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                                                                  EXHIBIT 10.4.3
 
                   FOURTH AMENDMENT TO AMENDED AND RESTATED
                      MORTGAGE LOAN WAREHOUSING AGREEMENT

     THIS FOURTH AMENDMENT TO AMENDED AND RESTATED MORTGAGE LOAN WAREHOUSING
AGREEMENT (the "Amendment") is made and dated as of the 25th day of February,
1998, by and among THE FIRST NATIONAL BANK OF CHICAGO, a national banking
association ("FNBC"), BANK OF AMERICA NATIONAL TRUST AND SAVINGS ASSOCIATION, a
national banking association, THE BANK OF NEW YORK, a banking corporation
organized under the laws of the State of New York, COMERICA BANK - CALIFORNIA, a
California banking corporation, FIRST UNION NATIONAL BANK, a national banking
association, and GUARANTY FEDERAL BANK, a federal savings bank (all of the above
individually a "Lender" and, collectively, the "Lenders"), FNBC, as
administrative agent for the Lenders (in such capacity, the "Administrative
Agent"), FIRST CHICAGO NATIONAL PROCESSING ASSOCIATION, a Delaware corporation,
as collateral agent for the Administrative Agent and the Lenders (in such
capacity, the "Collateral Agent"), and HEADLANDS MORTGAGE COMPANY, a California
corporation (the "Company").

                                    RECITALS

     A.  Pursuant to that certain Amended and Restated Mortgage Loan Warehousing
Agreement dated as of August 29, 1997 among the Administrative Agent, the
Collateral Agent, the Lenders and the Company (as amended to date, the
"Agreement"), the Lenders agreed to extend credit to the Company on the terms
and subject to the conditions set forth therein.  All capitalized terms not
otherwise defined herein shall have the meanings given to such terms in the
Agreement.

     B.  The Company and the Lenders desire to amend certain provisions of the
Agreement as more particularly described below.

     NOW, THEREFORE, in consideration of the foregoing Recitals and for other
good and valuable consideration, the receipt and adequacy of which are hereby
acknowledged, the parties hereto hereby agree as follows:

                                   AGREEMENT

     1.  Modification of Certain Financial Covenants.   To reflect the agreement
         -------------------------------------------                            
of the parties hereto to modify certain of the financial covenants set forth in
the Agreement, effective as of the Effective Date (as defined in Paragraph 8
below):

         (a) Paragraph 12(k) of the Agreement is hereby amended to read in its
entirety as follows:

             "12(k) Minimum Net Worth. Permit at any date its consolidated:
                    -----------------                                         

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                    (1) Effective Net Worth to be less than the sum of (i) the
          greater of: (A) the amount equal to $40,000,000.00 plus fifty percent
          (50%) of the Company's consolidated annual net income (if positive)
          earned each calendar year commencing with the year 1998, or (B) the
          amount equal to eighty percent (80%) of its consolidated Effective Net
          Worth as of the end of the month of occurrence of the initial public
          offering of the Company's common stock, minus such reductions
          thereafter that may occur as a result of the final determination of
          the exact amount of the Shareholder Distribution, plus fifty percent
          (50%) of the Company's consolidated annual net income (if positive)
          earned each calendar year (with the first year being a partial year
          commencing the month immediately following the month of occurrence of
          the initial public offering of the Company's common stock), plus, (ii)
          following the date of consummation of the initial public offering of
          the Company's common stock, eighty percent (80%) of net proceeds from
          all subsequent public and private Subordinated Debt and equity
          offerings of the Company; or

                    (2) Adjusted Tangible Net Worth to be less than the sum of
          (i) the greater of: (A) the amount equal to $70,000,000.00 plus fifty
          percent (50%) of the Company's consolidated annual net income (if
          positive) earned each calendar year commencing with the year 1998, or
          (B) the amount equal to eighty percent (80%) of its consolidated
          Adjusted Tangible Net Worth as of the end of the month of occurrence
          of the initial public offering of the Company's common stock, minus
          such reductions thereafter that may occur as a result of the final
          determination of the exact amount of the Shareholder Distribution,
          plus fifty percent (50%) of the Company's consolidated annual net
          income (if positive) earned each calendar year (with the first year
          being a partial year commencing the month immediately following the
          month of occurrence of the initial public offering of the Company's
          common stock), plus, (ii) following the consummation of the initial
          public offering of the Company's common stock, eighty percent (80%) of
          net proceeds from all subsequent public and private Subordinated Debt
          and equity offerings of the Company."

