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                                                                     EXHIBIT 4.2


                                AMENDMENT NO. 1
                                       TO
                        PREFERRED STOCK RIGHTS AGREEMENT

This AMENDMENT No. 1, dated as of February 12, 2003, to the Preferred Stock
Rights Agreement dated as of August 15, 2001 by and between Barra, Inc, a
Delaware corporation (the "COMPANY") and Mellon Investor Services LLC as rights
agent (the "RIGHTS AGENT") (the "RIGHTS AGREEMENT").

                                   WITNESSETH

            WHEREAS, the Company and the Rights Agent have heretofore executed
and entered into the Rights Agreement;

            WHEREAS, pursuant to Section 27 of the Rights Agreement, the Company
and the Rights Agent may from time to time supplement or amend the Rights
Agreement in accordance with the provisions of Section 27 thereof; and

            WHEREAS, the Board of Directors of the Company has determined that
it is in the best interest of the Company and the holders of the Rights to amend
the Rights Agreement as provided herein.

            NOW THEREFORE, in consideration of the foregoing and the mutual
agreements set forth herein, the Company and the Rights Agent agree as follows:

1.    Any term not defined herein shall have the meaning ascribed to it in the
      Rights Agreement.

2.    Section 1(a) shall be amended and restated in its entirety as follows:

            "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 then
            outstanding, but shall not include the Company, any Subsidiary of
            the Company or any employee benefit plan of the Company or of any
            Subsidiary of the Company, or any entity holding Common Shares for
            or pursuant to the terms of any such plan. Notwithstanding the
            foregoing, Andrew Rudd, the current Chairman of the Board of
            Directors of the Company, shall not be deemed an Acquiring Person
            unless and until he is the Beneficial Owner of 25% or more of the
            Common Shares then outstanding (as to Andrew Rudd, in each case in
            which the number "15%" is used in this Section or elsewhere in this
            Agreement in connection with any determination as to whether a
            Person is an "Acquiring Person," such number shall be read to equal
            the current percentage threshold applicable to Mr. Rudd under this
            Section 1(a)), and no Person shall be deemed to be 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
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            to 15% or more of the Common Shares of the Company then outstanding;
            provided, however, that if a Person shall become the Beneficial
            Owner of 15% or more of the Common Shares of the Company then
            outstanding by reason of share purchases by the Company and shall,
            after such share purchases by the Company, become the Beneficial
            Owner of any additional Common Shares of the Company (other than
            pursuant to a dividend or distribution paid or made by the Company
            on the outstanding Common Shares in Common Shares or pursuant to a
            split or subdivision of the outstanding Common Shares), then such
            Person shall be deemed to be an Acquiring Person unless upon
            becoming the Beneficial Owner of such additional Common Shares of
            the Company such Person does not beneficially own 15% or more of the
            Common Shares of the Company then outstanding. Notwithstanding the
            foregoing, (i) if the Company's Board of Directors determines in
            good faith that a Person who would otherwise be an "Acquiring
            Person," as defined pursuant to the foregoing provisions of this
            paragraph (a), has become such inadvertently (including, without
            limitation, because (A) such Person was unaware that it beneficially
            owned a percentage of the Common Shares that would otherwise cause
            such Person to be an "Acquiring Person," as defined pursuant to the
            foregoing provisions of this paragraph (a), or (B) such Person was
            aware of the extent of the Common Shares it beneficially owned but
            had no actual knowledge of the consequences of such beneficial
            ownership under this Agreement) and without any intention of
            changing or influencing control of the Company, and if such Person
            divested or divests as promptly as practicable a sufficient number
            of Common Shares so that such Person would no longer be an
            "Acquiring Person," as defined pursuant to the foregoing provisions
            of this paragraph (a), then such Person shall not be deemed to be or
            to have become an "Acquiring Person" for any purposes of this
            Agreement; and (ii) if, as of the date hereof, any Person is the
            Beneficial Owner of 15% or more of the Common Shares outstanding,
            such Person shall not be or become an "Acquiring Person," as defined
            pursuant to the foregoing provisions of this paragraph (a), unless
            and until such time as such Person shall become the Beneficial Owner
            of additional Common Shares (other than pursuant to a dividend or
            distribution paid or made by the Company on the outstanding Common
            Shares in Common Shares or pursuant to a split or subdivision of the
            outstanding Common Shares), unless, upon becoming the Beneficial
            Owner of such additional Common Shares, such Person is not then the
            Beneficial Owner of 15% or more of the Common Shares then
            outstanding.

3.    This Amendment shall be deemed to be a contract made under the laws of the
      State of Delaware and for all purposes shall be governed by and construed
      in accordance with the laws of such State applicable to contracts to be
      made and performed entirely within such State; provided, however, that all
      provisions regarding the rights, duties and obligations of the Rights
      Agent shall be 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.
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4.    This Amendment may be executed in any number of counterparts and each of
      such counterparts shall for all purposes be deemed to be an original, and
      all such counterparts shall together constitute but one and the same
      instrument.

5.    Except as expressly amended hereby, the Agreement shall remain in full
      force and effect.

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                                                                     Exhibit 4.2

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

BARRA, INC.                               MELLON INVESTOR SERVICES LLC

By: /s/ Kamal Duggirala                   By: /s/ Asa Drew
    --------------------------------          ----------------------------------
    Kamal Duggirala

Title: Chief Executive Officer            Title: Assistant Vice President
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