<PAGE>

                                                                     Exhibit 4.1



       _________________________________________________________________



                              AVICI SYSTEMS INC.

                                      and

                         MELLON INVESTOR SERVICES LLC
                                as Rights Agent

                                  __________

                               RIGHTS AGREEMENT

                         Dated as of December 6, 2001



       ________________________________________________________________
<PAGE>

                               TABLE OF CONTENTS
                               -----------------
<TABLE>
<CAPTION>
                                                                                                             Page
                                                                                                            -----
<S>                                                                                                        <C>
Section 1.      Certain Definitions...................................................................          1
Section 2.      Appointment of Rights Agent...........................................................          5
Section 3.      Issue of Right Certificates...........................................................          5
Section 4.      Form of Right Certificates............................................................          6
Section 5.      Countersignature and Registration.....................................................          7
Section 6.      Transfer, Split Up, Combination and Exchange of Right Certificates; Mutilated,
                Destroyed, Lost or Stolen Right Certificates..........................................          7
Section 7.      Exercise of Rights; Purchase Price; Expiration Date of Rights.........................          8
Section 8.      Cancellation and Destruction of Right Certificates....................................          9
Section 9.      Status and Availability of Preferred Shares...........................................          9
Section 10.     Preferred Shares Record Date..........................................................         10
Section 11.     Adjustment of Purchase Price, Number of Shares or Number of Rights....................         10
Section 12.     Certificate of Adjustment.............................................................         17
Section 13.     Consolidation, Merger or Sale or Transfer of Assets or Earning Power..................         17
Section 14.     Fractional Rights and Fractional Shares...............................................         18
Section 15.     Rights of Action......................................................................         20
Section 16.     Agreement of Right Holders............................................................         20
Section 17.     Right Certificate Holder Not Deemed a Stockholder.....................................         20
Section 18.     Concerning the Rights Agent...........................................................         21
Section 19.     Merger or Consolidation or Change of Name of Rights Agent.............................         21
Section 20.     Duties of Rights Agent................................................................         22
Section 21.     Change of Rights Agent................................................................         24
Section 22.     Issuance of New Right Certificates....................................................         24
Section 23.     Redemption............................................................................         25
Section 24.     Exchange..............................................................................         26
Section 25.     Notice of Certain Events..............................................................         27
Section 26.     Notices...............................................................................         28
Section 27.     Supplements and Amendments............................................................         29
Section 28.     Successors............................................................................         29
Section 29.     Benefits of this Agreement............................................................         29
</TABLE>

                                       i
<PAGE>

<TABLE>
<S>                                                                                                            <C>
Section 30.      Severability..........................................................................         29
Section 31.      Governing Law.........................................................................         29
Section 32.      Counterparts..........................................................................         30
Section 33.      Descriptive Headings..................................................................         30
Section 34.      Administration........................................................................         30
</TABLE>

EXHIBITS:

Exhibit A        Form of Certificate of Designation of Series A Junior
                 Participating Preferred Stock
Exhibit B        Form of Right Certificate
Exhibit C        Summary of Rights to Purchase Preferred Shares

                                      ii
<PAGE>

                               RIGHTS AGREEMENT


     Agreement, dated as of December 6, 2001, between Avici Systems Inc., a
Delaware corporation (the "Company"), and Mellon Investor Services LLC, a New
Jersey limited liability company, as rights agent (the "Rights Agent").

     WHEREAS, effective December 5, 2001, the Board of Directors of the Company
has authorized and declared a dividend of one preferred share purchase right (a
"Right") for each share of Common Stock, par value $0.0001 per share, of the
Company (a "Common Share") outstanding on the Close of Business on December 17,
2001 (the "Record Date") and has authorized the issuance of one Right with
respect to each additional Common Share that shall become outstanding between
the Record Date and the earliest of Close of Business on the Distribution Date,
the Redemption Date and the Close of Business on the Final Expiration Date, each
Right representing the right to purchase one one-thousandth of a Preferred Share
(as hereinafter defined), or such different amount and/or kind of securities as
shall be hereinafter provided.

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

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


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


          (1)  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 such other percentage as would
     otherwise result in such person becoming an Acquiring Person) or more of
     the Common Shares of the Company then outstanding; provided, however, that
                                                        --------  -------
     if a Person shall so become the Beneficial Owner of 15% (or such other
     percentage) or more of the Common Shares of the Company then outstanding by
     reason of an acquisition of Common Shares by the Company and shall, after
     such share purchases by the Company, become the Beneficial Owner of an
     additional 1% of the outstanding Common Shares of the Company, then such
     Person shall be deemed to be an "Acquiring Person"; and

          (2)  if the Board of Directors of the Company determines in good faith
    that a Person who would otherwise be an "Acquiring Person," as defined
    pursuant to the

                                       1
<PAGE>

     foregoing provisions of this paragraph, has become such inadvertently and
     without any plan or intention to seek or affect control of the Company, and
     such Person enters into an irrevocable commitment with the Company to
     divest, and thereafter divests in accordance with the terms of such
     commitment 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, then such Person
     shall not be deemed to have become an "Acquiring Person" for any purposes
     of this Agreement.


     "Affiliate" and "Associate" shall have the respective meanings ascribed to
such terms in Rule 12b-2 of the Exchange Act and Regulations, as in effect on
the date of this Agreement.


     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, for purposes of
     Section 13(d) of the Exchange Act and Rule 13d-3 of the Exchange Act
     Regulations (or any comparable or successor law or regulation);

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

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

                                       2
<PAGE>

     (B) of the immediately preceding paragraph (ii)) or disposing of any
     securities of the Company; provided, however, that in no case shall an
                                --------  -------
     officer or director of the Company be deemed (A) the Beneficial Owner of
     any securities beneficially owned by another officer or director of the
     Company solely by reason of actions undertaken by such persons in their
     capacity as officers or directors of the Company or (B) the Beneficial
     Owner of securities held of record by the trustee of any employee benefit
     plan of the Company or any Subsidiary of the Company for the benefit of any
     employee of the Company or any Subsidiary of the Company, other than the
     officer or director, by reason of any influence that such officer or
     director may have over the voting of the securities held in the plan.

     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.

     "Business Day" shall mean any day other than a Saturday, Sunday, or a day
on which banking institutions in Boston, Massachusetts and New Jersey are
authorized or obligated by law or executive order to close.

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

     "Common Shares" when used with reference to the Company shall mean the
shares of common stock, par value $0.0001 per share, of the Company.  "Common
Shares" when used with reference to any Person other than the Company shall mean
the capital stock (or equity interest) with the greatest voting power of such
other Person or, if such other Person is a Subsidiary of another Person, the
Person or Persons which ultimately control such first-mentioned Person.

     "Common Stock Equivalents" shall have the meaning set forth in Section
11(a)(iii)(B)(3) hereof.

     "Company" shall have the meaning set forth in the recitals to this
Agreement.

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

     "Current Value" shall have the meaning set forth in Section
11(a)(iii)(A)(1) hereof.

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

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

                                       3
<PAGE>

     "Exchange Act" shall mean the Securities Exchange Act of 1934, as amended.

     "Exchange Act Regulations" shall mean the General Rules and Regulations
under the Exchange Act.

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

     "Final Expiration Date" shall mean December 5, 2011.

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

     "Preferred Shares" shall mean shares of Series A Junior Participating
Preferred Stock, par value $0.01 per share, of the Company having such rights
and preferences upon adoption as are set forth in the form of Certificate of
Designation set forth as Exhibit A hereto.

     "Purchase Price" shall have the meaning set forth in Section 7(b) hereof.

     "Record Date" shall have the meaning set forth in the recitals to this
Agreement.

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

     "Right" shall have the meaning set forth in the recitals to this Agreement.

     "Redemption Date" shall have the meaning set forth in Section 23(b) hereof.

     "Right Certificate" shall mean a certificate evidencing a Right in
substantially the form of Exhibit B hereto.

     "Rights Agent" shall have the meaning set forth in the recitals to this
Agreement.

     "Section 11(a)(ii) Trigger Date" shall have the meaning set forth in
Section 11(a)(iii) hereof.

     "Shares Acquisition Date" shall mean the earlier of the date of (i) the
public announcement by the Company or an Acquiring Person that an Acquiring
Person has become such or (ii) the public disclosure of facts by the Company or
an Acquiring Person indicating that an Acquiring Person has become such.

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

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

                                       4
<PAGE>

     "Substitution Period" shall have the meaning set forth in Section
11(a)(iii) hereof. "Summary of Rights" shall mean the Summary of Rights to
Purchase Preferred Shares in substantially the form of Exhibit C hereto.

     "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 in no event be
liable for, the acts or omissions of any such Co-Rights Agent.

