Document:

Exhibit 10.5

            AMENDED AND RESTATED MORTGAGE LOAN CUSTODIAL AGREEMENT

PURCHASER:         UBS REAL ESTATE SECURITIES INC.

ADDRESS:           1285 AVENUE OF THE AMERICAS
                   NEW YORK, NEW YORK  10019
                   ATTENTION:  GEORGE A. MANGIARACINA
                   TELEPHONE:  (212) 713-3734
                   ATTENTION:  ROBERT CARPENTER
                   TELEPHONE:  (212) 713-8749

CUSTODIAN:         DEUTSCHE BANK NATIONAL TRUST COMPANY

ADDRESS:           1761 EAST ST. ANDREW PLACE
                   SANTA ANA, CALIFORNIA 92705-4934
                   ATTENTION: MORTGAGE CUSTODY- AH099C
                   TELEPHONE:  (714) 247-6000
                   FACSIMILE:  (714) 247-6058

SELLER:            AMERICAN HOME MORTGAGE INVESTMENT CORP.

ADDRESS:           520 BROADHOLLOW ROAD
                   MELVILLE, NEW YORK 11747
                   ATTENTION:  STEPHEN A. HOZIE, CHIEF FINANCIAL OFFICER
                   TELEPHONE:  (516) 396-7700

SELLER:            AMERICAN HOME MORTGAGE ACCEPTANCE, INC.

ADDRESS:           520 BROADHOLLOW ROAD
                   MELVILLE, NEW YORK 11747
                   ATTENTION:   STEPHEN A. HOZIE, CHIEF FINANCIAL OFFICER
                   TELEPHONE:  (516) 396-7700

SELLER:            AMERICAN HOME MORTGAGE HOLDINGS, INC.

ADDRESS:           520 BROADHOLLOW ROAD
                   MELVILLE, NEW YORK 11747
                   ATTENTION:  STEPHEN A. HOZIE, CHIEF FINANCIAL OFFICER
                   TELEPHONE:  (516) 396-7700

SELLER:            AMERICAN HOME MORTGAGE CORP.

ADDRESS:           520 BROADHOLLOW ROAD
                   MELVILLE, NEW YORK 11747

<PAGE>

                   ATTENTION:   MICHAEL STRAUSS, PRESIDENT
                   TELEPHONE:  (516) 396-7700

SELLER:            COLUMBIA NATIONAL, INCORPORATED

ADDRESS:           520 BROADHOLLOW ROAD
                   MELVILLE, NEW YORK 11747
                   ATTENTION: MICHAEL STRAUSS, PRESIDENT
                   TELEPHONE:  (516) 396-7700
                   ATTENTION: STEPHEN A. HOZIE, CHIEF FINANCIAL OFFICER
                   TELEPHONE:  (516) 396-7700

DATE:              FEBRUARY 6, 2004

                                       ii

<PAGE>

                                TABLE OF CONTENTS

                                                                            Page
                                                                            ----

Section 1.  Definitions ...................................................    2

Section 2.  Delivery of Documents by Seller ...............................    9

Section 3.  Custodian as Custodian for, and Bailee of, Purchaser,
            Assignee and Warehouse Lender .................................   11

Section 4.  Certification by Custodian; Delivery of Documents .............   12

Section 5.  [Reserved] ....................................................   15

Section 6.  Default .......................................................   15

Section 7.  Access to Documents ...........................................   16

Section 8.  Custodian's Fees and Expenses; Successor Custodian;
            Standard of Care ..............................................   16

Section 9.  Assignment by Purchaser .......................................   18

Section 10. Insurance .....................................................   19

Section 11. Delivery of Submission Packages ...............................   19

Section 12. Representations, Warranties and Covenants .....................   19

Section 13. No Adverse Interests ..........................................   21

Section 14. Amendments ....................................................   21

Section 15. Execution in Counterparts .....................................   21

Section 16. Agreement for Exclusive Benefit of Parties;
            Assignment ....................................................   21

Section 17. Effect of Invalidity of Provisions ............................   21

Section 18. GOVERNING LAW .................................................   22

Section 19. Consent to Service ............................................   22

Section 20. Notices .......................................................   22

Section 21. Certification .................................................   22

Section 22. Authorized Representatives ....................................   22

                                      iii
<PAGE>

Section 23. Construction ..................................................   22

Section 24. Effect of Amendment and Restatement ...........................   23

Exhibit A     Dry Submission Package
Exhibit B-1   Cash Window Submission Package
Exhibit B-2   Freddie Mac Document List
Exhibit B-3   Fannie Mae Document List
Exhibit B-4   Fannie Mae Bailee Letter
Exhibit C-1   Conduit Submission Package
Exhibit C-2   Conduit Bailee Letter
Exhibit D     Conversion Submission Packages
Exhibit E     Request for Certification
Exhibit F     Document Codes
Exhibit G-1   Warehouse Lender's Release
Exhibit G-2   Warehouse Lender's Wire Instructions
Exhibit H-1   Seller's Release
Exhibit H-2   Seller's Wire Instructions
Exhibit I-1   Purchaser's Wire Instructions to Seller
Exhibit I-2   Purchaser's Delivery Instructions to Custodian
Exhibit J     Notice by Assignee to Custodian of Purchaser's Default
Exhibit K     Limited Power of Attorney
Exhibit L     Unidentified Mortgage Loans List
Exhibit M     Form of Trust Receipt
Exhibit N     Form of Delivery Instructions
Exhibit O     Purchaser's Instructions to Custodian to Destroy Specified Files
Exhibit P     Form of Electronic Tracking Agreement
Exhibit Q     Authorized Representatives of Purchaser
Exhibit R     Authorized Representatives of Seller
Exhibit S     Authorized Representatives of Custodian
Schedule A   List of Conduits

                                       iv
<PAGE>

             AMENDED AND RESTATED MORTGAGE LOAN CUSTODIAL AGREEMENT

            THIS AMENDED AND RESTATED MORTGAGE LOAN CUSTODIAL AGREEMENT
("Agreement"), dated as of the date set forth on the cover page hereof (as
amended, supplemented or otherwise modified from time to time, "Agreement"),
among UBS REAL ESTATE SECURITIES INC. ("Purchaser" or "UBSRES"), Deutsche Bank
National Trust Company as Custodian (the "Custodian"), and the Sellers whose
names are set forth on the cover page hereof (each a "Seller" and, collectively,
the "Sellers").

                                    RECITALS

            WHEREAS, the Purchaser; American Home Mortgage Holdings, Inc.,
American Home Mortgage Corp. and Columbia National, Incorporated (in such
capacity, the "Original American Home Parties"); and the Custodian are parties
to the Mortgage Loan Custodial Agreement, dated as of February 26, 1999 as
amended, supplemented or otherwise modified prior to the date hereof (the
"Original Custodial Agreement");

            WHEREAS, in connection with the Original Custodial Agreement, (i)
the Purchaser has agreed to purchase, from time to time, at its sole election
from the Original American Home Parties, certain residential first mortgage
loans pursuant to the terms and conditions of one or more Purchase Agreements
(as defined therein) among Purchaser and the Original American Home Parties
relating to Dry Transactions, Cash Window Transactions or Conduit Transactions
(each as defined therein) and (ii) the Purchaser desired to have Custodian take
possession of the Mortgage Notes (as defined therein) evidencing the Mortgage
Loans (as defined therein), along with certain other documents specified
therein, as the custodian for and bailee of Purchaser or Assignee (as defined
therein) in accordance with the terms and conditions thereof;

            WHEREAS, the Purchaser, the Original American Home Parties and the
Custodian desire to amend and restate the Original Custodial Agreement as
provided herein;

            NOW, THEREFORE, for good and valuable consideration, the receipt and
sufficiency of which are hereby acknowledged, the parties hereto hereby agree
that the Original Custodial Agreement be amended and restated in its entirety as
follows:

                              PRELIMINARY STATEMENT

            Purchaser has agreed to purchase, from time to time, at its sole
election from the related Seller, certain residential first mortgage loans
pursuant to the terms and conditions of one or more Purchase Agreements among
Purchaser, such Seller and the other parties thereto relating to Dry
Transactions, Cash Window Transactions or Conduit Transactions. The related
Seller is obligated to service the Mortgage Loans pursuant to the terms and
conditions of the Purchase Agreements. Purchaser desires to have Custodian take
possession of the Mortgage Notes evidencing the Mortgage Loans, along with
certain other documents specified herein, as the custodian for and bailee of
Purchaser or Assignee in accordance with the terms and conditions hereof.

<PAGE>

            The parties hereto agree as follows:

            Section 1. Definitions. As used in this Agreement, the following
terms shall have the following meanings:

            "Agency": Freddie Mac or Fannie Mae, as applicable.

            "Applicable Agency Documents": The documents listed on Exhibit B-2
or Exhibit B-3, as applicable.

            "Applicable Guide": With respect to each Takeout Investor the
applicable guide published by such Takeout Investor setting forth the
requirements each Mortgage Loan needs to satisfy in order to be eligible for
purchase by such Takeout Investor, as such guide may be amended or supplemented
from time to time.

            "Assignee": With respect to this Agreement and any Mortgage Loan,
any assignee of the Purchaser pursuant to a pledge or rehypothecation of the
Mortgage Loan.

            "Assignment of Mortgage": An assignment of the Mortgage, notice of
transfer or equivalent instrument sufficient under the laws of the jurisdiction
wherein the related Mortgaged Property is located to reflect of record the sale
of a Mortgage Loan.

            "Bailee Letter": A Fannie Mae Bailee Letter or a Conduit Bailee
Letter, as applicable.

            "Business Day": Any day other than (a) a Saturday, Sunday or other
day on which banks located in the City of New York, New York or the city in
which the office of the Custodian are authorized or obligated by law or
executive order to be closed, or (b) any day on which UBS Real Estate Securities
Inc. is closed for business, provided that notice thereof shall have been given
not less than seven calendar days prior to such day.

            "Cash Window Submission Package": The documents listed on Exhibit
B-1, which shall be delivered by the related Seller to Custodian in connection
with each Cash Window Transaction.

            "Cash Window Transaction": A transaction initiated by Purchaser's
delivery of a Request for Certification which identifies Fannie Mae or Freddie
Mac as the Takeout Investor but does not include a Conversion Code.

            "Certification": With respect to a Mortgage Loan, the full
performance by Custodian of the procedures set forth in Sections 4(a) and 4(b).

            "Certification Code": A Mortgage Loan Absentee Code, a Mortgage Loan
Approval Code or a Mortgage Loan Suspension Code.

            "Certification Report": A Request for Certification to which
Custodian has added its Certification Codes, and which is transmitted via
electronic transmission by Custodian to Purchaser in an appropriate data layout
provided by Purchaser.

                                      -2-
<PAGE>

            "Commitment": A commitment executed by Takeout Investor and the
related Seller on Takeout Investor's letterhead evidencing Takeout Investor's
agreement to purchase one or more Mortgage Loans from such Seller and such
Seller's agreement to sell one or more Mortgage Loans to an investor in a
forward trade by the applicable Commitment Expiration Date.

            "Commitment Expiration Date": With respect to any Commitment, the
expiration date thereof.

            "Conduit": Any of the Entities listed on Schedule A, as amended or
supplemented from time to time.

            "Conduit Bailee Letter": The master bailee letter, in the form of
Exhibit C-2, for use by Custodian in connection with the delivery of a Conduit
Submission Package, provided, however, for the purposes of delivering the
related Conduit Submission Package, excluding (i) a copy of the Commitment, (ii)
the Warehouse Lender's Release or the related Seller's Release, as applicable,
and (iii) the original Assignment of Mortgage, in blank, to a Conduit.

            "Conduit Submission Package": The documents listed on Exhibit C-1,
which shall be delivered by a Seller to Custodian in connection with the related
Conduit Transaction.

            "Conduit Transaction": A transaction initiated by Purchaser's
delivery of a Request for Certification which identifies a Conduit as the
Takeout Investor but does not include a Conversion Code.

            "Confirmation": A confirmation confirming a trade between the
related Seller and Takeout Investor.

            "Conversion Code": With respect to a Mortgage Loan, the conversion
code set forth in Part II of Exhibit F, entered by Purchaser, along with the
Program Code, in the "PROG CODE" column of the related Request for Certification
indicating that (i) such Mortgage Loan was previously acquired by Purchaser in a
Dry Transaction and (ii) a Conversion Submission Package shall be received by
Custodian on the applicable Delivery Date.

            "Conversion Submission Package": One of the sets of documents listed
on Exhibit D, which shall be delivered by the related Seller to Custodian in
connection with each Conversion Transaction.

            "Conversion Transaction": With respect to a Mortgage Loan, a
transaction initiated by Purchaser's delivery to Custodian of a Request for
Certification containing a Conversion Code. A Conversion Transaction shall
always be preceded by a Dry Transaction.

            "Cumulative Position File": A list of all Mortgage Loans held by the
Custodian on each day which includes all information which would be on the
Custodian's Certification Report and additionally includes the shipping
information for each Mortgage Loan which has been released from the Custodian's
possession (i.e., airbill number, federal express tracking code or other
identifying information).

                                      -3-
<PAGE>

            "Custodian": Deutsche Bank National Trust Company, a national
banking association, and its permitted successors hereunder.

            "Delivery Date": With respect to a Mortgage Loan, the date set forth
on the related Request for Certification in the "DELIVERY DATE" column, which
shall be the Business Day on which the related Seller desires the applicable
portion of the related Submission Package be sent by Custodian to the Takeout
Investor, i.e., one Business Day prior to the Business Day on which such Seller
desires the applicable portion of the Submission Package to be received by the
Takeout Investor.

            "Delivery Instructions": With respect to a Mortgage Loan,
instructions prepared by the related Seller, in the form of Exhibit N indicating
the address for the delivery by Custodian of the applicable portion of the
related Submission Package.

            "Delivery Report": A report created by Custodian delivered to the
related Seller which identifies any loans delivered to an approved Takeout
Investor including the date delivered.

            "Dry Submission Package": The documents listed on Exhibit A, which
shall be delivered by the related Seller to Custodian in connection with each
Dry Transaction.

            "Dry Transaction": A transaction initiated by Purchaser's delivery
to Custodian of a Request for Certification, which does not identify a Takeout
Investor, and which does not include a Conversion Code.

            "Electronic Agent": The electronic agent identified in the
Electronic Tracking Agreement.

            "Electronic Tracking Agreement": The Electronic Tracking Agreement
substantially in the form set forth in Exhibit P hereto, dated as of the date
hereof, among Participant, Sellers, MERSCORP, Inc. and Mortgage Electronic
Registration Systems, Inc.; provided that if no Mortgage Loans are or will be
MERS Designated Mortgage Loans, all references herein to the Electronic Tracking
Agreement shall be disregarded.

            "Entity": Any individual, corporation, partnership, joint venture,
association, joint stock company, trust (including any beneficiary thereof),
unincorporated organization or government or any agency or political subdivision
thereof.

            "Exception Code": Each of the exception codes set forth in Part III
of Exhibit F, placed by Custodian on an Exception Report indicating missing
documents, incomplete documents and deficiencies in documents reviewed by
Custodian.

            "Exception Report": A list of document exceptions delivered by
Custodian to Purchaser in accordance with the terms of this Agreement.

            "Expected Delivery Date": The date identified on a Request for
Certification as the "Expected Delivery Date of Mortgage File", which shall be
the date on which the related

                                      -4-
<PAGE>

Seller has informed Purchaser that a Submission Package will be received by
Custodian from such Seller.

            "Fannie Mae": Fannie Mae and any successor thereto.

            "Fannie Mae Bailee Letter": The master bailee letter, in the form of
Exhibit B-4, for use by Custodian in connection with the delivery to Fannie Mae
of the Cash Window Submission Package, excluding (i) the original Assignment of
Mortgage, in blank, (ii) the Warehouse Lender's Release or the related Seller's
Release, as applicable, (iii) all modification agreements relating to a
Mortgage, (iv) the Delivery Instructions and (v) a copy of the Commitment.

            "Fannie Mae Commitment": A commitment executed by Fannie Mae and the
related Seller, evidencing Fannie Mae's agreement to purchase one or more
Mortgage Loans from such Seller and such Seller's agreement to sell one or more
Mortgage Loans to Fannie Mae by the applicable Commitment Expiration Date under
the Applicable Guide.

            "Freddie Mac": Freddie Mac and any successor thereto.

            "Freddie Mac Commitment": A commitment executed by Freddie Mac and
the related Seller evidencing Freddie Mac's agreement to purchase one or more
Mortgage Loans from such Seller and such Seller's agreement to sell one or more
Mortgage Loans to Freddie Mac by the applicable Commitment Expiration Date under
the Applicable Guide.

            "HUD": United States Department of Housing and Urban Development and
any successor thereto.

            "Interim Funder" shall mean with respect to each MERS Designated
Mortgage Loan, the Person named on the MERS System as the interim funder
pursuant to the MERS Procedures Manual.

            "Limited Power of Attorney": A limited power of attorney, in the
form of Exhibit K, executed by the related Seller and delivered to Custodian,
authorizing Custodian to complete Mortgage Note endorsements in the form
indicated thereon.

            "Loan Identification Data": The applicable information regarding a
Mortgage Loan, set forth on a Request for Certification, which shall include
Purchaser's reference number, the name of Purchaser's applicable program, the
Mortgage Loan number, the MERS Identification Number, the last name of the
Mortgagor, the address of the Mortgaged Property, the face amount of the
Mortgage Note, the number of months to maturity of the Mortgage Loan, and the
interest rate borne by the Mortgage Note and, solely with respect to Cash Window
Transactions, Conduit Transactions and Conversion Transactions, the name of the
Takeout Investor, the sale price of the Mortgage Loan to the Takeout Investor,
the commitment number, the Commitment Expiration Date, the Delivery Date, the
Release Payment, and the name of the Warehouse Lender.

            "Losses": Any and all losses, claims, damages, liabilities or
expenses (including reasonable attorney's fees) incurred by any person
specified; provided however that "Losses"

                                      -5-
<PAGE>

shall not include losses, claims, damages, liabilities or expenses which would
have been avoided had such person taken reasonable actions to mitigate such
losses, claims, damages, liabilities or expenses.

            "MERS Designated Mortgage Loan" shall have the meaning
assigned to such term in Section 3 of the Electronic Tracking Agreement, if any;
provided that no Mortgage Loan shall be considered a MERS Designated Mortgage
Loan unless an Electronic Tracking Agreement shall have been entered into.

            "MERS Identification Number" shall mean the eighteen digit
number permanently assigned to each MERS Designated Mortgage Loan.

            "MERS Procedures Manual" shall mean the MERS Procedures Manual
attached as Exhibit B to the Electronic Tracking Agreement, as it may be
amended, supplemented or modified from time to time.

            "MERS Report" shall mean the schedule listing MERS Designated
Mortgage Loans and other information prepared by the Electronic Agent pursuant
to the Electronic Tracking Agreement.

