:

                 RESOLVED, that pursuant to the authority granted to and vested
in the Board of Directors of the 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 $.001 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 X Junior Participating Preferred Stock:

                 Section 1.  Designation and Amount.  The shares of such series
shall be designated as "Series X Junior Participating Preferred Stock" (the
"Series X Preferred Stock") and the number of shares constituting the Series X
Preferred Stock shall be Fifty Eight Thousand (58,000).  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 X
Preferred Stock to a number less than the number of shares then outstanding
plus the number of shares reserved for issuance upon the exercise of
outstanding options, rights or warrants or upon the conversion of any
outstanding securities issued by the Corporation which are convertible into
Series X Preferred Stock.






<PAGE>   44

                 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 X Preferred Stock with respect to dividends,
         the holders of shares of Series X Preferred Stock, in preference to
         the holders of the Common Stock, par value $.001 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 X Preferred Stock, in an amount per
         share (rounded to the nearest cent) equal to, subject to the provision
         for adjustment hereinafter set forth, 1000 times the aggregate per
         share amount of all cash dividends, and 1000 times the aggregate per
         share amount (payable in kind) of all non-cash dividends or other
         distributions, other than a dividend payable in shares of Common Stock
         or a subdivision of the outstanding shares of Common Stock (by
         reclassification or otherwise), declared on the Common Stock since the
         immediately preceding Quarterly Dividend Payment Date or, with respect
         to the first Quarterly Dividend Payment Date, since the first issuance
         of any share or fraction of a share of Series X 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 or combination or consolidation of the
         outstanding shares of Common Stock (by reclassification or otherwise
         than by payment of a dividend in shares of Common Stock) into a
         greater or lesser number of shares of Common Stock, then in each such
         case the amount to which holders of shares of Series X 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 X Preferred Stock as provided in paragraph
         (A) of this Section immediately after it declares a dividend or
         distribution on the Common Stock (other than a dividend payable in
         shares of Common Stock).

                 (C)      Dividends shall begin to accrue and be cumulative on
         outstanding shares of Series X 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





                                       2

<PAGE>   45

         the record date for the determination of holders of shares of Series X
         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 X 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 X 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 X
Preferred Stock shall have the following voting rights:

                 (A)      Subject to the provision for adjustment hereinafter
         set forth, each share of Series X Preferred Stock shall entitle the
         holder thereof to 1000 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 or combination or
         consolidation of the outstanding shares of Common Stock (by
         reclassification or otherwise than by payment of a dividend in shares
         of Common Stock) into a greater or lesser number of shares of Common
         Stock, then in each such case the number of votes per share to which
         holders of shares of Series X Preferred Stock were entitled
         immediately prior to such event shall be adjusted by multiplying such
         number by a fraction, the numerator of which is the number of shares
         of Common Stock outstanding immediately after such event and the
         denominator of which is the number of shares of Common Stock that were
         outstanding immediately prior to such event.

                 (B)      Except as otherwise provided herein, in any other
         Certificate of Designation creating a series of Preferred Stock or any
         similar stock, or by law, the holders of shares of Series X 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 X Preferred Stock shall have no special
         voting rights and their consent shall not be required (except to the
         extent they are entitled to vote with holders of Common Stock as set
         forth herein) for taking any corporate action.





                                       3

<PAGE>   46

                 Section 4.  Certain Restrictions.

                 (A)      Whenever quarterly dividends or other dividends or
         distributions payable on the Series X 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 X 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 X 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 X Preferred Stock, except
                 dividends paid ratably on the Series X 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 X 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 X
                 Preferred Stock; or

                      (iv)        redeem or purchase or otherwise acquire for
                 consideration any shares of Series X Preferred Stock, or any
                 shares of stock ranking on a parity with the Series X
                 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.





                                       4

<PAGE>   47

                 Section 5.  Reacquired Shares.  Any shares of Series X
Preferred Stock purchased or otherwise acquired by the Corporation in any
manner whatsoever shall be retired and cancelled 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 Designation creating a series of Preferred Stock or any similar stock or as
otherwise required by law.