     Section 3.  Issue of Right Certificates.
                 ---------------------------

          (a)    Until the earlier of (i) the Close of Business on the Shares
Acquisition Date or (ii) the tenth Business Day (or such later date as may be
determined by action of the Board of Directors prior to such time as any Person
becomes an Acquiring Person) after the date of the commencement 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 any of the
Persons referred to in the preceding parenthetical) 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 (such date 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 Right Certificates) and not by separate Right Certificates, and (y)
the right to receive Right Certificates will be transferable only in connection
with the transfer of Common Shares.  As soon as practicable after the
Distribution Date, the Company will promptly notify the Rights Agent thereof,
and 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 and provided
with a shareholder list and all other relevant information, send) by first-
class, insured, postage-prepaid mail, to each record holder of Common Shares as
of the Close of Business on the Distribution Date, at the address of such holder
shown on the records of the Company, a Right Certificate evidencing one Right
for each Common Share so held.  As of and after the Distribution Date, the
Rights will be evidenced solely by such Right Certificates.

          (b)    On the Record Date, or as soon as practicable thereafter, the
Company will send a copy of the Summary of Rights by first-class, postage-
prepaid mail, to each record holder of Common Shares as of the Close of Business
on the Record Date, at the address of such holder shown on the records of the
Company.  With respect to certificates for Common Shares

                                       5
<PAGE>

outstanding as of the Record Date, until the Close of Business on 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 Close of Business on the Distribution Date
(or the earlier of the Redemption Date or the Close of Business on the Final
Expiration Date), the surrender for transfer of any certificate for Common
Shares outstanding on the Record Date, with or without a copy of the Summary of
Rights attached thereto, shall also constitute the transfer of the Rights
associated with the Common Shares evidenced thereby.

          (c)    Certificates for Common Shares which become outstanding
(including, without limitation, reacquired Common Shares referred to in the last
sentence of this paragraph  (c) after the Record Date but prior to the earliest
of the Close of Business on the Distribution Date, the Redemption Date or the
Close of Business on 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 Avici Systems Inc. and Mellon Investor
          Services LLC, dated as of December 6, 2001 (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 Avici Systems Inc.  Under
          certain circumstances, as set forth in the Rights Agreement,
          such Rights will be evidenced by separate certificates
          and will no longer be evidenced by this certificate.
          Avici Systems Inc. will mail to the holder of this
          certificate a copy of the Rights Agreement without charge
          after receipt of a written request therefor.  Under
          certain circumstances, as set forth in the Rights Agreement,
          Rights that are or were acquired or beneficially owned
          by Acquiring Persons (as defined in the Rights Agreement)
          may become null and void.

With respect to such certificates containing the foregoing legend, until the
Close of Business on the Distribution Date, the Rights associated with the
Common Shares represented by 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 Close of Business on the
Distribution Date, any Rights associated with such Common Shares shall be deemed
canceled and retired so that the Company shall not be entitled to exercise any
Rights associated with the Common Shares which are no longer outstanding.

     Section 4.  Form of Right Certificates.  The Right Certificates (and the
                 --------------------------
forms of election to purchase Preferred Shares 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 (but which
do not affect the rights, duties or responsibilities of the Rights

                                       6
<PAGE>

Agent) 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 other provisions of this
Agreement, the Right Certificates shall entitle the holders thereof to purchase
such number of one one-thousandths of a Preferred Share as shall be set forth
therein at the Purchase Price, but the number of one one-thousandths of a
Preferred Share and the Purchase Price shall be subject to adjustment as
provided herein.

     Section 5.  Countersignature and Registration.
                 ---------------------------------

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

          (b)    Following the Distribution Date and receipt by the Rights Agent
of all necessary information, the Rights Agent will keep or cause to be kept, at
its principal office, books for registration of the transfer of the Right
Certificates issued hereunder. Such books shall show the names and addresses of
the respective holders of the Right Certificates, the number of Rights evidenced
on its face by each of the Right Certificates and the date of each of the Right
Certificates.

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

          (a)    Subject to the provisions of Section 14 hereof, at any time
after the Close of Business on the Distribution Date, and prior to the earlier
of the Redemption Date or the Close of Business on the Final Expiration Date,
any Right Certificate or Right Certificates (other than Right Certificates
representing Rights that have become void pursuant to Section 11(a)(ii) hereof
or that have been exchanged pursuant to Section 24 hereof) may be transferred,
split up, combined or exchanged for another Right Certificate or Right
Certificates, entitling the registered holder to purchase a like number of one
one-thousandths of a Preferred Share as the Right

                                       7
<PAGE>

Certificate or Right Certificates surrendered then entitled such holder to
purchase. Any registered holder desiring to transfer, split up, combine or
exchange any Right Certificate or Right Certificates shall make such request in
writing delivered to the Rights Agent, and shall surrender the Right Certificate
or Right Certificates to be transferred, split up, combined or exchanged at the
office of the Rights Agent designated for such purpose. Thereupon the Rights
Agent shall countersign and deliver to the person entitled thereto a Right
Certificate or Right Certificates, as the case may be, as so requested. The
Company may require payment of a sum sufficient for any tax or governmental
charge that may be imposed in connection with any transfer, split up,
combination or exchange of Right Certificates. The Rights Agent shall have no
duty or obligation to take any action under any Section of this Agreement which
requires the payment by a Rights holder of applicable taxes and governmental
charges unless and until the Rights Agent is satisfied that all such taxes
and/or charges have been paid.

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

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

          (a)    The registered holder of any Right Certificate (other than a
holder whose Rights have become void pursuant to Section 11(a)(ii) hereof or
have been exchanged pursuant to Section 24 hereof) may exercise the Rights
evidenced thereby in whole or in part at any time after the Distribution Date
upon surrender of the Right Certificate, with the form of election to purchase
on the reverse side thereof duly executed, to the Rights Agent at its principal
office, together with payment of the Purchase Price for each one one-thousandth
of a Preferred Share as to which the Rights are exercised, prior to the Close of
Business on the Final Expiration Date.

          (b)    The purchase price for each one one-thousandth of a Preferred
Share to be purchased upon the exercise of a Right shall initially be Forty
Dollars ($40.00) (the "Purchase Price"), shall be subject to adjustment from
time to time as provided in Sections 11 and 13 hereof and shall be payable in
lawful money of the United States of America in accordance with paragraph (c)
below.

          (c)    Upon receipt of a Right Certificate representing exercisable
Rights, with the form of election to purchase and certificate duly executed,
accompanied by payment of the Purchase Price for the number of one one-
thousandths of a Preferred Share to be purchased, and an amount equal to any
applicable tax or charge required, to be paid by the holder of such Right
Certificate in accordance with Section 9 hereof  in cash, or 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 certificates for the number of one

                                       8
<PAGE>

one-thousandths of a Preferred Share to be purchased and the Company hereby
irrevocably authorizes its transfer agent to comply with all such requests, or
(B) requisition from any depository agent for the Preferred Shares depository
receipts representing such number of one one-thousandths of a Preferred Share as
are to be purchased (in which case certificates for the Preferred Shares
represented by such receipts shall be deposited by the transfer agent with the
depository agent) and the Company hereby directs the depository agent to comply
with such request, (ii) when appropriate, requisition from the Company the
amount of cash to be paid in lieu of issuance of fractional Preferred Shares in
accordance with Section 14 hereof, (iii) after receipt of such certificates or
depository receipts, cause the same to be delivered to or upon the order of the
registered holder of such Right Certificate, registered in such name or names as
may be designated by such holder and (iv) when necessary to comply with this
agreement, after receipt, deliver such cash to or upon the order of the
registered holder of such Right Certificate.

          (d)    In case the registered holder of any Right Certificate shall
exercise less than all the Rights evidenced thereby, a new Right Certificate
evidencing Rights equivalent to the Rights remaining unexercised shall be issued
by the Rights Agent to the registered holder of such Right Certificate or to
such registered holder's duly authorized assigns, subject to the provisions of
Sections 6 and 14 hereof.

          (e)    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 Right Certificate surrendered for
such exercise and (ii) provided such additional evidence of the identity of the
Beneficial Owner (or former Beneficial Owner) or Affiliates or Associates
thereof as the Company shall reasonably request.

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

     Section 9.  Status and Availability of Preferred Shares.
                 -------------------------------------------

          (a)    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

                                       9
<PAGE>

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 non-assessable shares.

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

          (c)    The Company covenants and agrees that it will use its best
efforts to 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 Section 7 hereof. Upon the
occurrence of any events resulting in an increase in the aggregate number of
shares of Preferred Stock (or other equity securities of the Company) issuable
upon exercise of all outstanding Rights above the number then reserved, the
Company shall make appropriate increases in the number of shares so reserved.

     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 Right Certificate evidencing such Rights was duly surrendered and
payment of the Purchase Price (and any applicable taxes and charges) was made.
Prior to the exercise of the Rights evidenced thereby, the holder of a Right
Certificate shall not be entitled to any rights of a holder of Preferred Shares
for which the Rights shall be exercisable, including, without limitation, the
right to vote, to receive dividends or other distributions or to exercise any
preemptive rights, and shall not be entitled to receive any notice of any
proceedings of the Company, except as provided herein.

     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

                                       10
<PAGE>

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, 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 this 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 the following paragraph of this subparagraph (ii)
and to Section 24 of this Agreement, in the event any Person shall become 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 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 such Person became an Acquiring
Person. In the event that any Person shall become an Acquiring Person and the
Rights shall then be outstanding, the Company shall not take any action that
would eliminate or diminish the benefits intended to be afforded by the Rights.

