EXECUTION VERSION WASHINGTON MUTUAL MORTGAGE SECURITIES CORP., as Depositor and Master Servicer and DEUTSCHE BANK NATIONAL TRUST COMPANY, as Trustee and DEUTSCHE BANK TRUST COMPANY DELAWARE, as Delaware Trustee POOLING AND SERVICING AGREEMENT $750,504,106.41 Washington Mutual Mortgage Securities Cor

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EXHIBIT 4.1

EXECUTION
VERSION

WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.,

as Depositor and Master Servicer

and

DEUTSCHE BANK NATIONAL TRUST COMPANY,

as Trustee

and

DEUTSCHE BANK TRUST COMPANY DELAWARE,

as Delaware Trustee



POOLING AND SERVICING AGREEMENT

$750,504,106.41

Washington Mutual Mortgage Securities Corp.

WaMu Mortgage Pass-Through Certificates

Series 2005-AR4

Cut-Off Date: March 1, 2005

TABLE OF CONTENTS

This Pooling and Servicing Agreement, dated and effective as of March 1, 2005 (this “ Agreement ”), is executed by and among Washington Mutual Mortgage Securities Corp., as depositor and Master Servicer (the “ Company ”), Deutsche Bank National Trust Company, a national banking association with a corporate trust office at 1761 East St. Andrew Place, Santa Ana, CA 92705, as Trustee (the “ Trustee ”), and Deutsche Bank Trust Company Delaware, as Delaware Trustee (the “ Delaware Trustee ”).  Capitalized terms used in this Agreement and not otherwise defined have the meanings ascribed to such terms in Article I hereof.

PRELIMINARY STATEMENT

The Company at the Closing Date is the owner of the Mortgage Loans and the other property being conveyed by it to the Trust. On the Closing Date, the Company will acquire the REMIC I Regular Interests and the Class R-1 Residual Interest from the Trust as consideration for its transfer to the Trust of the Mortgage Loans and certain other assets and will be the owner of the REMIC I Regular Interests and the Class R-1 Residual Interest.  Thereafter on the Closing Date, the Company will acquire the Certificates (other than the Class R Certificates) and the Class R-2 Residual Interest from the Trust as consideration for its transfer to the Trust of the REMIC I Regular Interests and will be the owner of the Certificates.  The Company has duly authorized the execution and delivery of this Agreement to provide for (i) the conveyance to the Trust of the Mortgage Loans and certain other assets, (ii) the issuance to the Company of the REMIC I Regular Interests and the Class R-1 Residual Interest representing in the aggregate the entire beneficial interest in REMIC I, (iii) the conveyance to the Trust of the REMIC I Regular Interests and (iv) the issuance to the Company of the Certificates, such Certificates (other than the portion of the Class R Certificates representing ownership of the Class R-1 Residual Interest) representing in the aggregate the entire beneficial interest in REMIC II. The Company is entering into this Agreement, and the Trustee and the Delaware Trustee are each accepting the trust created hereby, for good and valuable consideration, the receipt and sufficiency of which are hereby acknowledged.

The Certificates issued hereunder, other than the Junior Subordinate Certificates, have been offered for sale pursuant to a Prospectus, dated March 21, 2005, and a Prospectus Supplement, dated March 21, 2005, of the Company (together, the “ Prospectus ”). The Junior Subordinate Certificates have been offered for sale pursuant to a Private Placement Memorandum, dated March 24, 2005.  The Trust created hereunder is intended to be the “Trust” described in the Prospectus and the Private Placement Memorandum and the Certificates are intended to be the “Certificates” described therein. The following tables set forth the designation, type of interest, Certificate Interest Rate, initial Class Principal Balance and Final Maturity Date for the REMIC I Regular Interests, the Class R Residual Interests and the Certificates:

REMIC I Interests

As provided herein, with respect to REMIC I, the Company will cause an election to be made on behalf of REMIC I to be treated for federal income tax purposes as a REMIC. The REMIC I Regular Interests will be designated regular interests in REMIC I and the Class R-1 Residual Interest will be designated the sole class of residual interest in REMIC I, for purposes of the REMIC Provisions.

REMIC II Interests

As provided herein, with respect to REMIC II, the Company will cause an election to be made on behalf of REMIC II to be treated for federal income tax purposes as a REMIC. The Certificates (other than the Class R Certificates) will be designated regular interests in REMIC II and the Class R-2 Residual Interest will be designated the sole class of residual interest in REMIC II, for purposes of the REMIC Provisions.  As of the Cut-Off Date, the Mortgage Loans have an aggregate Principal Balance of $750,504,106.41 and the Certificates have an Aggregate Certificate Principal Balance of $750,504,106.41.

In addition, the Trust will issue the Class R Certificates, which will represent ownership of the Class R-1 and Class R-2 Residual Interests.

W I T N E S S E T H :

WHEREAS, the Company is a corporation duly organized and existing under and by virtue of the laws of the State of Delaware and has full corporate power and authority to enter into this Agreement and to undertake the obligations undertaken by it herein;

WHEREAS, the Trustee is a national banking association duly organized and existing under the laws of the United States of America and has full power and authority to enter into this Agreement;

WHEREAS, the Delaware Trustee is a banking corporation duly organized and existing under the laws of the State of Delaware and has full power and authority to enter into this Agreement;

WHEREAS, prior to the execution and delivery hereof, the Company and the Delaware Trustee have entered into the Original Trust Agreement, and the Delaware Trustee has filed the Certificate of Trust;

WHEREAS, it is the intention of the Company, the Trustee and the Delaware Trustee that the Trust created by this Agreement constitute a statutory trust under the Statutory Trust Statute, that this Agreement constitute the governing instrument of the Trust, and that this Agreement amend and restate the Original Trust Agreement;

WHEREAS, the Company is the owner of the Mortgage Loans identified in the Mortgage Loan Schedule hereto having unpaid Principal Balances on the Cut-Off Date as stated therein; and

WHEREAS, the Company has been duly authorized to create the Trust to (i) hold the Mortgage Loans and certain other property, (ii) issue the REMIC I Regular Interests and the Class R-1 Residual Interest, (iii) hold the REMIC I Regular Interests and (iv) issue the Certificates.

NOW, THEREFORE, in order to declare the terms and conditions upon which the REMIC I Regular Interests, the Class R Residual Interests and the Certificates are to be issued, and in consideration of the premises and of the purchase and acceptance of the Certificates by the Holders thereof, the Company covenants and agrees with the Trustee and the Delaware Trustee, for the equal and proportionate benefit of the respective Holders from time to time of the REMIC I Regular Interests and the Certificates, as applicable, as follows:

ARTICLE I

Section 1.01.        Definitions .

Whenever used in this Agreement, the following words and phrases, unless the context otherwise requires, shall have the following meanings:

Adjustment Date:   As to each Mortgage Loan, a Due Date on or about the fifth anniversary of the first Due Date and annually thereafter, as set forth in the related Mortgage Note, on which date an adjustment to the Mortgage Interest Rate of such Mortgage Loan becomes effective.

Aggregate Certificate Principal Balance :  At any given time, the sum of the then current Class Principal Balances of the Certificates.

