EXHIBIT (a) (5)


                            CALAMOS INVESTMENT TRUST

                                 AMENDMENT NO. 4
                                       TO
                    THE THIRD AMENDED AND RESTATED AGREEMENT
                            AND DECLARATION OF TRUST

      AMENDMENT NO. 4 to the Third Amended and Restated Agreement and
Declaration of Trust dated as of March 30, 2006, as amended (the "Declaration of
Trust") of Calamos Investment Trust (the "Trust"), made as of the 14th day of
December, 2006.

                                   WITNESSETH:

      WHEREAS, Article VII, Section 7.3 of the Declaration of Trust provides
that the Declaration of Trust may be amended at any time, so long as such
amendment does not adversely affect the rights of any shareholder and so long as
such amendment is not in contravention of applicable law, including the
Investment Company Act of 1940, as amended, by an instrument in writing signed
by an officer of the Trust pursuant to a vote of a majority of the Trustees; and

      WHEREAS, Article IV, Section 4.1 of the Declaration of Trust provides that
the Trustees of the Trust may establish and designate Sub-Trusts of the Trust
and classes thereof; and

      WHEREAS, the Trustees have previously established and designated ten
Sub-Trusts of the Trust (the "Series"), being Calamos Convertible Fund; Calamos
Growth and Income Fund; Calamos Global Growth and Income Fund; Calamos Growth
Fund; Calamos Market Neutral Income Fund; Calamos High Yield Fund; Calamos Value
Fund; Calamos Blue Chip; Calamos International Growth Fund; and Calamos
Multi-Fund Blend; and

      WHEREAS, the Trustees have previously established and designated four
classes for the Series, being Class A; Class B; Class C; and Class I; and

      WHEREAS, on December 14, 2006, the Trustees voted unanimously to (i)
designate a new Sub-Trust, the Calamos Global Equity Fund; (ii) designate a new
class, Class R, for the Series; and (iii) authorize the Secretary to execute and
file this Amendment No. 4 to the Declaration of Trust (the "Amendment");

      NOW, THEREFORE, effective immediately, the Declaration of Trust is hereby
amended as follows:

      I. The first paragraph of Article IV, Section 4.2 (other than subsections
(a) through (m) thereof) of the Declaration of Trust is hereby amended to read
in pertinent part as follows:

            "Section 4.2 ESTABLISHMENT AND DESIGNATION OF SUB-TRUSTS AND
            CLASSES. Without limiting the authority of the Trustees set forth in
            Section 4.1 to establish and designate any further Sub-Trusts, the
            Trustees hereby establish and designate eleven Sub-Trusts:




                        Calamos Blue Chip Fund
                        Calamos Convertible Fund
                        Calamos Growth and Income Fund
                        Calamos Global Growth and Income Fund
                        Calamos Growth Fund
                        Calamos Market Neutral Income Fund
                        Calamos High Yield Fund
                        Calamos Value Fund
                        Calamos International Growth Fund
                        Calamos Multi-Fund Blend
                        Calamos Global Equity Fund

            each of which shall have five classes of Shares, Class A, Class B,
            Class C, Class I and Class R, or such classes as may from time to
            time be established and designated. The Shares of such Sub-Trusts
            and any Shares of any further Sub-Trust or class that may from time
            to time be established and designated by the Trustees shall (unless
            the Trustees otherwise determine with respect to some further
            Sub-Trust or class at the time of establishing and designating the
            same) have the following relative rights and preferences:"

      The undersigned hereby certifies that Amendment No. 4 to the Third Amended
and Restated Agreement and Declaration of Trust set forth above has been duly
adopted in accordance with the provisions of the Declaration of Trust.

      IN WITNESS WHEREOF, the undersigned has hereto set his hand as of the day
and year first above written.

                                        By: /s/ James S. Hamman, Jr.
                                           -----------------------------
                                        Name: James S. Hamman, Jr.
                                        Title: Secretary

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