EXHIBIT 10.22

FOURTH AMENDMENT TO CREDIT AGREEMENT

THIS FOURTH AMENDMENT TO CREDIT AGREEMENT (this "Amendment") is entered
into as of March 11, 2003, among PMC COMMERCIAL TRUST, a real estate investment
trust organized under the laws of the State of Texas ("Borrower"), certain
Lenders, and BANK ONE, NA, a national banking association with its main office
in Chicago, Illinois, successor by merger to Bank One, Texas, N.A.
("Administrative Agent").

PRELIMINARY STATEMENT:

Borrower, Administrative Agent and Lenders are party to that certain
Credit Agreement (as renewed, extended, amended and restated, the "Credit
Agreement") dated as of November 29, 1999, pursuant to which the Lenders have
made and may hereafter make loans to Borrower. The parties hereto have agreed to
amend the Credit Agreement in order to (i) provide for a temporary increase in
the amount of the Commitment, and (ii) extend the maturity of the Revolving
Facility.

Accordingly, for adequate and sufficient consideration, the receipt of
which is hereby acknowledged, Borrower, Administrative Agent and Lenders agree
as follows:

1. Defined Terms; References. Unless otherwise stated in this Amendment (a)
terms defined in the Credit Agreement have the same meanings when used in this
Amendment and (b) references to "Sections," "Schedules" and "Exhibits" are to
sections, schedules and exhibits to the Credit Agreement.

2. Amendments.

(a) The defined term "Commitment" in Section 1.1 of the Credit
Agreement is amended in its entirety as follows:

"Commitment" means an amount (subject to reduction or
cancellation as herein provided) equal to (a)
$35,000,000 for the period between March 19, 2003,
and the Commitment Reduction Date, and (b)
$30,000,000 at any time thereafter. For purposes of
this paragraph, the term "Commitment Reduction Date"
means the earlier of (i) the closing date of the
first Asset Securitization to be completed after
March 19, 2003, and (ii) June 30, 2003.

(b) The defined term "Stated Termination Date" in Section 1.1 of the
Credit Agreement is amended in its entirety as follows:

"Stated Termination Date" means May 31, 2004.

3. Conditions Precedent. Notwithstanding any contrary provisions, the foregoing
paragraphs in this Amendment are not effective unless and until (a) the
representations and warranties in this Amendment are true and correct, (b)
Lender receives counterparts of this Amendment executed by each party named
below, and (c) Borrower executes and delivers to Bank One, NA, a renewal and
replacement Revolving Note in the stated principal amount of $35,000,000.

4. Ratifications. This Amendment modifies and supersedes all inconsistent terms
and provisions of the Credit Documents, and except as expressly modified and
superseded by this Amendment, the Credit Documents are ratified and confirmed
and continue in full force and effect. Borrower, Administrative Agent and
Lenders agree that the Credit Documents, as amended by this Amendment, continue
to be legal, valid, binding and enforceable in accordance with their respective
terms. Without limiting the generality of the foregoing, Borrower hereby
ratifies and confirms that all Liens heretofore granted to Administrative Agent
on behalf of the Lenders were intended to, do, and continue to secure the full
payment and performance of the Obligation. Borrower agrees to perform such acts
and duly authorize, execute, acknowledge, deliver, file and record such
additional assignments, security agreements, modifications or amendments to any
of the foregoing, and such other agreements, documents, and instruments as
Administrative Agent or Lenders may reasonably request in order to perfect and
protect those Liens and preserve and protect the rights of Administrative Agent
and Lenders in respect of all present and future Collateral.

5. Representations and Warranties. Borrower hereby represents and warrants to
Administrative Agent and Lenders that (a) this Amendment and any Credit
Documents to be delivered under this Amendment have been duly executed and
delivered by Borrower, (b) no action of, or filing with, any Governmental
Authority is required to authorize, or is otherwise required in connection with,
the execution, delivery, and performance by Borrower of this Amendment and any
Credit Document to be delivered under this Amendment, (c) this Amendment and any
Credit Documents to be delivered under this Amendment are valid and binding upon
Borrower and are enforceable against Borrower in accordance with their
respective terms, except as limited by any applicable Debtor Relief Laws, (d)
the execution, delivery and performance by Borrower of this Amendment and any
Credit Documents to be delivered under this Amendment do not require the consent
of any other Person and do not and will not constitute a violation of any
Governmental Requirements, agreements or understandings to which Borrower is a
party or by which Borrower is bound, (e) the representations and warranties
contained in the Credit Agreement, as amended by this Amendment, and any other
Credit Document are true and correct in all material respects as of the date of
this Amendment, and (f) as of the date of this Amendment, no Event of Default or
Potential Default exists or is imminent.

6. References. All references in the Credit Documents to the "Credit Agreement"
refer to the Credit Agreement as amended by this Amendment. This Amendment is a
"Credit Document" referred to in the Credit Agreement and the provisions
relating to Credit Documents in the Credit Agreement are incorporated by
reference, the same as if set forth verbatim in this Amendment.

7. Counterparts. This Amendment may be executed in any number of counterparts
with the same effect as if all signatories had signed the same document.

8. Parties Bound. This Amendment binds and inures to the benefit of Borrower,
Administrative Agent and each Lender, and, subject to Section 14 of the Credit
Agreement, their respective successors and assigns.

9. Entirety. THIS AMENDMENT, THE CREDIT AGREEMENT AS AMENDED BY THIS AMENDMENT,
AND THE OTHER CREDIT DOCUMENTS REPRESENT THE FINAL AGREEMENT BETWEEN THE PARTIES
FOR THE TRANSACTIONS THEREIN, AND MAY NOT BE CONTRADICTED BY EVIDENCE OF PRIOR,
CONTEMPORANEOUS, OR SUBSEQUENT ORAL AGREEMENTS BETWEEN THE PARTIES. THERE ARE NO
UNWRITTEN ORAL AGREEMENTS BETWEEN THE PARTIES.

EXECUTED as of the date first stated above.

BANK ONE, NA,
as Administrative Agent and a Lender

By: /s/ JOHN M. CURTIN
--------------------------------------
John M. Curtin, Vice President

PMC COMMERCIAL TRUST,
as Borrower

By: /s/ JAN F. SALIT
--------------------------------------
Name: Jan F. Salit
------------------------------------
Title: Executive Vice President
-----------------------------------

ANNEX A

SCHEDULE 2

<Table>
<Caption>
Name and Address of Lender Revolving Facility Commitment Percentage
-------------------------- ------------------ ---------------------

Bank One, NA
1717 Main Street, 3rd Floor
Dallas, TX 75201 $35,000,000 (subject to 100.000%
Attention: Bradley C. Peters, Vice reduction or cancellation as
President provided in the Credit
Tel 214/290-4146 Agreement)
Fax 214/290-2305

Total $35,000,000 100.000%
</Table>