     From and after the occurrence of such an event, any Rights that are or were
acquired or beneficially owned by such Acquiring Person (or any Associate or
Affiliate of such Acquiring Person) on or after the earlier of (x) the date of
such event and (y) the Distribution Date shall be void and any holder of such
Rights shall thereafter have no right to exercise such Rights under any
provision of this Agreement.  No Right 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 Right 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 Right
Certificate delivered to the Rights Agent for transfer to an Acquiring Person
whose Rights would be void pursuant to the preceding sentence or any Associate
or Affiliate thereof shall be canceled.

          (iii)  In the event that the number of Common Shares which are
authorized by the Company's certificate of incorporation and not outstanding or
subscribed for, or reserved or otherwise committed for issuance for purposes
other than upon exercise of the

                                       11
<PAGE>

Rights, are not sufficient to permit the holder of each Right to purchase the
number of Common Shares to which he would be entitled upon the exercise in full
of the Rights in accordance with the foregoing subparagraph (ii) of paragraph
(a) of this Section 11, or should the Board of Directors so elect, the Company
shall: (A) determine the excess of (1) the value of the Common Shares issuable
upon the exercise of a Right (calculated as provided in the last sentence of
this subparagraph (iii)) pursuant to Section 11(a)(ii) hereof (the "Current
Value") over (2) the Purchase Price (such excess, the "Spread"), and (B) with
respect to each Right, make adequate provision to substitute for such Common
Shares, upon payment of the applicable Purchase Price, any one or more of the
following having an aggregate value determined by the Board of Directors to be
equal to the Current Value: (1) cash, (2) a reduction in the Purchase Price, (3)
Common Shares or other equity securities of the Company (including, without
limitation, shares, or units of shares, of preferred stock which the Board of
Directors of the Company has determined to have the same value as shares of
Common Stock (such shares of preferred stock, "common stock equivalents")), (4)
debt securities of the Company, (5) other assets or (6) any combination of the
foregoing, having an aggregate value equal to the Current Value, where such
aggregate value has been determined by the Board of Directors of the Company,
based upon the advice of a nationally recognized investment banking firm
selected by the Board of Directors of the Company; provided, however, if the
                                                   --------  -------
Company shall not have made adequate provision to deliver value pursuant to
clause (B) above within thirty (30) days following the first occurrence of an
event triggering the rights to purchase Common Shares described in Section
11(a)(ii) (the "Section 11(a)(ii) Trigger Date"), then the Company shall be
obligated to deliver, upon the surrender for exercise of a Right and without
requiring payment of the Purchase Price, shares of Common Stock (to the extent
available) and then, if necessary, cash, which shares and cash have an aggregate
value equal to the Spread. If the Board of Directors of the Company shall
determine in good faith that it is likely that sufficient additional Common
Shares could be authorized for issuance upon exercise in full of the Rights, the
thirty (30) day period set forth above may be extended to the extent necessary,
but not more than ninety (90) days after the Section 11(a)(ii) Trigger Date, in
order that the Company may seek stockholder approval for the authorization of
such additional shares (such period, as it may be extended, the "Substitution
Period"). To the extent that the Company determines that some action need be
taken pursuant to the first and/or second sentences of this Section 11(a)(iii),
the Company (x) shall provide, subject to the last paragraph of Section
11(a)(ii) hereof, that such action shall apply uniformly to all outstanding
Rights, and (y) may suspend the exercisability of the Rights until the
expiration of the Substitution Period in order to seek any authorization of
additional shares and/or to decide the appropriate form of distribution to be
made pursuant to such first sentence and to determine the value thereof. In the
event of any such suspension, the Company shall make a public announcement, and
shall deliver to the Rights Agent a statement, stating that the exercisability
of the Rights has been temporarily suspended. At such time as the suspension is
no longer in effect, the Company shall make another public announcement, and
deliver to the Rights Agent a statement, so stating. For purposes of this
Section 11(a)(iii), the value of the Common Shares shall be the current per
share market price (as determined pursuant to Section 11(d)(i) hereof) of the
Common Shares on the Section 11(a)(ii) Trigger Date and the value of any common
stock equivalent shall be deemed to have the same value as the Common Shares on
such date.

                                       12
<PAGE>

          (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 adjusted by multiplying the Purchase Price in effect
immediately prior to such record date by a fraction, the numerator of which
shall be the number of Preferred Shares outstanding on such record date plus the
number of Preferred Shares which the aggregate offering price of the total
number of Preferred Shares and/or equivalent preferred shares so to be offered
(and/or the aggregate initial conversion price of the convertible securities so
to be offered) would purchase at such current market price and the denominator
of which shall be the number of Preferred Shares outstanding on such record date
plus the number of additional Preferred Shares and/or equivalent preferred
shares to be offered for subscription or purchase (or into which the convertible
securities so to be offered are initially convertible); provided, however, that
                                                        --------  -------
in no event shall the consideration to be paid upon the exercise of one Right be
less than the aggregate par value of the shares of capital stock of the Company
issuable upon exercise of one Right.  In case such subscription price may be
paid in a consideration part or all of which shall be in a form other than cash,
the value of such consideration shall be as determined in good faith by the
Board of Directors of the Company, whose determination shall be described in a
statement filed with the Rights Agent.  Preferred Shares owned by or held for
the account of the Company shall not be deemed outstanding for the purpose of
any such computation.  Such adjustment shall be made successively whenever such
a record date is fixed; and in the event that such rights, options or warrants
are not so issued, the Purchase Price shall be adjusted to be the Purchase Price
which would then be in effect if such record date had not been fixed.

          (c) In case the Company shall fix a record date for the making of a
distribution to all holders of the Preferred Shares (including any such
distribution made in connection with a consolidation or merger in which the
Company is the continuing or surviving corporation) of evidences of indebtedness
or assets (other than a regular quarterly cash dividend or a dividend payable in
Preferred Shares) or subscription rights or warrants (excluding those referred
to in Section 11(b) hereof), the Purchase Price to be in effect after such
record date shall be determined by multiplying the Purchase Price in effect
immediately prior to such record date by a fraction, the numerator of which
shall be the then current per share market price of the Preferred Shares on such
record date, less the fair market value (as determined in good faith by the
Board of Directors of the Company, whose determination shall be described in a
statement filed with the Rights Agent) of the portion of the assets or evidences
of indebtedness so to be distributed or of such subscription rights or warrants
applicable to one Preferred Share and the denominator of which shall be such
current per share market price of the Preferred Shares; provided, however, that
                                                        --------  -------
in no event shall the consideration to be paid upon the exercise of one Right be
less than the aggregate par value of the shares of capital stock of the Company
to be issued upon exercise of one Right.  Such adjustments shall be made
successively whenever such

                                       13
<PAGE>

a record date is fixed; and in the event that such distribution is not so made,
the Purchase Price shall again be adjusted to be the Purchase Price which would
then be in effect if such record date had not been fixed.

          (d)  (i)    For the purpose of any computation hereunder, the "current
per share market price" of any security (a "Security" for the purpose of this
Section 11(d)(i)) on any date shall be deemed to be the average of the daily
closing prices per share of such Security for the 30 consecutive Trading Days
(as such term is hereinafter defined) immediately prior to but not including
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 30 Trading Days after the ex-dividend
date for such dividend or distribution, or the record date for such subdivision,
combination or reclassification, then, and in each such case, the current per
share market price shall be appropriately adjusted to reflect the current market
price per share equivalent of such Security.  The closing price for each day
shall be the last sale price, regular way, or, in case no such sale takes place
on such day, the average of the closing bid and asked prices, regular way, in
either case as reported in the principal consolidated transaction reporting
system with respect to securities listed or admitted to trading on the Nasdaq
National Market System ("NASDAQ"), 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 NASDAQ
or such other system then in use, or, if on any such date the Security is not
quoted by any such organization, the average of the closing bid and asked prices
as furnished by a professional market maker making a market in the Security
selected by the Board of Directors of the Company.  The term "Trading Day" shall
mean a day on which the principal national securities exchange on which the
Security is listed or admitted to trading is open for the transaction of
business or, if the Security is not listed or admitted to trading on any
national securities exchange, a Business Day.

               (ii) For the purpose of any computation hereunder, the "current
per share market price" of the Preferred Shares shall be determined in
accordance with the method set forth in Section 11(d)(i). 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 1,000. 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, whose
determination shall be described in a statement filed with the Rights Agent.

                                       14
<PAGE>

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

          (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,
the number of such other shares so receivable upon exercise of any Right shall
thereafter 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 and 13 with respect to the Preferred Shares
shall apply on like terms to any such other shares.

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

          (h) Unless the Company shall have exercised its election as provided
in Section 11(i), 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 ten-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 hundred-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

                                       15
<PAGE>

adjustment to be made, and shall promptly give the Rights Agent a copy of such
announcement. This record date may be the date on which the Purchase Price is
adjusted or any day thereafter, but, if the Right Certificates have been
distributed, shall be at least 10 days later than the date of the public
announcement. If Right Certificates have been distributed, upon each adjustment
of the number of Rights pursuant to this Section 11(i), the Company shall, as
promptly as practicable, cause to be distributed to holders of record of Right
Certificates on such record date Right Certificates evidencing, subject to
Section 14 hereof, the additional Rights to which such holders shall be entitled
as a result of such adjustment, or, at the option of the Company, shall cause to
be distributed to such holders of record in substitution and replacement for the
Right Certificates held by such holders prior to the date of adjustment, and
upon surrender thereof, if required by the Company, new Right Certificates
evidencing all the Rights to which such holders shall be entitled after such
adjustment. Right Certificates 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 Right Certificates on the record date
specified in the public announcement.