            "MERS(R)System" shall mean the Electronic Agent's mortgage
electronic registry system, as more particularly described in the MERS
Procedures Manual.

            "Mortgage": A mortgage, deed of trust or other security instrument
creating a first lien on an estate in fee simple in real property securing a
Mortgage Note.

            "Mortgage Loan": A one-to-four family residential mortgage loan that
is subject to this Agreement.

            "Mortgage Loan Absentee Code": The mortgage loan absentee code, set
forth in Part III of Exhibit F, placed by Custodian on a Certification Report to
notify Purchaser that a Submission Package related to a Mortgage Loan listed on
a Request for Certification is not in Custodian's possession.

            "Mortgage Loan Approval Code": The mortgage loan approval code, set
forth in Part III of Exhibit F, placed by Custodian on a Certification Report to
notify Purchaser that Custodian's review of the applicable items in a Submission
Package is complete and that such items satisfy all the applicable requirements
set forth in Section 4(a) and Section 4(b).

            "Mortgage Loan Schedule": A listing prepared by Custodian, attached
to the Trust Receipt of all Mortgage Loans Custodian has annotated with a
Mortgage Loan Approval Code and that Purchaser has not communicated to Custodian
its release of interest therein.

            "Mortgage Loan Suspension Code": The mortgage loan suspension code,
set forth in Part III of Exhibit F, placed by Custodian on a Certification
Report to notify Purchaser that Custodian's review of the Submission Package has
determined that one or more of the documents in the Submission Package are
missing, incomplete or incorrect and/or do not satisfy one or more of the
requirements set forth in Section 4(a) or Section 4(b).

                                      -6-
<PAGE>

            "Mortgage Note": The note or other evidence of the indebtedness of a
Mortgagor secured by a Mortgage.

            "Mortgaged Property": The property subject to the lien of the
Mortgage securing a Mortgage Note.

            "Mortgagor": The obligor on a Mortgage Note.

            "Notice of Bailment": A notice, in the form of Schedule A to Exhibit
B-4 or C-2, as applicable, delivered by Custodian to Takeout Investor in
connection with each delivery to Takeout Investor of the applicable portion of
each Submission Package.

            "Original American Home Parties": Shall have the meaning assigned to
such term in the recitals hereof.

            "Officer's Certificate": A certificate signed by the Chairman of the
Board or the Vice Chairman of the Board or a President or a Vice President and
by the Treasurer or the Secretary or one of the Assistant Treasurers or
Assistant Secretaries of the applicable Seller, and delivered to the Purchaser
or the Custodian, as the case may be, as required by this Agreement.

            "Original Custodial Agreement": Shall have the meaning assigned to
such term in the recitals hereof.

            "Payee Number": The code used by Fannie Mae to indicate the wire
transfer instructions that will be used by Fannie Mae to purchase a Mortgage
Loan.

            "Person": Any individual, corporation, company, partnership, joint
venture, voluntary association, joint stock company, trust (including any
beneficiary thereof), limited liability company, unincorporated organization or
government or any agency, instrumentality or political subdivision thereof.

            "Program Code": Each of the codes, set forth in Part I of Exhibit F,
placed by the Purchaser in the "PROG CODE" column of a Request for Certification
indicating that the Mortgage Loan is being offered by the related Seller to
Purchaser in a Dry Transaction, Cash Window Transaction or a Conduit
Transaction, as applicable.

            "Purchase Agreement": Each Amended and Restated Mortgage Loan
Purchase Agreement, dated as of the date set forth on the cover page thereof,
among the Sellers and Purchaser, as each is amended from time to time providing
the terms of Dry Transactions, Cash Window Transactions, Conduit Transactions or
Conversion Transactions.

            "Purchase Date": With respect to a Mortgage Loan, the date on which
Purchaser purchases such Mortgage Loan from the related Seller.

            "Purchaser": UBS Real Estate Securities Inc. and its successors.

            "Purchaser's Payment": The amount set forth on the Request for
Certification in the "RELEASE PAYMENT" column.

                                      -7-
<PAGE>

            "Purchaser's Wire Instructions to Seller": The wire instructions,
set forth on Exhibit I-1, specifying the account which shall be used for the
payment of all amounts due and payable by the related Seller to Purchaser
hereunder.

            "Release Payment": The funds referred to in a Warehouse Lender's
Release or the related Seller's Release, as applicable.

            "Request for Certification": A report detailing Loan Identification
Data supplied by the related Seller to Purchaser, transmitted by Purchaser to
Custodian either via facsimile in the form of Exhibit E or transmitted
electronically in an appropriate data layout, regarding all Mortgage Loans being
offered for sale by such Seller to Purchaser on the Expected Delivery Date.

            "Re-warehouse Lender": Any lender providing financing to a
correspondent of the related Seller in any fractional amount for the purpose of
originating or purchasing Mortgage Loans, which lender has a security interest
in such Mortgage Loans as collateral for the obligations of such correspondent
to such lender; provided, however, that the Re-warehouse Lender shall not
include Purchaser.

            "Re-warehouse Release Letter": A letter, which may take the form of
a bailee letter, conditionally releasing all of Re-warehouse Lender's right,
title and interest in certain Mortgage Loans identified therein upon receipt of
payment by Re-warehouse Lender.

            "Seller": Shall have the meaning specified in the preamble hereof.

            "Sellers": Shall have the meaning specified in the preamble hereof.

            "Seller's Release": A letter, in the form of Exhibit H-1, delivered
by the related Seller when no Warehouse Lender has an interest in a Mortgage
Loan, conditionally releasing all of such Seller's right, title and interest in
such Mortgage Loan upon receipt of payment by such Seller.

            "Seller's Wire Instructions": The wire instructions, set forth in a
letter in the form of Exhibit H-2, to be used for the payment of funds to the
related Seller when no Warehouse Lender has an interest in the Mortgage Loans to
which such payment relates.

            "Submission Package": With respect to each Mortgage Loan, a Dry
Submission Package, a Cash Window Submission Package, a Conduit Submission
Package or a Conversion Submission Package, as applicable.

            "Successor Servicer": An entity designated by Purchaser, in
conformity with the Purchase Agreement, to replace the related Seller as
servicer for Purchaser, and, with respect to Cash Window Transactions, as
seller/servicer of the Mortgage Loans for the Agency.

            "Takeout Investor": An Agency or a Conduit, as applicable.

            "Trust Receipt": A receipt of Custodian, substantially in the form
of Exhibit M hereto, indicating that with respect to the Mortgage Loans listed
on the attached Mortgage Loan

                                      -8-
<PAGE>

Schedule, the Custodian has performed the procedures set forth in Sections 4(a)
and 4(b) hereof that it has received the Dry Submission Package, Cash Window
Submission Package, or the Conduit Submission Package, as applicable, and that
it is holding such documents as bailee and custodian of Purchaser. Any reference
in this Agreement to a Trust Receipt shall include the attached Mortgage Loan
Schedule.

            "Underwriter": Any party, including but not limited to a mortgage
loan pool insurer, who underwrites a Mortgage Loan prior to its purchase by
Purchaser.

            "Underwriter's Form": A Fannie Mae / Freddie Mac Form 1008/1077, HUD
92900WS, HUD92900.4, VA Form 26-6393, VA Form 26-1866, or a mortgage loan pool
insurance certificate, as applicable, completed by an Underwriter with respect
to a Mortgage Loan, indicating that such Mortgage Loan complies with its
underwriting requirements.

            "Unidentified Mortgage Loans List": A list of Mortgage Loans for
which Custodian has received the related Submission Packages from the related
Seller but which have not been identified by Purchaser in a Request for
Certification. Such list shall include, with respect to each Mortgage Loan, the
information set forth in Exhibit L.

            "Warehouse Lender": Any lender providing financing to the related
Seller in any fractional amount for the purpose of originating or purchasing
Mortgage Loans, which lender has a security interest in such Mortgage Loans as
collateral for the obligations of such Seller to such lender. In all Dry
Transactions and Conversion Transactions, Purchaser shall be the Warehouse
Lender.

            "Warehouse Lender's Release": A letter, in the form of Exhibit G-l,
from a Warehouse Lender to Purchaser, conditionally releasing all of Warehouse
Lender's right, title and interest in certain Mortgage Loans identified therein
upon receipt of payment by Warehouse Lender.

            "Warehouse Lender's Wire Instructions": The wire instructions, set
forth in a letter in the form of Exhibit G-2, from a Warehouse Lender to
Purchaser, setting forth wire instructions for all amounts due and payable to
such Warehouse Lender.

            Section 2. Delivery of Documents by Seller. (a) The related Seller
may, before the first purchase by Purchaser under a Purchase Agreement of a
Mortgage Loan, deliver to Custodian a Limited Power of Attorney; provided,
however, Custodian shall have no responsibility or obligation to act under such
Limited Power of Attorney.

            (b) If a Seller desires to engage in Cash Window Transactions, prior
to the first such transaction:

                  (1) relating to a Freddie Mac Commitment, such Seller shall
      deliver to Purchaser a copy of (i) Freddie Mac Form 1035 (Custodial
      Agreement), if applicable, duly executed by the related custodian and
      Freddie Mac, (ii) Freddie Mac Form 3 (Summary Agreement) or such other
      equivalent agreement as is acceptable to Purchaser, duly executed by such
      Seller and Freddie Mac, and (iii) Freddie Mac Form 1 (Fixed-Rate Mortgage
      Purchase Contract Conventional Home Mortgages - Original Cash) or Freddie

                                      -9-
<PAGE>

      Mac Form 9 (Fixed-Rate Mortgage Purchase Contract Conventional Home
      Mortgages - Gold Cash), or Freddie Mac Form 2 (Adjustable Rate Purchase
      Contract Conventional Home Mortgages); or

                  (2) relating to a Fannie Mae Commitment, such Seller shall
      deliver to Purchaser a copy of (i) Fannie Mae Form 2003 (Custodial
      Agreement) if applicable, duly executed by the related custodian and
      Fannie Mae, (ii) Fannie Mae Mortgage Selling and Servicing Contract, and
      Fannie Mae Form 482 (Designation of Payee - Wire Transfer Information),
      and (iii) either a Standard Mandatory Delivery Commitment or a Negotiated
      Mandatory Delivery Commitment or a Negotiated Market-Rate Standby
      Commitment.

            (c) With respect to each Mortgage Loan being offered by such Seller
for sale to Purchaser pursuant to a Purchase Agreement, such Seller shall
deliver to Custodian a Submission Package on the Expected Delivery Date. In no
event shall such Seller deliver to Custodian a Submission Package later than
11:00 a.m. New York City time on the related Expected Delivery Date. In
addition, the Purchaser shall deliver, no later than 10:30 a.m. New York City
time on the Expected Delivery Date, the Request for Certification in computer
readable format.

            (d) With respect to each Mortgage Loan being offered by such Seller
for sale to Purchaser pursuant to a Purchase Agreement, such Seller shall insure
that Purchaser has received a Request for Certification no later than 6:00 p.m.
New York City time on the Business Day immediately preceding the related
Purchase Date, which shall be forwarded by Purchaser to Custodian. Further, such
Seller shall insure that (i) Custodian shall be in possession of a Submission
Package for each Mortgage Loan identified on a Request for Certification, (ii)
with respect to Cash Window Transactions and Conduit Transactions, Purchaser is
in possession of a Commitment and either a Warehouse Lender's Release or a
Seller's Release from such Seller, as applicable, and (iii) with respect to Dry
Transactions, Purchaser is in possession of a Warehouse Lender's Release, a
Seller's Release from such Seller or a Re-warehouse Release Letter, as
applicable, no later than 3:00 p.m. New York City time on the related Purchase
Date. Upon receipt by Custodian of such Request for Certification, Custodian
shall ascertain whether it is in possession of a Submission Package for each
Mortgage Loan identified on a Request for Certification and shall certify, in
accordance with Section 4(a) and Section 4(b) herein, each Submission Package
and no later than 3:00 p.m. New York City time on the related Purchase Date,
transmit via facsimile or electronic transmission to Purchaser the applicable
Certification Code, if any. If Custodian is in possession of a Submission
Package, and determines, pursuant to Section 4(a) and 4(b), that such Submission
Package is complete, Custodian shall issue to Purchaser a Mortgage Loan Approval
Code. If Custodian is not in possession of a Submission Package relating to a
Mortgage Loan identified on a Request for Certification, or after the review
pursuant to Section 4(a) and 4(b) Custodian determines that the Submission
Package is incomplete, the Custodian shall notify the related Seller and shall
issue to Purchaser a Mortgage Loan Absentee Code or Mortgage Loan Suspension
Code respectively. Unless Purchaser notifies Custodian not later than 4:00 p.m.
New York City time on the related Purchase Date of its intent not to purchase
any of the Mortgage Loans, then not later than 5:30 p.m. New York City time on
the related Purchase Date, Custodian shall issue the related Trust Receipt to
Purchaser or the Assignee, by facsimile or electronic transmission.

                                      -10-
<PAGE>

            (e) Not later than 4:30 p.m. New York City time on each Business
Day, and within one Business Day after Purchaser's release of its interest in a
Mortgage Loan, Purchaser shall deliver to Custodian via facsimile or electronic
transmission a detailed listing of (i) all Mortgage Loans previously classified
by Purchaser as Dry Transactions which have been reclassified by Purchaser as
Cash Window Transactions or Conduit Transactions and (ii) any Mortgage Loans
with respect to which Purchaser has released its interest. Custodian
acknowledges that the delivery requirements for Mortgage Loans referenced in (i)
above shall take effect on the next Business Day. The Custodian shall deliver to
Purchaser on a daily basis, via facsimile or electronic transmission in a data
layout agreed to by Purchaser and Custodian, a report detailing: (i) all
Mortgage Loans that Custodian has certified with a Mortgage Loan Approval Code
on all prior Purchase Dates that Purchaser has not communicated to Custodian its
release of interest in, (ii) if the place of business of the Custodian appearing
on the cover page hereof is not the collateral location of each Mortgage Loan
appearing on such report, the date of shipment of each such Mortgage Loan to
such other collateral location.

            Section 3. Custodian as Custodian for, and Bailee of, Purchaser,
Assignee and Warehouse Lender. (a) With respect to each Mortgage Note, each
Assignment of Mortgage (except with respect to MERS Designated Mortgage Loans)
and all other documents constituting each Submission Package that are delivered
to Custodian or that at any time come into Custodian's possession, Custodian,
subject to the provisions of paragraphs (b) and (c) of this Section 3, shall act
solely in the capacity of custodian for, and bailee of, Purchaser. Custodian
shall, subject to the provisions of paragraphs (b) and (c) of this Section 3 and
except as otherwise required by Section 4, hold all documents constituting a
Submission Package received by it for the exclusive use and benefit of
Purchaser, and shall make disposition thereof only in accordance with this
Agreement. Custodian shall segregate and maintain continuous custody of all
documents constituting a Submission Package received by it in secure and fire
resistant facilities in accordance with customary standards for such custody and
shall mark its books and records to indicate that the Submission Package is
being held for Purchaser.

            (b) Purchaser hereby notifies Custodian that each Mortgage Loan
purchased by Purchaser from the related Seller shall be promptly assigned by
Purchaser to Assignee, as of the date of Purchase, as described in Section 9.
Upon notice, in the form of Exhibit J, by Assignee to Custodian of Purchaser's
default, Assignee may (i) require Custodian to act with respect to the related
Submission Packages solely in the capacity of custodian for, and bailee of,
Assignee, but nevertheless subject to and in accordance with the terms of this
Agreement, (ii) require Custodian to hold such Submission Packages for the
exclusive use and benefit of Assignee, (iii) assume the rights of Purchaser
under this Agreement to furnish instructions to Custodian as to the disposition
of such Submission Packages and such rights shall be exercisable solely by
Assignee and (iv) take all such actions under the Electronic Tracking Agreement,
if any, which are necessary to effectuate any of the foregoing. Custodian shall
give Assignee written acknowledgment to the effect set forth in (i), (ii) and
(iii), by executing such notice and returning a copy thereof to Assignee. In the
event that, prior to receipt of such notice from Assignee, Custodian delivered
any Submission Package to Purchaser, Takeout Investor or Purchaser's designee,
Custodian shall so notify Assignee, and Custodian shall not be deemed to hold
such Submission Package for Assignee unless and until such Submission Package is
redelivered to Custodian. The failure of Custodian to give the written
acknowledgment referred to above shall not affect the validity of such
assignment, pledge or grant of a security interest.

                                      -11-
<PAGE>

The effects of Assignee's notice to Custodian set forth above shall continue
until Custodian is otherwise notified in writing by Assignee. The terms of this
Agreement shall not apply to any Submission Package physically delivered by
Custodian to Assignee.

            (c) The related Seller and Purchaser acknowledge that Warehouse
Lender, if any, identified from time to time in each Warehouse Lender's Release
to be received by Custodian pursuant to Section 2(c), is a warehouse lender for
such Seller. The related Seller and Purchaser acknowledge that, in accordance
with the terms of each Warehouse Lender's Release to be received by the
Custodian pursuant to Section 2(c), pursuant to which each such Warehouse Lender
conditionally releases its security interest in the Mortgage Loan referred to in
the related Warehouse Lender's Release, such release shall not be effective
until the Release Payment is received in accordance with the Warehouse Lender's
Wire Instructions. Until receipt of a Release Payment, the interest of the
related Warehouse Lender in a Mortgage Loan shall continue and remain in full
force and effect.

            (d) If any additional documents relating to the Submission Package
come into the Custodian's possession, the provisions of paragraphs (a), (b) and
(c) of this Section 3 shall apply to such additional documents in the same
manner as such provisions apply to related Submission Package.

            (e) Purchaser shall notify Custodian on each Business Day, in
writing of all Mortgage Loans purchased by Purchaser on such Business Day which
relate to this Agreement.

            (f) On or prior to 7:00 p.m. New York time, Custodian shall deliver
to Purchaser a Cumulative Position Report reflecting all Mortgage Loans held by
Custodian as of such time under this Agreement.

            Section 4. Certification by Custodian; Delivery of Documents. (a)
With respect to each Mortgage Loan that Purchaser desires to purchase, Purchaser
shall deliver to Custodian a Request for Certification. Upon receipt by
Custodian of a Request for Certification, Custodian shall perform the following
procedures with respect to each Mortgage Loan listed on such Request for
Certification:

            (i) Custodian shall ascertain whether it is in possession of a
      Submission Package for each Mortgage Loan identified on a Request for
      Certification. If Custodian is not in possession of a Submission Package
      relating to a Mortgage Loan identified on a Request for Certification,
      Custodian shall annotate its Certification Report in the appropriate space
      provided with a Mortgage Loan Absentee Code. If Custodian is in possession
      of Submission Packages delivered by the related Seller which do not relate
      to any of the Mortgage Loans listed on a Request for Certification,
      Custodian shall generate an Unidentified Mortgage Loans List and shall
      deliver such List promptly to Purchaser. Purchaser shall deliver a copy of
      such Unidentified Mortgage Loans List to such Seller. No action shall be
      taken by Custodian, other than in accordance with a notice in the form of
      Exhibit I-2 or Exhibit O, with respect to Mortgage Loans appearing on an
      Unidentified Mortgage Loans List until any such Mortgage Loans are
      included in a Request for Certification.