     (b) Paragraph 12(n) of the Agreement is hereby amended to read in its
entirety as follows:

         "12(n)    Maximum Total Liabilities.  Permit its consolidated Total
                      -------------------------                                
      Liabilities at any date to exceed the sum of:

                   (1) One hundred percent (100%) of Cash and/or cash
            equivalents (excluding restricted cash), plus

                   (2) Ninety-eight percent (98%) of the outstanding principal
            balance of all Eligible Mortgage Loans (other than Eligible HELOC
            Assets, Eligible High LTV Mortgage Loans, Eligible Non-Conforming
            Mortgage Loans with a Loan-to-Value Ratio in excess of eighty
            percent (80%), which 

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            Eligible Non-Conforming Mortgage Loans are not covered by private
            mortgage insurance, and Eligible A- Mortgage Loans), plus

                   (3) Ninety-five percent (95%) of the outstanding principal
            balance of all Eligible HELOC Assets, plus

                   (4) Ninety percent (90%) of the outstanding principal
            balance of all Eligible High LTV Mortgage Loans, plus

                   (5) Ninety-six percent (96%) of the outstanding principal
            balance of all Eligible Non-Conforming Mortgage Loans with a Loan-
            to-Value Ratio in excess of eighty percent (80%), which Eligible
            Non-Conforming Mortgage Loans are not covered by private mortgage
            insurance, plus

                   (6) Ninety-five percent (95%) of the outstanding principal
            balance of all Eligible A- Mortgage Loans, plus

                   (7) Eighty percent (80%) of:  (i) the outstanding principal
            balance of all Mortgage Loans excluded from the definition of
            "Eligible Mortgage Loan," and (ii) REO net of reserves, plus

                   (8) Eighty percent (80%) of its current advances and
            receivables, plus

                   (9) The lesser of: (i) seventy percent (70%) multiplied by
            the Quoted Market Value of the Eligible Servicing Portfolio, and
            (ii) one percent (1%) of the outstanding principal balance of the
            Eligible Servicing Portfolio, plus

                   (10) Seventy percent (70%) of all REMIC-related Mortgage-
            Backed Securities held for sale and marked to market quarterly (as
            shown on the Company's financial statements), plus

                   (11) Fifty percent (50%) of:  (i) all other securities held
            for investment (net of reserves), and (ii) excess servicing (as
            shown on the Company's financial statements)."

     2.  Permitted Other Debt.  To reflect the agreement of the parties hereto
         --------------------                                                 
to eliminate any dollar restriction on the amount of Indebtedness which the
Company may owe under repurchase agreements, effective as of the Effective Date,
                                                                                
Exhibit N to the Agreement is hereby replaced by Replacement Exhibit N attached
---------                                        ---------------------         
hereto.

     3.  Approved Repo Lenders.  To reflect the agreement of the parties hereto
         ---------------------                                                 
to approve the inclusion of an additional Approved Repo Lender and to reflect
certain name changes of existing Approved 

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Repo Lenders, effective as of the Effective Date, the current schedule of
Approved Repo Lenders is hereby amended and restated in its entirety in the form
attached hereto as Amendment Exhibit A.
                   ------------------- 

     4.  Definition of Eligible Mortgage Loan.  To reflect the agreement of the
         ------------------------------------                                  
parties hereto to modify the eligibility requirements for the inclusion of
certain Mortgage Loans in the calculation of the Collateral Value of the
Borrowing Base, effective as of the Effective Date:

         (a) Subparagraph (m) of the definition of "Eligible Mortgage Loan" is
hereby amended to delete the reference to "one percent (1%) of the Aggregate
Credit Limit" appearing in the first proviso thereto and replace the same with a
reference to "five percent (5%) of the Aggregate Credit Limit".