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

          (k) Before taking any action that would cause an adjustment reducing
the Purchase Price below one one-thousandth of the then par value 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 non-
assessable 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 (and shall give prompt written
notice of such election to the Rights Agent) 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 (i) combination or subdivision of the Preferred Shares, (ii)
issuance wholly for cash of any Preferred Shares at less than the current market
price, (iii) issuance wholly for cash of Preferred Shares or securities which by
their terms are

                                       16
<PAGE>

convertible into or exchangeable for Preferred Shares, (iv) dividends on
Preferred Shares payable in Preferred Shares or (v) issuance of any 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 other than by payment of dividends in Common
Shares) into a greater or lesser number of Common Shares, then in any such case
(i) 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 (ii) 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 whenever such a dividend is declared or paid or such a subdivision,
combination or consolidation is effected.

     Section 12.  Certificate of Adjustment.  Whenever an adjustment is made as
                  -------------------------
provided in Sections 11 and/or 13 hereof, the Company shall promptly (a) prepare
a certificate setting forth such adjustment, and a brief statement of the facts
and computations accounting for such adjustment, (b) file with the Rights Agent
and with each transfer agent for the Common Shares or the Preferred Shares a
copy of such certificate and (c) mail a brief summary thereof to each holder of
a Right Certificate in accordance with Section 25 hereof.  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 therein contained and
shall have no duty with respect to 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. In the event that, at any time after a Person becomes an
-------------
Acquiring Person, directly or indirectly, (i) the Company shall consolidate
with, or merge with and into, any other Person, (ii) any Person shall
consolidate with the Company, or merge with and into the Company and the Company
shall be the continuing or surviving corporation of such merger and, in
connection with such merger, all or part of the Common Shares shall be changed
into or exchanged for stock or other securities of any other Person (or the
Company) or cash or any other property, or (iii) the Company shall sell or
otherwise transfer (or one or more of its Subsidiaries shall sell or otherwise
transfer), in one or more transactions, assets or earning power aggregating 50%
or more of the assets or earning power of the Company and its Subsidiaries
(taken as a whole) to any other Person 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 (A) each holder of a Right (except as otherwise provided

                                       17
<PAGE>

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 (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 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; (B) 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; (C) the
term "Company" shall thereafter be deemed to refer to such issuer; and (D) 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 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 covenants and agrees that it 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. For purposes hereof, the "earning power" of the Company and its
Subsidiaries shall be determined in good faith by the Company's Board of
Directors on the basis of the operating earnings of each business operated by
the Company and its Subsidiaries during the three fiscal years preceding the
date of such determination (or, in the case of any business not operated by the
Company or any Subsidiary during three full fiscal years preceding such date,
during the period such business was operated by the Company or any Subsidiary).


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

          (a)     The Company shall not be required to issue fractions of Rights
or to distribute Right Certificates which evidence fractional Rights. In lieu of
such fractional Rights, there shall be paid to the registered holders of the
Right Certificates with regard to which such fractional Rights would otherwise
be issuable, an amount in cash equal to the same fraction of the current market
value of a whole Right. For the purposes of this Section 14(a), the current
market value of a whole Right shall be the closing price of the Rights for the
Trading Day immediately prior to the date on which such fractional Rights would
have been otherwise issuable. The closing price for any day shall be the last
sale price, regular way, or, in case no such sale takes place on such day, the
average of the closing bid and asked prices, regular way, in either case as
reported in the principal consolidated transaction reporting system with respect
to securities listed or admitted to trading on the New York Stock Exchange or,
if the Rights are not

                                       18
<PAGE>

listed or admitted to trading on the New York Stock Exchange, as reported in the
principal consolidated transaction reporting system with respect to securities
listed on the principal national securities exchange on which the Rights are
listed or admitted to trading or, if the Rights are not listed or admitted to
trading on any national securities exchange, the last quoted price or, if not so
quoted, the average of the high bid and low asked prices in the over-the-counter
market, as reported by NASDAQ or such other system then in use or, if on any
such date the Rights are not quoted by any such organization, the average of the
closing bid and asked prices as furnished by a professional market maker making
a market in the Rights selected by the Board of Directors of the Company. If on
any such date no such market maker is making a market in the Rights, the fair
value of the Rights on such date as determined in good faith by the Board of
Directors of the Company shall be used.

          (b) The Company shall not be required to issue fractions of Preferred
Shares (other than fractions which are integral multiples of one one-thousandth
of a Preferred Share) upon exercise of the Rights or to distribute certificates
which evidence fractional Preferred Shares (other than fractions which are
integral multiples of one one-thousandth of a Preferred Share).  Fractions of
Preferred Shares in integral multiples of one one-thousandth of a Preferred
Share may, at the election of the Company, be evidenced by depository receipts,
pursuant to an appropriate agreement between the Company and a depository
selected by it; provided, that such agreement shall provide that the holders of
such depository receipts shall have all the rights, privileges and preferences
to which they are entitled as beneficial owners of the Preferred Shares
represented by such depository receipts.  In lieu of fractional Preferred Shares
that are not integral multiples of one one-thousandth of a Preferred Share, the
Company shall pay to each registered holder of Right Certificates at the time
such Rights are exercised as herein provided an amount in cash equal to the same
fraction of the current market value of one Preferred Share as the fraction of
one Preferred Share that such holder would otherwise receive upon the exercise
of the aggregate number of rights exercised by such holder.  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.

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

          (d) Whenever a payment for fractional Rights or fractional shares is
to be made by the Rights Agent, the Corporation shall (i) promptly prepare and
deliver to the Rights Agent a certificate setting forth in reasonable detail the
facts related to such payments and the prices and/or formulas utilized in
calculating such payments, and (ii) provide sufficient monies to the Rights
Agent in the form of fully collected funds to make such payments.  The Rights
Agent shall be fully protected in relying upon such a certificate and shall have
no duty with respect to, and shall not be deemed to have knowledge of any
payment for fractional Rights or fractional shares under any Section of this
Agreement relating to the payment of fractional Rights or fractional shares
unless and until the Rights Agent shall have received such a certificate and
sufficient monies.

                                       19
<PAGE>

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

     Section 16.  Agreement of Right Holders.  Every holder of a Right, by
                  --------------------------
accepting the same, consents and agrees with the Company and the Rights Agent
and with every other holder of a Right that:


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

          (b)     after the Distribution Date, the Right Certificates are
transferable only on the registry books maintained by the Rights Agent if
surrendered at the principal office of the Rights Agent, duly endorsed or
accompanied by a proper instrument of transfer with a completed form of
certification; and

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


     Section 17.  Right Certificate Holder Not Deemed a Stockholder.  No holder,
                  -------------------------------------------------
as such, of any Right Certificate shall be entitled to vote, receive dividends
or be deemed for any purpose the holder of the Preferred Shares or any other
securities of the Company which may at any time be issuable on the exercise of
the Rights represented thereby nor shall anything contained herein or in any
Right Certificate be construed to confer upon the holder of any Right
Certificate, as such, any of the rights of a stockholder of the Company or any
right to vote for the election of directors or upon any matter submitted to
stockholders at any meeting thereof, or to give or withhold consent to any
corporate action, or to receive notice of meetings or other actions affecting
stockholders (except as provided in Section 25 hereof), or to receive dividends
or

                                       20
<PAGE>

subscription rights, or otherwise, until the Right or Rights evidenced by such
Right Certificate shall have been exercised in accordance with the provisions
hereof.

     Section 18.  Concerning the Rights Agent.
                  ---------------------------

          (a)     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 preparation, administration, delivery,
execution and amendment of this Agreement and the exercise and performance of
its duties hereunder. The Company also agrees to indemnify the Rights Agent for,
and to hold it harmless against, any loss, liability, damage, judgment, fine,
penalty, claim, demand, settlement, cost or expense, incurred without gross
negligence, bad faith or willful misconduct on the part of the Rights Agent
(each as finally determined by a court of competent jurisdiction) for any action
taken, suffered or omitted by the Rights Agent in connection with the acceptance
and administration of this Agreement, including without limitation, the costs
and expenses of defending against any claim or liability in connection
therewith. The costs and expenses incurred in enforcing this right of
indemnification shall be paid by the Company. The provisions of this Section 18
and Section 20 below shall survive the termination of this Agreement, the
exercise or expiration of the Rights and the resignation or removal of the
Rights Agent.

          (b)     The Rights Agent shall be authorized and protected and shall
incur no liability for or in respect of any action taken, suffered or omitted by
it in connection with its acceptance and administration of this Agreement in
reliance upon any Right Certificate or certificate for Preferred 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. The Rights Agent shall not be deemed to have knowledge of
any event of which it was supposed to receive notice thereof hereunder, and the
Rights Agent shall be fully protected and shall incur no liability for failing
to take any action in connection therewith unless and until it has received such
notice in writing.