Appraised Value :  With respect to any (i) Mortgage Loan that is not a Streamlined Mortgage Loan or ROV Mortgage Loan, the lesser of (a) the value set forth on the appraisal made in connection with the origination of such Mortgage Loan as the value of the related Mortgaged Property and (b) the purchase price paid for the Mortgaged Property, provided, however , that if such Mortgage Loan was originated in connection with the refinance of a mortgage loan, such value shall be based solely on the appraisal made in connection with the origination of such Mortgage Loan; (ii) ROV Mortgage Loan, the lesser of (a) the value set forth on the residential appraisal review made in connection with the origination of such Mortgage Loan as the value of the related Mortgaged Property and (b) the purchase price paid for the Mortgaged Property, provided, however , that if such ROV Mortgage Loan was originated in connection with the refinance of a mortgage loan, such value shall be based solely on the residential appraisal review made in connection with the origination of such ROV Mortgage Loan; and (iii) Streamlined Mortgage Loan, the value set forth in the appraisal made in connection with the origination of the mortgage loan being refinanced.

Assignment of Proprietary Lease :  With respect to a Cooperative Loan, the assignment or mortgage of the related Cooperative Lease from the Mortgagor to the originator of the Cooperative Loan.

Auction Administrator : The meaning given to such term in Section 3.17(a).

Auction Administration Agreement : The Auction Administration Agreement, dated as of March 24, 2005, between GCD and the Auction Administrator

Auction Certificates : The Class A-1, Class A-2A, Class A-2B, Class A-3, Class A-4A and Class A-4B Certificates.

Authenticating Agent :  Any authenticating agent appointed by the Trustee pursuant to Section 8.11.

Authorized Denomination :  With respect to each Class of Certificates (other than the Class X and Class R Certificates), an initial Certificate Principal Balance equal to $25,000 and multiples of $1 in excess thereof, except that one Certificate of each Class of the Junior Subordinate Certificates may be issued in an amount that is not an integral multiple of $1.  With respect to the Class X Certificates, a Class Notional Amount as of the Cut-Off Date equal to $100,000 and multiples of $1 in excess thereof.  With respect to the Class R Certificates, one Certificate with a Percentage Interest equal to 0.01% and one Certificate with a Percentage Interest equal to 99.99%.

Bankruptcy Loss :  A loss on a Mortgage Loan arising out of (i) a reduction in the scheduled Monthly Payment for such Mortgage Loan by a court of competent jurisdiction in a case under the United States Bankruptcy Code, other than any such reduction that arises out of clause (ii) of this definition of “Bankruptcy Loss,” including, without limitation, any such reduction that results in a permanent forgiveness of principal, or (ii) with respect to any Mortgage Loan, a valuation, by a court of competent jurisdiction in a case under such Bankruptcy Code, of the related Mortgaged Property in an amount less than the then outstanding Principal Balance of such Mortgage Loan.

Beneficial Holder :  A Person holding a beneficial interest in any Book-Entry Certificate as or through a DTC Participant or an Indirect DTC Participant or a Person holding a beneficial interest in any Definitive Certificate.

Benefit Plan Opinion :  With respect to any Certificate presented for registration in the name of any Person, an Opinion of Counsel acceptable to and in form and substance satisfactory to the Trustee and the Company to the effect that the purchase or holding of such Certificate is permissible under applicable law, will not constitute or result in a non-exempt prohibited transaction under Section 406 of ERISA or Section 4975 of the Code, and will not subject the Trust, the Trustee, the Delaware Trustee, the Master Servicer or the Company to any obligation or liability (including obligations or liabilities under Section 406 of ERISA or Section 4975 of the Code) in addition to those undertaken in this Agreement, which Opinion of Counsel shall not be an expense of the Trust, the Trustee, the Delaware Trustee, the Master Servicer or the Company.

Book-Entry Certificates :  The Class A, Class X and Senior Subordinate Certificates, beneficial ownership and transfers of which shall be made through book entries as described in Section 5.07.

Business Day :  Any day other than (i) a Saturday or a Sunday, (ii) a day on which banking institutions in Stockton, California, Chicago, Illinois, New York, New York, Seattle, Washington or any city in which the Corporate Trust Office is located (which shall initially be Santa Ana, California) are authorized or obligated by law or executive order to be closed or, (iii) as used (a) for purposes of determining the Distribution Date (pursuant to the definition thereof) in January 2010 or (b) in the Swap Agreement and the Auction Administration Agreement, also a day on which banking institutions in London, England are authorized or obligated by law or executive order to be closed.

Buydown Agreement :  An agreement between a Person and a Mortgagor pursuant to which such Person has provided a Buydown Fund.

Buydown Fund :  A fund provided by the originator of a Mortgage Loan or another Person with respect to a Buydown Loan which provides an amount sufficient to subsidize regularly scheduled principal and interest payments due on such Buydown Loan for a period. Buydown Funds may be (i) funded at the par values of future payment subsidies, or (ii) funded in an amount less than the par values of future payment subsidies, and determined by discounting such par values in accordance with interest accruing on such amounts, in which event they will be deposited in an account bearing interest. Buydown Funds may be held in a separate Buydown Fund Account or may be held in a Custodial Account for P&I or a Custodial Account for Reserves and monitored by a Servicer.

Buydown Fund Account :  A separate account or accounts created and maintained pursuant to Section 3.02 (a) with a financial institution approved by the Master Servicer, (b) within FDIC insured accounts (or other accounts with comparable insurance coverage acceptable to the Rating Agencies) created, maintained and monitored by a Servicer or (c) in a separate non-trust account without FDIC or other insurance in an Eligible Institution (including the Trustee). Such account or accounts may be non-interest bearing or may bear interest. In the event that a Buydown Fund Account is established pursuant to clause (b) of the preceding sentence, amounts held in such Buydown Fund Account shall not exceed the level of deposit insurance coverage on such account; accordingly, more than one Buydown Fund Account may be established.

Buydown Loan :  A Mortgage Loan for which the Mortgage Interest Rate has been subsidized through a Buydown Fund provided at the time of origination of such Mortgage Loan.

Carry-Forward Subsequent Recoveries Amount :  For any Distribution Date, the excess, if any, of (i) the Subsequent Recoveries for such Distribution Date over (ii) the amount by which the Class Principal Balance of the Class of Subordinate Certificates with the lowest priority is increased in respect of Subsequent Recoveries on such Distribution Date pursuant to the definition of “Class Principal Balance” herein.

Certificate :  Any one of the Certificates issued pursuant to this Agreement, executed by the Trustee and authenticated by or on behalf of the Trustee hereunder in substantially one of the forms set forth in Exhibit A and B hereto. The additional matter appearing in Exhibit H shall be deemed incorporated into Exhibit A as though set forth at the end of such Exhibit.

Certificate Account :  The separate trust account created and maintained with the Trustee, the Investment Depository or any other bank or trust company acceptable to the Rating Agencies which is incorporated under the laws of the United States of America or any state thereof pursuant to Section 3.04, which account shall bear a designation clearly indicating that the funds deposited therein are held in trust for the benefit of the Trust or any other account serving a similar function acceptable to the Rating Agencies. Funds in the Certificate Account may be invested in Eligible Investments pursuant to Section 3.04(b) and reinvestment earnings thereon shall be paid to the Master Servicer as additional servicing compensation. Funds deposited in the Certificate Account (exclusive of the Master Servicing Fee) shall be held in trust for the Certificateholders and for the uses and purposes set forth in Section 2.01, Section 3.04, Section 3.05, Section 4.01 and Section 4.04.

