Exhibit 99.1350CERT

         Certification Pursuant to Section 906 of the Sarbanes Oxley Act

I, Robert C. Doll, Jr., President of Merrill Lynch Low Duration Fund of Merrill
Lynch Investment Managers Funds, Inc. and Low Duration Master Portfolio of Fund
Asset Management Master Trust (together, the "Fund"), certify that:

      1.    The N-CSR of the Fund (the "Report") fully complies with the
            requirements of Section 13(a) or 15(d) of the Securities Exchange
            Act of 1934; and

      2.    The information contained in the Report fairly presents, in all
            material respects, the financial condition and results of operations
            of the Fund.

Dated: February 24, 2005

                                                /s/ Robert C. Doll, Jr.
                                                --------------------------------
                                                Robert C. Doll, Jr.,
                                                President of
                                                Merrill Lynch Low Duration Fund
                                                of Merrill Lynch Investment
                                                Managers Funds, Inc. and Low
                                                Duration Master Portfolio of
                                                Fund Asset Management Master
                                                Trust

A signed original of this written statement required by Section 906, or other
document authenticating, acknowledging, or otherwise adopting the signature that
appears in typed form within the electronic version of this written statement
required by Section 906, has been provided to Merrill Lynch Low Duration Fund of
Merrill Lynch Investment Managers Funds, Inc. and Low Duration Master Portfolio
of Fund Asset Management Master Trust and will be retained by Merrill Lynch Low
Duration Fund of Merrill Lynch Investment Managers Funds, Inc. and Low Duration
Master Portfolio of Fund Asset Management Master Trust and furnished to the
Securities and Exchange Commission or its staff upon request.



Exhibit 99.1350CERT

         Certification Pursuant to Section 906 of the Sarbanes Oxley Act

I, Donald C. Burke, Chief Financial Officer of Merrill Lynch Low Duration Fund
of Merrill Lynch Investment Managers Funds, Inc. and Low Duration Master
Portfolio of Fund Asset Management Master Trust (together, the "Fund"), certify
that:

      1.    The N-CSR of the Fund (the "Report") fully complies with the
            requirements of Section 13(a) or 15(d) of the Securities Exchange
            Act of 1934; and

      2.    The information contained in the Report fairly presents, in all
            material respects, the financial condition and results of operations
            of the Fund.

Dated: February 24, 2005

                                                /s/ Donald C. Burke
                                                --------------------------------
                                                Donald C. Burke,
                                                Chief Financial Officer of
                                                Merrill Lynch Low Duration Fund
                                                of Merrill Lynch Investment
                                                Managers Funds, Inc. and Low
                                                Duration Master Portfolio of
                                                Fund Asset Management Master
                                                Trust

A signed original of this written statement required by Section 906, or other
document authenticating, acknowledging, or otherwise adopting the signature that
appears in typed form within the electronic version of this written statement
required by Section 906, has been provided to Merrill Lynch Low Duration Fund of
Merrill Lynch Investment Managers Funds, Inc. and Low Duration Master Portfolio
of Fund Asset Management Master Trust and will be retained by Merrill Lynch Low
Duration Fund of Merrill Lynch Investment Managers Funds, Inc. and Low Duration
Master Portfolio of Fund Asset Management Master Trust and furnished to the
Securities and Exchange Commission or its staff upon request.