     Section 19.  Merger or Consolidation or Change of Name of Rights Agent.
                  ---------------------------------------------------------

          (a)     Any Person into which the Rights Agent or any successor Rights
Agent may be merged or with which it may be consolidated, or any Person
resulting from any merger or consolidation to which the Rights Agent or any
successor Rights Agent shall be a party, or any Person succeeding to the
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 Person would be eligible for appointment as a
successor Rights Agent under the provisions of Section 21 hereof. In case at the
time such successor Rights Agent shall succeed to the agency created by this
Agreement, any of the Right Certificates shall have been countersigned but not
delivered, any such successor Rights Agent may adopt the countersignature of the
predecessor

                                       21
<PAGE>

Rights Agent and deliver such Right Certificates so countersigned; and in case
at that time any of the Right Certificates shall not have been countersigned,
any successor Rights Agent may countersign such Right Certificates either in the
name of the predecessor Rights Agent or in the name of the successor Rights
Agent; and in all such cases such Right Certificates shall have the full force
provided in the Right Certificates and in this Agreement.

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

     Section 20.  Duties of Rights Agent.  The Rights Agent undertakes only the
                  ----------------------
duties and obligations expressly set forth in this Agreement and no implied
duties or obligations shall be read into this Agreement against the Rights
Agent.  The Rights Agent shall perform those duties and obligations upon the
following terms and conditions, by all of which the Company and the holders of
Right Certificates, by their acceptance thereof, shall be bound:

          (a)     The Rights Agent may consult with legal counsel (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 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 to
take 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 President, a Vice President, the Treasurer or the Secretary of the
Company and delivered to the Rights Agent; and such certificate shall be full
authorization and protection to the Rights Agent for any action taken or
suffered by it under the provisions of this Agreement in reliance upon such
certificate.

          (c)     The Rights Agent shall be liable hereunder only for its own
gross negligence, bad faith or willful misconduct (each as finally determined by
a court of competent jurisdiction). Anything to the contrary notwithstanding, in
no event shall the Rights Agent be liable for special, punitive, indirect,
consequential or incidental loss or damage of any kind whatsoever (including but
not limited to lost profits), even if the Rights Agent has been advised of the
likelihood of such loss or damage. Any liability of the Rights Agent under this
Rights Agreement will be limited to the amount of fees paid by the Company to
the Rights Agent.

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

                                       22
<PAGE>

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 responsibility in respect
of the validity of this Agreement or the execution and delivery hereof (except
the due execution hereof by the Rights Agent) or in respect of the validity or
execution of any Right Certificate (except its countersignature thereof); nor
shall it be responsible for any breach by the Company of any covenant or
condition contained in this Agreement or in any Right Certificate; nor shall it
be responsible for any adjustment required under the provisions of Sections 11
or 13 hereof or responsible for the manner, method or amount of any such
adjustment or the ascertaining of the existence of facts that would require any
such adjustment (except with respect to the exercise of Rights evidenced by
Right Certificates after actual notice of any such adjustment); nor shall it by
any act hereunder be deemed to make any representation or warranty as to the
authorization or reservation of any shares of Preferred Shares to be issued
pursuant to this Agreement or any Right Certificate or as to whether any
Preferred Shares will, when so issued, be validly authorized and issued, fully
paid and nonassessable.

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

          (g)  The Rights Agent is hereby authorized and directed to accept
instructions with respect to the performance of its duties hereunder from any
one of the Chairman of the Board, the President, a 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 such instructions shall be full
authorization and protection to the Rights Agent, and the Rights Agent shall not
be liable for any action taken, suffered or omitted to be taken by it in
accordance with instructions of any such officer.

          (h)  The Rights Agent and any stockholder, affiliate, 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 pecuniary interested in any
transaction in which the Company may be interested, or contract with or lend
money to the Company or otherwise act as fully and freely as though it were not
Rights Agent under this Agreement. Nothing herein shall preclude the Rights
Agent from acting in any other capacity for the Company or for any other Person.

          (i)  The Rights Agent may execute and exercise any of the rights or
powers hereby vested in it or perform any duty hereunder either itself or by or
through its attorneys or agents, and the Rights Agent shall not be answerable or
accountable for any act, default, neglect or misconduct of any such attorneys or
agents or for any loss to the Company resulting from any such act, default,
neglect or misconduct, absent gross negligence, bad faith or willful misconduct
(each as finally determined by a court of competent jurisdiction) in the
selection and continued employment thereof.

                                       23
<PAGE>

     (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
it believes that repayment of such funds or adequate indemnification against
such risk or liability is not reasonably assured to it.

     Section 21.  Change of Rights Agent.  The Rights Agent or any successor
                  ----------------------
Rights Agent may resign and be discharged from its duties under this Agreement
upon 30 days' notice in writing mailed to the Company and to each transfer agent
of the Common Shares and the Preferred Shares by registered or certified mail,
and to the holders of the Right Certificates by first-class mail. The Company
may remove the Rights Agent or any successor Rights Agent upon 30 days' notice
in writing, mailed to the Rights Agent or successor Rights Agent, as the case
may be, and to each transfer agent of the Common Shares and the Preferred Shares
by registered or certified mail, and to the holders of the Right Certificates by
first-class mail. If the Rights Agent shall resign or be removed or shall
otherwise become incapable of acting, the Company shall appoint a successor to
the Rights Agent. If the Company shall fail to make such appointment within a
period of 30 days after giving notice of such removal or after it has been
notified in writing of such resignation or incapacity by the resigning or
incapacitated Rights Agent or by the holder of a Right Certificate (who shall,
with such notice, submit his Right Certificate for inspection by the Company),
then the registered holder of any Right Certificate may apply to any court of
competent jurisdiction for the appointment of a new Rights Agent. Any successor
Rights Agent, whether appointed by the Company or by such a court, shall be (i)
a Person organized and doing business under the laws of the United States or of
any state of the United States, in good standing, which is subject to
supervision or examination by federal or state authority and which has at the
time of its appointment as Rights Agent a combined capital and surplus of at
least $100 million, or (ii) an Affiliate of a Person described in clause (i).
After appointment, the successor Rights Agent shall be vested with the same
powers, rights, duties and responsibilities as if it had been originally named
as Rights Agent without further act or deed; but the predecessor Rights Agent
shall deliver and transfer to the successor Rights Agent any property at the
time held by it hereunder, and execute and deliver any further assurance,
conveyance, act or deed necessary for the purpose. Not later than the effective
date of any such appointment the Company shall file notice thereof in writing
with the predecessor Rights Agent and each transfer agent of the Common Shares
and the Preferred Shares, and mail a notice thereof in writing to the registered
holders of the Right Certificates. Failure to give any notice provided for in
this Section 21, however, or any defect therein, shall not affect the legality
or validity of the resignation or removal of the Rights Agent or the appointment
of the successor Rights Agent, as the case may be.

     Section 22.  Issuance of New Right Certificates.  Notwithstanding any of
                  ----------------------------------
the provisions of this Agreement or of the Rights to the contrary, the Company
may, at its option, issue new Right Certificates evidencing Rights in such form
as may be approved by its Board of Directors to reflect any adjustment or change
in the Purchase Price and the number or kind or class of shares or other
securities or property purchasable under the Right Certificates made in
accordance with the provisions of this Agreement.  In addition, in connection
with the issuance or sale of shares of Common Stock following the Distribution
Date and prior to the Final Expiration Date, the Company (a) shall, with respect
to shares of Common Stock so issued or

                                       24
<PAGE>

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, issue Right Certificates representing the
appropriate number of Rights in connection with such issuance or sale; provided,
                                                                       --------
however, that (i) no such Right Certificate shall be issued 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 Right 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 Right Certificate shall be issued if, and
to the extent that, appropriate adjustment shall otherwise have been made in
lieu of the issuance thereof.

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

          (a)  The Board of Directors of the Company may, at its option, at any
time prior to the earlier of (i) the Close of Business on the tenth calendar
date following the Shares Acquisition Date (or such later calendar date
following the Shares Acquisition Date as may be determined by the Board of
Directors in its sole discretion), or (ii) the Final Expiration Date, redeem all
but not less than all of the then outstanding Rights at a redemption price of
$0.01 per Right, appropriately adjusted to reflect any stock split, stock
dividend or similar transaction occurring after the date hereof (such redemption
price being hereinafter referred to as the "Redemption Price").  The redemption
of the Rights by the Board of Directors may be made effective at such time, on
such basis and subject to such conditions as the Board of Directors in its sole
discretion may establish.

          (b)  Immediately upon the time of the effectiveness of the redemption
of the Rights pursuant to paragraph (a) of this Section 23 or such earlier time
as may be determined by the Board of Directors of the Company in the action
ordering such redemption (although not earlier than the time of such action)
(such time the "Redemption Date"), and without any further action and without
any notice, the right to exercise the Rights shall 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 (and prompt
written notice of such redemption to the Rights Agent); 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 pursuant to paragraph (a), the
Company 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, whether or not the holder
receives the notice.  If the payment of the Redemption Price is not included
with such notice, each such notice shall state the method by which the payment
of the Redemption Price will be made.  Neither the Company nor any of its
Affiliates or Associates may redeem, acquire or purchase for value any Rights at
any time in any manner other than that specifically set forth in

                                       25
<PAGE>

this Section 23 or in Section 24 hereof, other than in connection with the
purchase of Common Shares prior to the Distribution Date.

