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                                                                    EXHIBIT 10.4

                            NUVEEN INVESTMENTS, INC.
                              333 WEST WACKER DRIVE
                             CHICAGO, ILLINOIS 60606

                                February 1, 2003

Barra, Inc.
2100 Milvia Street
Berkeley, California 94704
Attention: Kamal Duggirala

Maestro, LLC
555 California Street, Suite 2975
San Francisco, California 94104
Attention: Neil L. Rudolph

The Individuals Listed on the
Signature Pages Hereto
555 California Street, Suite 2975
San Francisco, California 94104

Gentlemen:

         We refer to the Acquisition Agreement by and among Barra, Inc.
("Barra"), Symphony Asset Management, Inc. ("SAMI," which has been subsequently
liquidated into Barra), Maestro, LLC ("Maestro" and, together with SAMI, the
"Members" and each a "Member"), Praveen K. Gottipalli, Michael J. Henman, Neil
L. Rudolph and Jeffrey L. Skelton (collectively, the "Company Principals"),
Symphony Asset Management LLC (the "Company" and, together with Barra, the
Members and the Company Principals, the "Symphony Parties" and each a "Symphony
Party") and Nuveen Investments, Inc. (formerly known as The John Nuveen Company)
("Buyer"), dated as of June 15, 2001, as amended (the "Acquisition Agreement"),
pursuant to which Buyer acquired all of the Membership Interests (as defined in
the Acquisition Agreement) of the Company on the terms and subject to the
conditions set forth therein. Capitalized terms used but not defined in this
letter agreement have the meanings given to such terms in the Acquisition
Agreement. This letter agreement amends the Acquisition Agreement as set forth
herein. Except as set forth herein, all of the terms and conditions of the
Acquisition Agreement shall remain in effect without modification and shall be
deemed to apply to this letter agreement, including without limitation those
provisions set forth in Article X thereof. The parties agree, in consideration
of the covenants and agreements set forth herein, and intending to be legally
bound, as follows:

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Barra, Inc., Maestro, LLC, et al.
February 1, 2003
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         1.       In clause (d) of Exhibit R to the Acquisition Agreement, the
number "$130 million" (appearing twice) is hereby amended to read "$120
million."

         2.       Exhibit R to the Acquisition Agreement is hereby amended to
add thereto the following paragraph (i):

         "(i) (A) The contingent purchase price consideration to be paid
         pursuant to Section 1.5 of the Acquisition Agreement shall include a
         quarterly Contingent New Asset Payment as described below. Any
         Contingent New Asset Payments shall be paid by Buyer solely to Maestro,
         and shall be paid within the forth-five (45) calendar days following
         the end of the fiscal quarter to which the Contingent New Asset Payment
         relates; provided that if Maestro disputes the Fee Accounting (as
         defined below) pursuant to the terms of sub-paragraph (C) below, the
         Contingent New Asset Payment shall instead be paid within five Business
         Days of the resolution of such dispute pursuant to the terms of
         sub-paragraph (C) below. Payments of the Contingent New Asset Payment
         shall be made by Buyer in cash to the account designated in Wire
         Transfer instructions provided to Buyer by Maestro not less than two
         Business Days prior to the date on which the applicable Contingent New
         Asset Payment is due.

         (B) Contingent New Asset Payment shall mean an amount equal to the sum
         of:

(1)      the product of (x) 0.004 and (y) the New Hedged Assets for the
applicable fiscal quarter (or such shorter period as provided below); plus

(2)      the product of (x) 0.002 and (y) the New Traditional Client Assets for
the applicable fiscal quarter (or such shorter period as provided below); plus

(3)      the product of (x) 0.001 and (y) the New Other Assets for the
applicable fiscal quarter (or such shorter period as provided below).

Notwithstanding the foregoing, in no event shall the aggregate of all Contingent
New Asset Payments exceed $3.0 million. The applicable fiscal quarter shall
initially mean the period from February 1, 2003 through June 30, 2003, and shall
thereafter mean each subsequent fiscal quarter beginning with the quarter
commencing July 1, 2003 and ending September 30, 2003; provided, that the final
fiscal quarter shall be the fiscal quarter ending September 30, 2006 and
thereafter the right of Maestro to receive Contingent New Asset Payments shall
terminate except with respect to any unpaid amount relating to a period ending
on or before September 30, 2006. As used herein, the following terms shall have
the following meanings:

"New Hedged Assets" shall mean the dollar amount of the gross new client assets
invested in funds (whether or not registered pursuant to the Investment Company
Act) or separate accounts managed or sub-advised by the Company for which the
Company is

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Barra, Inc., Maestro, LLC, et al.
February 1, 2003
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contracted to be paid a fee that is based on both assets under management and
the investment performance of the fund or account.

"New Traditional Client Assets" shall mean the dollar amount of the gross new
client assets invested in funds or separate accounts managed or sub-advised by
the Company which do not come within the definition of New Hedged Assets (e.g.,
a long-only account paying an asset based fee) and which are raised through
existing clients and prospects of the Company.