                                      -12-
<PAGE>

            (ii) With respect to each Request for Certification Custodian shall:

                  (A) verify the Loan Identification Data appearing in (1) the
            "LAST NAME" column by comparing such Loan Identification Data to the
            information in the Mortgage Note and Assignment of Mortgage, (2) the
            "NOTE DATE" (indicating any Mortgage Note with a date which is
            greater than 30 days prior with the appropriate exception code),
            "FACE AMOUNT", "# OF MONTHS TO MATURITY" and "NOTE RATE" columns by
            comparing such Loan Identification Data to the information in the
            Mortgage Note and (3) the "MERS IDENTIFICATION NUMBER" column by
            comparing such Loan Identification Data to the information in the
            Mortgage Note;

                  (B) if the Program Code indicates a Cash Window Transaction,
            verify the Loan Identification Data appearing in the "LOAN #" column
            by comparing the related information in any of the related
            Applicable Agency Documents;

                  (C) if the Program Code indicates a Cash Window Transaction,
            Conduit Transaction or Conversion Transaction, verify the Loan
            Identification Data appearing in the "TAKEOUT INVESTOR", "SALE
            PRICE", "COMMITMENT #", and "COMMITMENT EXPIRATION DATE" columns by
            comparing such Loan Identification Data to the information appearing
            in the Commitment; and

                  (D) if the Program Code indicates a Cash Window Transaction or
            a Conduit Transaction, verify the Loan Identification Data appearing
            in the "WAREHOUSE LENDER" column by comparing such Loan
            Identification Data to the information appearing in the Warehouse
            Lender's Release or such Seller's Release, as applicable.

After applying the applicable procedures set forth in clauses (A), (B) and (C)
above, any discrepancies between the Loan Identification Data and documents
comprising the Submission Package shall be noted by Custodian on the Exception
Report.

            (b) With respect to each Request for Certification, following
completion by Custodian of the procedures set forth in Section (4)(a).

            (i) Custodian shall review each applicable set of documents
      comprising the Submission Package and shall ascertain whether (A) each
      such document is in Custodian's possession, (B) each such document
      accurately conforms with the Loan Identification Data set forth in Section
      4(a)(ii), (C) each such document appears regular on its face, (D) each
      such document in the Submission Package appears on its face to conform to
      the requirements of Exhibit A, Exhibit B-l, Exhibit C-1 or Exhibit F, as
      applicable, (E) unless the Program Code indicates either a Dry Transaction
      or a Conversion Transaction, the Mortgage Loan is listed on a schedule
      attached to a Warehouse Lender's Release or a Seller's Release from the
      related Seller, as the case may be, (F) either (1) if the Release Payment
      is a dollar amount, the amount appearing in the "RELEASE PAYMENT" column
      on the Request for Certification is equal to or

                                      -13-
<PAGE>

      exceeds the Release Payment, or (2) if the Program Code indicates either a
      Dry Transaction or a Conversion Transaction, or if the Release Payment is
      a formula, as indicated in Exhibit G-1, the Custodian need not verify the
      amount, if any, appearing in the "RELEASE PAYMENT" column and (G) (1) with
      respect to the wire transfer instructions as set forth in Freddie Mac Form
      987 (Wire Transfer Authorization for a Cash Warehouse Delivery) such wire
      transfer instructions are identical to Purchaser's Wire Instructions to
      the related Seller or (2) the Payee Number set forth on Fannie Mae Form
      1068 (Fixed-Rate, Graduated-Payment, or Growing-Equity Mortgage Loan
      Schedule) or Fannie Mae Form 1069 (Adjustable-Rate Mortgage Loan
      Schedule), as applicable, is identical to the Payee Number that has been
      identified by Purchaser in the Request for Certification.

            (ii) If Custodian determines that the documents in the Submission
      Package and the Mortgage Loan to which they relate conform in all respects
      with Section 4(b)(i), Custodian shall so indicate in the space provided in
      its Certification Report with a Mortgage Loan Approval Code. If Custodian
      determines that the documents in a Submission Package and the Mortgage
      Loan to which they relate conform in all respects with Section 4(b)(i)
      except that the endorsement of the Mortgage Note is missing, Custodian
      may, but shall not be obligated to, prepare such endorsement pursuant to
      the Limited Power of Attorney. If documents in the Submission Package do
      not conform in all respects with Section 4(b)(i) or are missing and/or do
      not conform, Custodian shall indicate such on its Exception Report.

            (c) The Custodian shall have no obligation to provide a
Certification Report with respect to (i) any Submission Package received after
11:00 a.m. (New York City time) or (ii) any Submission Packages delivered in
excess of 100 Submission Packages without two (2) Business Days prior notice
from the related Seller(s) (in any event not to exceed 175 Submission Packages)
on any Expected Delivery Date. Provided that the Custodian has received the
Submission Packages in accordance with clauses (i) and (ii) above, the Custodian
shall prepare and deliver to Purchaser, by 3:00 p.m. (New York City time), the
Certification Report. All applicable documents comprising a Submission Package
relating to a Mortgage Loan with respect to which Custodian has assigned a
Mortgage Loan Approval Code shall be delivered by Custodian in such reasonable
order as Custodian may determine, via overnight courier in accordance with the
Delivery Instructions on the applicable Delivery Date and under cover of a fully
completed Bailee Letter prepared by Custodian. In those cases where a copy of
any intervening mortgage assignment, or an unrecorded original of any
intervening mortgage assignment are delivered to the Custodian, the related
Seller shall cause the original of such instrument to be recorded. If Delivery
Instructions direct Custodian to deliver a Submission Package to a location that
is not a Takeout Investor's office as listed on Schedule A, which may be amended
from time to time by Purchaser, Custodian must receive Purchaser's written
consent to make deliveries to such location prior to complying with such
Delivery Instructions. Upon receipt of one written approval from Purchaser, such
written approval shall, unless Custodian receives a notice from Purchaser to the
contrary, be deemed to apply to all Delivery Instructions delivered in the
future by the related Seller that list such location. With respect to a Dry
Transaction, Custodian must receive Purchaser's consent prior to making each and
every delivery of a Dry Submission Package in accordance with the Delivery
Instructions. Custodian shall deliver a Delivery Report to the related Seller
and, upon request, to Purchaser by facsimile

                                      -14-
<PAGE>

or electronic transmission. Following delivery by Custodian of the applicable
portion of a Submission Package to a Takeout Investor, and subsequent to
Purchaser's communication to Custodian that the Mortgage Loan has been purchased
by the Takeout Investor, all remaining documents comprising such Submission
Package shall be held by Custodian for 120 (one hundred twenty) calendar days
and then will be delivered by Custodian to the related Seller at such Seller's
expense.

            If, on any Business Day, Custodian assigns a Mortgage Loan
Suspension Code to any Submission Package, Custodian shall deliver to the
related Seller, by facsimile or electronic transmission, a report detailing each
such Suspension Package for which such Mortgage Loan Suspension Code was
assigned. All applicable documents comprising a Submission Package relating to a
Mortgage Loan with respect to which Custodian has assigned a Mortgage Loan
Suspension Code shall be held by Custodian until receipt from the related Seller
of instructions. On each Business Day during which a Mortgage Loan shall have a
Mortgage Loan Suspension Code assigned to it, such Seller shall instruct
Custodian as to the action, if any, Custodian should take with respect to such
Mortgage Loan.

            (d) As outlined in Section 2(d), Custodian shall deliver to
Purchaser or the Assignee, no later than 5:30 p.m. New York City time on the
related Purchase Date, by facsimile transmission followed by overnight courier
to Assignee, a Trust Receipt or Trust Receipts with respect to the Mortgage
Loans listed on the Mortgage Loan Schedule(s) attached thereto. The Trust
Receipt(s) will represent the Mortgage Loans for which the Custodian has issued
a Mortgage Loan Approval Code on any Business Day less any Mortgage Loans as to
which the Purchaser has notified Custodian that its interest has been released;
provided, however, that the aggregate original principal balance of the Mortgage
Loans listed on a Mortgage Loan Schedule shall not exceed an amount determined
by Purchaser and agreed to by Custodian, which agreement will not be
unreasonably withheld. Each Trust Receipt of a series, as identified by an
alphanumeric number thereon, that is delivered by Custodian to Purchaser shall,
upon such delivery, supercede and cancel any prior Trust Receipt of the same
series.

            (e) At any time following the delivery of a Trust Receipt, in the
event Custodian becomes aware of any defect with respect to such Submission
Package or the related forms, including the return of documents to the Custodian
from Takeout Investor due to a defect in such documents, the Custodian shall
give prompt oral notice of such defect to the Purchaser, followed by a written
specification thereof.

            Section 5. [Reserved].

            Section 6. Default. If the related Seller fails to fulfill any of
its obligations under the Purchase Agreement, the Electronic Tracking Agreement,
if any, or hereunder or in connection with the exercise by Purchaser of any
remedy pursuant to Section 3 of the Purchase Agreement then, subject to the
provisions of Section 3(c) hereof, Purchaser may, by notice to Custodian and
with its prior consent, (a) appoint Custodian as its delegee to complete the
endorsements on the Mortgage Notes held by Custodian and to complete and record
at Purchaser's expense the related blank Assignments of Mortgages relating to
the affected Mortgage Loan in accordance with Purchaser's instructions, when
applicable, (b) require Custodian to deliver to Purchaser, Takeout Investor or
Successor Servicer the Submission

                                      -15-
<PAGE>

Packages (or any portion thereof specified by Purchaser) in Custodian's
possession or under Custodian's control to which the failure relates, and (c)
take such actions under the Electronic Tracking Agreement, if any, on behalf of
the Purchaser as are necessary to effectuate the foregoing.

            Section 7. Access to Documents. Upon reasonable prior written notice
to Custodian, Purchaser (and if the Mortgage Loans have been assigned, Assignee)
and its agents, accountants, attorneys and auditors will be permitted during
normal business hours at the Custodian's offices to examine and copy at their
expense the Submission Packages, documents, records and other papers in
possession of or under the control of Custodian relating to any or all of the
Mortgage Loans in which Purchaser has an interest. Upon the request of Purchaser
(or, if applicable, Assignee) and at the cost and expense of Purchaser (or, if
applicable, Assignee), Custodian shall provide such Purchaser (or, if
applicable, Assignee) with copies of the Mortgage Notes, Assignments of Mortgage
and other documents in Custodian's possession relating to any of the Mortgage
Loans in which Purchaser (or, if applicable, Assignee) has an interest.

            Section 8. Custodian's Fees and Expenses; Successor Custodian;
Standard of Care. (a) It is understood that the Sellers will be charged for
Custodian's fees for its services and shall reimburse Custodian for any expense
it has incurred under this Agreement in such amounts and in the manner set forth
in a separate letter agreement among Sellers and Custodian. Notwithstanding the
foregoing, Custodian has no lien on, and shall not attempt to place a lien on,
any of the Mortgage Loans or proceeds thereof to secure the payment of its fees.
The obligations of each Seller under this Section 8(a) shall survive the
resignation or removal of the Custodian hereunder and the termination of this
Agreement.

            (b) Custodian may resign at any time and be discharged of the duties
and obligations created by this Agreement by giving not less than sixty (60)
days' written notice to Sellers and Purchaser.

            (c) Such resignation shall take effect upon the earlier of (i) the
appointment of a successor Custodian by Purchaser and delivery of all the
Submission Packages and any portion of the related documents in Custodian's
possession to the successor Custodian, and (ii) the delivery of all the
Submission Packages and any portion of the related documents in Custodian's
possession to the Purchaser or its designee pursuant to (c) below.

            (d) In the event of any such resignation, Custodian shall promptly
transfer to the successor Custodian all Submission Packages and related
documents in Custodian's possession and the successor Custodian shall hold
Submission Packages and related documents in accordance with this Agreement.
Purchaser shall be responsible for all expenses associated with the transfer of
the Submission Packages and any related documents in Custodian's possession and
for any fee of the successor Custodian in excess of the fees of the initial
Custodian hereunder. The Purchaser shall have 60 days in which to appoint and
designate an acceptable successor Custodian. If the Purchaser fails to appoint a
successor Custodian within such 60-day period, then Custodian shall deliver
possession and custody of the Submission Packages and any related Submission
Packages in Custodian's possession to Purchaser at the address specified on the
cover page hereof, or if a timely written designation is received by Custodian,
to any designee of Purchaser.

                                      -16-
<PAGE>

            (e) Custodian shall have responsibility only for the Submission
Packages and the contents thereof which have been actually delivered to it and
which have not been released to the related Seller, Purchaser, the Agency or
Assignee or their respective agent or designee in accordance with this
Agreement. The standard of care to be exercised by Custodian in the performance
of its duties under this Agreement shall be to exercise the same degree of care
as Custodian exercises when it holds mortgage loan documents as security for
similar mortgage warehouse loan customers. Custodian is an agent, bailee and
custodian only and is not intended to be, nor shall it be construed to be
(except only as agent, bailee and custodian), a representative, trustee or
fiduciary of or for the related Seller, the Agency, Purchaser or Assignee.

            (f) Custodian shall incur no liability to any Entity for Custodian's
acts or omissions hereunder, except for liabilities which (i) arise from
Custodian's gross negligence or willful misconduct or (ii) solely with respect
to the Purchaser, which arise from Custodian negligently or intentionally
failing to (A) issue an accurate Certification Report; provided, however, any
such liability shall not be incurred with respect to the issuance of an
inaccurate Certification Report if the defect causing such inaccuracy would not
have been ascertainable by the Custodian applying the procedures expressly set
forth in this Agreement, (B) timely deliver the Submission Package in accordance
with the Delivery Instructions or Purchaser's written instructions, as
applicable, (C) prevent the loss, damage or destruction of any document included
in a Submission Package when held by Custodian, (D) issue a Trust Receipt which
applies to a Mortgage Loan with respect to which the procedures set forth in
Section 4 hereof have not been completed by the Custodian in accordance with
this Agreement, (E) include a Bailee Letter, including Purchaser's Wire
Instructions, in the form of Exhibit I-1, in each Submission Package delivered
to a Takeout Investor or a Dry Transaction Takeout Investor, as applicable or
(F) include a Notice of Bailment, in the form of Schedule A to Exhibit B-4,
including Purchaser's Wire Instructions, in each Submission Package delivered to
Fannie Mae; provided, however, Custodian shall have no liability hereunder if
Custodian's failure to perform resulted from the inaction or action of any other
Entity, other than Entities that are affiliated with Custodian or are acting
under the direct control of Custodian. Custodian's liability under this
Agreement shall be limited to direct damages resulting from aforesaid. In
addition Custodian shall not be liable, directly or indirectly, for (1) any
losses, claims, damages, liabilities or expenses which would have been avoided
had any Entity making a claim taken reasonable action to mitigate such losses,
claims, damages, liabilities or expenses or (2) special, punitive or
consequential damages, even if Custodian has been advised of the possibility of
such damages; provided, however, that if Custodian's actions or inactions as set
forth above result in a decline in the market value of a Mortgage Loan thereby
causing direct damages to the Purchaser, such damages shall not be deemed
special or consequential damages.

            (g) Custodian may consult with counsel and shall be entitled to
conclusively rely upon the advice of its legal counsel from time to time and
shall not be liable for any action or inaction by it in reliance upon such
advice. Custodian also shall be entitled to conclusively rely upon any notice,
document, correspondence, request or directive received by it from any Seller,
Takeout Investor, Purchaser or Assignee, as the case may be, that Custodian
believes to be genuine and to have been signed or presented by the proper and
duly authorized officer or representative thereof, and shall not be obligated to
inquire as to the authority or power of any

                                      -17-
<PAGE>

person so executing or presenting such documents or as to the truthfulness or
correctness of any statements set forth therein.

            (h) Each Seller hereby jointly and severally indemnifies, defends
and holds Custodian and its officers, directors, employees, representatives and
agents harmless from and against any claim, legal action, liability, obligation,
damages, penalty, judgment, suit or loss that is initiated against or incurred
by Custodian, including court costs and reasonable attorneys' fees and
disbursements, in connection with Custodian's performance of its duties under
this Agreement, including those involving ordinary negligence, but excluding
those involving gross negligence or willful misconduct of Custodian; such
indemnification shall survive the resignation or removal of the Custodian
hereunder and the termination of this Agreement.

            (i) Custodian undertakes to perform such duties and only such duties
as are specifically set forth in this Agreement, it being expressly understood
that there are no implied duties or obligations hereunder.

            (j) Custodian shall not be required by any provision of this
Agreement to expend or risk its own funds in the performance of its duties under
this Agreement if it shall have reasonable grounds for believing that repayment
of such funds is not assured to it or indemnity satisfactory to it against such
risk or liability.

            (k) Custodian may rely on the validity of documents and, to the
extent permitted hereby, oral communications delivered to it, without
investigation as to their authenticity or legal effectiveness and Sellers and
Purchaser will jointly and severally hold the Custodian harmless from any claim
which may arise or be asserted against the Custodian because of the invalidity
of any such documents or oral communications or their failure to fulfill their
intended purpose.

            (l) If the Custodian shall have at any time received conflicting
instructions from the Purchaser or a Seller with respect to any of the
Custodian's Submission Packages, and the conflict between such instructions
cannot be resolved by reference to the terms of this Agreement, the Custodian
shall be entitled to rely exclusively on the instructions of the Purchaser.

            (m) If Custodian requests written instructions from any Seller or
Purchaser, as the case may be, with respect to any act, action or failure to act
in connection with this Agreement, Custodian shall be entitled to refrain from
taking such action unless and until Custodian receives written instructions from
such Seller or Purchaser, as the case may be.

            Section 9. Assignment by Purchaser. Purchaser hereby notifies
Custodian that Purchaser may assign, as of the date of the purchase of all of
its right, title and interest in and to all Mortgage Loans purchased by
Purchaser pursuant to the Purchase Agreement and all rights of Purchaser under
the Purchase Agreement, this Agreement and the Electronic Tracking Agreement, if
any, in respect of such Mortgage Loans represented thereby to Assignee, subject
only to an obligation on the part of Assignee to deliver each such Mortgage Loan
to Custodian or to Purchaser to permit Custodian, Purchaser or its designee to
make delivery thereof to Takeout Investor, but not otherwise. Each Seller hereby
irrevocably consents to such assignment.

                                      -18-
<PAGE>

Assignment by Purchaser of the Mortgage Loans as provided in this Section 9
shall not release Purchaser from its obligations otherwise under this Agreement.
Subject to any limitations in any agreement between Assignee and Purchaser,
Assignee may, upon notice of Purchaser's default as provided in Section 3(b)
hereof, directly enforce and exercise such rights under this Agreement that have
been assigned or pledged to it and, until otherwise notified by Assignee,
Purchaser shall no longer have any of such rights. Custodian shall assume that
any assignment from Purchaser to Assignee is subject to no limitations that are
not expressly set forth in this Agreement.