Certificateholder or Holder :  With respect to the Certificates, the Person in whose name a Certificate is registered in the Certificate Register, except that, solely for the purposes of giving any consent pursuant to this Agreement, any Certificate registered in the name of the Company, the Master Servicer or any affiliate thereof shall be deemed not to be outstanding and the Percentage Interest evidenced thereby shall not be taken into account in determining whether the requisite percentage of Percentage Interests necessary to effect any such consent has been obtained; provided, that the Trustee may conclusively rely upon an Officer’s Certificate to determine whether any Person is an affiliate of the Company or the Master Servicer.  With respect to the REMIC I Regular Interests, the owner of the REMIC I Regular Interests, which as of the Closing Date shall be the Trust.

Certificate Interest Rate :  For each Class of Certificates and REMIC I Regular Interests, the per annum rate set forth as the Certificate Interest Rate for such Class in the Preliminary Statement hereto.

Certificate of Trust :  The certificate of trust filed with respect to the Trust with the Secretary of State in accordance with Section 3810(a) of the Statutory Trust Statute.

Certificate Principal Balance :  For each Certificate of any Class, the portion of the related Class Principal Balance, if any, represented by such Certificate.

Certificate Register and Certificate Registrar :  The register maintained and the registrar appointed, respectively, pursuant to Section 5.03.

Class :  All REMIC I Regular Interests or the Class R-1 Residual Interest having the same priority and rights to payments on the Mortgage Loans from the REMIC I Available Distribution Amount, and all REMIC II Regular Interests or the Class R-2 Residual Interest having the same priority and rights to payments on the REMIC I Regular Interests from the REMIC II Available Distribution Amount, as applicable, which REMIC I Regular Interests, REMIC II Regular Interests and Class R Residual Interests, as applicable, shall be designated as a separate Class, and which, in the case of the Certificates (including the Class R Certificates representing ownership of the Class R Residual Interests), shall be set forth in the applicable forms of Certificates attached hereto as Exhibits A and B. Each Class of REMIC I Regular Interests and the Class R-1 Residual Interest shall be entitled to receive the amounts allocated to such Class pursuant to the definition of “REMIC I Distribution Amount” only to the extent of the REMIC I Available Distribution Amount for such Distribution Date remaining after distributions in accordance with prior clauses of the definition of “REMIC I Distribution Amount” and each Class of REMIC II Regular Interests and the Class R-2 Residual Interest shall be entitled to receive the amounts allocated to such Class pursuant to the definition of “REMIC II Distribution Amount” only to the extent of the REMIC II Available Distribution Amount for such Distribution Date remaining after distributions in accordance with prior clauses of the definition of “REMIC II Distribution Amount.” 

Class A Certificates :  The Class A-1, Class A-2A, Class A-2B, Class A-3, Class A-4A, Class A-4B and Class A-5 Certificates.

Class A-L Regular Interests :  The Class A-1-L, Class A-2A-L, Class A-2B-L, Class A-3-L, Class A-4A-L, Class A-4B-L and Class A-5-L Regular Interests.

Class A-1 Certificates :  The Certificates designated as “Class A-1” on the face thereof in substantially the form attached hereto as Exhibit A.

Class A-1-L Regular Interest :  The uncertificated undivided beneficial interest in REMIC I which constitutes a REMIC I Regular Interest and is entitled to distributions as set forth herein.

Class A-2A Certificates :  The Certificates designated as “Class A-2A” on the face thereof in substantially the form attached hereto as Exhibit A.

Class A-2A-L Regular Interest :  The uncertificated undivided beneficial interest in REMIC I which constitutes a REMIC I Regular Interest and is entitled to distributions as set forth herein.

Class A-2B Certificates :  The Certificates designated as “Class A-2B” on the face thereof in substantially the form attached hereto as Exhibit A.

Class A-2B-L Regular Interest :  The uncertificated undivided beneficial interest in REMIC I which constitutes a REMIC I Regular Interest and is entitled to distributions as set forth herein.

Class A-3 Certificates :  The Certificates designated as “Class A-3” on the face thereof in substantially the form attached hereto as Exhibit A.

Class A-3-L Regular Interest :  The uncertificated undivided beneficial interest in REMIC I which constitutes a REMIC I Regular Interest and is entitled to distributions as set forth herein.

Class A-4A Certificates :  The Certificates designated as “Class A-4A” on the face thereof in substantially the form attached hereto as Exhibit A.

Class A-4A-L Regular Interest :  The uncertificated undivided beneficial interest in REMIC I which constitutes a REMIC I Regular Interest and is entitled to distributions as set forth herein.

Class A-4B Certificates :  The Certificates designated as “Class A-4B” on the face thereof in substantially the form attached hereto as Exhibit A.

Class A-4B-L Regular Interest :  The uncertificated undivided beneficial interest in REMIC I which constitutes a REMIC I Regular Interest and is entitled to distributions as set forth herein.

Class A-5 Certificates :  The Certificates designated as “Class A-5” on the face thereof in substantially the form attached hereto as Exhibit A.

Class A-5-L Regular Interest :  The uncertificated undivided beneficial interest in REMIC I which constitutes a REMIC I Regular Interest and is entitled to distributions as set forth herein.

Class B Certificates :  The Class B-1, Class B-2, Class B-3, Class B-4, Class B-5 and Class B-6 Certificates.

Class B-L Regular Interests :  The Class B-1-L, Class B-2-L, Class B-3-L, Class B-4-L, Class B-5-L and Class B-6-L Regular Interests.

Class B-1 Certificates :  The Certificates designated as “Class B-1” on the face thereof in substantially the form attached hereto as Exhibit A.

Class B-1-L Regular Interest :  The uncertificated undivided beneficial interest in REMIC I which constitutes a REMIC I Regular Interest and is entitled to distributions as set forth herein.

Class B-2 Certificates :  The Certificates designated as “Class B-2” on the face thereof in substantially the form attached hereto as Exhibit A.

Class B-2-L Regular Interest :  The uncertificated undivided beneficial interest in REMIC I which constitutes a REMIC I Regular Interest and is entitled to distributions as set forth herein.

Class B-3 Certificates :  The Certificates designated as “Class B-3” on the face thereof in substantially the form attached hereto as Exhibit A.

Class B-3-L Regular Interest :  The uncertificated undivided beneficial interest in REMIC I which constitutes a REMIC I Regular Interest and is entitled to distributions as set forth herein.

Class B-4 Certificates :  The Certificates designated as “Class B-4” on the face thereof in substantially the form attached hereto as Exhibit A.

Class B-4-L Regular Interest :  The uncertificated undivided beneficial interest in REMIC I which constitutes a REMIC I Regular Interest and is entitled to distributions as set forth herein.

Class B-5 Certificates :  The Certificates designated as “Class B-5” on the face thereof in substantially the form attached hereto as Exhibit A.