         (b) Subparagraph (iii) of subparagraph (q)(1) of the definition of
"Eligible Mortgage Loan" is hereby amended to delete the reference to "thirty
percent (30%) of the Aggregate Credit Limit" appearing in subparagraph (x)
thereof and to replace the same with a reference to "forty percent (40%) of the
Aggregate Credit Limit" and to delete the reference to "twenty percent (20%) of
the Aggregate Credit Limit" appearing in subparagraph (y) thereof and to replace
the same with a reference to "thirty percent (30%) of the Aggregate Credit
Limit".

     5.  Reduction of Certain Sublimits.  To reflect the agreement of the
         ------------------------------                                  
parties hereto to reduce the sublimits applicable to No-Equity Mortgage Loans
and Eligible Manufactured Housing Mortgage Loans which may be included in the
calculation of the Collateral Value of the Borrowing Base, effective as of the
Effective Date:

         (a)  The definition of "No-Equity Mortgage Loan" set forth in Paragraph
16 of the Agreement is hereby amended to delete the reference to "ten percent
(10%) of the Aggregate Credit Limit" appearing in the last proviso thereto and
replace the same with a reference to "five percent (5%) of the Aggregate Credit
Limit".

         (b)  Subparagraph (d) of the definition of "Eligible Manufactured
Housing Mortgage Loan" set forth in Paragraph 16 of the Agreement is hereby
amended to delete the reference to "ten percent (10%) of the Aggregate Credit
Limit" appearing therein and replace the same with a reference to "five million
dollars ($5,000,000.00)".

     6.  Reaffirmation of Other Loan Documents.  The Company hereby affirms and
         -------------------------------------                                 
agrees that (a) the execution and delivery by the Company of and the performance
of its obligations under this Amendment shall not in any way amend, impair,
invalidate or otherwise affect any of the obligations of the Company or the
rights of the Administrative Agent, the Collateral Agent or the Lenders under
the Agreement, the Security Agreement or any other Loan Document, (b) the term
"Obligations" as defined in Paragraph 16 of the Agreement includes, without
limitation, the Obligations of the Company under the Agreement as amended by
this Amendment, (c) the Security Agreement remains in full force and effect and
such agreement constitutes a continuing first priority security interest in and
lien upon the Collateral, and (d) for any and all purposes, any reference to the
Agreement following the effective date of this Amendment shall constitute a

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reference to the Agreement as amended to date, including, without limitation, by
this Amendment.

     7.  Modification of Related Documents.  All reports and other forms
         ---------------------------------                              
utilized in connection with the day-to-day operations of the credit facility
evidenced by the Agreement shall be deemed modified consistent with the
provisions of this Amendment.

     8.  Effective Date.  The amendments set forth above shall be effective on
         --------------                                                       
the earliest date (the "Effective Date") upon which the Administrative Agent has
received (a) duly executed copies of this Amendment from each of the Lenders,
the Administrative Agent, the Collateral Agent and the Company, (b) such board
resolutions, incumbency certificates and other additional documentation as the
Administrative Agent may request in connection herewith, and (c) for
distribution to each of the Lenders an amendment fee equal to one thousand five
hundred dollars ($1,500) per Lender.

     9.  Representations and Warranties.  The Company hereby represents and
         ------------------------------                                    
warrants to the Administrative Agent and the Lenders as follows:

         (a) The Company has the corporate power and authority and the legal
right to execute, deliver and perform this Amendment and has taken all necessary
corporate action to authorize the execution, delivery and performance of this
Amendment.  This Amendment has been duly executed and delivered on behalf of the
Company and constitutes the legal, valid and binding obligation of the Company
enforceable against the Company in accordance with its terms.  The execution,
delivery and performance of this Amendment will not violate any Requirement of
Law or Contractual Obligation or require any consent, approval or authorization
of, or registration, declaration or filing with, any Governmental Authority.