            Section 10. Insurance. Custodian shall, at its own expense, maintain
at all times during the existence of this Agreement such (a) fidelity insurance,
(b) theft of documents insurance, (c) forgery insurance and (d) errors and
omissions insurance as Custodian deems, from time to time appropriate.

            Section 11. Delivery of Submission Packages. Prior to any shipment
of a Mortgage Loan hereunder, Custodian shall have received from the related
Seller written instructions as to the method of shipment and shipper(s) the
Custodian is directed to utilize in connection with the delivery of Submission
Packages related to Mortgage Loans in the performance of the Custodian's duties
hereunder. The applicable Seller shall select shipper(s) from a list of
shippers, approved by both Custodian and Purchaser, provided by Purchaser to
such Seller. Furthermore, the related Seller shall provide Custodian Delivery
Instructions by 11:00 a.m. New York City time on the Delivery Date for same day
shipment together with an electronic transmission of such delivery instructions.
The applicable Seller will arrange for the provision of such services at its
sole cost and expense (or, at the Custodian's option, reimburse the Custodian
for all costs and expenses incurred by the Custodian consistent with such
instructions) and will maintain such insurance against loss or damage to
Submission Packages as the applicable Seller deems appropriate. It is expressly
agreed that in no event shall the Custodian have any liability for any losses or
damages to any person, including without limitation, the Sellers, arising out of
actions of the Custodian consistent with instructions of the Seller (including,
without limitation, losses or damages arising out of non-performance or faulty
performance by a shipper). Any delivery of Submission Packages under this
Agreement shall be by personal delivery, recognized courier delivery service, or
registered or certified first class mail, postage prepaid, return receipt
requested, as designated by the related Seller. In the event Custodian does not
receive such written instructions, Custodian shall be authorized to use any
nationally recognized courier service. In no event shall Custodian, without the
prior consent of Purchaser, permit delivery to be made to any Seller or an agent
of any Seller.

            Section 12. Representations, Warranties and Covenants. (a) By
Custodian. Custodian hereby represents and warrants to, and covenants with, each
Seller and Purchaser that, as of the date hereof and at all times while
Custodian is performing services under this Agreement:

            (i) Custodian is duly organized, validly existing and in good
      standing under the laws of the jurisdiction of its incorporation; and

            (ii) Custodian has the full power and authority to hold each
      Mortgage Loan and to execute, deliver and perform, and to enter into and
      perform its duties and

                                      -19-
<PAGE>

      obligations as contemplated by, this Agreement, has duly authorized the
      execution, delivery and performance of this Agreement and has duly
      executed and delivered this Agreement, and this Agreement constitutes a
      legal, valid and binding obligation of Custodian, enforceable against it
      in accordance with its terms, except as the enforcement thereof may be
      limited by applicable receivership, conservatorship or similar debtor
      relief laws and except that certain equitable remedies may not be
      available regardless of whether enforcement is sought in equity or law.

            (b) By Seller. Each Seller hereby represents and warrants to, and
covenants with, Custodian and Purchaser that, as of the date hereof and
throughout the term of this Agreement:

            (i) Seller is duly organized, validly existing and in good standing
      under the laws of the jurisdiction of its incorporation;

            (ii) Seller has the full power and authority to hold each of its
      Mortgage Loans and to execute, deliver and perform, and to enter into and
      consummate all transactions contemplated by, this Agreement, has duly
      authorized the execution, delivery and performance of this Agreement and
      has duly executed and delivered this Agreement, and this Agreement
      constitutes a legal, valid and binding obligation of Seller, enforceable
      against it in accordance with its terms, except as the enforcement thereof
      may be limited by applicable receivership, conservatorship or similar
      debtor relief laws and except that certain equitable remedies may not be
      available regardless of whether enforcement is sought in equity or law;
      and

            (iii) As of the date hereof, with respect to the Original Custodial
      Agreement, no default has occurred and is continuing and the Original
      American Home Parties are not in default with respect to any of such
      Original American Home Parties' obligations thereunder.

            (c) By Purchaser. Purchaser hereby represents and warrants to, and
covenants with, Custodian and the Sellers that, as of the date hereof and
throughout the term of this Agreement:

            (i) Purchaser is acquiring the Mortgage Loans for its own account
      only and not for any other person;

            (ii) Purchaser considers itself a substantial, sophisticated
      institutional investor having such knowledge and experience in financial
      and business matters that it is capable of evaluating the merits and risks
      of investment in the Mortgage Loans;

            (iii) Purchaser has been furnished with all information regarding
      the related Mortgage Loans that it has requested from the related Seller;

            (iv) Purchaser is duly organized, validly existing and in good
      standing under the laws of the jurisdiction of its incorporation; and

                                      -20-
<PAGE>

            (v) Purchaser has the full power and authority to hold each Mortgage
      Loan and to execute, deliver and perform, and to enter into and consummate
      all transactions contemplated by, this Agreement, has duly authorized the
      execution, delivery and performance of this Agreement and has duly
      executed and delivered this Agreement, and this Agreement constitutes a
      legal, valid and binding obligation of Purchaser, enforceable against it
      in accordance with its terms, except as the enforcement thereof may be
      limited by applicable receivership, conservatorship or similar debtor
      relief laws and except that certain equitable remedies may not be
      available regardless of whether enforcement is sought in equity or law.

            Section 13. No Adverse Interests. By its acceptance of each
Submission Package, Custodian covenants and warrants to Purchaser that: (a) as
of the date of payment by Purchaser of the Release Payment, Custodian, solely in
its capacity as Custodian, holds no adverse interests, by way of security or
otherwise, in the related Mortgage Loan and (b) Custodian hereby waives and
releases any such interest in such Mortgage Loan which it, acting solely in its
capacity as Custodian, has or which it may thereafter acquire prior to the time
of release of such Mortgage Loan from the terms of this Agreement.

            Section 14. Amendments. This Agreement may be amended from time to
time only by written agreement of each Seller, Purchaser and Custodian except
that, if this Agreement shall have been assigned by Purchaser, no amendment
shall be effective unless the amendment is also signed by Assignee. Purchaser
shall give at least five (5) days' prior written notice to Assignee of any
proposed amendment to this Agreement and shall furnish Assignee with a copy of
each such amendment within five days after it is executed and delivered.

            Section 15. Execution in Counterparts. This Agreement may be
executed in any number of counterparts, each of which shall be deemed an
original, but all of which shall constitute one and the same instrument.

            Section 16. Agreement for Exclusive Benefit of Parties; Assignment.
This Agreement is for the exclusive benefit of the parties hereto and their
respective successors and permitted assigns hereunder and shall not be deemed to
give any legal or equitable right, remedy or claim to any other person
whatsoever. This Agreement shall bind the parties hereto and their respective
successors, but, except for the assignments provided in Sections 3(b) and 9,
shall not be assigned or pledged by any party without the prior written consent
of the other parties. Written notice from Assignee to Custodian (with a copy to
Purchaser) that Purchaser has defaulted in any material respect under any
funding or loan agreement relating to the financing of Purchaser's purchase of
Mortgage Loans shall be conclusive for all purposes of this Agreement.

            Section 17. Effect of Invalidity of Provisions. In case any one or
more of the provisions contained in this Agreement should be or become invalid,
illegal or unenforceable in any respect, the validity, legality and
enforceability of the remaining provisions contained herein or therein shall in
no way be affected, prejudiced or disturbed thereby.

                                      -21-
<PAGE>

            Section 18. GOVERNING LAW.

            THIS AGREEMENT SHALL BE GOVERNED BY AND CONSTRUED IN ACCORDANCE WITH
THE LAWS OF THE STATE OF NEW YORK, WITHOUT REGARD TO CONFLICT OF LAWS RULES.

            Section 19. Consent to Service. Each party irrevocably consents to
the service of process by registered or certified mail, postage prepaid, to it
at its address given in or pursuant to Section 19. This Agreement is subject to,
and any dispute arising hereof will be determined by, a court of competent
jurisdiction in and under the laws of the State of New York. Each of the parties
hereto submit to the exclusive jurisdiction of the United States District Courts
for the Southern District of New York and of any court sitting in the Borough of
Manhattan, New York for the purposes of all legal proceedings arising out of or
relating to this Agreement or the transactions contemplated hereby.

            Section 20. Notices. Any notices, consents, directions and other
communications given under this Agreement shall be in writing and shall be
deemed to have been duly given when delivered by facsimile or electronic
transmission, or personally delivered at, or sent by overnight courier to the
addresses of the parties hereto set forth on the cover page hereof or such other
address as any party shall give in a notice to the other parties pursuant to
this Section 20.

            Section 21. Certification. Custodian hereby acknowledges that each
time it enters the Approval Code on a Request for Certification in the "Approval
Code" column, it is making an express representation and warranty to Purchaser
that it has performed the Certification as specified in Sections 4(a) and (b)
with respect to the related Mortgage Loan.

            Custodian makes no representations as to, and shall not be
responsible to verify: (i) the validity, legality, enforceability,
recordability, sufficiency, due authorization or genuineness of any documents
contained in each Submission Package identified on a Mortgage Loan Schedule, or
(ii) the collectability, insurability, effectiveness or suitability of any such
Mortgage Loan.

            Section 22. Authorized Representatives. Each individual designated
as an authorized representative of Purchaser or its successors or assigns, each
Seller and Custodian, respectively (an "Authorized Representative"), is
authorized to give and receive notices, requests and instructions and to deliver
certificates and documents in connection with this Agreement on behalf of
Purchaser, such Seller and Custodian, as the case may be, and the specimen
signature for each such Authorized Representative, initially authorized
hereunder, is set forth on Exhibits Q, R and S hereof, respectively. From time
to time, Purchaser, the Sellers and Custodian or their respective successors or
permitted assigns may, by delivering to the others a revised annex, change the
information previously given pursuant to this Section 22, but each of the
parties hereto shall be entitled to rely conclusively on the then current annex
until receipt of a superseding annex.

            Section 23. Construction. The headings in this Agreement are for
convenience only and are not intended to influence its construction. References
to Sections and Exhibits in

                                      -22-
<PAGE>

this Agreement are to the Sections of and Exhibits to this Agreement. The
Exhibits are part of this Agreement. In this Agreement, the singular includes
the plural, the plural the singular, and the words "and" and "or" are used in
the conjunctive or disjunctive as the sense and circumstances may require.

            Section 24. Effect of Amendment and Restatement. Upon the execution
of this Agreement and the Purchase Agreement by all parties hereto and thereto,
the Original Custodial Agreement shall be amended, restated and superseded in
its entirety by this Agreement. The parties hereto acknowledge and agree that
(a) the liens and security interests granted under the Original Custodial
Agreement are in full force and effect and, upon the amendment and restatement
of the Original Custodial Agreement and the related documents, such liens and
security interests secure and continue to secure the payment and performance of
Seller's obligations under this Agreement and the related documents, and (b)
upon the effectiveness of such amendment and restatement, all outstanding
Mortgage Loans under, and as defined in, the Original Custodial Agreement, shall
be deemed to be outstanding as Mortgage Loans hereunder mutatis mutandis, in
each case on the terms and conditions set forth in this Agreement.

                     [SIGNATURES COMMENCE ON FOLLOWING PAGE]

                                      -23-
<PAGE>

            IN WITNESS WHEREOF, the Sellers, Purchaser and Custodian have caused
this Agreement to be duly executed as of the date and year first above written.

                                       AMERICAN HOME MORTGAGE
                                         INVESTMENT CORP.

                                       By:  /s/ Michael Strauss
                                          --------------------------------------
                                          Name:   Michael Strauss
                                          Title:  President

                                       AMERICAN HOME MORTGAGE
                                         ACCEPTANCE, INC.

                                       By:  /s/ Michael Strauss
                                          --------------------------------------
                                          Name:   Michael Strauss
                                          Title:  President

                                       AMERICAN HOME MORTGAGE
                                         HOLDINGS, INC., as Seller

                                       By:  /s/ Michael Strauss
                                          --------------------------------------
                                          Name:   Michael Strauss
                                          Title:  President

                                       AMERICAN HOME MORTGAGE CORP., as
                                         Seller

                                       By:  /s/ Michael Strauss
                                          --------------------------------------
                                          Name:   Michael Strauss
                                          Title:  President
<PAGE>

                                       COLUMBIA NATIONAL, INCORPORATED,
                                          as Seller

                                       By:  /s/ Michael Strauss
                                          --------------------------------------
                                          Name:   Michael Strauss
                                          Title:  President

                                       UBS REAL ESTATE SECURITIES INC., as
                                          Purchaser

                                       By:  /s/ George A. Mangiaracina
                                          --------------------------------------
                                          Name:   George A. Mangiaracina
                                          Title:  Managing Director

                                       By:  /s/ Robert Carpenter
                                          --------------------------------------
                                          Name:   Robert Carpenter
                                          Title:  Director

<PAGE>

                                       DEUTSCHE BANK NATIONAL TRUST COMPANY,
                                          as Custodian

                                       By:  /s/ Andrew Hays
                                          --------------------------------------
                                          Name:   Andrew Hays
                                          Title:  Associate

                                       By:  /s/ Jerome W. Harney
                                          --------------------------------------
                                          Name:  Jerome W. Harney
                                          Title:  Vice PresidentExhibit 10.6

           AMENDED AND RESTATED MORTGAGE LOAN PARTICIPATION AGREEMENT

PARTICIPANT:       UBS REAL ESTATE SECURITIES INC.

ADDRESS:           1285 AVENUE OF THE AMERICAS
                   NEW YORK, NEW YORK 10019
                   ATTENTION: GEORGE A. MANGIARACINA
                   ATTENTION: ROBERT CARPENTER

SELLER:            AMERICAN HOME MORTGAGE INVESTMENT CORP.

ADDRESS:           520 BROADHOLLOW ROAD
                   MELVILLE, NEW YORK 11747
                   ATTENTION:  STEPHEN A. HOZIE, CHIEF FINANCIAL OFFICER

SELLER:            AMERICAN HOME MORTGAGE ACCEPTANCE, INC.

ADDRESS:           520 BROADHOLLOW ROAD
                   MELVILLE, NEW YORK 11747
                   ATTENTION:  STEPHEN A. HOZIE, CHIEF FINANCIAL OFFICER

SELLER:            AMERICAN HOME MORTGAGE HOLDINGS, INC.

ADDRESS:           520 BROADHOLLOW ROAD
                   MELVILLE, NEW YORK 11747
                   ATTENTION:  STEPHEN A. HOZIE, CHIEF FINANCIAL OFFICER

SELLER:            AMERICAN HOME MORTGAGE CORP.

ADDRESS:           520 BROADHOLLOW ROAD
                   MELVILLE, NEW YORK 11747
                   ATTENTION:  MICHAEL STRAUSS, PRESIDENT

<PAGE>

SELLER:            COLUMBIA NATIONAL, INCORPORATED

ADDRESS:           520 BROADHOLLOW ROAD
                   MELVILLE, NEW YORK 11747
                   ATTENTION:  MICHAEL STRAUSS, PRESIDENT
                   ATTENTION: STEPHEN A. HOZIE, CHIEF FINANCIAL OFFICER

DATE OF AGREEMENT: FEBRUARY 6, 2004

                                      -ii-
<PAGE>

                                TABLE OF CONTENTS

                                                                            Page
                                                                            ----

Section 1.  Definitions ...................................................    2

Section 2.  Procedures for Purchases of Participation Certificates ........    9

Section 3.  Issuance of Securities ........................................   10

Section 4.  Servicing of the Mortgage Loans ...............................   13

Section 5.  Takeout Commitments ...........................................   14

Section 6.  Transfers of Participation Certificates and Securities by
            Participant ...................................................   15

Section 7.  Record Title to Mortgage Loans; Intent of Parties; Security
            Interest ......................................................   15

Section 8.  Representations and Warranties ................................   16

Section 9.  Covenants of Sellers ..........................................   21

Section 10. Confidentiality ...............................................   25

Section 11. Term ..........................................................   25

Section 12. Exclusive Benefit of Parties; Assignment ......................   26

Section 13. Amendments; Waivers; Cumulative Rights ........................   26

Section 14. Execution in Counterparts .....................................   26

Section 15. Effect of Invalidity of Provisions ............................   26

Section 16. Governing Law .................................................   26

Section 17. Notices .......................................................   26

Section 18. Entire Agreement ..............................................   26

Section 19. Costs of Enforcement ..........................................   26

Section 20. Consent to Service ............................................   27

Section 21. Submission to Jurisdiction; Waivers ...........................   27

Section 22. Construction ..................................................   28

Section 23. Effect of Amendment and Restatement ...........................   28

                                      -i-
<PAGE>

Exhibit A   Participation Certificate

Exhibit B   Trade Assignment

Exhibit C   Document List

Exhibit D   Warehouse Lender's Release

Exhibit E   Assignment

Exhibit F   Authorized Signatories

Exhibit G   Form of Opinion

Exhibit H   UCC-1 Financing Statement

Annex A     Sellers' Delivery Instructions

                                      -ii-
<PAGE>

           AMENDED AND RESTATED MORTGAGE LOAN PARTICIPATION AGREEMENT

            Amended and Restated Mortgage Loan Participation Agreement
("Agreement"), dated as of the date set forth on the cover page hereof, among
UBS Real Estate Securities Inc. ("Participant") and each of the Sellers whose
names are set forth on the cover page hereof (each a "Seller" and, collectively,
the "Sellers").

                                    RECITALS

            WHEREAS, the Participant and American Home Mortgage Holdings, Inc.,
American Home Mortgage Corp. and Columbia National, Incorporated (in such
capacity, the "Original American Home Parties") are parties to the Mortgage Loan
Participation Agreement, dated as of July 25, 2003 as amended, supplemented or
otherwise modified prior to the date hereof (the "Original Participation
Agreement");

            WHEREAS, pursuant to the Original Participation Agreement, one or
more of the Original American Home Parties may have, in its sole discretion,
offered to sell to Participant from time to time Participation Certificates (as
defined therein), and Participant, in its sole discretion, may have agreed to
purchase such Participation Certificates from such Seller in accordance with the
terms and conditions set forth in the Original Participation Agreement;

            WHEREAS, the Original American Home Parties and the Participant
desire to amend and restate the Original Participation Agreement as provided
herein; and

            NOW, THEREFORE, for good and valuable consideration, the receipt and
adequacy of which are hereby acknowledged, the parties hereto hereby agree that
the Original Participation Agreement be amended and restated in its entirety as
follows:

                              PRELIMINARY STATEMENT

            Sellers desire to sell to Participant from time to time
Participation Certificates evidencing a 100% undivided ownership interest in
certain Mortgage Loans eligible in the aggregate to back Securities with the
terms described in related Takeout Commitments.