Class B-5-L Regular Interest :  The uncertificated undivided beneficial interest in REMIC I which constitutes a REMIC I Regular Interest and is entitled to distributions as set forth herein.

Class B-6 Certificates :  The Certificates designated as “Class B-6” on the face thereof in substantially the form attached hereto as Exhibit A.

Class B-6-L Regular Interest :  The uncertificated undivided beneficial interest in REMIC I which constitutes a REMIC I Regular Interest and is entitled to distributions as set forth herein.

Class Notional Amount :  With respect to the Class X Certificates, the Class X Notional Amount.

Class Principal Balance :  For any Class of Certificates, for any Class of REMIC I Regular Interests and for the Class R-1 Residual Interest, the applicable initial Class Principal Balance therefor set forth in the Preliminary Statement hereto (or, in the case of the Class R Certificates, the Class Principal Balance of the Class R-1 Residual Interest), corresponding to the rights of such Class in payments of principal due to be passed through to the Certificateholders or the Holders of the REMIC I Regular Interests from principal payments on the Mortgage Loans or the REMIC I Regular Interests, as applicable, as reduced from time to time by (x) distributions of principal to the Certificateholders or the Holders of the REMIC I Regular Interests of such Class and (y) the portion of Realized Losses allocated to the Class Principal Balance of such Class pursuant to the definition of “Realized Loss” with respect to a given Distribution Date. For any Distribution Date, the reduction of the Class Principal Balance of any Class of Certificates and REMIC I Regular Interests pursuant to the definition of “Realized Loss” shall be deemed effective after the determination and distribution of principal on such Class pursuant to the definitions of “REMIC I Distribution Amount” and “REMIC II Distribution Amount.”

Notwithstanding the foregoing, any amounts distributed in respect of principal losses pursuant to paragraph (I)(xxiii) of the definition of “REMIC I Distribution Amount” shall not cause a reduction in the Class Principal Balances of the REMIC I Regular Interests or their Corresponding Classes.

In addition to the foregoing, on each Distribution Date, the Class Principal Balance of the Class of Subordinate Certificates with the lowest priority then outstanding (and its Corresponding Class) shall be increased by an amount equal to the lesser of (i) the Subsequent Recoveries for such Distribution Date and (ii) the amount of Realized Losses allocated to such Class on previous Distribution Dates (the amount in this clause (ii) reduced by the amount, if any, by which such Class Principal Balance has been increased on prior Distribution Dates pursuant to this paragraph).

The Class Principal Balance for the Class A-1 Certificates shall be referred to as the “Class A-1 Principal Balance,” the Class Principal Balance for the Class A-1-L Regular Interest shall be referred to as the “Class A-1-L Principal Balance” and so on.  The Class Principal Balance for the Class X Certificates shall be zero.

Class R Certificates :  The Certificates designated as “Class R” on the face thereof in substantially the form attached hereto as Exhibit B, representing ownership of the Class R-1 and Class R-2 Residual Interests, each of which Class of Residual Interests has been designated as the sole class of “residual interest” in REMIC I and REMIC II, respectively, pursuant to Section 2.06 and Section 2.11, respectively, for purposes of Section 860G(a)(2) of the Code.

Class R Residual Interests :  The Class R-1 and Class R-2 Residual Interests (which shall be transferable only as a unit evidenced by the Class R Certificates, in accordance with the applicable provisions of Section 5.01).

Class R-1 Residual Interest :  The uncertificated undivided beneficial interest in REMIC I which has been designated as the single class of “residual interest” in REMIC I pursuant to Section 2.06.  The Class R-1 Residual Interest, together with the REMIC I Regular Interests, shall be deemed to be a separate series of beneficial interests in the assets of the Trust consisting of the REMIC I Assets pursuant to Section 3806(b)(2) of the Statutory Trust Statute.

Class R-2 Residual Interest :  The uncertificated undivided beneficial interest in REMIC II which has been designated as the single class of “residual interest” in REMIC II pursuant to Section 2.11.  The Class R-2 Residual Interest, together with the REMIC II Regular Interests, shall be deemed to be a separate series of beneficial interests in the assets of the Trust consisting of the REMIC II Assets pursuant to Section 3806(b)(2) of the Statutory Trust Statute.

Class X Certificates :  The Certificates designated as “Class X” on the face thereof in substantially the form attached hereto as Exhibit A.

Class X Notional Amount :  For any Distribution Date (i) in or before January 2010, the aggregate Class Principal Balance of the Class A-1, Class A-2A, Class A-3 and Class A-4A Certificates immediately before such Distribution Date and (ii) in or after February 2010, zero.

Clean-Up Call Option Date :  The date on which the aggregate principal balance of the Mortgage Loans has been reduced to less than the Clean-Up Call Percentage of that balance as of the Cut-Off Date.

Clean-Up Call Percentage :  10%.

Clearing Agency :  An organization registered as a “clearing agency” pursuant to Section 17A of the Securities Exchange Act of 1934, as amended, which initially shall be DTC.

Closing Date :  March 24, 2005, which is the date of settlement of the sale of the Certificates to the original purchasers thereof.

Code :  The Internal Revenue Code of 1986, as amended.

Company :  Washington Mutual Mortgage Securities Corp., a Delaware corporation, or its successor-in-interest.

Compensating Interest : For any Distribution Date, the least of (i) the sum of (a) the aggregate Master Servicing Fee payable with respect to the Mortgage Loans on such Distribution Date, (b) the aggregate Payoff Earnings with respect to the Mortgage Loans for such Distribution Date and (c) the aggregate Payoff Interest with respect to the Mortgage Loans for such Distribution Date; (ii) the aggregate Uncollected Interest with respect to the Mortgage Loans for such Distribution Date and (iii) 1/12 of 0.125% of the aggregate Principal Balance of the Mortgage Loans immediately preceding such Distribution Date.

Cooperative :  A private, cooperative housing corporation which owns or leases land and all or part of a building or buildings, including apartments, spaces used for commercial purposes and common areas therein and whose board of directors authorizes, among other things, the sale of Cooperative Stock.

Cooperative Apartment :  A dwelling unit in a multi-dwelling building owned or leased by a Cooperative, which unit the Mortgagor has an exclusive right to occupy pursuant to the terms of a proprietary lease or occupancy agreement.

Cooperative Lease :  With respect to a Cooperative Loan, the proprietary lease or occupancy agreement with respect to the Cooperative Apartment occupied by the Mortgagor and relating to the related Cooperative Stock, which lease or agreement confers an exclusive right to the holder of such Cooperative Stock to occupy such apartment.

Cooperative Loans :  Any of the Mortgage Loans made in respect of a Cooperative Apartment, evidenced by a Mortgage Note and secured by (i) a Security Agreement, (ii) the related Cooperative Stock Certificate, (iii) an assignment or mortgage of the Cooperative Lease, (iv) financing statements and (v) a stock power (or other similar instrument), and ancillary thereto, a Recognition Agreement, each of which was transferred and assigned to the Trust pursuant to Section 2.04.

Cooperative Stock :  With respect to a Cooperative Loan, the single outstanding class of stock, partnership interest or other ownership instrument in the related Cooperative.

Cooperative Stock Certificate :  With respect to a Cooperative Loan, the stock certificate or other instrument evidencing the related Cooperative Stock.

