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                                                                     EXHIBIT 4.6

                        FIRST MERCHANTS CAPITAL TRUST III
                                 TRUST AGREEMENT

     This TRUST AGREEMENT, dated as of December 12, 2001 (this "Trust
Agreement"), among (i) First Merchants Corporation, an Indiana corporation (the
"Depositor"), (ii) First Union Trust Company, National Association, as trustee,
and (iii) Michael L. Cox, Larry R. Helms, Esq. and Mark K. Hardwick, each an
individual, as trustees (each of such trustees in (ii) and (iii) a "Trustee" and
collectively, the "Trustees"). The Depositor and the Trustees hereby agree as
follows:

     1.   The trust created hereby (the "Trust") shall be known as "First
Merchants Capital Trust III" in which name the Trustees, or the Depositor to the
extent provided herein, may engage in the transactions contemplated hereby, make
and execute contracts, and sue and be sued.

     2.   The Depositor hereby assigns, transfers, conveys and sets over to the
Trustees the sum of $10.00. The Trustees hereby acknowledge receipt of such
amount in trust from the Depositor, which amount shall constitute the initial
trust estate. The Trustees hereby declare that they will hold the trust estate
in trust for the Depositor. It is the intention of the parties hereto that the
Trust created hereby constitute a business trust under Chapter 38 of Title 12 of
the Delaware Code, 12 Del. C. Section 3801, et seq. (the "Business Trust Act"),
and that this document constitutes the governing instrument of the Trust. The
Trustees are hereby authorized and directed to execute and file a certificate of
trust with the Delaware Secretary of State in accordance with the provisions of
the Business Trust Act.

     3.   The Depositor and the Trustees will enter into an amended and restated
Trust Agreement, satisfactory to each such party and substantially in the form
included as an exhibit to the 1933 Act Registration Statement (as defined
below), to provide for the contemplated operation of the Trust created hereby
and the issuance of the Preferred Securities and Common Securities referred to
therein. Prior to the execution and delivery of such amended and restated Trust
Agreement, the Trustees shall not have any duty or obligation hereunder or with
respect to the trust estate, except as otherwise required by applicable law or
as may be necessary to obtain prior to such execution and delivery of any
licenses, consents or approvals required by applicable law or otherwise.

     4.   The Depositor and the Trustees hereby authorize and direct the
Depositor, as the sponsor of the Trust, (i) to file with the Securities and
Exchange Commission (the "Commission") and execute, in each case on behalf of
the Trust, (a) the Registration Statement on Form S-3 (the "1933 Act
Registration Statement"), including any pre-effective or post-effective
amendments to the 1933 Act Registration Statement, relating to the registration
under the Securities Act of 1933, as amended, (the "1933 Act") of the Preferred
Securities of the Trust (including any registration statement for the same
offering that is to be effective upon filing pursuant to Rule 462(b) under the
1933 Act), and (b) a Registration Statement on Form 8-A (the "1934 Act
Registration Statement") (including all pre-effective and post-effective
amendments

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thereto) relating to the registration of the Preferred Securities of the Trust
under the Securities Exchange Act of 1934, as amended; (ii) to file with Nasdaq
or a national stock exchange (each, an "Exchange") and execute on behalf of the
Trust one or more listing applications and all other applications, statements,
certificates, agreements and other instruments as shall be necessary or
desirable to cause the Preferred Securities to be listed on any of the
Exchanges; (iii) to file and execute on behalf of the Trust such applications,
reports, surety bonds, irrevocable consents, appointments of attorney for
service of process and other papers and documents as shall be necessary or
desirable to register the Preferred Securities under the securities or blue sky
laws of such jurisdictions as the Depositor, on behalf of the Trust, may deem
necessary or desirable; and (iv) to execute on behalf of the Trust that certain
Underwriting Agreement relating to the Preferred Securities, among the Trust,
the Depositor and the Underwriter named therein, substantially in the form
included as an exhibit to the 1933 Act Registration Statement. In the event that
any filing referred to in clauses (i), (ii) and (iii) above is required by the
rules and regulations of the Commission, an Exchange or state securities or blue
sky laws, to be executed on behalf of the Trust by one or more of the Trustees,
each of the Trustees, in its, her or his capacity as a Trustee of the Trust, is
hereby authorized and, to the extent so required, directed to join in any such
filing and to execute on behalf of the Trust any and all of the foregoing, it
being understood that First Union Trust Company, National Association in its
capacity as a Trustee of the Trust shall not be required to join in any such
filing or execute on behalf of the Trust any such document unless required by
the rules and regulations of the Commission, the Exchange or state securities or
blue sky laws. In connection with the filings referred to above, the Depositor
and Michael L. Cox, Larry R. Helms, Esq. and Mark K. Hardwick, each as Trustees
and not in their individual capacities, hereby constitute and appoint Michael L.
Cox, Larry R. Helms, Esq. and Mark K. Hardwick, and each of them, as its true
and lawful attorneys-in-fact and agents, with full power of substitution and
resubstitution, for the Depositor or such Trustee or in the Depositor's or such
Trustees' name, place and stead, in any and all capacities, to sign any and all
amendments (including post-effective amendments) to the 1933 Act Registration
Statement and the 1934 Act Registration Statement and to file the same, with all
exhibits thereto, and other documents in connection therewith, with the
Commission, the Exchange and administrators of the state securities or blue sky
laws, granting unto said attorneys-in-fact and agents full power and authority
to do and perform each and every act and thing requisite and necessary to be
done in connection therewith, as fully to all intents and purposes as the
Depositor or such Trustee might or could to in person, hereby ratifying and
confirming all that said attorneys-in-fact and agents or any of them, or their
respective substitute or substitutes, shall do or cause to be done by virtue
hereof.