                 Section 6.  Liquidation, Dissolution or Winding Up.  Upon any
liquidation, dissolution or winding up of the 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 X
Preferred Stock unless, prior thereto, the holders of shares of Series X
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 X
Preferred Stock shall be entitled to receive an aggregate amount per share,
subject to the provision for adjustment hereinafter set forth, equal to 1000
times the aggregate amount to be distributed per share to holders of shares of
Common 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 X Preferred Stock, except distributions made ratably on the Series X
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 or combination or consolidation of the
outstanding shares of Common Stock (by reclassification or otherwise than by
payment of a dividend in shares of Common Stock) into a greater or lesser number
of shares of Common Stock, then in each such case the aggregate amount to which
holders of shares of Series X Preferred Stock were entitled immediately prior to
such event under the proviso in clause (1) of the preceding sentence shall be
adjusted by multiplying such amount by a fraction the numerator of which is the
number of shares of Common Stock outstanding immediately after such event and
the denominator of which is the number of shares of Common Stock that were
outstanding immediately prior to such event.

                 Section 7.  Consolidation, Merger, etc.  In case the
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 X Preferred Stock shall at the same time be
similarly exchanged or changed into an amount per share, subject to the
provision for adjustment hereinafter set forth, equal to 1000 times the
aggregate amount of stock, securities, cash and/or any other property (payable
in kind), as the case may be, into which or for which each share of Common
Stock is changed or exchanged.  In the event the Corporation shall at any time
declare or pay any dividend on the Common Stock payable in shares of Common
Stock, or effect a subdivision or combination or consolidation of the





                                       5

<PAGE>   48
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 X 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 X Preferred
Stock shall not be redeemable.

                 Section 9.  Rank.  The Series X 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.

                 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 X Preferred
Stock so as to affect them adversely without the affirmative vote of the
holders of at least a majority of the outstanding shares of Series X Preferred
Stock, voting together as a single class.


                 IN WITNESS WHEREOF, this Certificate of Designation is
executed on behalf of the Corporation by its Chairman, President and Chief
Executive Officer and attested to by its Secretary this 22nd day of July, 1997.


                                        /s/ William H. Rastetter, Ph.D.
                                        --------------------------------------


                                        Name:    William H. Rastetter, Ph.D.
                                        Title:   Chairman, President and Chief
                                                 Executive Officer


Attest:


/s/ Kenneth J. Woolcott              
- --------------------------------------
Kenneth J. Woolcott
Secretary





                                       6

<PAGE>   49
                                                                       Exhibit B

                           Form of Rights Certificate

Certificate No. R-                                             ________ Rights



       NOT   EXERCISABLE   AFTER  JULY  21,  2007,  OR  EARLIER  IF
       REDEMPTION  OR  EXCHANGE  OCCURS.  THE RIGHTS ARE SUBJECT TO
       REDEMPTION  AT THE OPTION OF THE  COMPANY AT $.001 PER RIGHT
       AND TO  EXCHANGE  ON  THE  TERMS  SET  FORTH  IN THE  RIGHTS
       AGREEMENT. UNDER CERTAIN CIRCUMSTANCES,  RIGHTS BENEFICIALLY
       OWNED BY AN ACQUIRING PERSON OR AN AFFILIATE OR ASSOCIATE OF
       AN ACQUIRING PERSON (AS SUCH TERMS ARE DEFINED IN THE RIGHTS
       AGREEMENT)  AND ANY  SUBSEQUENT  HOLDER OF SUCH  RIGHTS  MAY
       BECOME NULL AND VOID. [THE RIGHTS REPRESENTED BY THIS RIGHTS
       CERTIFICATE ARE OR WERE  BENEFICIALLY  OWNED BY A PERSON WHO
       WAS  OR  BECAME  AN  ACQUIRING  PERSON  OR AN  AFFILIATE  OR
       ASSOCIATE OF AN ACQUIRING  PERSON (AS SUCH TERMS ARE DEFINED
       IN  THE  RIGHTS   AGREEMENT).   ACCORDINGLY,   THIS   RIGHTS
       CERTIFICATE  AND THE  RIGHTS  REPRESENTED  HEREBY MAY BECOME
       NULL  AND  VOID  IN  THE  CIRCUMSTANCES  SPECIFIED  IN  SUCH
       AGREEMENT.]*/


