EXHIBIT 10.1

AMENDMENT TO

401(k) PLAN

Morgan Stanley & Co. Incorporated (the “Corporation”) hereby amends the Morgan
Stanley 401(k) Plan (the “401(k) Plan”) as follows:

Effective as of the day prior to the closing of the secondary offering that
takes Morgan Stanley’s voting interest in MSCI Inc. and Barra, Inc. below 80%,
Appendix B of the 401(k) Plan shall be amended (i) by adding “—the day prior to
the Closing Date (as defined below)” at the end of the entries for MSCI Inc. and
Barra, Inc. in the list of Participating Companies contained therein, and
(ii) by adding the following new section at the end thereof:

“Cessation of Participation of MSCI/Barra. Effective on the day prior to the
closing of the secondary offering that takes Morgan Stanley’s voting interest in
MSCI Inc. and Barra, Inc. below 80% (the “Closing Date”), (i) MSCI Inc. and
Barra, Inc. (collectively “MSCI/Barra”) shall cease to be a Participating
Company in the Plan; (ii) employees of MSCI/Barra shall cease to actively
participate in the Plan; and (iii) current employees of MSCI/Barra on the day
prior to the Closing Date shall become fully vested in all amounts allocated to
their Accounts. An employee of MSCI/Barra who would have been eligible to
receive a Retirement Contribution for 2008 pursuant to Section 6(e) of the Plan
but for MSCI/Barra’s cessation of participation on the day prior to the Closing
Date shall receive such a contribution for the year based on his or her Years of
Service and Retirement Contribution Earnings, if any, to the day prior to the
Closing Date.”

 

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IN WITNESS WHEREOF, the Corporation has caused this Amendment to be executed on
its behalf as of this 10th day of July, 2008.

 

MORGAN STANLEY & CO.
INCORPORATED By:   /S/ KAREN JAMESLEY Title: Global Head of Human Resources