     Section 24.  Exchange.
                  --------

          (a) The Board of Directors of the Company may, at its option, at any
time after any Person becomes an Acquiring Person, exchange all or part of the
then outstanding and exercisable Rights (which shall not include Rights that
have become void pursuant to the provisions of Section 11(a)(ii) hereof) for
Common Shares at an exchange ratio of one Common Share per Right, appropriately
adjusted to reflect any stock split, stock dividend or similar transaction
occurring after the date hereof (such exchange ratio being hereinafter referred
to as the "Exchange Ratio").  Notwithstanding the foregoing, the Board of
Directors shall not be empowered to effect such exchange at any time after any
Person (other than the Company, any Subsidiary of the Company, any employee
benefit plan of the Company or any such Subsidiary, or any entity holding Common
Shares for or pursuant to the terms of any such plan), together with all
Affiliates and Associates of such Person, becomes the Beneficial Owner of a
majority 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 (with prompt
written notice thereof to the Rights Agent); provided, however, that the failure
                                             --------  -------
to give, or any defect in, such notice shall not affect the validity of such
exchange.  The Company promptly shall mail a notice of any such exchange to all
of the holders of such Rights at their last addresses as they appear upon the
registry books of the Rights Agent.  Any notice which is mailed in the manner
herein provided shall be deemed given, whether or not the holder receives the
notice.  Each such notice of exchange will state the method by which the
exchange of the Common Shares for Rights will be effected and, in the event of
any partial exchange, the number of Rights which will be exchanged.  Any partial
exchange shall be effected pro rata based on the number of Rights (other than
Rights which have become void pursuant to the provisions of Section 11(a)(ii)
hereof) held by each holder of Rights.

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

          (d) In the event that there shall not be sufficient Common Shares,
Preferred Shares or common stock equivalents authorized by the Company's
certificate of incorporation

                                       26
<PAGE>

and not outstanding or subscribed for, or reserved or otherwise committed for
issuance for purposes other than upon exercise of Rights, to permit any exchange
of Rights as contemplated in accordance with this Section 24, the Company shall
take all such action as may be necessary to authorize additional Common Shares,
Preferred Shares or common stock equivalents for issuance upon exchange of the
Rights.

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

     Section 25.  Notice of Certain Events.
                  ------------------------

          (a)     In case the Company shall after the Distribution Date propose
(i) to pay any dividend payable in stock of any class to the holders of its
Preferred Shares or to make any other distribution to the holders of its
Preferred Shares (other than a regular quarterly cash dividend), (ii) to offer
to the holders of its Preferred Shares rights or warrants to subscribe for or to
purchase any additional Preferred Shares or shares of stock of any class or any
other securities, rights or options, (iii) to effect any reclassification of its
Preferred Shares (other than a reclassification involving only the subdivision
of outstanding Preferred Shares), (iv) to effect any consolidation or merger
into or with, or to effect any sale or other transfer (or to permit one or more
of its Subsidiaries to effect any sale or other transfer), in one or more
transactions, of 50% or more of the assets or earning power of the Company and
its Subsidiaries (taken as a whole) to, any other Person, (v) to effect the
liquidation, dissolution or winding up of the Company, or (vi) to declare or pay
any dividend on the Common Shares payable in Common Shares or to effect a
subdivision, combination or consolidation of the Common Shares (by
reclassification or otherwise than by payment of dividends in Common Shares),
then, in each such case, the Company shall give to each holder of a Right
Certificate, in accordance with Section 26 hereof, a notice of such proposed
action, which shall specify the record date for the 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 10 days prior to the record date
for determining holders of the Preferred Shares for purposes of such action, and
in the case of any such other action, at least 10 days prior to the date of the
taking of such proposed action or the date of participation therein by the
holders of the Common Shares and/or Preferred Shares, whichever shall be the
earlier.

          (b)     In case any event set forth in Section 11(a)(ii) hereof shall
occur, then the Company shall as soon as practicable thereafter give to the
Rights Agent and to each holder of a

                                       27
<PAGE>

Right 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.

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

                  Avici Systems Inc.
                  101 Billerica Avenue, Bldg. 2
                  N. Billerica, Massachusetts 01862
                  Facsimile No.:  (978) 964-2250
                  Attention:  General Counsel

                  Copy to:

                  Testa, Hurwitz & Thibeault, LLP
                  125 High Street
                  Boston, Massachusetts  02110
                  Facsimile No.:  (617) 248-7100

                  Attention: John A. Meltaus, Esq.


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


                  Mellon Investor Services LLC
                  111 Founders Plaza, 11th Floor
                  East Hartford, CT 06108

                  Attention: Relationship Manager
                  Facsimile No.: (860) 528-6472

                  With a copy to:

                  Mellon Investor Services LLC
                  85 Challenger Road
                  Ridgefield Park, New Jersey 07660
                  Attention:  General Counsel
                  Facsimile No.: (201) 296-4004

                                      28
<PAGE>

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


     Section 27.  Supplements and Amendments.  The Company may from time to
                  --------------------------
time, and the Rights Agent shall, if the Company so directs, but subject to the
other provisions of this Section, supplement or amend this Agreement without the
approval of any holders of Right Certificates in order to cure any ambiguity, to
correct or supplement any provision contained herein which may be defective or
inconsistent with any other provisions herein, or to make any change to or
delete any provision hereof or to adopt any other provisions with respect to the
Rights which the Company may deem necessary or desirable; provided, however,
                                                          --------  -------
that from and after such time as any Person becomes an Acquiring Person, this
Agreement shall not be amended or supplemented in any manner which would
adversely affect the interests of the holders of Rights (other than an Acquiring
Person and its Affiliates and Associates).  Upon the delivery of a certificate
from an appropriate officer of the Corporation which states that the proposed
supplement or amendment is in compliance with the terms of this Section 27, and
provided that such supplement or amendment does not change or increase the
Rights Agent's rights, duties or obligations, the Rights Agent shall execute
such supplement or amendment.  Any supplement or amendment authorized by this
Section 27 will be evidenced by a writing signed by the Company and the Rights
Agent.


     Section 28.  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.  Benefits of this Agreement.  Nothing in this Agreement shall
                  --------------------------
be construed to give to any person or entity other than the Company, the Rights
Agent and the registered holders of the Right Certificates (and, prior to the
Distribution Date, the Common Shares) any legal or equitable right, remedy or
claim under this Agreement; but this Agreement shall be for the sole and
exclusive benefit of the Company, the Rights Agent and the registered holders of
the Right Certificates (and, prior to the Distribution Date, the Common Shares).


     Section 30.  Severability.  If any term, provision, covenant or restriction
                  ------------
of this Agreement is held by a court of competent jurisdiction or other
authority to be invalid, void or unenforceable, the remainder of the terms,
provisions, covenants and restrictions of this Agreement shall remain in full
force and effect and shall in no way be affected, impaired or invalidated.


     Section 31.  Governing Law.  This Agreement and each Right Certificate
                  -------------
issued hereunder shall be deemed to be a contract made under the laws of the
State of Delaware and for all purposes shall be governed by and construed in
accordance with the laws of such State applicable to contracts to be made and
performed entirely within such State; provided, however, that all provisions
                                      --------  -------
regarding the rights, duties and obligations of the Rights Agent shall be

                                       29
<PAGE>

governed by and construed in accordance with the laws of the State of New York
applicable to contracts made and to be performed entirely within such State.


     Section 32.  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 33.  Descriptive Headings; Construction.  Descriptive headings of
                  ----------------------------------
the several Sections of this Agreement are inserted for convenience only and
shall not control or affect the meaning or construction of any of the provisions
hereof.  Whenever the content of this Agreement permits, the masculine gender
shall include the feminine and neuter genders, and reference to singular or
plural shall be interchangeable with the other.


     Section 34.  Administration.  The Board of Directors of the Company shall
                  --------------
have the exclusive power and authority to administer and interpret the
provisions of this Agreement and to exercise all rights and powers specifically
granted to the Board of Directors or the Company or as may be necessary,
desirable or advisable in the administration of this Agreement.  All such
actions, calculations, determinations and interpretations which are done or made
by the Board of Directors in good faith shall be final, conclusive and binding
on the Company, the Rights Agent, the holders of the Rights and all other
parties and shall not subject the Board of Directors to any liability to the
holders of the Rights.  The Rights Agent shall always be entitled to assume that
the Company's Board of Directors acted in good faith and shall be fully
protected and incur no liability in reliance thereon.


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


Attest:                             AVICI SYSTEMS INC.



/s/ Peter C. Anastos                By: /s/ Paul F. Brauneis
---------------------------             ------------------------



Attest:                             MELLON INVESTOR SERVICES LLC



/s/ Lynore LeConche                 By: /s/ Jacqueline Wadsworth
---------------------------             ------------------------

                                       30
<PAGE>

                                                                       EXHIBIT A



                                     FORM


                                      of


                          CERTIFICATE OF DESIGNATION

                                      of

                 SERIES A JUNIOR PARTICIPATING PREFERRED STOCK

                                      of

                              AVICI SYSTEMS INC.

