<PAGE>

                                 EXHIBIT 10.19

                      THIRD AMENDMENT TO CREDIT DOCUMENTS
                      -----------------------------------

     This Third Amendment to Credit Documents is made as of February 11, 2000
(the "Amendment") by and among Prism Mortgage Company, an Illinois corporation
(the "Borrower"), Pacific Guarantee Mortgage Corporation, a California
corporation, Mortgage Market, Inc., an Oregon corporation, PointSource
Financial, L.L.C., an Illinois limited liability company, Infiniti Mortgage,
L.L.C., an Illinois limited liability company, First City Financial Corp., a
Colorado corporation, the lenders identified on the signature pages hereof (the
"Lenders"), and Bank One, NA, a national banking association formerly known as
The First National Bank of Chicago, as administrative agent for the Lenders
("Agent").

                                 1.  RECITALS

     The Borrower, the Borrowing Subsidiaries, the Agent and the Lenders are
parties to a certain Credit Agreement dated as of March 31, 1999, as amended by
an Amendment to Credit Documents dated as of May 24, 1999 and a Second Amendment
to Credit Documents dated as of October 7, 1999 (as so amended, the "Credit
Agreement"), pursuant to which the Lenders have agreed to provide a revolving
credit facility to the Borrower and the Borrowing Subsidiaries on the terms and
conditions set forth in the Credit Agreement.  Any capitalized term not
expressly defined herein shall have the meaning ascribed to such term in the
Credit Agreement.

     The Borrower, the Borrowing Subsidiaries, the Agent, and the Lenders desire
to amend the Credit Agreement to revise the definition of Change in Control.

     NOW, THEREFORE, the parties hereto agree as follows:

     1.   Change in Control. The definition of Change in Control in Article I of
          -----------------
the Credit Agreement is hereby deleted and replaced with the following:

          "Change in Control" means (i) any Person or group of Persons acting
     together shall, directly or indirectly, acquire and beneficially own more
     than 35% of the outstanding shares of voting stock of Borrower's parent
     corporation, Prism Financial Corporation (excluding the stock held in Bruce
     Abrams' estate and the subsequent transfer of ownership from his estate to
     his wife) or (ii) the Borrower shall cease to be a Wholly-Owned Subsidiary
     of Prism Financial Corporation."

     2.   Collateral Audit.  The Borrower shall, within fifteen days after the
          ----------------
date hereof, retain PricewaterhouseCoopers LLP to conduct an independent
collateral audit of the Mortgage Loans pledged as Collateral.

     3.   Miscellaneous.
          -------------

          (a)  All references to the Credit Agreement in the Loan Documents
shall be deemed to refer to the Credit Agreement as amended by this Amendment.
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          (b)  The Borrower and each Borrowing Subsidiary each hereby represents
and warrants to the Lenders that on the date of execution hereof, both prior to
and after giving effect to this Amendment, (i) the representations and
warranties of the Borrower and the Borrowing Subsidiaries contained in the Loan
Documents are accurate and complete in all respects, and (ii) no Default or
Unmatured Default has occurred and is continuing.

          (c)  In all other respects, the Credit Agreement and the other Loan
Documents are and remain unmodified and in full force and effect and are hereby
ratified and confirmed.  This Amendment may be executed in any number of
counterparts, all of which taken together shall constitute one agreement, and
any of the parties hereto may execute this Amendment by signing any such
counterpart.

          (d)  The Borrower agrees to reimburse the Agent for all reasonable
out-of-pocket expenses (including legal fees and expenses) incurred in
connection with the preparation, negotiation and consummation of this Amendment.
Notwithstanding the provisions of Section 2.7.5 of the Credit Agreement, the
Lenders agree that the amendment fee of $2,500 per Lender referred to therein
shall not apply to or be payable in connection with this Amendment.

     IN WITNESS WHEREOF, the parties hereto have executed this Amendment as of
the date first above written.