Corporate Trust Office :  The corporate trust office of the Trustee in the State of California, at which at any particular time its corporate trust business with respect to this Agreement shall be administered, which office at the date of the execution of this Agreement is located at 1761 East St. Andrew Place, Santa Ana, CA 92705, Attention: Trust Administration WA05A4.

Corporation :  Any Person (other than an individual, partnership, joint venture or unincorporated organization) incorporated, associated, organized, chartered or existing under the laws of any state or under the federal laws of the United States of America; provided , that such Person have indefinite existence under the law of its domicile.

Corresponding Class :  With respect to the Class A and Class B Certificates and the REMIC I Regular Interests, the “Corresponding Class” shall be as indicated in the following table:

Credit Support Depletion Date :  The first Distribution Date on which the aggregate Class Principal Balance of the Class B Certificates has been or will be reduced to zero as a result of principal distributions thereon and the allocation of Realized Losses on such Distribution Date.

Cumulative Carry-Forward Subsequent Recoveries Amount :  For any Distribution Date, the sum of (i) the Carry-Forward Subsequent Recoveries Amount for such Distribution Date and (ii) the Carry-Forward Subsequent Recoveries Amounts for prior Distribution Dates to the extent such Carry-Forward Subsequent Recoveries Amounts have not been applied in reduction of Realized Losses on prior Distribution Dates pursuant to the first paragraph of the definition of “Realized Loss” herein.

Curtailment :  Any payment of principal on a Mortgage Loan, made by or on behalf of the related Mortgagor, other than a Monthly Payment, a Prepaid Monthly Payment or a Payoff, which is applied to reduce the outstanding principal balance of the Mortgage Loan.  (Prepayment penalties are not payments of principal and hence Curtailments do not include prepayment penalties).

Curtailment Shortfall :  For any Distribution Date and for any Curtailment applied with a Monthly Payment in the Prior Period other than a Prepaid Monthly Payment, an amount equal to one month’s interest on such Curtailment at the applicable Pass-Through Rate on such Mortgage Loan.

Custodial Account for P&I :  The Custodial Account for principal and interest established and maintained by each Servicer pursuant to its Selling and Servicing Contract and caused by the Master Servicer to be established and maintained pursuant to Section 3.02 (a) with a financial institution approved by the Master Servicer such that the rights of the Master Servicer, the Trust, the Trustee, the Delaware Trustee and the Certificateholders thereto shall be fully protected against the claims of any creditors of the applicable Servicer and of any creditors or depositors of the institution in which such account is maintained, (b) within FDIC insured accounts (or other accounts with comparable insurance coverage acceptable to the Rating Agencies) created, maintained and monitored by a Servicer or (c) in a separate non-trust account without FDIC or other insurance in an Eligible Institution (including the Trustee). In the event that a Custodial Account for P&I is established pursuant to clause (b) of the preceding sentence, amounts held in such Custodial Account for P&I shall not exceed the level of deposit insurance coverage on such account; accordingly, more than one Custodial Account for P&I may be established. Any amount that is at any time not protected or insured in accordance with the first sentence of this definition of “Custodial Account for P&I” shall promptly be withdrawn from such Custodial Account for P&I and be remitted to the Investment Account.

Custodial Account for Reserves :  The Custodial Account for Reserves established and maintained by each Servicer pursuant to its Selling and Servicing Contract and caused by the Master Servicer to be established and maintained pursuant to Section 3.02 (a) with a financial institution approved by the Master Servicer such that the rights of the Master Servicer, the Trust, the Trustee, the Delaware Trustee and the Certificateholders thereto shall be fully protected against the claims of any creditors of the applicable Servicer and of any creditors or depositors of the institution in which such account is maintained, (b) within FDIC insured accounts (or other accounts with comparable insurance coverage acceptable to the Rating Agencies) created, maintained and monitored by a Servicer or (c) in a separate non-trust account without FDIC or other insurance in an Eligible Institution (including the Trustee). In the event that a Custodial Account for Reserves is established pursuant to clause (b) of the preceding sentence, amounts held in such Custodial Account for Reserves shall not exceed the level of deposit insurance coverage on such account; accordingly, more than one Custodial Account for Reserves may be established. Any amount that is at any time not protected or insured in accordance with the first sentence of this definition of “Custodial Account for Reserves” shall promptly be withdrawn from such Custodial Account for Reserves and be remitted to the Investment Account.

Custodial Agreement :  The agreement, if any, between the Trustee and a Custodian (or the Trustee, a Custodian and the Master Servicer) providing for the safekeeping of the Mortgage Files on behalf of the Trust.

Custodian :  A custodian which is appointed by the Trustee with the consent of the Master Servicer, as provided in Article II hereof, pursuant to a Custodial Agreement. Any Custodian so appointed shall act as agent on behalf of the Trustee.  The reasonable fees and expenses of the Custodian shall be paid by the Master Servicer.  The Trustee shall remain at all times responsible under the terms of this Agreement, notwithstanding the fact that certain duties have been assigned to a Custodian.

Cut-Off Date :  March 1, 2005.

Definitive Certificates :  Certificates in definitive, fully registered and certificated form.

DelawareTrustee :  Deutsche Bank Trust Company Delaware, or its successor-in-interest as provided in Section 8.09, or any successor trustee appointed as herein provided.

Depositary Agreement :  The Letter of Representations, dated March 23, 2005 by and among DTC, the Trust and the Trustee. The Trustee is authorized to enter into the Depositary Agreement on behalf of the Trust. 

Destroyed Mortgage Note :  A Mortgage Note the original of which (or a portion of the original of which) was permanently lost or destroyed and has not been replaced.

Determination Date :  A day not later than the 10th day preceding a related Distribution Date, as determined by the Master Servicer.

Disqualified Organization :  Any Person which is not a Permitted Transferee, but does not include any Pass-Through Entity which owns or holds a Residual Certificate and of which a Disqualified Organization, directly or indirectly, may be a stockholder, partner or beneficiary.

Distribution Date :  With respect to distributions on the REMIC I Regular Interests and the Certificates, the 25th day (or, if such 25th day is not a Business Day, the Business Day immediately succeeding such 25th day) of each month, with the first such date being April 25, 2005.  The “related Due Date” for any Distribution Date is the Due Date immediately preceding such Distribution Date.

DTC :  The Depository Trust Company.

DTC Participant :  A broker, dealer, bank, other financial institution or other Person for whom DTC effects book-entry transfers and pledges of securities deposited with DTC.

Due Date :  The day on which the Monthly Payment for each Mortgage Loan is due.