                _______________________________________________

                        (Pursuant to Section 151 of the

                       Delaware General Corporation Law)

               ________________________________________________



          Avici Systems Inc., a corporation organized and existing under the
General Corporation Law of the State of Delaware (hereinafter called the
"Corporation"), hereby certifies that the following resolution was adopted by
the Board of Directors of the Corporation as required by Section 151 of the
General Corporation Law at a meeting duly called and held on December 5, 2001:


          RESOLVED, that pursuant to the authority granted to and vested in the
Board of Directors of this Corporation (hereinafter called the "Board of
Directors" or the "Board") in accordance with the provisions of the Fourth
Restated Certificate of Incorporation of the Corporation (the "Certificate of
Incorporation"), the Board of Directors hereby creates a series of Preferred
Stock, par value $0.01 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:


          Section 1.  Designation and Amount.  The shares of this series shall
                      ----------------------
be designated as "Series A Junior Participating Preferred Stock" (the "Series A
Preferred Stock") and the number of shares constituting the Series A Preferred
Stock shall be one hundred thousand (100,000).  Such number of shares may be
increased or decreased by resolution of the Board of Directors; provided, that
no decrease shall reduce the number of shares of Series A Preferred Stock to a
number less than the number of shares then outstanding plus the number of shares
reserved for issuance upon the exercise of outstanding options, rights or
warrants or upon the conversion of any outstanding securities issued by the
Corporation convertible into Series A Preferred Stock.

                                      A-1
<PAGE>

     Section 2.  Dividends and Distributions.
                 ---------------------------

          (a)  Subject to the rights of the holders of any shares of any series
of Preferred Stock (or any other stock) ranking prior and superior to the Series
A Preferred Stock with respect to dividends, the holders of shares of Series A
Preferred 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 last day of March, June, September and December
in each year (each such date being referred to herein as a "Quarterly Dividend
Payment Date"), commencing on the first Quarterly Dividend Payment Date after
the first issuance of a share or fraction of a share of Series A Preferred
Stock, in an amount (if any) per share of Series A Preferred Stock (rounded to
the nearest cent), subject to the provision for adjustment hereinafter set
forth, equal to 1,000 times the aggregate per share amount of all cash
dividends, and 1,000 times the aggregate per share amount (payable in kind) of
all non-cash dividends or other distributions, other than a dividend payable in
shares of Common Stock, par value $0.0001 per share (the "Common Stock"), of the
Corporation or a subdivision of the outstanding shares of Common Stock (by
reclassification or otherwise), declared on the Common Stock since the
immediately preceding Quarterly Dividend Payment Date or, with respect to the
first Quarterly Dividend Payment Date, since the first issuance of any share or
fraction of a share of Series A Preferred Stock.  In the event the Corporation
shall at any time declare or pay any dividend on the Common Stock payable in
shares of Common Stock, or effect a subdivision or combination or consolidation
of the outstanding shares of Common Stock (by reclassification or otherwise than
by payment of a dividend in shares of Common Stock) into a greater or lesser
number of shares of Common Stock, then in each such case the amount to which
holders of shares of Series A Preferred Stock were entitled immediately prior to
such event under the preceding sentence shall be adjusted by multiplying such
amount by a fraction, the numerator of which is the number of shares of Common
Stock outstanding immediately after such event and the denominator of which is
the number of shares of Common Stock that were outstanding immediately prior to
such event.


          (b)  The Corporation shall declare a dividend or distribution on the
Series A Preferred Stock as provided in paragraph (A) of this Section
immediately after it declares a dividend or distribution on the Common Stock
(other than a dividend payable in shares of Common Stock).


          (c)  Dividends due pursuant to paragraph (A)  of this Section shall
begin to accrue and be cumulative on outstanding shares of Series A Preferred
Stock from the Quarterly Dividend Payment Date next preceding the date of issue
of such shares, unless the date of issue of such shares is prior to the record
date for the first Quarterly Dividend Payment Date, in which case dividends on
such shares shall begin to accrue from the date of issue of such shares, or
unless the date of issue is a Quarterly Dividend Payment Date or is a date after
the record date for the determination of holders of shares of Series A Preferred
Stock entitled to receive a quarterly dividend and before such Quarterly
Dividend Payment Date, in either of which events such dividends shall begin to
accrue and be cumulative from such Quarterly Dividend Payment Date.  Accrued but
unpaid dividends shall not bear interest.  Dividends paid on the shares of
Series A Preferred Stock in an amount less than the total amount of such
dividends at the time accrued and

                                      A-2
<PAGE>

payable on such shares shall be allocated pro rata on a share-by-share basis
among all such shares at the time outstanding. The Board of Directors may fix a
record date for the determination of holders of shares of Series A Preferred
Stock entitled to receive payment of a dividend or distribution declared
thereon, which record date shall be not more than 60 days prior to the date
fixed for the payment thereof.

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

          (a)  Subject to the provision for adjustment hereinafter set forth,
each share of Series A Preferred Stock shall entitle the holder thereof to 1,000
votes on all matters submitted to a vote of the stockholders of the Corporation.
In the event the Corporation shall at any time declare or pay any dividend on
the Common Stock payable in shares of Common Stock, or effect a subdivision or
combination or consolidation of the outstanding shares of Common Stock (by
reclassification or otherwise than by payment of a dividend in shares of Common
Stock) into a greater or lesser number of shares of Common Stock, then in each
such case the number of votes per share to which holders of shares of Series A
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 the Certificate of Incorporation,
including any other Certificate of Designations creating a series of Preferred
Stock or any similar stock, or by law, the holders of shares of Series A
Preferred Stock and the holders of shares of Common Stock and any other capital
stock of the Corporation having general voting rights shall vote together as one
class on all matters submitted to a vote of stockholders of the Corporation.

          (c)  Except as set forth herein, or as otherwise required by law,
holders of Series A 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.  Without limiting the generality of the foregoing, the number of
authorized shares of Preferred Stock may be increased or decreased (but not
below the number of shares thereof then outstanding) by the affirmative vote of
the holders of a majority of the stock of the Corporation entitled to vote,
irrespective of the provisions of Section 242(b)(2) of the General Corporation
Law.


     Section 4.  Certain Restrictions.
                 --------------------

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

                                      A-3
<PAGE>

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

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

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

          (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.

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


     Section 6.  Liquidation, Dissolution or Winding Up.  Upon any liquidation,
                 --------------------------------------
dissolution or winding up of the Corporation the holders of shares of Series A
Preferred Stock shall be entitled to receive an aggregate amount per share of
Series A Preferred Stock, subject to the provision for adjustment hereinafter
set forth, equal to 1,000 times the aggregate amount to be distributed per share
to holders of shares of Common Stock plus an amount equal to any accrued and
unpaid dividends. 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 A
Preferred Stock were entitled immediately prior to such event under 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

                                      A-4
<PAGE>

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 A Preferred Stock shall at the same time be similarly exchanged or
changed into an amount per share, subject to the provision for adjustment
hereinafter set forth, equal to 1,000 times the aggregate amount of stock,
securities, cash and/or any other property (payable in kind), as the case may
be, into which or for which each share of Common Stock is changed or exchanged.
In the event the Corporation shall at any time declare or pay any dividend on
the Common Stock payable in shares of Common Stock, or effect a subdivision or
combination or consolidation of the outstanding shares of Common Stock (by
reclassification or otherwise than by payment of a dividend in shares of Common
Stock) into a greater or lesser number of shares of Common Stock, then in each
such case the amount set forth in the preceding sentence with respect to the
exchange or change of shares of Series A 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.  Amendment.  The Restated Certificate of Incorporation shall not
                 ---------
be amended in any manner, including in a merger or consolidation, which would
alter, change, or repeal the powers, preferences or special rights of the Series
A Preferred Stock so as to affect them adversely without the affirmative vote of
the holders of at least two-thirds of the outstanding shares of Series A
Preferred Stock, voting together as a single class.

     Section 9.  Rank.  The Series A Preferred Stock shall rank, with respect to
                 ----
the payment of dividends and upon liquidation, dissolution and winding up,
junior to all series of Preferred Stock.


          IN WITNESS WHEREOF, this Certificate of Designation is executed on
behalf of the Corporation by its Chief Financial Officer and Senior Vice
President of Finance and Administration this 6th day of December, 2001.



AVICI SYSTEMS INC.



By: _____________________________

    Name:   Paul F. Brauneis
    Title:  Chief Financial Officer and
            Senior Vice President of
            Finance and Administration

                                      A-5
<PAGE>

                                                                       EXHIBIT B

Form of Right Certificate
Certificate No. R-  _______ Rights

NOT EXERCISABLE AFTER DECEMBER 5, 2011 OR EARLIER IF REDEMPTION OR EXCHANGE
OCCURS.  THE RIGHTS ARE SUBJECT TO REDEMPTION AT $0.01 PER RIGHT AND TO EXCHANGE
ON THE TERMS SET FORTH IN THE RIGHTS AGREEMENT.  UNDER CERTAIN CIRCUMSTANCES,
RIGHTS THAT ARE OR WERE ACQUIRED OR BENEFICIALLY OWNED BY AN ACQUIRING PERSON OR
ANY ASSOCIATES OR AFFILIATES THEREOF (AS SUCH TERMS ARE DEFINED IN THE RIGHTS
AGREEMENT) OR ANY SUBSEQUENT HOLDER OF SUCH RIGHTS MAY BECOME NULL AND VOID.