         (b) At and as of the date of execution hereof and at and as of the
Effective Date of this Amendment and both prior to and after giving effect
hereto:  (1) the representations and warranties of the Company contained in the
Loan Documents are accurate and complete in all respects, and (2) there has not
occurred an Event of Default or Potential Default.

     10. No Other Amendment.  Except as expressly amended herein, the Loan
         ------------------                                               
Documents shall remain in full force and effect as currently written.

     11. Counterparts.  This Amendment may be executed in any number of
         ------------                                                  
counterparts, each of which when so executed shall be deemed to be an original
and all of which when taken together shall constitute one and the same
agreement.

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


                          HEADLANDS MORTGAGE COMPANY,
                          a California corporation


                          By:
                              --------------------------------
                          Name:
                              --------------------------------
                          Title:
                              --------------------------------



                          THE FIRST NATIONAL BANK OF CHICAGO,
                          a national banking association, as Administrative
                          Agent and a Lender


                          By:
                              --------------------------------
                          Name:
                              --------------------------------
                          Title:
                              --------------------------------



                          BANK OF AMERICA NATIONAL TRUST AND SAVINGS
                          ASSOCIATION,
                          a national banking association, as a Lender


                          By:
                              --------------------------------
                          Name:
                              --------------------------------
                          Title:
                              --------------------------------



                          THE BANK OF NEW YORK,
                          a banking corporation organized under
                          the laws of the State of New York, as a Lender


                          By:
                              --------------------------------
                          Name:
                              --------------------------------
                          Title:
                              --------------------------------

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                          COMERICA BANK-CALIFORNIA,
                          a California banking corporation, as a Lender


                          By:
                              --------------------------------
                          Name:
                              --------------------------------
                          Title:
                              --------------------------------



                          FIRST UNION NATIONAL BANK,
                          a national banking association, as a Lender


                          By:
                              --------------------------------
                          Name:
                              --------------------------------
                          Title:
                              --------------------------------



                          GUARANTY FEDERAL BANK,
                          a federal savings bank, as a Lender


                          By:
                              --------------------------------
                          Name:
                              --------------------------------
                          Title:
                              --------------------------------



                          FIRST CHICAGO NATIONAL PROCESSING CORPORATION, a
                          Delaware corporation, as Collateral Agent


                          By:
                              --------------------------------
                          Name:
                              --------------------------------
                          Title:
                              --------------------------------

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                                                           REPLACEMENT EXHIBIT N
                                                           ---------------------
                                                                                

                                  SCHEDULE OF
                              PERMITTED OTHER DEBT
                                      AND
                        (*) PERMITTED OTHER SECURED DEBT
                           (AS OF FEBRUARY 25, 1998)
                                        
  1. Indebtedness owed under repurchase agreements and gestation repurchase
     credit facilities entered into by the Company from time to time with
     Approved Repo Lenders.

  2. Indebtedness owed under any servicing secured facility (including the
     Servicing Secured Credit Agreement) in an aggregate amount not to exceed at
     any one time outstanding $30,000,000.00.*

  3. Indebtedness owed under credit facilities entered into by and between the
     Company and Residential Funding Corporation ("RFC") from time to time
     secured by Mortgage Loans that are delinquent or in foreclosure or subject
     to a Take-Out Commitment issued by RFC, manufactured housing loans and REO
     properties in an aggregate amount not to exceed at any one time outstanding
     $15,000,000.00.*

  4. Indebtedness owed under any deposit-backed interest rate exchange
     agreements and/or investment arbitrage lines, entered into in the ordinary
     course of business.*

  5. Indebtedness of HMSI to third party lenders in an amount not to exceed
     $5,000,000.00 in the aggregate at any time outstanding, the proceeds of
     which Indebtedness shall be used by HMSI to finance advance receivables.*

  6. Indebtedness of HMSI secured by liens on the retained interests in
     securitizations of HMSI in connection with yield maintenance arrangements
     on securities issued through HMSI.

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                                                             AMENDMENT EXHIBIT A
                                                             -------------------

                                  SCHEDULE OF
                             APPROVED REPO LENDERS

      [To be provided by the Company and approved by the Majority Lenders]

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