CALAMOS INVESTMENT TRUST March 26, 2010

Exhibit (d)(12)

CALAMOS INVESTMENT TRUST

March 26, 2010

Calamos Advisors LLC
0000 Xxxxxxx Xxxxx
Xxxxxxxxxx, Xxxxxxxx 00000

Ladies and Gentlemen:

      Re:      Management Agreement

Pursuant to paragraph 1(b) of the Management Agreement (the “Agreement”) between Calamos Investment Trust and Calamos Advisors LLC dated December 13, 2004, as amended, we hereby notify you that the board of trustees of Calamos Investment Trust have established an additional sub-trust, designated Calamos Discovery Growth Fund (the “New Fund”), and have appointed you as Manager to act as manager and investment adviser to that Sub-Trust on the terms and conditions set forth in the Agreement, except that the advisory fee applicable to the New Fund shall be calculated as follows:

The base fee rate shall be at the annual rate of 1.00% of the first $500 million of the average daily net assets; 0.90% of the next $500 million of the average daily net assets; and 0.80% in excess of $1 billion.

     Please sign below to evidence the acceptance of your appointment as Manager for the Sub-Trust designated Calamos Discovery Growth Fund, as set forth above and in the Agreement.

	Very truly yours, CALAMOS INVESTMENT TRUST
	By:	/s/ Xxxxxx Xxxxx
		Xxxxxx Xxxxx
		Secretary

     Appointment as Manager for the Sub-Trust designated Calamos Discovery Growth Fund, as set forth above and in the Agreement is accepted this ___day of March 2010.

	CALAMOS ADVISORS LCC
	By:	/s/ Xxxxxx X. Xxxxx
		Xxxxxx X. Xxxxx
		Senior Vice President, Director of Operations