Eligible Institution :  An institution having (i) the highest short-term debt rating, and one of the two highest long-term debt ratings of the Rating Agencies, (ii) with respect to any Custodial Account for P&I and special Custodial Account for Reserves, an unsecured long-term debt rating of at least one of the two highest unsecured long-term debt ratings of the Rating Agencies, (iii) with respect to any Buydown Fund Account or Custodial Account which also serves as a Buydown Fund Account, the highest unsecured long-term debt rating by the Rating Agencies, or (iv) the approval of the Rating Agencies.  Such institution may be the Servicer if the applicable Selling and Servicing Contract requires the Servicer to provide the Master Servicer with written notice on the Business Day following the date on which the Servicer determines that such Servicer’s short-term debt and unsecured long-term debt ratings fail to meet the requirements of the prior sentence.  Notwithstanding the foregoing, Washington Mutual Bank, FA shall be an “Eligible Institution” if the following conditions are satisfied: (i) Washington Mutual Bank, FA is acting as Servicer, (ii) if S&P is a Rating Agency as defined herein, the long-term unsecured debt obligations of Washington Mutual Bank, FA are rated no lower than “A-” by S&P and the short-term unsecured debt obligations of Washington Mutual Bank, FA are rated no lower than “A-2” by S&P, (iii) if Fitch is a Rating Agency as defined herein, the long-term unsecured debt obligations of Washington Mutual Bank, FA are rated no lower than “A” by Fitch and the short-term unsecured debt obligations of Washington Mutual Bank, FA are rated no lower than “F1” by Fitch and (iv) if Moody’s is a Rating Agency as defined herein, the long-term unsecured debt obligations of Washington Mutual Bank, FA are rated no lower than “A2” by Moody’s and the short-term unsecured debt obligations of Washington Mutual Bank, FA are rated no lower than “P-1” by Moody’s; provided, that if the long-term or short-term unsecured debt obligations of Washington Mutual Bank, FA are downgraded by any of the Rating Agencies to a rating lower than the applicable rating specified in this sentence, Washington Mutual Bank, FA shall cease to be an “Eligible Institution” ten Business Days after notification of such downgrade.

Eligible Investments :  Any one or more of the obligations or securities listed below in which funds deposited in the Investment Account, the Certificate Account, the Custodial Account for P&I and the Custodial Account for Reserves may be invested:

(i)                  Obligations of, or guaranteed as to principal and interest by, the United States of America or any agency or instrumentality thereof when such obligations are backed by the full faith and credit of the United States of America;

(ii)                Repurchase agreements on obligations described in clause (i) of this definition of “Eligible Investments,” provided that the unsecured obligations of the party (including the Trustee in its commercial capacity) agreeing to repurchase such obligations have at the time one of the two highest short term debt ratings  of the Rating Agencies and provided that such repurchaser’s unsecured long term debt has one of the two highest unsecured long term debt ratings of the Rating Agencies;

(iii)               Federal funds, certificates of deposit, time deposits and bankers’ acceptances of any U.S. bank or trust company incorporated under the laws of the United States of America or any state (including the Trustee in its commercial capacity), provided that the debt obligations of such bank or trust company (or, in the case of the principal bank in a bank holding company system, debt obligations of the bank holding company) at the date of acquisition thereof have one of the two highest short term debt ratings of the Rating Agencies and unsecured long term debt has one of the two highest unsecured long term debt ratings of the Rating Agencies;

(iv)              Obligations of, or obligations guaranteed by, any state of the United States of America or the District of Columbia, provided that such obligations at the date of acquisition thereof shall have the highest long-term debt ratings available for such securities from the Rating Agencies;

(v)                Commercial paper of any corporation incorporated under the laws of the United States of America or any state thereof, which on the date of acquisition has the highest commercial paper rating of the Rating Agencies, provided that the corporation has unsecured long term debt that has one of the two highest unsecured long term debt ratings of the Rating Agencies;

(vi)              Securities (other than stripped bonds or stripped coupons) bearing interest or sold at a discount that are issued by any corporation incorporated under the laws of the United States of America or any state thereof and have the highest long-term unsecured rating available for such securities from the Rating Agencies; provided, however , that securities issued by any such corporation will not be investments to the extent that investment therein would cause the outstanding principal amount of securities issued by such corporation that are then held as part of the Investment Account or the Certificate Account to exceed 20% of the aggregate principal amount of all Eligible Investments then held in the Investment Account and the Certificate Account; and

(vii)             Units of taxable money market funds (which may be 12b-1 funds, as contemplated under the rules promulgated by the Securities and Exchange Commission under the Investment Company Act of 1940), which funds have the highest rating available for such securities from the Rating Agencies or which have been designated in writing by the Rating Agencies as Eligible Investments;

provided, however , that such obligation or security is held for a temporary period pursuant to Section 1.860G-2(g)(1) of the Treasury Regulations, and that such period can in no event exceed thirteen months.

In no event shall an instrument be an Eligible Investment if such instrument (a) evidences a right to receive only interest payments with respect to the obligations underlying such instrument or (b) has been purchased at a price greater than the outstanding principal balance of such instrument.

ERISA :  The Employee Retirement Income Security Act of 1974, as amended.

ERISA Restricted Certificate :  Any Senior Subordinate Certificate.

Event of Default :  Any event of default as specified in Section 7.01.

Excess Liquidation Proceeds :  With respect to any Distribution Date, the sum of (i) the excess, if any, of aggregate Liquidation Proceeds received during the Prior Period over the amount that would have been received if Payoffs had been made with respect to such Mortgage Loans on the date such Liquidation Proceeds were received and (ii) any Excess Subsequent Recoveries for such Distribution Date.

Excess Subsequent Recoveries : For any Distribution Date, the excess, if any, of (i) amounts received by the Master Servicer during the Prior Period (after deduction of amounts reimbursable under Section 3.05(a)(i) and (ii)) in connection with the liquidation of defaulted Mortgage Loans after such Mortgage Loans became Liquidated Mortgage Loans over (ii) the Subsequent Recoveries for such Distribution Date.

Fannie Mae :  The entity formerly known as the Federal National Mortgage Association, or any successor thereto.

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

FHA :  Federal Housing Administration, or any successor thereto.

Final Maturity Date :  With respect to each Class of the REMIC I Regular Interests and the Certificates, the date set forth in the applicable table contained in the Preliminary Statement hereto.

Fitch : Fitch Ratings, provided that at any time it be a Rating Agency.

Freddie Mac :  The entity formerly known as the Federal Home Loan Mortgage Corporation, or any successor thereto.

GCD :  Greenwich Capital Derivatives, Inc.

Index :  Initially, either One-Year CMT or One-Year LIBOR, as set forth on the Mortgage Loan Schedule.  In the event such initial Index is no longer available, the Master Servicer will select a substitute Index in accordance with the terms of the related Mortgage Note and in compliance with applicable law.

Indirect DTC Participants :  Entities such as banks, brokers, dealers or trust companies, that clear through or maintain a custodial relationship with a DTC Participant, either directly or indirectly.

Initial Custodial Agreement :  The Custodial Agreement, dated the date hereof, among the Trustee, the Master Servicer and the Initial Custodian.

Initial Custodian :  Washington Mutual Bank fsb, which has been designated by the Company to be appointed by the Trustee to act as Custodian, and whose appointment has been approved by the Master Servicer.

Insurance Proceeds :  Amounts paid or payable by the insurer under any Primary Insurance Policy or any other insurance policy (including any replacement policy permitted under this Agreement) covering any Mortgage Loan or Mortgaged Property, including, without limitation, any hazard insurance policy required pursuant to Section 3.07, any title insurance policy required pursuant to Section 2.08 and any FHA insurance policy or VA guaranty.

