FORM OF LETTER AGREEMENT SYSTEMATIC MID CAP VALUE FUND Investment Management Agreement

Exhibit d.13

FORM OF

LETTER AGREEMENT

SYSTEMATIC MID CAP VALUE FUND

Investment Management Agreement

December [15], 2006

Managers Investment Group LLC

000 Xxxxxxxxxxx Xxxxxx

Xxxxxxx, Xxxxxxxxxxx 00000

Attn: Xxxxx Xxxxxxxx

Re: Investment Management Agreement between Managers Investment Group LLC and Managers AMG Funds, dated as of October 19, 1999

Ladies and Gentlemen:

Pursuant to Section 1(b) of the Investment Management Agreement between Managers Investment Group LLC (f/k/a The Managers Funds LLC) and Managers AMG Funds (the “Trust”), dated October 19, 1999 and as amended from time to time, the Trust hereby advises you that it is creating a new series to be named Systematic Mid Cap Value Fund (the “New Fund”), and that the Trust desires Managers Investment Group LLC to provide management and investment advisory services with respect to the New Fund pursuant to the terms and conditions of the Investment Management Agreement. Attached as Appendix A is an amendment to Schedule A to the Investment Management Agreement.

Please acknowledge your agreement to provide such management and investment advisory services to the New Fund by executing this letter agreement in the space provided below and then returning it to the undersigned.

Sincerely,

Managers AMG Funds

By:

Name:

Title:

ACKNOWLEDGED AND ACCEPTED

Managers Investment Group LLC

By:

Name:

Title:

Date:

AMENDMENT TO

SCHEDULE A

Systematic Mid Cap Value Fund

Advisory Fees pursuant to Section 2(a)

The Trust shall pay to the Advisor an annual gross investment advisory fee equal to 0.75% of the average daily net assets of the Systematic Mid Cap Value Fund. Such fee shall be accrued daily and paid as soon as practical after the last day of each calendar month.

Administration Fees Pursuant to Section 2(b)

None.