                               Rights Certificate

                        IDEC PHARMACEUTICALS CORPORATION


                 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 July 22, 1997, 1997 (the "Rights Agreement"),
between IDEC Pharmaceuticals Corporation, a Delaware





______________________

     */  The portion of the legend in bracket shall be inserted only if
applicable and shall replace the preceding sentence.

                                      B-1.



<PAGE>   50

corporation (the "Company"), and ChaseMellon Shareholder Services LLC (the
"Rights Agent"), to purchase from the Company at any time after the Distribution
Date (as such term is defined in the Rights Agreement) and prior to 5:00 P.M.,
New York, New York time, on July 21, 2007, at the office of the Rights Agent
designated for such purpose, or at the office of its successor as Rights Agent,
one one-thousandth of a fully paid non-assessable share of Series X Junior
Participating Preferred Stock, par value $.001 per share (the "Preferred
Shares") of the Company, at a purchase price of $200.00 per one one-thousandth
of a Preferred Share (the "Purchase Price"), upon presentation and surrender of
this Rights Certificate with the Form of Election to Purchase duly executed.
The number of Rights evidenced by this Rights Certificate (and the number of one
one-thousandths of a Preferred Share which may be purchased upon exercise
hereof) set forth above, and the Purchase Price set forth above, are the number
and Purchase Price as of July 22, 1997 based on the Preferred Shares as
constituted at such date.  As provided in the Rights Agreement, the Purchase
Price and the number of one one-thousandths of a Preferred Share which may be
purchased upon the exercise of the Rights evidenced by this Rights Certificate
are subject to modification and adjustment upon the happening of certain events.

                 This Rights 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 Rights
Certificates.  Copies of the Rights Agreement are on file at the principal
executive offices of the Company.

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

                 Subject to the provisions of the Rights Agreement, the Rights
evidenced by this Certificate may be redeemed by the Company at a redemption
price of $.001 per Right.

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





                                      B-2.


<PAGE>   51

                 No holder of this Rights 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 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 Rights
Certificate shall have been exercised as provided in the Rights Agreement.

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

                 WITNESS the signature of the proper officers of the Company
and its corporate seal.  Dated as of ___________, 1997.




ATTEST:                                    IDEC PHARMACEUTICALS CORPORATION



____________________________               By______________________________




Countersigned:

ChaseMellon Shareholder Services LLC
as Rights Agent


By______________________________
  Authorized Signatory





                                      B-3.



<PAGE>   52

                   Form of Reverse Side of Rights Certificate

                               FORM OF ASSIGNMENT


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

               FOR VALUE RECEIVED ________________________________ hereby
sells, assigns and transfers unto
_______________________________________________________________________________
________________________________________________________________ (Please print
name and address of transferee) this Rights Certificate, together with all
right, title and interest therein, and does hereby irrevocably constitute and
appoint _______________ ___ Attorney, to transfer this Rights Certificate on
the books of the within-named Company, with full power of substitution.


Dated:  ______________________, ____
                                


                                                   ____________________________
                                                             Signature

Signature Guaranteed:

                 Signatures must be guaranteed by a participant in a Securities
Transfer Association Inc. recognized signature guarantee medallion program.

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

                                 CERTIFICATION

                 The undersigned hereby certifies that the Rights evidenced by
this Rights Certificate are not beneficially owned by an Acquiring Person or an
Affiliate or Associate thereof (as defined in the Rights Agreement).