Interest Distribution Amount :  For any Distribution Date, for any Class of REMIC I Regular Interests and the Class R-1 Residual Interest, the amount of interest accrued during the Prior Period, at the related Certificate Interest Rate for such Class for such Distribution Date, on the respective Class Principal Balance immediately before such Distribution Date, reduced by Uncompensated Interest Shortfall and the interest portion of Realized Losses allocated to such Class on such Distribution Date pursuant to the definitions of “Uncompensated Interest Shortfall” and “Realized Loss,” respectively.

For any Distribution Date, for any Class of Class A and Class X Certificates, the amount of interest accrued during the Prior Period (or, in the case of the Class A-1, Class A-2A and Class A-2B Certificates, during the No-Delay Class A Accrual Period), at the related Certificate Interest Rate for such Class for such Distribution Date, on the respective Class Principal Balance or Class Notional Amount, as applicable, immediately before such Distribution Date, reduced by Uncompensated Interest Shortfall and the interest portion of Realized Losses allocated to such Class on such Distribution Date pursuant to the definitions of “Uncompensated Interest Shortfall” and “Realized Loss,” respectively.

The computation of interest accrued shall be made on the basis of a 360-day year of twelve 30-day months. The interest accrual period for each Class of Regular Interests or Certificates shall be deemed to consist of 30 days, except that with respect to the computation of interest accrued on the Class A-1, Class A-2A and Class A-2B Certificates for the first Distribution Date, the No-Delay Class A Accrual Period shall be deemed to consist of 31 days.

Investment Account :  The commingled account (which shall be commingled only with investment accounts related to series of pass-through certificates with a class of certificates which has a rating equal to the highest of the Ratings of the Certificates) maintained by the Master Servicer in the trust department of the Investment Depository pursuant to Section 3.03 and which bears a designation acceptable to the Rating Agencies.

Investment Depository :  JPMorgan Chase Bank, N.A., or another bank or trust company designated from time to time by the Master Servicer. The Investment Depository shall at all times be an Eligible Institution.

Junior Subordinate Certificates :  The Class B-4, Class B-5 and Class B-6 Certificates.

Last Scheduled Distribution Date :  With respect to any Class of Certificates, the Final Maturity Date for such Class.

Lender :  An institution from which the Company purchased any Mortgage Loans pursuant to a Selling and Servicing Contract.

Liquidated Mortgage Loan :  A Mortgage Loan (other than a Mortgage Loan with respect to which a Payoff has been made) for which the Master Servicer or the applicable Servicer has determined in accordance with its customary servicing practices that it has received all amounts which it expects to recover from or on account of such Mortgage Loan, whether from Insurance Proceeds, Liquidation Proceeds or otherwise. For purposes of this definition, acquisition of a Mortgaged Property by the Trust shall not constitute final liquidation of the related Mortgage Loan.

Liquidation Principal :  The principal portion of Liquidation Proceeds received with respect to each Mortgage Loan which became a Liquidated Mortgage Loan (but not in excess of the principal balance thereof) during the Prior Period.

Liquidation Proceeds :  Amounts after deduction of amounts reimbursable under Section 3.05(a)(i) and (ii) received and retained in connection with the liquidation of defaulted Mortgage Loans, whether through foreclosure or otherwise, other than any Subsequent Recoveries.

Loan-to-Value Ratio :  The original principal amount of a Mortgage Loan divided by the Original Value; provided, however, that references to “current Loan-to-Value Ratio” or “Loan-to-Value Ratio as of the Cut-Off Date” in Section 2.08 shall be deemed to mean the then current Principal Balance of a Mortgage Loan divided by the Original Value.

Lowest Class B Owner :  An owner unaffiliated with the Company or the Master Servicer of (i) a 100% interest in the Class of Class B Certificates with the lowest priority or (ii) a 100% interest in a class of securities representing such interest in such Class specified in clause (i) above.

Margin :  For each Mortgage Loan, the applicable fixed per annum percentage rate specified in the applicable Mortgage Note and designated as such in the Mortgage Loan Schedule.

Master Servicer :  The Company, or any successor thereto appointed as provided pursuant to Section 7.02, acting to service and administer the Mortgage Loans pursuant to Section 3.01.

Master Servicer Business Day :  Any day other than a Saturday, a Sunday, or a day on which banking institutions in Chicago, Illinois are authorized or obligated by law or executive order to be closed.

Master Servicing Fee :  For each Mortgage Loan, the fee charged by the Master Servicer for supervising the mortgage servicing and advancing certain expenses, equal to 1/12 of the product of (i) the Master Servicing Fee Rate for such Mortgage Loan and (ii) the outstanding Principal Balance of such Mortgage Loan, payable monthly from the Certificate Account, the Investment Account or the Custodial Account for P&I.

Master Servicing Fee Rate :  For each Mortgage Loan, the per annum rate set forth for such Mortgage Loan in the Mortgage Loan Schedule, equal to 0.050%.

MERS :  Mortgage Electronic Registration Systems, Inc., a Delaware corporation, or any successor thereto.

MERS Loan :  Any Mortgage Loan registered on the MERS® System for which MERS appears as the mortgagee of record on the Mortgage or on an assignment thereof.

MERS® System :  The system of electronically recording transfers of Mortgages maintained by MERS.

MIN :  The Mortgage Identification Number for a MERS Loan.

MOM Loan :  A Mortgage Loan that was registered on the MERS® System at the time of origination thereof and for which MERS appears as the mortgagee of record on the Mortgage.

Monthly P&I Advance :  An advance of funds by the Master Servicer pursuant to Section 4.02 or a Servicer pursuant to its Selling and Servicing Contract to cover delinquent principal and interest installments.

Monthly Payment :  The scheduled payment of principal (if any) and interest on a Mortgage Loan (including any amounts due from a Buydown Fund, if any) which is due on the related Due Date for such Mortgage Loan.

Moody’s :  Moody’s Investors Service, Inc., provided that at any time it be a Rating Agency.

Mortgage :  The mortgage, deed of trust or other instrument securing a Mortgage Note.

Mortgage File :  The following documents or instruments with respect to each Mortgage Loan transferred and assigned by the Company pursuant to Section 2.04, (X) with respect to each Mortgage Loan that is not a Cooperative Loan:

(i)                  The original Mortgage Note endorsed (A) in blank, without recourse, or (B) to “Deutsche Bank National Trust Company, as Trustee, without recourse” or to “WaMu Mortgage Pass-Through Certificates Series 2005-AR4 Trust, without recourse” and all intervening endorsements evidencing a complete chain of endorsements from the originator to the Trustee or the Trust, as applicable, or, in the event of any Destroyed Mortgage Note, a copy or a duplicate original of the Mortgage Note, together with an original lost note affidavit from the originator of the Mortgage Loan or the Company (or any affiliate of the Company from which the Company acquired the Mortgage Loan), as applicable, stating that the original Mortgage Note (or portion thereof, as applicable) was lost, misplaced or destroyed, together with a copy of the Mortgage Note; provided, however, that in the event the Company acquired the Mortgage Loan from an affiliate of the Company, then the Mortgage Note need not be endorsed in blank or to Deutsche Bank National Trust Company or the Trust as provided above (but, if not so endorsed, shall be made payable to, or endorsed by the mortgagee named therein to, such affiliate of the Company);