                         PRISM MORTGAGE COMPANY, an Illinois corporation

                         By: /s/ David Fisher
                            ------------------------------------
                         Name:   David Fisher
                              ----------------------------------
                         Title:  Senior VP
                               ---------------------------------

                         PACIFIC GUARANTEE MORTGAGE CORPORATION, a California
                         corporation

                         By: /s/ David Fisher
                            ------------------------------------
                         Name:   David Fisher
                              ----------------------------------
                         Title:  Senior VP
                               ---------------------------------

                         MORTGAGE MARKET, INC., an Oregon corporation

                         By: /s/ David Fisher
                            ------------------------------------
                         Name:   David Fisher
                              ----------------------------------
                         Title:  Senior VP
                               ---------------------------------

                                      -2-
<PAGE>

                         POINTSOURCE FINANCIAL, L.L.C., an Illinois limited
                         liability company

                         By: Prism Mortgage Company, its Manager

                              By: /s/ David Fisher
                                 ------------------------------------
                              Name:   David Fisher
                                   ----------------------------------
                              Title:  Senior VP
                                    ---------------------------------

                         INFINITI MORTGAGE, L.L.C., an Illinois limited
                         liability company

                         By: Prism Mortgage Company, its Manager

                              By: /s/ David Fisher
                                 ------------------------------------
                              Name:   David Fisher
                                   ----------------------------------
                              Title:  Senior VP
                                    ---------------------------------

                         FIRST CITY FINANCIAL CORP., a Colorado corporation


                         By: /s/ David Fisher
                            -----------------------------------------
                         Name:   David Fisher
                              ---------------------------------------
                         Title:  Senior VP
                               --------------------------------------

                         BANK ONE, NA, Individually and as Agent


                         By: /s/ Thomas J. Connally
                            -----------------------------------------
                         Name:   Thomas J. Connally
                              ---------------------------------------
                         Title:  Vice President
                               --------------------------------------

                         THE BANK OF NEW YORK

                         By: /s/ Perry D. Gasling
                            -----------------------------------------
                         Name:   Perry D. Gasling
                              ---------------------------------------

                                      -3-
<PAGE>

                         Title:  Managing Director
                               --------------------------------------

                         COMERICA BANK

                         By: /s/ Mandy J. Lark
                            -----------------------------------------
                         Name:   Mandy J. Lark
                              ---------------------------------------
                         Title:  Asst. Vice President
                               --------------------------------------

                         FIRST UNION NATIONAL BANK

                         By: /s/ Peter G. Perna
                            -----------------------------------------
                         Name:   Peter G. Perna
                              ---------------------------------------
                         Title:  Vice President
                               --------------------------------------

                         GUARANTY FEDERAL BANK, F.S.B.

                         By: /s/ Sean A. Tobias
                            -----------------------------------------
                         Name:   Sean A. Tobias
                              ---------------------------------------
                         Title:  Vice President
                               --------------------------------------

                         HIBERNIA NATIONAL BANK

                         By: /s/ Stephanie F. Tyner
                            -----------------------------------------
                         Name:   Stephanie F. Tyner
                              ---------------------------------------
                         Title:  VP
                               --------------------------------------

                         LASALLE BANK NATIONAL ASSOCIATION

                         By: /s/ David Scherer
                            -----------------------------------------
                         Name:   David Scherer
                              ---------------------------------------
                         Title:  Vice President
                               --------------------------------------

                         MERCANTILE BANK

                         By: /s/ Mark Rieger
                            -----------------------------------------
                         Name:   Mark Rieger
                              ---------------------------------------
                         Title:  Vice President
                               --------------------------------------

                                      -4-
<PAGE>

                         U.S. BANK NATIONAL ASSOCIATION

                         By: /s/ Edwin D. Jenkins
                            -----------------------------------------
                         Name:   Edwin D. Jenkins
                              ---------------------------------------
                         Title:  VP
                               --------------------------------------

                                      -5-