                               Right Certificate
                               Avici Systems Inc.


     This certifies that _______________________, or registered assigns, is the
registered owner of the number of Rights set forth above, each of which entitles
the owner thereof, subject to the terms, provisions and conditions of the Rights
Agreement, dated as of December 6, 2001 (the "Rights Agreement"), between Avici
Systems Inc., a Delaware corporation (the "Company"), and Mellon Investor
Services LLC, a New Jersey limited liability company (the "Rights Agent"), to
purchase from the Company at any time after the Distribution Date (as such term
is defined in the Rights Agreement) and prior to 5:00 P.M., Boston,
Massachusetts time, on December 5, 2011, at the office of the Rights Agent
designated for such purpose, or at the office of its successor as Rights Agent,
one one-thousandth of a fully paid non-assessable share of Series A Junior
Participating Preferred Stock, par value $0.01 per share (the "Preferred
Shares"), of the Company, at a purchase price of $40.00 per one one-thousandth
of a Preferred Share (the "Purchase Price"), upon presentation and surrender of
this Right Certificate with the certification and the Form of Election to
Purchase duly executed.  The number of Rights evidenced by this Right
Certificate (and the number of one one-thousandths of a Preferred Share which
may be purchased upon exercise hereof) set forth above, and the Purchase Price
set forth above, are the number and Purchase Price as of December 6, 2001, 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 Right Certificate are subject to modification and adjustment upon the
happening of certain events.

     From and after the occurrence of an event described in Section 11(a)(ii) of
the Rights Agreement, if the Rights evidenced by this Right Certificate are or
were at any time on or after the earlier of (x) the date of such event and (y)
the Distribution Date (as such term is defined in the Rights Agreement) acquired
or beneficially owned by an Acquiring Person or an Associate or Affiliate of an
Acquiring Person (as such terms are defined in the Rights Agreement), such
Rights shall become void, and any holder of such Rights shall thereafter have no
right to exercise such Rights.

                                      B-1
<PAGE>

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

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

     Subject to the provisions of the Rights Agreement, at the Company's option,
the Rights evidenced by this Certificate (i) may be redeemed by the Company at a
redemption price of $0.01 per Right or (ii) may be exchanged in whole or in part
for shares of the Company's Common Stock, par value $0.01 per share, or
Preferred Shares.

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

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

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

                                      B-2
<PAGE>

     WITNESS the facsimile signature of the proper officers of the Company and
its corporate seal.  Dated as of ____ __, 200_.



ATTEST:                            AVICI SYSTEMS INC.





_____________________________      By: _____________________________

Countersigned:



MELLON INVESTOR SERVICES LLC



By: _________________________
    Authorized Signature

                                      B-3
<PAGE>

                   Form of Reverse Side of Right Certificate

                   FORM OF ASSIGNMENT

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


     FOR VALUE RECEIVED _________________________________ hereby sells, assigns
and transfers unto _____________________________________________________________
                    (Please print name and address of transferee)

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

Dated: ________________, _____


                              _________________________________
                              Signature


Signature Guaranteed:

     Signatures must be guaranteed by a member firm of a registered national
securities exchange, a member of the National Association of Securities Dealers,
Inc., or a commercial bank or trust company having an office or correspondent in
the United States.


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

                                  CERTIFICATE

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


                              _________________________________
                              Signature


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

                                      B-4
<PAGE>

                    Form of Reverse Side of Right Certificate continued

                    FORM OF ELECTION TO PURCHASE

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


To Avici Systems Inc.:

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


Please insert social security
or other identifying number

_________________________________________________________________
(Please print name and address)

_________________________________________________________________

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


Please insert social security
or other identifying number

_________________________________________________________________
(Please print name and address)

_________________________________________________________________

_________________________________________________________________


Dated: _______________, _____


                              _________________________________
                              Signature


Signature Guaranteed:

     Signatures must be guaranteed by a member firm of a registered national
securities exchange, a member of the National Association of Securities Dealers,
Inc., or a commercial bank or trust company having an office or correspondent in
the United States.

                                      B-5
<PAGE>

             Form of Reverse Side of Right Certificate  continued
             ----------------------------------------------------

     The undersigned hereby certifies that the Rights evidenced by this Right
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 must
conform to the name as written upon the face of this Right Certificate in every
particular, without alteration or enlargement or any change whatsoever.

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

                                      B-6
<PAGE>

                                                                       EXHIBIT C



                              AVICI SYSTEMS INC.
                         SUMMARY OF RIGHTS TO PURCHASE
                               PREFERRED SHARES

     On December 5, 2001 the Board of Directors of Avici Systems Inc. declared a
dividend of one preferred share purchase right (a "Right") for each outstanding
share of common stock, par value $0.0001 per share (the "Common Shares")
outstanding on December 17, 2001 (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 A Junior Participating
Preferred Stock, par value $0.01 per share (the "Preferred Shares"), of the
Company, at a price of $40.00 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 Rights Agents (the "Rights Agent").

     Until the earlier to occur of (i) a public announcement that a person or
group of affiliated or associated persons (an "Acquiring Person") has 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 or 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
certificates evidencing the Rights ("Right Certificates") will be mailed to
holders of record of the Common Shares as of the Close of Business on the
Distribution Date and such separate Right Certificates alone will evidence the
Rights.

     The Rights are not exercisable until the Distribution Date.  The Rights
will expire on

                                      C-1
<PAGE>

December 5, 2011 (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 a quarterly dividend
payment of 1,000 times the dividend declared per Common Share.  In the event of
liquidation, the holders of the Preferred Shares will be entitled to an
aggregate payment of 1,000 times the aggregate payment made per Common Share.
Each Preferred Share will have 1,000 votes, voting together with the Common
Shares.  In the event of any merger, consolidation or other transaction in which
Common Shares are exchanged, each Preferred Share will be entitled to receive
1,000 times the amount received per Common Share.  These rights are protected by
customary antidilution provisions.

     Because of the nature of the Preferred 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.

     From and after the occurrence of an event described in Section 11(a)(ii) of
the Rights Agreement, if the Rights evidenced by this Right Certificate are or
were at any time on or after the earlier of (x) the date of such event and (y)
the Distribution Date (as such term is defined in the Rights Agreement) acquired
or beneficially owned by an Acquiring Person or an Associate or Affiliate of an
Acquiring Person (as such terms are defined in the Rights Agreement), such
Rights shall become void, and any holder of such Rights shall thereafter have no
right to exercise such Rights.

     In the event that, at any time after a Person becomes an Acquiring Person,
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

                                      C-2
<PAGE>

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
becomes an Acquiring Person, proper provision shall be made so that each holder
of a Right, other than Rights beneficially owned by the Acquiring Person and its
Affiliates and Associates (which will thereafter be void), will thereafter have
the right to receive upon exercise that number of Common Shares having a market
value of two times the exercise price of the Right. If the Company does not have
sufficient Common Shares to satisfy such obligation to issue Common Shares, or
if the Board of Directors so elects, the Company shall deliver upon payment of
the exercise price of a Right an amount of cash or securities equivalent in
value to the Common Shares issuable upon exercise of a Right; provided that, if
the Company fails to meet such obligation within 30 days following the later of
(x) the first occurrence of an event triggering the right to purchase Common
Shares and (y) the date on which the Company's right to redeem the Rights
expires, the Company must deliver, upon exercise of a Right but without
requiring payment of the exercise price then in effect, Common Shares (to the
extent available) and cash equal in value to the difference between the value of
the Common Shares otherwise issuable upon the exercise of a Right and the
exercise price then in effect. The Board of Directors may extend the 30-day
period described above for up to an additional 90 days to permit the taking of
action that may be necessary to authorize sufficient additional Common Shares to
permit the issuance of Common Shares upon the exercise in full of the Rights.

     At any time after any Person becomes an Acquiring Person and prior to the
acquisition by any person or group of a majority 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 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 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 depository
receipts) and in lieu thereof, an adjustment in cash will be made based on the
market price of the Preferred Shares on the last trading day prior to the date
of exercise.

     At any time prior to ten days after the time any Person becomes an
Acquiring Person (including public announcement thereof), the Board of Directors
of the Company may redeem the Rights in whole, but not in part, at a price of
$0.01 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 terms of the Rights may be amended by the Board of Directors of the
Company without the consent of the holders of the Rights, except that from and
after such time as any

                                      C-3
<PAGE>

person becomes an Acquiring Person no such amendment may adversely affect the
interests of the holders of the Rights (other than the Acquiring Person and its
Affiliates and Associates).

     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 Agreement has been filed with the Securities and Exchange
Commission as an Exhibit to a Registration Statement on Form 8-A dated December
6, 2001.  A copy of the 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 Agreement, which is hereby
incorporated herein by reference.

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