Exhibit 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


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<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


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<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


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<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.


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<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).


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<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.


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<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