"New Other Assets" shall mean the dollar amount of the gross new client assets
invested in funds or separate accounts managed or sub-advised by the Company
which do not come within the definition of New Hedged Assets or New Traditional
Client Assets (e.g., a long-only account paying an asset based fee raised
through Nuveen distribution channels).

Notwithstanding anything to the contrary set forth herein, new client assets
managed or sub-advised by Symphony which pay fees that are nominal or were not
negotiated on an arms' length basis shall not be included as New Hedged Assets,
New Traditional Client Assets or New Other Assets for purposes of calculating
the Contingent New Asset Payments.

         (C) Buyer shall prepare and deliver not later than the thirtieth (30th)
calendar day following the end of the applicable fiscal quarter a statement
setting forth the New Hedged Assets, New Traditional Client Assets and New Other
Assets (collectively, the "New Assets") for the applicable period (the "New
Assets Accounting"), which New Assets Accounting shall set forth in reasonable
detail the calculation of such New Assets and shall be made in a manner
consistent in all respects with the foregoing terms of this letter agreement.
Following receipt by Maestro of the New Assets Accounting, solely for the
purpose of reviewing such New Assets Accounting as it relates to the applicable
Contingent New Assets Payment, Buyer shall provide Maestro access, during normal
business hours at the request of Maestro, to the books and records of Buyer and
its Subsidiaries and to their personnel and accountants to the extent reasonably
necessary to review the accuracy of the applicable New Asset Accounting;
provided, however, that such access shall be conducted in a manner that does not
unreasonably interfere with the operation of the business of Buyer and its
Subsidiaries. Within fifteen (15) calendar days after delivery to Maestro of the
Fee Accounting, Maestro may dispute all or a portion of such Fee Accounting by
giving written notice (a "New Asset Dispute Notice") to Buyer of such dispute
setting forth in reasonable detail the basis for such dispute (any such dispute,
a "New Asset Dispute"). If Maestro does not dispute the Fee Accounting during
such 15 day period, the Fee Accounting shall be final and binding upon the
parties. If Maestro shall deliver a New Asset Dispute Notice during such 15 day
period, Maestro and Buyer shall promptly commence good faith negotiations with a
view to resolving such dispute, and any resolution of such dispute shall be
reflected in a written agreement signed by both such parties. If Maestro and
Buyer are unable to resolve such dispute within thirty (30) calendar days
following deliver of such New Asset Dispute Notice,

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Barra, Inc., Maestro, LLC, et al.
February 1, 2003
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such dispute shall thereafter be referred to an Independent Accounting Firm for
a resolution of such Dispute in accordance with the terms of this paragraph (i);
provided, that any Dispute relating to the interpretation of this Agreement that
is not resolved by the parties after good faith negotiations shall be resolved
pursuant to the arbitration process described in Section 9.8 of the Acquisition
Agreement. The determinations of the Independent Accounting Firm with respect to
any New Asset Dispute shall be rendered within thirty (30) calendar days after
referral to such firm or as soon thereafter as reasonably practicable, shall be
final and binding upon the parties, and the amount so determined shall be used
to calculate and pay the Contingent New Asset Payment. Maestro and Buyer agree
that the procedures set forth in this paragraph (i) or incorporated herein shall
be the sole and exclusive remedy with respect to the determination of the amount
of any Contingent New Asset Payment. All of the fees and expenses of any
Independent Accounting Firm retained pursuant to the foregoing shall be paid 50%
by Buyer and 50% by Maestro."

         Please acknowledge your understanding of our agreement as set forth
herein by signing this letter in the space provided on the next page and
returning a copy to the undersigned. Upon execution and delivery by all of the
parties set forth below, the Acquisition Agreement shall be deemed amended to
the extent set forth in this letter.

                                                 Very truly yours,

                                                 NUVEEN INVESTMENTS, INC.

                                                 By: /s/ Alan G. Berkshire
                                                     --------------------------
                                                 Name: Alan G. Berkshire
                                                 Title: Senior Vice President

Accepted and agreed to as of
the 1st day of February, 2003:

BARRA, INC.

By: /s/ Greg Stockett
    -------------------------------
Name: Greg Stockett
Title: Chief Financial Officer

MAESTRO, LLC

By: /s/ Neil L. Rudolph
    -------------------------------
Name: Neil L. Rudolph
Title: Member

/s/ Praveen K. Gottipalli
---------------------------
PRAVEEN K. GOTTIPALLI

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Barra, Inc., Maestro, LLC, et al.
February 1, 2003
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/s/ Michael J. Henman
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MICHAEL J. HENMAN

/s/ Neil L. Rudolph
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NEIL L. RUDOLPH

/s/ Jeffrey L. Skelton
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JEFFREY L. SKELTON

SYMPHONY ASSET MANAGEMENT LLC

By: Nuveen Investments, Inc., its Managing Member

By: /s/ Alan G. Berkshire
    ----------------------
Name: Alan G. Berkshire
Title: Senior Vice President