            Participant desires and may in its sole discretion purchase such
Participation Certificates from Sellers in accordance with the terms and
conditions set forth in this Agreement. Sellers, subject to the terms hereof,
will cause (a) Mortgage Loans evidenced by a Participation Certificate to back a
GNMA Security issued by Sellers and guaranteed by GNMA, a FNMA Security issued
and guaranteed by FNMA or a FHLMC Security issued and guaranteed by FHLMC and
(b) Delivery of such GNMA Security, FNMA Security or FHLMC Security by GNMA,
FNMA or FHLMC to Participant or its designee, which GNMA Security, FNMA Security
or FHLMC Security will be purchased by a Takeout Investor.

            Participant's willingness to purchase any Participation Certificate
evidencing particular Mortgage Loans is based on Participant's expectation, in
reliance upon Sellers' representations and warranties herein, that such Mortgage
Loans in the aggregate, constitute a pool or pools of mortgage loans that are
eligible to back a Security and that the Security, in the

<PAGE>

amount and with the terms described in the related Takeout Commitment, will be
issued and Participant will receive Delivery thereof within the time period
agreed upon among Participant and Sellers and reflected in the terms of such
Participation Certificate.

            The amount of the Purchase Price and the Performance Fee to be paid
by Participant to Sellers with respect to each Participation Certificate will be
calculated on the expectation of Participant, based upon the representations and
warranties of the Sellers herein, that Participant will receive Delivery of the
Security to be backed by the Mortgage Loans evidenced by the Participation
Certificate purchased by Participant on the specified Anticipated Delivery Date
and that failure to receive such Delivery will result in a material decrease in
the market value of the Participation Certificate and the underlying Mortgage
Loans considered as a whole. During the period from the purchase of a
Participation Certificate to Delivery of the related Security, Participant
expects to rely entirely upon such Sellers to service the Mortgage Loans
evidenced by the applicable Participation Certificate, it being acknowledged
that the continued effectiveness of such Seller's Agency Approvals during such
period constitutes an essential factor in the calculation by Participant of the
Purchase Price and the Performance Fee paid to such Sellers for the related
Participation Certificate and that loss of such Agency Approvals by such Sellers
would result in a material decrease in the market value of the Participation
Certificate and the underlying Mortgage Loans considered as a whole.

            The parties hereto hereby agree as follows:

            Section 1. Definitions.

            Capitalized terms used but not defined herein shall have the
meanings set forth in the Custodial Agreement. As used in this Agreement, the
following terms shall have the following meanings:

            "Accepted Servicing Practices": With respect to each Mortgage Loan,
such standards which comply with the applicable standards and requirements
under: (i) an applicable Agency Program and related provisions of the applicable
Agency Guide pursuant to which the related Mortgage Loan is intended to be
purchased, and/or (ii) any applicable FHA and/or VA program and related
provisions of applicable FHA and/or VA servicing guidelines.

            "Act of Insolvency": With respect to the related Seller, (a) the
commencement by such Seller as debtor of any case or proceeding under any
bankruptcy, insolvency, reorganization, liquidation, dissolution or similar law,
or such Seller's seeking the appointment of a receiver, trustee, custodian or
similar official for such Seller or any substantial part of its property, or (b)
the commencement of any such case or proceeding against such Seller, or
another's seeking such appointment, or the filing against such Seller of an
application for a protective decree which (1) is consented to or not timely
contested by such Seller, (2) results in the entry of an order for relief, such
an appointment, the issuance of such a protective decree or the entry of an
order having a similar effect, or (3) is not dismissed within sixty (60) days,
(c) the making by such Seller of a general assignment for the benefit of
creditors, or (d) the admission in writing by such Seller that such Seller is
unable to pay its debts as they become due or the nonpayment generally by such
Seller of its debts as they become due.

                                      -2-
<PAGE>

            "Agency": The Government National Mortgage Association ("GNMA"), the
Federal National Mortgage Association ("FNMA"), and the Federal Home Loan
Mortgage Corporation ("FHLMC"), as applicable.

            "Agency Approvals": As defined in Section 8(a)(viii) of this
Agreement.

            "Agency Guide": The GNMA Mortgage-Backed Securities Guide; the
Fannie Mae Selling Guide and the Fannie Mae Servicing Guide; the Freddie Mac
Sellers' and Servicers' Guide; as applicable, in each case as such Agency Guide
may be amended from time to time.

            "Agency Program": The specific purchase program under the relevant
Agency Guide or as otherwise approved by the Agency.

            "Anticipated Delivery Date": With respect to a Security, the date
specified in the related Form HUD 11705 (Schedule of Subscribers), Fannie Mae
Form 2014 (Delivery Schedule), or FHLMC Form 939 (Settlement and Information
Multiple Registration Form), as applicable, on which it is anticipated that
Delivery of the Security by the Applicable Agency will be made.

            "Applicable Agency" As defined in Section 3(a)(l).

            "Assignee": As defined in Section 6.

            "Assignment of Mortgage": As defined in Section 6.

            "Authorized Signatory": An officer of the related Seller who is
authorized and empowered to cause Participation Certificates evidencing Mortgage
Loans to back a Security issued by such Seller and guaranteed by an Agency, and
is indicated on the Authorized Signatories of such Seller attached hereto as
Exhibit F.

            "Code": The Internal Revenue Code of 1986, as amended from time to
time.

            "Collateral": As defined in Section 7(c).

            "Custodial Account": As defined in Section 4(b)(i).

            "Custodial Agreement": The Custodial Agreement, dated as of the date
set forth on the cover sheet thereof, among Sellers, Participant and Custodian.

            "Custodian": The Custodian (which, under the appropriate
circumstance, may include FHLMC as Custodian) set forth on the cover page hereof
and its permitted successors under the Custodial Agreement.

            "Defective Mortgage Loan": With respect to a Participation
Certificate, a mortgage loan that is not in Strict Compliance with the GNMA
Program, FNMA Program or FHLMC Program, as applicable.

                                      -3-
<PAGE>

            "Delivery": The later to occur of (a) the issuance of the related
Security and (b) the transfer of all of the right, title and ownership interest
in that Security to Participant.

            "Discount": With respect to each Participation Certificate, the
amount of the adjustment to the Trade Price of the related Security agreed upon
by the related Sellers and Participant to reserve for the possibility that such
Sellers may be unable to perform their obligations under this Agreement in
accordance with their terms.

            "Electronic Agent": MERSCORP, Inc., and its successors in interest.

            "Electronic Tracking Agreement": The Electronic Tracking Agreement,
dated as of the date hereof, among Participant, Sellers, MERSCORP, Inc. and
Mortgage Electronic Registration Systems, Inc.; provided that if no Mortgage
Loans are or will be MERS Designated Mortgage Loans, all references herein to
the Electronic Tracking Agreement shall be disregarded.

            "FDIC": Federal Deposit Insurance Corporation or any successor
thereto.

            "FHA": The Federal Housing Administration or any successor thereto.

            "FHLMC": Federal Home Loan Mortgage Corporation or any successor
thereto.

            "FHLMC as Custodian": With respect to FHLMC Participation
Certificates, the circumstances in which the related Seller elects to appoint
FHLMC (as opposed to some other third party as permitted by the FHLMC Guide) as
Custodian for the FHLMC Mortgage Loans subject to the FHLMC Participation
Certificates to be purchased by Participant hereunder.

            "FHLMC Guide": The Freddie Mac Sellers' and Servicers' Guide, as
such Guide may hereafter from time to time be amended.

            "FHLMC Mortgage Loan": With respect to any FHLMC Participation
Certificate or any FHLMC Security, a mortgage loan that is in Strict Compliance
with the eligibility requirements specified for the applicable FHLMC Program
described in the FHLMC Guide.

            "FHLMC Participation Certificate": With respect to the FHLMC
Program, a certificate, in the form of Exhibit A, issued by the related Seller
and authenticated by Custodian, evidencing the 100% undivided ownership interest
in the Mortgage Loans that are either (a) set forth on a copy of the FHLMC Form
11 (Mortgage Submission Schedule) attached to such Participation Certificate or
(b) identified on a computer tape compatible with MIDANET as belonging to the
mortgage loan pool described in such Participation Certificate.

            "FHLMC Program": The FHLMC Home Mortgage Guarantor Program or the
FHLMC FHA/VA Home Mortgage Guarantor Program, as described in the FHLMC Guide.

            "FHLMC Security": A modified pass-through mortgage-backed
participation certificate, evidenced by a book-entry credit made by a Securities
Intermediary that is a participant of the Federal Reserve Bank of New York,
issued and guaranteed, with respect to timely payment of interest and ultimate
payment of principal, by FHLMC and backed by a pool

                                      -4-
<PAGE>

of FHLMC Mortgage Loans, in substantially the principal amount and with
substantially the other terms as specified with respect to such FHLMC Security
in the related Takeout Commitment, if any.

            "FNMA" or "Fannie Mae": Federal National Mortgage Association or any
successor thereto.

            "FNMA as Custodian": With respect to FNMA Participation
Certificates, the circumstances in which the related Seller elects to appoint
FNMA (as opposed to some other third party as permitted by the FNMA Guide) as
Custodian for the FNMA Mortgage Loans subject to the FNMA Participation
Certificates to be purchased by Participant hereunder.

            "FNMA Guide": The Fannie Mae MBS Selling and Servicing Guide, as
such Guide may hereafter from time to time be amended.

            "FNMA Mortgage Loan": With respect to any FNMA Participation
Certificate or any FNMA Security, a mortgage loan that is in Strict Compliance
with the eligibility requirements specified for the applicable FNMA Program
described in the FNMA Guide.

            "FNMA Participation Certificate": With respect to the FNMA Program,
a certificate, in the form of Exhibit A, authenticated by Custodian, evidencing
the 100% undivided ownership interest in the Mortgage Loans set forth on Fannie
Mae Form 2005 (Schedule of Mortgages).

            "FNMA Program": The FNMA Guaranteed Mortgage-Backed Securities
Programs, as described in the FNMA Guide.

            "FNMA Security": An ownership interest in a pool of FNMA Mortgage
Loans, evidenced by a book-entry credit made by a Securities Intermediary that
is a participant of the Federal Reserve Bank of New York, in substantially the
principal amount and with substantially the other terms as specified with
respect to such FNMA Security in the related Takeout Commitment, if any.

            "GNMA": Government National Mortgage Association or any successor
thereto.

            "GNMA Guide": The GNMA Mortgage-Backed Securities Guide I or II, as
such Guide may hereafter from time to time be amended.

            "GNMA Mortgage Loan": With respect to any GNMA Participation
Certificate or any GNMA Security, a mortgage loan that is in Strict Compliance
with the eligibility requirements specified for the applicable GNMA Program in
the applicable GNMA Guide.

            "GNMA Participation Certificate": With respect to the GNMA Program,
a certificate, in the form of Exhibit A, issued by the related Seller and
authenticated by Custodian, evidencing the 100% undivided ownership interest in
the Mortgage Loans set forth on the Form HUD 11706 (Schedule of Pooled
Mortgages).

                                      -5-
<PAGE>

            "GNMA Program": The GNMA Mortgage-Backed Securities Programs, as
described in a GNMA Guide.

            "GNMA Security": A fully-modified pass-through mortgage-backed
certificate guaranteed by GNMA, evidenced by a book-entry credit made by a
Securities Intermediary that is a participant of The Depository Trust Company
and backed by a pool of GNMA Mortgage Loans, in substantially the principal
amount and with substantially the other terms as specified with respect to such
GNMA Security in the related Takeout Commitment, if any.

            "HUD": The United States Department of Housing and Urban Development
or any successor thereto.

            "Interim Funder": With respect to each MERS Designated Mortgage
Loan, the Person named on the MERS(R) System as the interim funder pursuant to
the MERS Procedures Manual.

            "Investor": With respect to each MERS Designated Mortgage Loan, the
Person named on the MERS(R) System as the investor pursuant to the MERS
Procedures Manual.

            "Issuance Date": With respect to a Security, the first day of the
month in which the Security is issued.

            "Losses": Any and all losses, claims, damages, liabilities or
expenses (including reasonable attorneys' fees) incurred by any person
specified; provided, however, that "Losses" shall not include any losses,
claims, damages, liabilities or expenses which would have been avoided had such
person taken reasonable actions to mitigate such losses, claims, damages,
liabilities or expenses.

            "MERS Designated Mortgage Loan": Mortgage Loans for which (a) the
related Seller has designated or will designate MERS as, and has taken or will
take such action as is necessary to cause MERS to be, the mortgagee of record,
as nominee for such Seller, in accordance with MERS Procedure Manual and (b)
such Seller has designated or will designate the Participant as the Investor and
Interim Funder on the MERS(R) System.

            "MERS Procedure Manual": The MERS Procedures Manual attached as
Exhibit B to the Electronic Tracking Agreement, as it may be amended,
supplemented or otherwise modified from time to time.

            "MERS Report": The schedule listing MERS Designated Mortgage Loans
and other information prepared by the Electronic Agent pursuant to the
Electronic Tracking Agreement.

            "MERS(R) System": The Electronic Agent's mortgage electronic
registry system, as more particularly described in the MERS Procedures Manual.

            "MIDANET": The FHLMC automated system by which sellers and servicers
of mortgage loans to FHLMC transfer mortgage summary and record data or mortgage
accounting

                                      -6-
<PAGE>

and servicing information from their computer system or service bureau to FHLMC,
as more fully described in the FHLMC Guide.

            "Mortgage": A mortgage, deed of trust or other security instrument,
securing a Mortgage Note.

            "Mortgage Loan": A GNMA Mortgage Loan, a FNMA Mortgage Loan or a
FHLMC Mortgage Loan.

            "Mortgage Note": A promissory note evidencing a Mortgage Loan.

            "Original American Home Parties": Shall have the meaning assigned to
such term in the recitals hereof.

            "Original Participation Agreement": Shall have the meaning assigned
to such term in the recitals hereof.

            "OTS": Office of Thrift Supervision or any successor thereto.

            "Parent Company": A corporation or other entity owning, directly or
indirectly, more than 50% of the outstanding shares of voting stock of American
Home Mortgage Investment Corp., American Home Mortgage Acceptance, Inc.,
American Home Mortgage Holdings, Inc., American Home Mortgage Corp. and/or
Columbia National, Incorporated.

            "Participant": UBS Real Estate Securities Inc. and its successors in
interest, including, but not limited to, any lender, designee or assignee to
whom a Participation Certificate or a Security shall be pledged or assigned.

            "Participation Certificate": A GNMA Participation Certificate, a
FNMA Participation Certificate or a FHLMC Participation Certificate.

            "Pass-Through Rate": With respect to a Participation Certificate,
the rate of interest specified as the Pass-Through Rate in such Participation
Certificate, which rate shall continue in effect until the latest of (a) the
Settlement Date of the related Security, (b) either the date on which Receipt of
the Security occurs or, if such Receipt occurs on such date after 12:00 noon,
New York City time the next Business Day on which Participant is permitted under
applicable laws and regulations to make delivery of the Security to the Takeout
Investor and, if applicable, (c) the date on which the related Seller completes
its Performance of its obligations under Section 3(c)(2).

            "Performance Fee": With respect to each Participation Certificate,
an amount equal to the Discount plus the Yield Compensation Adjustment, less any
reduction pursuant to Section 3(b), which amount shall be payable to the related
Seller by Participant as compensation to such Seller for its services in
connection with the issuance of a Security.

            "Purchase Date": With respect to a Participation Certificate, the
date on which Participant elects to purchase such Participation Certificate.

                                      -7-
<PAGE>

            "Purchase Price": With respect to each Participation Certificate,
the Trade Price of the Security to be backed by the Mortgage Loans evidenced by
the Participation Certificate, less the Discount. Accrued interest shall be
allocated in accordance with Section 3(a)(3).

            "Receipt": The Delivery of a Security, upon notice by the related
Seller to Participant, not later than 12:00 noon, New York City time, on the
second (2nd) Business Day prior to the applicable Settlement Date, of (a) the
amount of any change in the principal amount of the Mortgage Loans backing such
Security, and (b) with respect to FHLMC Securities, the FHLMC Mortgage Loan pool
number applicable to such Security. If the related Seller fails to so notify
Participant, "Receipt" shall be deemed to have occurred on the later of (1) the
second (2nd) Business Day after the date on which such Seller provides such
notification to Participant and (2) the date on which Participant receives
Delivery of the Security.

            "REIT Seller": As the case may be, American Home Mortgage Investment
Corp. and American Home Mortgage Acceptance, Inc.

             "REIT Status": With respect to any Person, such Person's status as
a real estate investment trust, as defined in Section 856(a) of the Code, that
satisfies the conditions and limitations set forth in Section 856(b) and 856(c)
of the Code.

            "RTC": Resolution Trust Corporation or any successor thereto.

            "Securities Intermediary": As defined in Section 8-102(a)(14) of the
Uniform Commercial Code.

            "Security": A GNMA Security, a FNMA Security or a FHLMC Security.

            "Servicing Rights": Any and all of the following: (a) any and all
rights to service the Mortgage Loans; (b) any payments to or monies received by
the related Sellers or any other Person for servicing the Mortgage Loans; (c)
any late fees, penalties or similar payments with respect to the Mortgage Loans;
(d) all agreements or documents creating, defining or evidencing any such
servicing rights to the extent they relate to such servicing rights and all
rights of such Sellers or any other Person thereunder; (e) escrow payments or
other similar payments with respect to the Mortgage Loans and any amounts
actually collected by such Sellers or any other Person with respect thereto; and
(f) all accounts and other rights to payment related to the Mortgage Loans.

            "Settlement Date": The date specified in a Takeout Commitment upon
which the related Security is scheduled to be delivered, against payment, to the
specified Takeout Investor.

            "Strict Compliance" shall mean compliance of the related Sellers and
the Mortgage Loans with the requirements of the GNMA Guide, FNMA Guide or FHLMC
Guide, as applicable and as amended by any agreements between such Seller and
the Applicable Agency, sufficient to enable such Sellers to issue and GNMA to
guarantee or FNMA or FHLMC to issue and guarantee a Security, provided that
until copies of any such agreements between such Seller and the Applicable
Agency have been provided to Participant by such Sellers, such agreements shall
be deemed, as between such Seller and Participant, not to amend the requirements
of the GNMA Guide, FNMA Guide or FHLMC Guide, as applicable.

                                      -8-
<PAGE>

            "Successor Servicer": An entity with the necessary Agency Approvals,
as the circumstances may require, and designated by Participant, in conformity
with Section 3(c)(2), to replace the related Seller as issuer and servicer,
mortgagee or seller/servicer of the Mortgage Loans or the Securities related
thereto.

            "Takeout Commitment": A trade confirmation from the Takeout Investor
to the related Seller confirming the details of a forward trade between the
Takeout Investor and such Seller with respect to one or more Securities, which
trade confirmation shall be enforceable and in full force and effect, and shall
be validly and effectively assigned to Participant pursuant to a Trade
Assignment, and relate to pools of Mortgage Loans that satisfy the "good
delivery standards" of the Public Securities Association as set forth in the
Public Securities Association Uniform Practices Guide.