                                                   ____________________________
                                                             Signature


            Form of Reverse Side of Rights Certificate -- continued





                                      B-4.



<PAGE>   53

                          FORM OF ELECTION TO PURCHASE
                          ----------------------------

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


To IDEC PHARMACEUTICALS CORPORATION

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

Please insert social security
or other identifying number__________________________________________________
                                     (Please print name and address)

If such number of Rights shall not be all the Rights evidenced by this Rights
Certificate, a new Rights 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:

               Signatures must be guaranteed by a participant in a Securities
Transfer Association Inc. recognized signature guarantee medallion program.





                                      B-5.



<PAGE>   54
                                                 Form of Reverse Side of Rights
Certificate -- continued


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


                                 CERTIFICATION

               The undersigned hereby certifies that the Rights evidenced by
this Rights Certificate are not beneficially owned by an Acquiring Person or an
Affiliate or Associate thereof (as defined in the Rights Agreement).


                                                   ____________________________
                                                             Signature

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



                                     NOTICE


               The signature in the foregoing Forms of Assignment and Election
to Purchase must conform to the name as written upon the face of this Rights
Certificate in every particular, without alteration or enlargement or any
change whatsoever.

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










                                      B-6.

<PAGE>   55
                                   Exhibit C


                         SUMMARY OF RIGHTS TO PURCHASE
                                PREFERRED SHARES











<PAGE>   56
                        IDEC PHARMACEUTICALS CORPORATION

                         SUMMARY OF RIGHTS TO PURCHASE
                                PREFERRED SHARES


                 On July 22, 1997, the Board of Directors of IDEC
Pharmaceuticals Corporation (the "Company") declared a dividend of one preferred
share purchase right (a "Right") for each outstanding share of Common Stock (the
"Common Stock"), par value $.001 per share (the "Common Shares"), of the
Company.  The dividend is payable on August 11, 1997 (the "Record Date") to the
stockholders of record on that date.  Each Right entitles the registered holder
to purchase from the Company one one-thousandth of a share of Series X Junior
Participating Preferred Stock, par value $.001 per share (the "Preferred
Shares"), of the Company at a price of $200.00 per one one-thousandth of a
Preferred Share (the "Purchase Price"), subject to adjustment.  The description
and terms of the Rights are set forth in a Rights Agreement dated as of July 22,
1997 (the "Rights Agreement") between the Company and Rights Agent (the "Rights
Agent").

                 Until the earlier to occur of (i) 10 business days following a
public announcement that a person or group of affiliated or associated persons
(an "Acquiring Person") have acquired beneficial ownership of 15% or more of
the outstanding Common Shares or (ii) 10 business days (or such later date as
may be determined by action of the Board of Directors prior to such time as any
Person becomes an Acquiring Person) following the commencement of, or
announcement of an intention to make, a tender offer or exchange offer the
consummation of which would result in the beneficial ownership by a person or
group of 15% or more of such outstanding Common Shares (the earlier of such
dates 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 with a copy of this Summary of Rights
attached thereto.

                 The Rights Agreement provides that, until the Distribution
Date, 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 Record Date, upon
transfer or new issuance of Common Shares will contain a notation incorporating
the Rights Agreement by reference.  Until the Distribution Date (or earlier
redemption or expiration of the Rights), the surrender for transfer of any
certificates for Common Shares, outstanding as of the Record Date, even without
such notation or a copy of this Summary of Rights being attached thereto, 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





                                       1.

<PAGE>   57

certificates evidencing the Rights ("Rights 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 Rights Certificates alone will evidence the
Rights.

                 The Rights are not exercisable until the Distribution Date.
The Rights will expire at the close of business on July 21, 2007 (the "Final
Expiration Date"), unless the Final Expiration Date is extended or unless the
Rights are earlier redeemed by the Company, in each case as described below.