     5.   This Trust Agreement may be executed in one or more counterparts.

     6.   The number of Trustees initially shall be four and thereafter the
number of Trustees shall be such number as shall be fixed from time to time by a
written instrument signed by the Depositor which may increase or decrease the
number of Trustees; provided, however, that to the extent required by the
Business Trust Act, one Trustee shall either be a natural person who is a
resident of the State of Delaware or, if not a natural person, an entity which
has its principal place of business in the State of Delaware and otherwise meets
the requirements of applicable Delaware law. Subject to the foregoing, the
Depositor is entitled to appoint or

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remove without cause any Trustee at any time. The Trustees may resign upon 30
days' prior notice to the Depositor.

     7.   This Trust Agreement shall be governed by, and construed in accordance
with, the laws of the State of Delaware (without regard to conflict of laws of
principles).

     8.   The Trustees (the "Fiduciary Indemnified Persons") shall not be
liable, responsible or accountable in damages or otherwise to the Trust, the
Depositor, the Trustees or any holder of the Trust's securities (the Trust, the
Depositor and any holder of the Trust's securities being a "Covered Person") for
any loss, damage or claim incurred by reason of any act or omission performed or
omitted by the Fiduciary Indemnified Persons in good faith on behalf of the
Trust and in a manner the Fiduciary Indemnified Persons reasonably believed to
be within the scope of authority conferred on the Fiduciary Indemnified Persons
by this Trust Agreement or by law, except that the Fiduciary Indemnified Persons
shall be liable for any such loss, damage or claim incurred by reason of the
Fiduciary Indemnified Person's gross negligence or willful misconduct with
respect to such acts or omissions.

          The Fiduciary Indemnified Persons shall be fully protected in relying
in good faith upon the records of the Trust and upon such information, opinions,
reports or statements presented to the Trust by any person as to matters the
Fiduciary Indemnified Persons reasonably believes are within such other person's
professional or expert competence and who has been selected with reasonable care
by or on behalf of the Trust, including information, opinions, reports or
statements as to the value and amount of the assets, liabilities, profits,
losses or any other facts pertinent to the existence and amount of assets from
which distributions to holders of Trust's securities might properly be paid.

     9.   The Depositor agrees, to the fullest extent permitted by applicable
law,

          (a)  to indemnify and hold harmless each Fiduciary Indemnified Person,
or any of its officers, directors, shareholders, employees, representatives or
agents, from and against any loss, damage, liability, tax, penalty, expense or
claim of any kind or nature whatsoever incurred by the Fiduciary Indemnified
Persons by reason of the creation, operation or termination of the Trust in a
manner the Fiduciary Indemnified Persons reasonably believed to be within the
scope of authority conferred on the Fiduciary Indemnified Persons by this Trust
Agreement, except that no Fiduciary Indemnified Persons shall be entitled to be
indemnified in respect of any loss, damage or claim incurred by the Fiduciary
Indemnified Persons by reason of gross negligence or willful misconduct with
respect to such acts or omissions; and

          (b)  to advance expenses (including legal fees) incurred by a
Fiduciary Indemnified Person in defending any claim, demand, action, suit or
proceeding shall, from time to time, prior to the final disposition of such
claim, demand, action, suit or proceeding, upon receipt by the Trust of an
undertaking by or on behalf of such Fiduciary Indemnified Persons to repay such
amount if it shall be determined that such Fiduciary Indemnified Person is not
entitled to be indemnified as authorized in the preceding subsection.

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     10.  The provisions of Section 9 shall survive the termination of this
Trust Agreement or the earlier resignation or removal of the Fiduciary
Indemnified Persons.

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     IN WITNESS WHEREOF, the parties hereto have caused this Trust Agreement to
be duly executed as of the day and year first above written.

FIRST MERCHANTS CORPORATION,
AS DEPOSITOR

By:  /s/ Michael L. Cox
   --------------------------------------
     Name:  Michael L. Cox
          -----------------------------
     Title: President & CEO
           ----------------------------

FIRST UNION TRUST COMPANY, NATIONAL ASSOCIATION,
AS TRUSTEE

By:   /s/ Edward L. Truitt, Jr.
   --------------------------------------
   Name:  Edward L. Truitt, Jr.
        ---------------------------------
   Title: Vice President
         --------------------------------

     /s/ Michael L. Cox                  , as Trustee
-----------------------------------------
  Michael L. Cox

     /s/ Larry R. Helms                  , as Trustee
-----------------------------------------
  Larry R. Helms, Esq.

     /s/ Mark K. Hardwick                , as Trustee
-----------------------------------------
  Mark K. Hardwick