            "Takeout Investor": A securities dealer or other financial
institution, acceptable to Participant, who has made a Takeout Commitment.

            "Trade Assignment": A letter substantially in the form of Exhibit B.

            "Trade Price": The price specified in a Takeout Commitment at which
a Takeout Investor is obligated to purchase the Security specified in such
Takeout Commitment.

            "VA": The United States Veterans Administration or any successor
thereto.

            "Warehouse Lender": Any lender providing financing to the related
Sellers for the purpose of originating Mortgage Loans, which has a security
interest in such Mortgage Loans as collateral for the obligations of such
Sellers to such lender.

            "Wire Instructions": The wire instructions set forth opposite the
name of the Warehouse Lender in a letter, in the form of Exhibit E to the
Custodial Agreement, executed by the related Seller and Custodian, receipt of
which has been acknowledged by Participant.

            "Yield Compensation Adjustment": Subject to any further adjustment
provided in this Agreement, an amount (which may be a negative number) equal to:

                                    A(BC-DE)
                                       360

where (i) A equals the number of days in the period beginning on the date
Participant purchases such Participation Certificate to but not including the
Settlement Date, (ii) B equals the aggregate principal amount of the Mortgage
Loans evidenced by a Participation Certificate, (iii) C equals the interest rate
(expressed as a decimal) on the Security backed by the Mortgage Loans subject to
such Participation Certificate, (iv) D equals the Purchase Price and (v) E
equals the Pass-Through Rate (expressed as a decimal) specified in such
Participation Certificate.

            Section 2. Procedures for Purchases of Participation Certificates.

            (a) Participant may, in its sole discretion from time to time,
purchase one or more Participation Certificates from the related Seller. Such
Seller, on behalf of Participant, shall

                                      -9-
<PAGE>

arrange for the Delivery to Participant of a Security backed by the Mortgage
Loans evidenced by any Participation Certificate so purchased, which Security
shall be subject to a Takeout Commitment. Participant's obligation to purchase
any Participation Certificate which Participant elects to purchase, shall be
subject to the receipt by the Participant of the documents listed in Exhibit C
from such Seller, in form and substance satisfactory to Participant, and the
execution of the Custodial Agreement relating to the Participation Certificate
by such Seller and Custodian and delivery thereof to Participant.
Notwithstanding the satisfaction of the conditions specified in this Section
2(a), Participant is not obligated to purchase any Participation Certificate
offered to it hereunder.

            (b) If Participant elects to purchase any Participation Certificate,
Participant shall pay to the related Seller, on the Purchase Date, the amount of
the Purchase Price for such Participation Certificate. In the event that
Participant does not transmit the Purchase Price, (i) any Participation
Certificate delivered by Custodian to Participant in anticipation of such
purchase shall automatically be null and void, (ii) Participant will not
consummate the transactions contemplated in the applicable Trade Assignment and
(iii) to the extent that Participant shall nevertheless receive the Security
backed by the Mortgage Loans to which such Participation Certificate relates
prior to its becoming null and void as provided in clause (i) above, Participant
shall take all reasonable actions necessary to ensure that such Security shall
be delivered in accordance with such Seller's delivery instructions specified in
Annex A.

            (c) The terms and conditions of the purchase of each Participation
Certificate shall be as set forth in this Agreement. Each Participation
Certificate shall be deemed to incorporate, and the related Seller shall be
deemed to make as of the applicable dates specified in Section 8, for the
benefit of Participant and each Assignee of such Participation Certificate, the
representations and warranties set forth in Section 8 in respect of such
Participation Certificate and the Mortgage Loans evidenced by such Participation
Certificate.

            Section 3. Issuance of Securities.

            (a) (1) With respect to Mortgage Loans evidenced by a Participation
Certificate which Participant has elected to purchase, the related Seller shall
instruct (and, if such Seller fails to instruct, then Participant may instruct)
Custodian to deliver to GNMA, FNMA or FHLMC, as applicable (the "Applicable
Agency"), the documents listed in Exhibits C-l, C-2 or C-3 of the Custodial
Agreement in respect of such Mortgage Loans, in the manner and at the time set
forth in the Custodial Agreement. Such Seller shall thereafter promptly deliver
to the Applicable Agency any and all additional documents requested by the
Applicable Agency to enable the Applicable Agency to make Delivery to
Participant of a Security backed by such Mortgage Loans on the related
Anticipated Delivery Date. Such Seller shall not revoke such instructions to
Custodian and shall not revoke its instructions to the Applicable Agency to make
Delivery to Participant or its designee of a Security backed by such Mortgage
Loans.

            (2) The related Seller shall notify Participant, not later than
12:00 noon, New York City time, on the second (2nd) Business Day prior to the
applicable Settlement Date, (i) of the amount of any change in the principal
amount of the Mortgage Loans backing each such Security related to such
Settlement Date and (ii) with respect to FHLMC Securities, the FHLMC mortgage
loan pool number applicable to each Security to which such Settlement Date
relates.

                                      -10-
<PAGE>

Upon Delivery of such Security to Participant or its designee, Participant shall
cease to have any interest under such Participation Certificate in the Mortgage
Loans backing such Security, notwithstanding anything to the contrary in the
Participation Certificate.

            (3) With respect to each Participation Certificate that Participant
elects to purchase hereunder, Participant shall owe to the related Seller, on
the later to occur of four (4) Business Days after the Purchase Date or on the
date of Receipt by Participant of the related Security, a Performance Fee. If a
Participation Certificate is purchased by Participant after the first (1st) day
of the month in which the Settlement Date occurs, Participant shall also pay to
such Seller on the date of Receipt by Participant of the Security backed by the
related Mortgage Loans an amount equal to the accrued interest on the related
Security at the rate specified in the related Takeout Commitment from the first
day of such month to and including the day immediately preceding the date
Participant purchased such Participation Certificate. If a Participation
Certificate is purchased by Participant in the month prior to the month in which
the Settlement Date occurs, the related Seller, as servicer, shall pay to
Participant all interest payments which accrue on such Participation Certificate
during the period from the date of purchase of such Participation Certificate
through and including the last day of the month prior to the month in which such
Settlement Date occurs. Notwithstanding the foregoing, no amounts shall be owed
by Participant to such Seller upon issuance of such Security in the
circumstances contemplated in Section 3(c)(2). Except as otherwise provided in
this Section 3(a)(3) and in Section 3(b), and subject to Participant's right of
set-off set forth in Section 3(g), any Performance Fee owed by Participant with
respect to a Participation Certificate shall be paid by Participant to the
related Seller not later than the Settlement Date of the related Security. It is
understood by the related Seller and Participant that, if such Seller requests
and Participant agrees to pay the Performance Fee prior to the Settlement Date
of the related Security, the amount of such Performance Fee shall be adjusted as
mutually agreed by such Seller and Participant.

            (b) Unless Receipt of a Security backed by the Mortgage Loans
evidenced by a Participation Certificate purchased hereunder has occurred by
12:00 noon, New York City time, on the related Settlement Date, (1) the
Performance Fee relating to such Participation Certificate shall be reduced
daily for the period from the Settlement Date to but not including the earlier
of the date of Receipt of such Security and the date of satisfaction of the
obligations of the related Seller pursuant to the exercise by Participant of any
remedial election authorized by this Section 3 by an amount equal to (A) the
Purchase Price of such Participation Certificate multiplied by (B) the result
obtained by dividing (i) the Pass-Through Rate for such Participation
Certificate plus one percent (1%) by (ii) three hundred and sixty (360) and (2)
the Performance Fee, if any, relating to such Participation Certificate shall
not be payable until the end of the period specified in clause (1) of this
paragraph.

            (c) (1) If a breach by any Seller of this Agreement results in any
Mortgage Loan being a Defective Mortgage Loan at the time of the delivery of the
related Participation Certificate to Participant, Participant in its sole
discretion may require that such Seller, upon receipt of notice from Participant
of its exercise of such right, either (i) immediately repurchase Participant's
ownership interest in such Defective Mortgage Loan by remitting to Participant
the allocable amount paid by Participant for such Defective Mortgage Loan plus
interest at the Pass-Through Rate on the principal amount thereof from the date
of Participant's purchase of such Participation Certificate to the date of such
repurchase, or (ii) deliver to Custodian a Mortgage

                                      -11-
<PAGE>

Loan eligible to back such Security in exchange for such Defective Mortgage
Loan, which newly delivered Mortgage Loan shall be in all respects acceptable to
Participant in Participant's sole discretion, and such newly delivered Mortgage
Loan will thereupon become one of the Mortgage Loans evidenced by the
Participation Certificate. If the aggregate principal balance of any Mortgage
Loans that are accepted by Participant pursuant to clause (ii) of the
immediately preceding sentence is less than the aggregate principal balance of
any Defective Mortgage Loan that is being replaced by such Mortgage Loan, the
related Seller shall remit with such Mortgage Loan to Participant an amount
equal to the difference between the aggregate principal balance of the new
Mortgage Loan accepted by Participant and the aggregate principal balance of the
Defective Mortgage Loan being replaced thereby.

            (2) If the related Seller fails to comply with its obligations in
the manner described in Section 3(c)(1), or such Seller is in breach of Section
8(a)(viii) or 8(b)(vii), not later than the third (3rd) calendar day after
receipt by such Seller of notice from Participant (or if such day is not a
Business Day, the next Business Day thereafter), such Seller's rights and
obligations to service the Mortgage Loans evidenced by such Participation
Certificate, as provided in this Agreement, shall terminate. If an Act of
Insolvency occurs at any time, such Seller's rights and obligations to service
the Mortgage Loans, as provided in this Agreement, shall terminate immediately,
without any notice or action by Participant. Upon any such termination,
Participant is hereby authorized and empowered as the exclusive agent for the
related Seller to sell and transfer such rights to service the Mortgage Loans
for such price and on such terms and conditions as Participant shall reasonably
determine. Such Seller shall not otherwise attempt to sell or transfer such
rights to service without the prior consent of Participant. Such Seller shall
perform all acts and take all action so that the Mortgage Loans and all files
and documents relating to such Mortgage Loans held by such Seller, together with
all escrow amounts relating to such Mortgage Loans, are delivered to Successor
Servicer. To the extent that the approval of the Applicable Agency is required
for any such sale or transfer, the related Seller shall fully cooperate with
Participant to obtain such approval. Upon exercise by Participant of its
remedies under this Section 3(c)(2), such Seller hereby authorizes Participant
to receive all amounts paid by any purchaser of such rights to service the
Mortgage Loans and to remit such amounts to such Seller subject to Participant's
rights of set-off under this Agreement. Upon exercise by Participant of its
remedies under this Section 3(c)(2), Participant's obligation to pay and the
related Seller's right to receive any portion of the Performance Fee relating to
such Mortgage Loans shall automatically be canceled and become null and void,
provided that such cancellation shall in no way relieve such Seller or otherwise
affect the obligation of such Seller to indemnify and hold Participant harmless
as specified in Section 3(e).

            (d) Mortgage Loans required to be delivered to Successor Servicer by
Section 3(c)(2) shall be delivered free of any servicing rights in favor of the
related Seller and free of any title, interest, lien, encumbrance or claim of
any kind of such Seller. The related Seller shall deliver or cause to be
delivered all files and documents relating to such Mortgage Loans held by such
Seller to Successor Servicer. The related Seller shall promptly take such
actions and furnish to Participant such documents that Participant deems
necessary or appropriate to enable Participant to obtain a Security backed by
such Mortgage Loans or to enforce such Mortgage Loans, as appropriate.

                                      -12-
<PAGE>

            (e) The related Seller agrees to indemnify and hold Participant and
its assigns harmless from and against all Losses (including, without limitation,
Losses incurred by Participant on account of fees paid by Participant to the
Applicable Agency to cause the Securities to be issued or any Losses in
connection with any indemnification by Participant of the Applicable Agency)
resulting from or relating to any breach or failure to perform by such Seller of
any representation, warranty. covenant, term or condition made or to be
performed by Seller under this Agreement.

            (f) No exercise by Participant of its rights under this Section 3
shall relieve any Seller of responsibility or liability for any breach of this
Agreement.

            (g) The related Seller hereby grants Participant a right of set-off
against the payment of any amounts that may be due and payable to Participant
from such Seller, such right to be upon any and all monies or other property of
such Seller held or received by Participant or due and owing from Participant to
such Seller.

            Section 4. Servicing of the Mortgage Loans.

            (a) It is expressly acknowledged that the Servicing Rights relating
to the Mortgage Loans evidenced by each Participation Certificate purchased by
Participant hereunder have been sold, assigned, and transferred by the related
Seller to Participant along with the ownership interest in such Mortgage Loans
as evidenced by a Participation Certificate. The related Seller shall service
and administer the Mortgage Loans evidenced by a Participation Certificate on
behalf of Participant on an interim basis in accordance with accepted and
prudent mortgage loan servicing standards and procedures generally accepted in
the mortgage banking industry for the same type of mortgage loans as the
Mortgage Loans and in a manner at least equal in quality to the servicing such
Seller provides for mortgage loans which it owns and in accordance with the
requirements of the GNMA Program, FNMA Program or FHLMC Program, as the case may
be, provided that the related Seller shall at all times comply with applicable
law, FHA regulations and VA regulations and the requirements of any private
mortgage insurer so that the FHA insurance, VA guarantee or any other applicable
insurance or guarantee in respect of any Mortgage Loan is not voided or reduced.
The related Seller shall at all times maintain accurate and complete records of
its servicing of the Mortgage Loans, and Participant may, at any time during
such Seller's business hours on reasonable notice, examine and make copies of
such records. On the second (2nd) day of each calendar month, or at any other
time upon Participant's request, the related Seller shall deliver to Participant
reports regarding the status of each Mortgage Loan in accordance with Section
9(g) and Section 9(h), which shall include, but shall not be limited to, a
description of those Mortgage Loans in default for more than thirty (30) days,
and any circumstances that could materially adversely affect any of such
Mortgage Loans, Participant's ownership of any of such Mortgage Loans or the
collateral securing any of such Mortgage Loans. The related Seller shall deliver
such a report to Participant every thirty (30) days until (i) Delivery of the
related Security to Participant or (ii) the exercise by Participant of any
remedial election pursuant to Section 3. The related Seller agrees and
acknowledges that Participant may, at any time, terminate the servicing of the
Mortgage Loans by such Seller and transfer servicing to another Person on such
date as Participant may determine in its sole discretion. In the event that
anything in this Agreement is interpreted as constituting one or more interim
servicing contracts, each such servicing contract shall terminate automatically
upon the

                                      -13-
<PAGE>

earlier of (i) Delivery of the related Security to Participant or (ii)
Participant's notice to the related Seller directing such Seller to transfer
servicing (provided, such Seller's obligations as set forth herein to cooperate
in the transfer of such servicing shall not terminate until such servicing has
actually been transferred in full).

            (b) Within two (2) Business Days of notice from Participant or with
respect to each Participation Certificate, on the Settlement Date:

            (i) The Sellers shall establish and maintain a separate custodial
      account (the "Custodial Account") entitled "[Name of Seller(s)], in trust
      for UBS Real Estate Securities Inc. and its assignees under the "Mortgage
      Loan Participation Agreement dated [the date of this Agreement]" and shall
      promptly deposit into such Custodial Account, in the form received with
      any necessary endorsements, all collections received in respect of each
      Mortgage Loan evidenced by a Participation Certificate that are payable to
      Participant as the owner of such Participation Certificate; and

            (ii) at the Participant's sole option, upon written notice from the
      Participant, the related Seller shall transfer servicing of the Mortgage
      Loans to a Successor Servicer designated by the Participant.

            (c) Amounts deposited in the Custodial Account with respect to any
Mortgage Loan shall be held in trust for Participant as the owner of the
Mortgage Loans and shall be released only as follows:

            (i) Except as otherwise provided in Section 4(c)(ii), upon Delivery
      of the Security backed by such Mortgage Loans to Participant and either
      (i) receipt by Participant or its designee of the purchase price for the
      Security from the Takeout Investor or (ii) if earlier, on the date
      required by the GNMA Guide, FNMA Guide or FHLMC Guide, as the case may be,
      amounts deposited in the Custodial Account shall be released in accordance
      with Section 3(a)(3). Notwithstanding the foregoing, all amounts deposited
      in the Custodial Account shall be paid to related Seller upon the Delivery
      of the related Security to Participant if, and to the extent that, the
      amounts due and payable to Participant hereunder have been set-off against
      the Purchase Price for the related Participation Certificate or the
      Performance Fee relating to the Mortgage Loans underlying such
      Participation Certificate. The amounts paid to the related Seller (if any)
      pursuant to this Section 4(c)(i) shall constitute such Seller's sole
      compensation for servicing the Mortgage Loans as provided in this Section
      4.

            (ii) If a Successor Servicer takes delivery of such Mortgage Loans
      either under the circumstances set forth in clause (b)(ii) above, or
      otherwise, all amounts deposited in the Custodial Account shall be paid to
      Participant promptly upon such delivery.

            (iii) During the period that any Seller acts as servicer, all
      amounts deposited in the Custodial Account shall be released only in
      accordance with Participant's written instructions.

            Section 5. Takeout Commitments. Each Seller hereby assigns to
Participant, free of any security interest, lien, claim or encumbrance of any
kind, each Sellers' rights under each

                                      -14-
<PAGE>

Takeout Commitment to deliver the Security specified therein to the related
Takeout Investor and to receive the purchase price therefor from such Takeout
Investor. Subject to Participant's rights under Section 3, Participant agrees
that it will satisfy the Takeout Commitment on the Settlement Date specified
therein. Each Seller understands that, as a result of this Section 5 and each
Trade Assignment, Participant will succeed to the rights and obligations of such
Seller with respect to each Takeout Commitment subject to a Trade Assignment,
and that in satisfying each such Takeout Commitment, Participant will stand in
the shoes of such Seller and, consequently, will be acting as a non-dealer in
exercising its rights and fulfilling its obligations assigned pursuant to this
Section 5 and each Trade Assignment. Each Trade Assignment delivered by any
Seller to Participant pursuant to Section 2 shall be delivered by the related
Seller in a timely manner sufficient to enable Participant to facilitate the
settlement of the related trade on the trade date in accordance with Chapter 8
of the Bond Market Association's Uniform Practices for the Clearance and
Settlement of Mortgage-Backed Securities and other Related Securities, as
amended from time to time.

            Section 6. Transfers of Participation Certificates and Securities by
Participant. Participant may, in its sole discretion and without the consent of
the related Seller, assign all of its right, title and interest or grant a
security interest in any Participation Certificate, any Mortgage Note, Mortgage
and any assignment of Mortgages (an "Assignment of Mortgage"), each Security in
respect thereof of which Delivery is made to Participant and all rights of
Participant under this Agreement (including, but not limited to, the Custodial
Account) in respect of such Participation Certificate, Mortgage Note, Mortgage,
Assignment of Mortgage and such Security, to any person (an "Assignee"), subject
only to an obligation on the part of the Assignee to deliver each such Security
to a Takeout Investor pursuant to Section 5 or to Participant to permit
Participant or its designee to make delivery thereof to a Takeout Investor
pursuant to Section 5. Assignment by Participant of a Participation Certificate
as provided in this Section 6 will not release Participant from its obligations
otherwise under this Agreement.