                 The Purchase Price payable, and the number of Preferred Shares
or other securities or property issuable, upon exercise of the 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 at a
price, or securities convertible into Preferred Shares with a conversion price,
less than the then-current market price of the Preferred Shares or (iii) upon
the distribution to holders of the Preferred Shares of evidences of
indebtedness or assets (excluding regular periodic cash dividends paid out of
earnings or retained earnings or dividends payable in Preferred Shares) or of
subscription rights or warrants (other than those referred to above).

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

                 Preferred Shares purchasable upon exercise of the Rights will
not be redeemable.  Each Preferred Share will be entitled to an aggregate
dividend of 1000 times the dividend declared per Common Share.  In the event of
liquidation, the holders of the Preferred Shares will be entitled to an
aggregate payment of 1000 times the payment made per Common Share.  Each
Preferred Share will have 1000 votes, voting together with the Common Shares.
Finally, in the event of any merger, consolidation or other transaction in
which Common Shares are exchanged, each Preferred Share will be entitled to
receive 1000 times the amount received per Common Share.  These rights are
protected by customary antidilution provisions.

                 Because of the nature of the Preferred Shares' dividend,
liquidation and voting rights, the value of the one one-thousandth interest in
a Preferred Share purchasable upon exercise of each Right should approximate
the value of one Common Share.

                 In the event that, following the Distribution Date, the
Company is acquired in a merger or other business combination transaction with
an Acquiring Person or an affiliate thereof, or 50% or more of its consolidated
assets or earning power are sold to





                                       2.

<PAGE>   58

an Acquiring Person or an affiliate thereof, proper provision will be made so
that each holder of a Right will thereafter have the right to receive, upon
exercise thereof at the then current exercise price of the Right, that number
of shares of common stock of the acquiring company which at the time of such
transaction will have a market value of two times the exercise price of the
Right.

                 In the event that any person or group of affiliated or
associated persons becomes the beneficial owner of 15% or more of the
outstanding Common Shares (except pursuant to a tender offer for all of the
Common Shares at a price and on terms determined by a majority of the
Continuing Directors to be fair to and otherwise in the best interests of the
Company and its stockholders) proper provision shall be made so that each
holder of a Right, other than Rights beneficially owned by the Acquiring Person
(which will thereafter be void), will thereafter have the right to receive upon
exercise that number of Common Shares (or cash, other securities or property)
having a market value of two times the exercise price of the Right.

                 At any time after the acquisition by a person or group of
affiliated or associated persons of beneficial ownership of 15% or more of the
outstanding Common Shares and prior to the acquisition by such person or group
of 50% or more of the outstanding Common Shares, the Board of Directors of the
Company may exchange the Rights (other than Rights owned by such person or
group which have become void), in whole or in part, at an exchange ratio of one
Common Share (or a fraction of a Preferred Share having equivalent market
value) per Right (subject to adjustment).

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

                 At any time within ten (10) business days after a person or
group of affiliated or associated persons acquire beneficial ownership of 15%
or more of the outstanding Common Shares (unless the Board of Directors extends
such ten-day period), the Board of Directors of the Company may redeem the
Rights in whole, but not in part, at a price of $.001 per Right (the
"Redemption Price"), upon the approval of a majority of the Continuing
Directors.  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.  The Rights are also
redeemable under other circumstances as specified in the Rights Agreement.





                                       3.

<PAGE>   59

                 The terms of the Rights may be amended by the Board of
Directors of the Company without the consent of the holders of the Rights upon
the approval of a majority of the Continuing Directors, including an amendment
to lower certain thresholds described above to not less than the greater of (i)
any percentage greater than the largest percentage of the outstanding Common
Shares then known to the Company to be beneficially owned by any person or
group of affiliated or associated persons and (ii) 10%, except that from and
after a Distribution Date no such amendment may adversely affect the interests
of the holders of the Rights.

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

                 A copy of the Rights Agreement has been filed with the
Securities and Exchange Commission as an Exhibit to a Registration Statement on
Form 8-A.  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 hereby incorporated herein by reference.





                                       4.