            Without limitation of the foregoing, an assignment of the
Participation Certificate to an Assignee, as described in this Section 6, shall
be effective upon delivery of the Participation Certificate to the Assignee or
its designee, together with a duly executed Assignment in the Form of Exhibit E.

            Section 7. Record Title to Mortgage Loans; Intent of Parties;
Security Interest.

            (a) From and after the issuance and delivery of the related
Participation Certificate, and subject to the remedies of Participant in Section
3, Seller shall remain the last named payee or endorsee of each Mortgage Note
and the mortgagee or assignee of record of each Mortgage (except with respect to
a MERS Designated Mortgage Loan) in trust for the benefit of Participant, for
the sole purpose of facilitating the servicing of such Mortgage Loan and the
issuance of a Security backed by such Mortgage Loan. Where Seller has appointed
FHLMC or FNMA, as applicable, as Custodian, the parties hereto acknowledge that
the Mortgage Notes acquired hereunder have been deposited with FHLMC or FNMA, as
applicable, to facilitate the issuance of FHLMC Securities or FNMA Securities,
as applicable, with respect thereto and that prior to such issuance FHLMC or
FNMA, as applicable, is holding such Mortgage Notes as Custodian for
Participant.

                                      -15-
<PAGE>

            (b) The related Seller shall maintain a complete set of books and
records for each Mortgage Loan which shall be clearly marked to reflect the
ownership interest in each Mortgage Loan of the holder of the related
Participation Certificate and with respect to each MERS Designated Mortgage
Loan, such Seller shall designate the Participant as the Investor and Interim
Funder on the MERS(R) System.

            (c) Participant and Sellers confirm that the transactions
contemplated herein are intended to be sales of the Mortgage Loans by Sellers to
Participant rather than borrowings secured by the Mortgage Loans. In the event,
for any reason, any transaction is construed by any court or regulatory
authority as a borrowing rather than as a sale, the Sellers and Participant
intend that Participant or its Assignee, as the case may be, shall have a
perfected first priority security interest in the Participation Certificates,
any Custodial Accounts, the Mortgage Loans subject to each Participation
Certificate (including all servicing rights related thereto), all documents
evidencing the Mortgage Loans, the Securities to be issued as contemplated
hereunder and all proceeds thereof, the Takeout Commitments and the proceeds of
any and all of the foregoing (collectively, the "Collateral"), free and clear of
adverse claims. In such case, Sellers shall be deemed to have hereby granted to
Participant or its Assignee, as the case may be, a first priority security
interest in and lien upon the Collateral, free and clear of adverse claims. In
such event, this Agreement shall constitute a security agreement, the Custodian
shall be deemed to be an independent custodian for purposes of perfection of the
security interest granted to Participant, and Participant or each such Assignee
shall have all of the rights of a secured party under applicable law.

            Section 8. Representations and Warranties.

            (a) Each Seller hereby represents and warrants to Participant as of
the date hereof and as of the date of each issuance and delivery of a
Participation Certificate that:

            (i) All representations and warranties made and all information
      (including, without limitation, any financial information concerning any
      Seller) and documents or copies of documents furnished by Sellers to
      Participant pursuant to or in connection with this Agreement are and will
      be true and correct at the time when made and at all times thereafter or,
      if limited to a specific date, as of the date to which they refer;

            (ii) Such Seller is duly organized, validly existing and in good
      standing under the laws of the state of its organization or of the United
      States of America and has all licenses necessary to carry on its business
      as now being conducted and is licensed, qualified and in good standing to
      do business in each jurisdiction in which it is legally required to do so.
      Such Seller has all requisite power and authority (including, if
      applicable, corporate power) to execute and deliver this Agreement, the
      Electronic Tracking Agreement and the Custodial Agreement and to perform
      in accordance herewith and therewith; the execution, delivery and
      performance of this Agreement, the Electronic Tracking Agreement and the
      Custodial Agreement (including all instruments of transfer to be delivered
      pursuant to this Agreement, the Electronic Tracking Agreement and the
      Custodial Agreement) by such Seller and the consummation of the
      transactions contemplated hereby and thereby have been duly and validly
      authorized. Each of this Agreement, the Electronic Tracking Agreement and
      the Custodial Agreement evidences

                                      -16-
<PAGE>

      the valid, binding and enforceable obligation of such Seller and all
      requisite action (including, if applicable, corporate action) has been
      taken by such Seller to make this Agreement, the Electronic Tracking
      Agreement and the Custodial Agreement valid and binding upon such Seller
      in accordance with its terms;

            (iii) This Agreement, the Custodial Agreement, the Electronic
      Tracking Agreement and every document to be executed by such Seller
      pursuant hereto and thereto is and will be valid, binding and a subsisting
      obligation of such Seller, enforceable in accordance with its respective
      terms. No consents or approvals are required to be obtained by any Seller
      or its Parent Company for the execution, delivery and performance of this
      Agreement, the Electronic Tracking Agreement or the Custodial Agreement by
      Seller;

            (iv) The consummation of the transactions contemplated by this
      Agreement, the Electronic Tracking Agreement and the Custodial Agreement
      are in the ordinary course of business of such Seller and will not result
      in the breach of any provision of the charter or by-laws of such Seller or
      result in the breach of any provision of, or conflict with or constitute a
      default under or result in the acceleration of any obligation under, any
      agreement, indenture, loan or credit agreement or other instrument to
      which any Seller, the Mortgage Loans or any of Sellers' property is
      subject, or result in the violation of any law, rule, regulation, order,
      judgment or decree to which any Seller, the Mortgage Loans or Sellers'
      property is subject. Without limiting the generality of the foregoing, the
      consummation of the transactions contemplated herein or therein will not
      violate any policy, regulation or guideline of the FHA or VA or result in
      the voiding or reduction of the FHA insurance, VA guarantee or any other
      insurance or guarantee in respect of any Mortgage Loan, and such insurance
      or guarantee is in full force and effect or shall be in full force and
      effect as required by the applicable GNMA Guide, FNMA Guide or FHLMC
      Guide;

            (v) Such Seller has not sold, assigned, transferred, pledged or
      hypothecated any interest in any Participation Certificate to any person
      other than Participant, and upon delivery of a Participation Certificate
      to Participant, Participant will be the sole owner thereof, free and clear
      of any lien, claim or encumbrance;

            (vi) All information relating to such Seller that such Seller has
      delivered or caused to be delivered to Participant, including, but not
      limited to, all documents related to this Agreement, the Electronic
      Tracking Agreement, the Custodial Agreement or such Seller's financial
      statements, and all such information hereafter furnished by such Seller,
      does not and will not contain any untrue statement of a material fact or
      omit to state a material fact necessary to make the statements made
      therein or herein in light of the circumstances under which they were
      made, not misleading. Such Seller has disclosed in writing any and all
      facts relating to such Seller that materially and adversely affect or may
      affect the business operations or financial condition of such Seller or
      the ability of such Seller to perform its obligations under this
      Agreement, the Electronic Tracking Agreement or the Custodial Agreement;

                                      -17-
<PAGE>

            (vii) There are no actions, suits or proceedings pending, or to the
      knowledge of any Seller threatened, including any claims for which an
      action, suit or proceeding has not been commenced, against or affecting
      such Seller or any of its assets in any court or before any arbitrator or
      before any governmental commission, board, bureau or other administrative
      agency that, in any such case, if adversely determined, would have a
      material adverse effect on the financial condition or business of such
      Seller or the ability of such Seller to perform under this Agreement, the
      Electronic Tracking Agreement and the Custodial Agreement;

            (viii) If applicable with respect to each Mortgage Loan evidenced by
      a Participation Certificate sold hereunder, such Seller (and each
      servicer) is approved by GNMA as an approved issuer, Fannie Mae as an
      approved lender, Freddie Mac as an approved seller/servicer (as the case
      may be) and by FHA as an approved mortgagee and by VA as an approved VA
      lender, in each case in good standing (such collective approvals and
      conditions, "Agency Approvals"), with no event having occurred or such
      Seller (or any subservicer) having any reason whatsoever to believe or
      suspect will occur prior to the Delivery of the Security by the related
      Agency, including without limitation a change in insurance coverage which
      would either make such Seller (or any servicer) unable to comply with the
      eligibility requirements for maintaining all such Agency Approvals or
      require notification to the relevant Agency or to HUD, FHA or VA. Should
      such Seller (or any servicer), for any reason, cease to possess all such
      Agency Approvals, or should notification to the relevant Agency or to HUD,
      FHA or VA be required, such Seller shall so notify Participant immediately
      in writing. Notwithstanding the preceding sentence, such Seller shall take
      all necessary action to maintain all of its (and each servicer's) Agency
      Approvals at all times during the term of this Agreement. The related
      Seller (and any servicer) has adequate financial standing, servicing
      facilities, procedures and experienced personnel necessary for the sound
      servicing of mortgage loans of the same types as may from time to time
      constitute Mortgage Loans and in accordance with Accepted Servicing
      Practices;

            (ix) The Custodian is an eligible custodian under the Agency Guide
      and Agency Program;

            (x) Such Seller and their Subsidiaries have filed all Federal income
      tax returns and all other material tax returns that are required to be
      filed by them and have paid all taxes due pursuant to such returns or
      pursuant to any assessment received by it or any of its Subsidiaries,
      except for any such taxes as are being appropriately contested in good
      faith by appropriate proceedings diligently conducted and with respect to
      which adequate reserves have been provided. The charges, accruals and
      reserves on the books of such Seller and their Subsidiaries in respect of
      taxes and other governmental charges are, in the opinion of each Seller,
      adequate;

            (xi) Neither such Seller nor any of its Subsidiaries are an
      "investment company", or a company "controlled" by an "investment
      company", within the meaning of the Investment Company Act of 1940, as
      amended;

                                      -18-
<PAGE>

            (xii) Upon the filing of financing statements on Form UCC-1 naming
      Participant as "Secured Party", each Seller as "Debtor" and describing the
      Collateral, in the jurisdiction and recording office listed on Exhibit H
      attached hereto, the security interest granted hereunder in the Collateral
      will constitute a fully perfected security interest under the Uniform
      Commercial Code in all right, title and interest of Seller in, to and
      under such Collateral, which can be perfected by filing under the Uniform
      Commercial Code; and

            (xiii) As of the date hereof, each Seller's chief executive office
      is 520 Broadhollow Road, Melville, New York 11747. As of the date hereof,
      and during the four months immediately preceding the date hereof, hereof,
      Seller's jurisdiction of organization is as follows: American Home
      Mortgage Investment Corp., Maryland, American Home Mortgage Acceptance,
      Inc., Maryland, American Home Mortgage Holdings, Inc., Delaware, American
      Home Mortgage Corp., New York, and/or Columbia National, Incorporated,
      Maryland.

            (xiv) Such Seller's exact legal name is, and for the immediately
      preceding four months has been, as set forth on the signature page hereto.

            (xv) Such Seller has used any trade name or assumed name.

            (xvi) No Seller has merged with, or acquired all or substantially
      all of the assets of, any other person or entity within the immediately
      preceding year (except for (a) American Home Mortgage Investment Corp.'s
      acquisition of Apex Mortgage Capital, Inc. and (b) American Home Mortgage
      Holdings, Inc. merger with AHM Merger Sub, Inc.).

            (b) Each Seller hereby represents and warrants to Participant with
respect to each Mortgage Loan as of the date of the payment by Participant of
the Purchase Price of the related Participation Certificate that:

            (i) Such Mortgage Loan was, immediately prior to the sale to
      Participant of the related Participation Certificate, owned solely by the
      related Seller, is not subject to any lien, claim or encumbrance,
      including, without limitation, any such interest pursuant to a loan or
      credit agreement for warehousing mortgage loans, and was originated and
      serviced in accordance with all applicable law and regulations, including
      without limitation the Federal Truth-in-Lending Act, the Real Estate
      Settlement Procedures Act, regulations issued pursuant to any of the
      aforesaid, and any and all rules, requirements, guidelines and
      announcements of the Applicable Agency, and, as applicable, the FHA and
      VA, as the same may be amended from time to time;

            (ii) The improvements on the land securing such Mortgage Loan are
      and will be kept insured at all times by responsible insurance companies
      reasonably acceptable to Participant against fire and extended coverage
      hazards under policies, binders or certificates of insurance with a
      standard mortgagee clause in favor of such Seller and its assigns,
      providing that such policy may not be canceled without prior notice to
      such Seller. Any proceeds of such insurance shall be held in trust for the
      benefit of

                                      -19-
<PAGE>

      Participant. The scope and amount of such insurance shall satisfy the
      rules, requirements, guidelines and announcements of the Applicable
      Agency, and shall in all cases be at least equal to the lesser of (A)
      principal amount of such Mortgage Loan or (B) the maximum amount permitted
      by applicable law, and shall not be subject to reduction below such amount
      through the operation of a coinsurance, reduced rate contribution or
      similar clause;

            (iii) Each Mortgage is a valid first lien on the mortgaged property
      and covered by an attorney's opinion of title acceptable to GNMA, FNMA or
      FHLMC, as applicable, or by a policy of title insurance on a standard ALTA
      or similar lender's form in favor of the related Seller and its assigns,
      subject only to exceptions permitted by the GNMA, FNMA or FHLMC Program,
      as applicable. Such Seller shall hold in trust for Participant such policy
      of title insurance, and, upon request of Participant, shall immediately
      deliver such policy to Participant or to the Custodian on behalf of
      Participant;

            (iv) To the extent applicable, such Mortgage Loan is either insured
      by the FHA under the National Housing Act, guaranteed by the VA under the
      Servicemen's Readjustment Act of 1944 or is otherwise insured or
      guaranteed in accordance with the requirements of the GNMA, FNMA or FHLMC
      Program, as applicable, and is not subject to any defect that would
      prevent recovery in full or in part against the FHA, VA or other insurer
      or guarantor, as the case may be;

            (v) Such Mortgage Loan is in Strict Compliance with the requirements
      and specifications (including, without limitation, all representations and
      warranties required in respect thereof) set forth in the GNMA Guide, FNMA
      Guide or FHLMC Guide, as applicable;

            (vi) Such Mortgage Loan conforms in all respects with all
      requirements of the Takeout Commitment applicable to the Security to be
      backed by such Mortgage Loan; and

            (vii) To the extent applicable, each Mortgage Loan is being serviced
      by a mortgage sub-servicer having all Agency Approvals necessary to make
      such Mortgage Loan eligible to back a GNMA, FNMA or FHLMC Security, as
      applicable.

            (c) Each of American Home Mortgage Investment Corp. and American
Home Mortgage Acceptance, Inc. hereby represents, warrants and covenants to
Participant that it is a REIT Seller and it has not engaged in any material
"prohibited transactions" as defined in Section 857(b)(6)(B)(iii) and (C) of the
Code. Each REIT Seller for its current "tax year" (as defined in the Code) is
entitled to a dividends paid deduction under the requirements of Section 857 of
the Code with respect to any dividends paid by it with respect to each such year
for which it claims a deduction in its Form 1120-REIT filed with the United
States Internal Revenue Service for such year.

            The representations and warranties of such Seller in this Section 8
are unaffected by and supersede any provision in any endorsement of any Mortgage
Loan or in any assignment

                                      -20-
<PAGE>

with respect to such Mortgage Loan to the effect that such endorsement or
assignment is without recourse or without representation or warranty.

            Section 9. Covenants of Sellers. Each Seller hereby covenants and
agrees with Participant as follows:

            (a) Such Seller shall deliver to Participant:

            (i) Within one hundred twenty (120) days after the end of each
      fiscal year of each Seller, consolidated balance sheets of each Seller and
      its consolidated subsidiaries and the related consolidated statements of
      income showing the financial condition of each Seller and its consolidated
      subsidiaries as of the close of such fiscal year and the results of
      operations during such year, and a consolidated statement of cash flows,
      as of the close of such fiscal year, setting forth, in each case, in
      comparative form the corresponding figures for the preceding year, all the
      foregoing consolidated financial statements to be reported on by, and to
      carry the report (acceptable in form and content to Participant) of an
      independent public accountant of national standing acceptable to
      Participant;

            (ii) Within sixty (60) days after the end of each of the first three
      (3) fiscal quarters of each fiscal year of each Seller, unaudited
      consolidated balance sheets and consolidated statements of income, all to
      be in a form acceptable to Participant, showing the financial condition
      and results of operations of each Seller and its consolidated subsidiaries
      on a consolidated basis as of the end of each such quarter and for the
      then elapsed portion of the fiscal year, setting forth, in each case, in
      comparative form the corresponding figures for the corresponding periods
      of the preceding fiscal year, certified by a financial officer of each
      Seller (acceptable to Participant) as presenting fairly the financial
      position and results of operations of each Seller and its consolidated
      subsidiaries and as having been prepared in accordance with generally
      accepted accounting principles consistently applied, in each case, subject
      to normal year-end audit adjustments;

            (iii) Within forty-five (45) days after the end of each of the first
      eleven months of each fiscal year of each Seller, unaudited consolidated
      balance sheets and consolidated statements of income, all to be in a form
      acceptable to Participant, showing the financial condition and results of
      operation of each Seller and its consolidated subsidiaries on a
      consolidated basis as of the end of each such month and for the then
      elapsed portion of the fiscal year, setting forth, in each case, in
      comparative form the corresponding figures for the corresponding periods
      of the preceding fiscal year, certified by a financial officer of each
      Seller (acceptable to Participant) as presenting fairly the financial
      position and results of operations of each Seller and its consolidated
      subsidiaries and as having been prepared in accordance with generally
      accepted accounting principles consistently applied, in each case, subject
      to normal year-end audit adjustments;

            (iv) Promptly upon receipt thereof, a copy of each other report
      submitted to each Seller by its independent public accountants in
      connection with any annual, interim or special audit of such Seller;

                                      -21-
<PAGE>

            (v) Promptly upon becoming aware thereof, notice of (1) the
      commencement of, or any determination in, any legal, judicial or
      regulatory proceedings, (2) any dispute between any Seller or its Parent
      Company and any governmental or regulatory body, (3) any event or
      condition, which, in any case of (1) or (2), if adversely determined,
      would have a material adverse effect on (A) the validity or enforceability
      of this Agreement, (B) the financial condition or business operations of
      such Seller, (C) the Agency Approvals of such Seller or (D) the ability of
      such Seller to fulfill its obligations under this Agreement or (4) any
      material adverse change in the business, operations, prospects or
      financial condition of such Seller, including, without limitation, the
      insolvency of such Seller or its Parent Company;

            (vi) Promptly upon becoming available, copies of all financial
      statements, reports, notices and proxy statements sent by its Parent
      Company, such Seller or any of such Seller's consolidated subsidiaries in
      a general mailing to their respective stockholders and of all reports and
      other material (including copies of all registration statements under the
      Securities Act of 1933, as amended) filed by any of them with any
      securities exchange or with the Securities and Exchange Commission or any
      governmental authority succeeding to any or all of the functions of said
      Commission;

            (vii) Promptly upon becoming available, copies of any press releases
      issued by their Parent Company or such Seller and copies of any annual and
      quarterly financial reports and any reports on Form H-(b)12 which its
      Parent Company or such Seller may be required to file with the OTS or the
      RTC or comparable reports which a Parent Company or such Seller may be
      required to file with the FDIC or any other federal banking agency
      containing such financial statements and other information concerning such
      Parent Company's or such Seller's business and affairs as is required to
      be included in such reports in accordance with the rules and regulations
      of the OTS, the RTC, the FDIC or such other banking agency, as may be
      promulgated from time to time;

            (viii) Such supplements to the aforementioned documents and such
      other information regarding the operations, business, affairs and
      financial condition of its Parent Company, Sellers or any of Sellers'
      consolidated subsidiaries as Participant may request;

            (ix) Promptly upon becoming available, copies of any reports any
      REIT Seller may be required to file with the Internal Revenue Service;

            (x) Prior to the date of any purchase of a Participation Certificate
      by Participant hereunder, a copy of (1) the articles of incorporation,
      certificate of formation or other organizational documents of such Seller
      and any amendments thereto certified by the Secretary of State,
      Comptroller of Currency, Internal Revenue Service or similar official of
      such Seller's jurisdiction of organization, (2) a copy of such Seller's
      by-laws, together with any amendments thereto, (3) a copy of the
      resolutions adopted by such Seller's Board of Directors authorizing such
      Seller to enter into this Agreement, the Electronic Tracking Agreement and
      the Custodial Agreement and authorizing one or more of such Seller's
      officers to execute the documents related to this Agreement, the
      Electronic Tracking Agreement and the Custodial Agreement, (4) a
      certificate of

                                      -22-
<PAGE>

      incumbency and signature of such officer of such Seller's executing any
      document in connection with this Agreement, the Electronic Tracking
      Agreement and the Custodial Agreement, (5) a certificate reflecting each
      Authorized Signatory of such Seller, in the form of Exhibit F hereto, and
      (6) an opinion of counsel to such Seller, in the form of Exhibit G hereto;

            (xi) Neither such Seller nor any affiliate thereof will acquire at
      any time any Participation Certificate or any other economic interest in
      or obligation with respect to any Mortgage Loan;

            (xii) Under generally accepted accounting principles ("GAAP") and
      for federal income tax purposes, such Seller will report each sale of a
      Participation Certificate to the Participant as a sale of the ownership
      interest in the Mortgage Loans evidenced by that Participation
      Certificate. Such Seller has been advised by or has confirmed with its
      independent public accountants that the foregoing transactions will be so
      classified under GAAP;

            (xiii) The consideration received by such Seller upon the sale of
      each Participation Certificate will constitute reasonably equivalent value
      and fair consideration for the ownership interest in the Mortgage Loans
      evidenced by that Participation Certificate;

            (xiv) Such Seller will be solvent at all relevant times prior to,
      and will not be rendered insolvent by, any sale of a Participation
      Certificate to the Participant; and

            (xv) Such Seller will not sell any Participation Certificate to the
      Participant with any intent to hinder, delay or defraud any of the
      Seller's creditors.

            (b) Each Seller shall take all necessary action to maintain its
Agency Approvals at all times during the term of this Agreement. If, for any
reason, any Seller ceases to maintain such Agency Approvals, such Seller shall
so notify Participant immediately.

            (c) Each Seller shall comply, in all material respects, with all
laws, rules and regulations to which it is or may become subject.

            (d) Each Seller shall, upon request of Participant, promptly execute
and deliver to Participant all such other and further documents and instruments
of transfer, conveyance and assignment, and shall take such other action as
Participant may require more effectively to transfer, convey, assign to and vest
in Participant and to put Participant in possession of the property to be
transferred, conveyed, assigned and delivered hereunder and otherwise to carry
out more effectively the intent of the provisions under this Agreement.

            (e) Each Seller shall ensure that all proceeds paid by a Takeout
Investor resulting from Takeout Commitments that relate to any Security backed
by Mortgage Loans evidenced by a Participation Certificate purchased by
Participant pursuant to the terms of this Agreement are paid to Participant by
such Takeout Investor in accordance with Participant's wire instructions to such
Seller.

                                      -23-
<PAGE>

            (f) Each Seller acknowledges that the Participant has the right to
perform continuing due diligence reviews with respect to the Mortgage Loans, for
purposes of verifying compliance with the representations, warranties and
specifications made hereunder, or otherwise, and such Seller agrees that upon
reasonable (but no less than one (1) Business Day's) prior notice to such
Seller, the Participant or its authorized representatives will be permitted
during normal business hours to examine, inspect, make copies of, and make
extracts of, the mortgage files and any and all documents, records, agreements,
instruments or information relating to such Mortgage Loans in possession, or
under the control, of such Seller and/or Custodian. Such Seller also shall make
available to the Participant a knowledgeable financial or accounting officer for
the purpose of answering questions respecting the mortgage files and Mortgage
Loans. Such Seller and Participant further agree that all out-of-pocket costs
and expenses incurred by the Participant in connection with the Participant's
activities pursuant to this Section 9(f) shall be paid for by such Seller,
provided that Participant shall pay any such costs if such due diligence is
conducted more often than two (2) times in a calendar year.

            (g) Each Seller shall provide Participant with a monthly report,
which report shall include, among other items, a summary of such Seller's
delinquency and loss experience with respect to mortgage loans serviced by such
Seller, any Servicer or any designee of either, with respect to any MERS
Designated Mortgage Loan, MERS Reports, plus any such additional reports as
Participant may reasonably request with respect to such Seller's or any
Servicer's servicing portfolio or pending originations of mortgage loans. Such
Seller shall not cause the Mortgage Loans to be serviced by any servicer other
than a servicer expressly approved in writing by Participant.

            (h) On the second (2nd) Business Day of each month, each Seller
shall furnish to Participant or shall cause the Servicer to furnish to
Participant, a remittance report, in hard copy and electronic format acceptable
to Participant, containing information regarding funds collected during the
prior calendar month. This report shall contain the following information:

            (i) Mortgage Loan number;

            (ii) Note Rate;

            (iii) Remittances allocable to principal and interest;

            (iv) Paid through date;

            (v) Mortgage Loan balance;

            (vi) Delinquency status;

            (vii) Whether the Mortgaged Property is in foreclosure or has become
      an real estate owned property;

            (viii) Whether any Mortgagor is the subject of any bankruptcy
      action; and

            (ix) Any other information that Participant may reasonably request.

                                      -24-
<PAGE>

            (i) Each Seller shall pay and discharge all taxes, assessments and
governmental charges or levies imposed on it or on its income or profits or on
any of its property prior to the date on which penalties attach thereto, except
for any such tax, assessment, charge or levy the payment of which is being
contested in good faith and by proper proceedings and against which adequate
reserves are being maintained.

            (j) Each Seller covenants and agrees to take all actions required of
it in compliance with the terms of the Electronic Tracking Agreement.

            (k) Unless any Seller shall have given Participant at least thirty
(30) days' prior written notice, each Seller shall not (i) change its name,
organizational identity or jurisdiction of organization or (ii) merge with or
into, acquire all or substantially all of the assets of, or transfer all or
substantially all of its assets to, any other person or entity (except in the
ordinary course of business or except in a transaction or series of transactions
between two or more Sellers).

            (l) Each REIT Seller covenants and agrees that it shall at all times
continue to be (i) qualified as a real estate investment trust as defined in
Section 856 of the Code for so long as the Board of Directors deems it in the
best interests of the stockholders of such REIT Seller to remain so qualified
and (ii) entitled to a dividends paid deduction under Section 857 of the Code
with respect to dividends paid by it with respect to each taxable year for which
it claims a deduction on its Form 1120 - REIT filed with the United States
Internal Revenue Service for such year, or the entering into by any REIT Seller
of any material "prohibited transactions" as defined in Sections 857(b) and
856(c) of the Code. After the occurrence and during the continuation of any
monetary default or any default that results in the acceleration or required
prepayment of any indebtedness pursuant to the terms of this Agreement or any
other agreement between a Seller and Participant, no Seller shall make any
payment on account of, or set apart assets for, a sinking or other analogous
fund for the purchase, redemption, defeasance, retirement or other acquisition
of any equity or partnership interest of such Sellers, whether now or hereafter
outstanding, or make any other distribution in respect of any of the foregoing
or to any shareholder or equity owner of such Seller, either directly or
indirectly, whether in cash or property or in obligations of such Seller or any
of such Seller's consolidated Subsidiaries.

            Section 10. Confidentiality. Each Seller hereby acknowledges and
agrees that (1) all written or computer-readable information provided by
Participant to such Seller regarding Participant and (2) the terms of this
Agreement (the "Participant Confidential Information"), shall be kept
confidential and each of their respective contents will not be divulged to any
party without Participant's consent except to the extent that (i) such Seller
deems appropriate to do so in working with legal counsel, auditors, taxing
authorities or other governmental agencies or regulatory bodies or in order to
comply with any applicable federal or state laws, (ii) any portion of
Participant Confidential Information is in the public domain other than due to a
breach of this covenant, or (iii) such Seller deems appropriate in connection
with exercising any or all of such Seller's rights or remedies or complying with
any obligations under this Agreement.

            Section 11. Term. This Agreement shall continue in effect until
terminated as to future transactions by written instruction signed by either
Sellers or Participant and delivered to the other, provided that no termination
will affect the obligations hereunder as to any of the

                                      -25-
<PAGE>

Participation Certificates then outstanding hereunder or any Security not yet
delivered to the related Takeout Investor.

            Section 12. Exclusive Benefit of Parties; Assignment. This Agreement
is for the exclusive benefit of the parties hereto and their respective
successors and assigns and shall not be deemed to give any legal or equitable
right to any other person, including the Takeout Investor and Custodian. Except
as provided in Section 6, no rights or obligations created by this Agreement may
be assigned by either party hereto without the prior written consent of the
other party.

            Section 13. Amendments; Waivers; Cumulative Rights. This Agreement
may be amended from time to time only by written agreement of Sellers and
Participant. Any forbearance, failure or delay by Participant in exercising any
right, power or remedy hereunder shall not be deemed to be a waiver thereof, and
any single or partial exercise by Participant of any right, power or remedy
hereunder shall not preclude the further exercise thereof. Every right, power
and remedy of Participant shall continue in full force and effect until
specifically waived by Participant in writing. No right, power or remedy shall
be exclusive, and each such right, power or remedy shall be cumulative and in
addition to any other right, power or remedy, whether conferred hereby or
hereafter available at law or in equity or by statute or otherwise.

            Section 14. Execution in Counterparts. This Agreement may be
executed in any number of counterparts, each of which shall be deemed an
original, but all of which shall constitute one and the same instrument.

            Section 15. Effect of Invalidity of Provisions. In case any one or
more of the provisions contained in this Agreement should be or become invalid,
illegal or unenforceable in any respect, the validity, legality and
enforceability of the remaining provisions contained herein or therein shall in
no way be affected, prejudiced or disturbed thereby.

            Section 16. GOVERNING LAW. THIS AGREEMENT SHALL BE GOVERNED BY AND
CONSTRUED IN ACCORDANCE WITH THE LAWS OF THE STATE OF NEW YORK, WITHOUT REGARD
TO CONFLICT OF LAWS RULES.

            Section 17. Notices. Any notices, consents, elections, directions
and other communications given under this Agreement shall be in writing and
shall be deemed to have been duly given when telecopied or delivered by
overnight courier to, personally delivered to, or on the third day following the
placing thereof in the mail, first class postage prepaid to, the respective
addresses set forth on the cover page hereof for Sellers or Participant, or to
such other address as any party shall give notice to the other parties pursuant
to this Section 17. Notices to any Assignee shall be given to such address as
the Assignee shall provide to Seller in writing.

            Section 18. Entire Agreement. This Agreement, the Participation
Certificates and the Custodial Agreement contain the entire agreement between
the parties hereto with respect to the subject matter hereof, and supersede all
prior and contemporaneous agreements between them, oral or written, of any
nature whatsoever with respect to the subject matter hereof.

            Section 19. Costs of Enforcement. In addition to any other indemnity
specified in this Agreement, in the event of a breach by any Seller of this
Agreement, the

                                      -26-
<PAGE>

Custodial Agreement, a Participation Certificate or a Takeout
Commitment, such Seller agrees to pay the reasonable attorneys' fees and
expenses of Participant, and/or, when applicable, any Assignee, incurred in the
enforcement of the Agreement as a consequence of such breach.

            Section 20. Consent to Service. Each party irrevocably consents to
the service of process by registered or certified mail, postage prepaid, to it
at its address given in or pursuant to Section 17.

            Section 21. Submission to Jurisdiction; Waivers.

            EACH PARTY HEREBY IRREVOCABLY AND UNCONDITIONALLY:

            (i) SUBMITS FOR ITSELF AND ITS PROPERTY IN ANY LEGAL ACTION OR
      PROCEEDING RELATING TO THIS MORTGAGE LOAN PARTICIPATION AGREEMENT AND THE
      OTHER DOCUMENTS, OR FOR RECOGNITION AND ENFORCEMENT OF ANY JUDGMENT IN
      RESPECT THEREOF, TO THE EXCLUSIVE GENERAL JURISDICTION OF THE COURTS OF
      THE STATE OF NEW YORK, THE FEDERAL COURTS OF THE UNITED STATES OF AMERICA
      FOR THE SOUTHERN DISTRICT OF NEW YORK, AND APPELLATE COURTS FROM ANY
      THEREOF;

            (ii) CONSENTS THAT ANY SUCH ACTION OR PROCEEDING MAY BE BROUGHT IN
      SUCH COURTS AND, TO THE EXTENT PERMITTED BY LAW, WAIVES ANY OBJECTION THAT
      IT MAY NOW OR HEREAFTER HAVE TO THE VENUE OF ANY SUCH ACTION OR PROCEEDING
      IN ANY SUCH COURT OR THAT SUCH ACTION OR PROCEEDING WAS BROUGHT IN AN
      INCONVENIENT COURT AND AGREES NOT TO PLEAD OR CLAIM THE SAME;

            (iii) AGREES THAT SERVICE OF PROCESS IN ANY SUCH ACTION OR
      PROCEEDING MAY BE EFFECTED BY MAILING A COPY THEREOF BY REGISTERED OR
      CERTIFIED MAIL (OR ANY SUBSTANTIALLY SIMILAR FORM OF MAIL), POSTAGE
      PREPAID, TO ITS ADDRESS SET FORTH ON THE COVER PAGE HERETO OR AT SUCH
      OTHER ADDRESS OF WHICH PARTICIPANT SHALL HAVE BEEN NOTIFIED;

            (iv) AGREES THAT NOTHING HEREIN SHALL AFFECT THE RIGHT TO EFFECT
      SERVICE OF PROCESS IN ANY OTHER MANNER PERMITTED BY LAW OR SHALL LIMIT THE
      RIGHT TO SUE IN ANY OTHER JURISDICTION; AND

            (v) WAIVES, TO THE FULLEST EXTENT PERMITTED BY APPLICABLE LAW, ANY
      AND ALL RIGHT TO TRIAL BY JURY IN ANY LEGAL PROCEEDING ARISING OUT OF OR
      RELATING TO THIS MORTGAGE LOAN PARTICIPATION AGREEMENT, ANY OTHER DOCUMENT
      RELATING THERETO OR THE TRANSACTIONS CONTEMPLATED HEREBY OR THEREBY.

                                      -27-
<PAGE>

            Section 22. Construction. The headings in this Agreement are for
convenience only and are not intended to influence its construction. References
to Sections, Exhibits and Annexes in this Agreement are to the Sections of and
Exhibits and Annexes to this Agreement. The Exhibits and Annexes are part of
this Agreement, and are incorporated herein by reference. In this Agreement, the
singular includes the plural, the plural the singular, and the words "and" and
"or" are used in the conjunctive or disjunctive as the sense and circumstances
may require.

            Section 23. Effect of Amendment and Restatement. Upon the execution
of this Agreement by all parties hereto and the delivery of the opinion required
by Section 9(a)(x), the Original Participation Agreement shall be amended,
restated and superseded in its entirety by this Agreement. The parties hereto
acknowledge and agree that (a) the liens and security interests granted under
the Original Participation Agreement are in full force and effect and, upon the
amendment and restatement of the Original Participation Agreement and the
related documents, such liens and security interests secure and continue to
secure the payment and performance of Seller's obligations under this Agreement
and the related documents, and (b) upon the effectiveness of such amendment and
restatement, all outstanding Participation Certificates under, and as defined
in, the Original Participation Agreement, shall be deemed to be outstanding as
Participation Certificates hereunder mutatis mutandis, in each case on the terms
and conditions set forth in this Agreement. Furthermore, the provisions of this
Agreement shall relate back to and shall govern all aspects of all sales of
Participation Certificates by the Sellers to the Purchase beginning December 18,
2003.

                   [SIGNATURES COMMENCE ON FOLLOWING PAGE]

                                      -28-
<PAGE>

            IN WITNESS WHEREOF, Participant and Sellers have duly executed this
Agreement as of the date and year set forth on the cover page hereof.

                                       UBS REAL ESTATE SECURITIES INC.

                                       By:  /s/ George A. Mangiaracina
                                          --------------------------------------
                                          Name:   George A. Mangiaracina
                                          Title:  Managing Director

                                       By:  /s/ Robert Carpenter
                                          --------------------------------------
                                          Name:   Robert Carpenter
                                          Title:  Director

                                       AMERICAN HOME MORTGAGE
                                         INVESTMENT CORP.

                                       By:  /s/ Michael Strauss
                                          --------------------------------------
                                          Name:   Michael Strauss
                                          Title:  President

                                       AMERICAN HOME MORTGAGE
                                         ACCEPTANCE, INC.

                                       By:  /s/ Michael Strauss
                                          --------------------------------------
                                          Name:   Michael Strauss
                                          Title:  President

                                       AMERICAN HOME MORTGAGE
                                         HOLDINGS, INC.

                                       By:  /s/ Michael Strauss
                                          --------------------------------------
                                          Name:   Michael Strauss
                                          Title:  President

<PAGE>

                                       AMERICAN HOME MORTGAGE CORP.

                                       By:  /s/ Michael Strauss
                                          --------------------------------------
                                          Name:  Michael Strauss
                                          Title: President

                                       COLUMBIA NATIONAL, INCORPORATED

                                       By:  /s/ Michael Strauss
                                          --------------------------------------
                                          Name:  Michael Strauss
                                          Title: President

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