(ii)        The Buydown Agreement, if applicable;

(iii)       A Mortgage that is either

(1)        (x) the original recorded Mortgage with evidence of recording thereon for the jurisdiction in which the Mortgaged Property is located (which original recorded Mortgage, in the case of a MOM Loan, shall set forth the MIN and shall indicate that the Mortgage Loan is a MOM Loan), (y) unless the Mortgage Loan is a MERS Loan, an original Mortgage assignment thereof duly executed and acknowledged in recordable form (A) in blank or (B) to “Deutsche Bank National Trust Company, as Trustee,” or to “WaMu Mortgage Pass-Through Certificates Series 2005-AR4 Trust,” and (z) unless the Mortgage Loan is a MOM Loan, recorded originals of all intervening assignments evidencing a complete chain of assignment, from the originator to the name holder or the payee endorsing the related Mortgage Note (or, in the case of a MERS Loan other than a MOM Loan, from the originator to MERS); or

(2)        (x) a copy (which may be in electronic form) of the Mortgage (which Mortgage, in the case of a MOM Loan, shall set forth the MIN and shall indicate that the Mortgage Loan is a MOM Loan) which represents a true and correct reproduction of the original Mortgage and which has either been certified (i) on the face thereof by the public recording office in the appropriate jurisdiction in which the Mortgaged Property is located, or (ii) by the originator, the related Lender or the escrow or title company which provided closing services in connection with such Mortgage Loan as a true and correct copy the original of which has been sent for recordation, (y) unless the Mortgage Loan is a MERS Loan, an original Mortgage assignment thereof duly executed and acknowledged in recordable form (A) in blank or (B) to “Deutsche Bank National Trust Company, as Trustee,” or to “WaMu Mortgage Pass-Through Certificates Series 2005-AR4 Trust” and (z) unless the Mortgage Loan is a MOM Loan, true and correct copies, certified by the applicable county recorder or by the originator or Lender as described above, of all intervening assignments evidencing a complete chain of assignment from the originator to the name holder or the payee endorsing the related Mortgage Note (or, in the case of a MERS Loan other than a MOM Loan, from the originator to MERS);

provided, however, that in the event the Company acquired the Mortgage Loan from an affiliate of the Company, then the Mortgage File need not include a Mortgage assignment executed in blank or to Deutsche Bank National Trust Company or the Trust as provided in clause (X)(iii)(1)(y) or (X)(iii)(2)(y) above, as applicable (but the Mortgage File shall, unless the Mortgage Loan was originated by such affiliate of the Company, include an intervening Mortgage assignment to such affiliate as provided in clause (X)(iii)(1)(z) or (X)(iii)(2)(z) above, as applicable); and

(iv)       For any Mortgage Loan that has been modified or amended, the original instrument or instruments effecting such modification or amendment;

and (Y) with respect to each Cooperative Loan:

(i)         The original Mortgage Note endorsed (A) in blank, without recourse, or (B) to “Deutsche Bank National Trust Company, as Trustee, without recourse” or to “WaMu Mortgage Pass-Through Certificates Series 2005-AR4 Trust, without recourse” and all intervening endorsements evidencing a complete chain of endorsements, from the originator to the Trustee or the Trust, as applicable, or, in the event of any Destroyed Mortgage Note, a copy or a duplicate original of the Mortgage Note, together with an original lost note affidavit from the originator of the Cooperative Loan or the Company (or any affiliate of the Company from which the Company acquired the Mortgage Loan), as applicable, stating that the original Mortgage Note (or portion thereof, as applicable) was lost, misplaced or destroyed, together with a copy of the Mortgage Note; provided, however, that in the event the Company acquired the Cooperative Loan from an affiliate of the Company, then the Mortgage Note need not be endorsed in blank or to Deutsche Bank National Trust Company or the Trust as provided above (but, if not so endorsed, shall be made payable to, or endorsed by the originator or successor lender named therein to, such affiliate of the Company);

(ii)        A counterpart of the Cooperative Lease and the Assignment of Proprietary Lease to the originator of the Cooperative Loan;

(iii)       The related Cooperative Stock Certificate, representing the related Cooperative Stock pledged with respect to such Cooperative Loan, together with an undated stock power (or other similar instrument) executed in blank;

(iv)       The Recognition Agreement;

(v)        The Security Agreement;

(vi)       Copies of the original UCC financing statement, and any continuation statements, filed by the originator of such Cooperative Loan as secured party, each with evidence of recording thereof, evidencing the interest of the originator under the Security Agreement and the Assignment of Proprietary Lease;

(vii)      Copies of the filed UCC assignments or amendments of the security interest referenced in clause (vi) above showing an unbroken chain of title from the originator to the Trust, each with evidence of recording thereof, evidencing the interest of the assignee under the Security Agreement and the Assignment of Proprietary Lease;

(viii)      An executed assignment of the interest of the originator in the Security Agreement, the Assignment of Proprietary Lease and the Recognition Agreement, showing an unbroken chain of title from the originator to the Trust; and

(ix)       For any Cooperative Loan that has been modified or amended, the original instrument or instruments effecting such modification or amendment;

provided, however, that in the event the Company acquired the Cooperative Loan from an affiliate of the Company, then the Mortgage File need not include (1) a UCC assignment or amendment of the security interest referenced in clause (Y)(vi) above to the Trust as provided in clause (Y)(vii) above (but the Mortgage File shall, unless the Cooperative Loan was originated by such affiliate of the Company, include a UCC assignment or amendment of such security interest to such affiliate) or (2) an assignment of the interest of the originator in the Security Agreement, the Assignment of Proprietary Lease and the Recognition Agreement to the Trust as provided in clause (Y)(viii) above (but the Mortgage File shall, unless the Cooperative Loan was originated by such affiliate of the Company, include an assignment of such interest to such affiliate).

Mortgage Interest Rate :  For any Mortgage Loan, the per annum rate at which interest accrues on such Mortgage Loan pursuant to the terms of the related Mortgage Note.

Mortgage Loan Schedule :  The schedule, as amended from time to time, of Mortgage Loans attached hereto as Exhibit D, which shall set forth as to each Mortgage Loan the following, among other things:

(i)         its loan number,

(ii)        the address of the Mortgaged Property,

(iii)       the name of the Mortgagor,

(iv)       the Original Value of the property subject to the Mortgage,

(v)        the Principal Balance as of the Cut-Off Date,

(vi)       the Mortgage Interest Rate, as of the Cut-Off Date, borne by the Mortgage Note and the Rate Ceiling, Rate Floor, subsequent Periodic Cap, Index and Margin, as applicable, borne by the Mortgage Note,

(vii)      whether a Primary Insurance Policy is in effect as of the Cut-Off Date, and, if so, whether such Primary Insurance Policy is a Special Primary Insurance Policy,

(viii)      the maturity of the Mortgage Note,

(ix)       the Master Servicing Fee Rate and the Servicing Fee Rate, and

(x)        whether it imposes penalties for early prepayments.

Mortgage Loans :  The mortgage loans and cooperative loans (if any) listed on the Mortgage Loan Schedule and transferred and assigned to the Trust pursuant hereto. With respect to each Mortgage Loan that is a Cooperative Loan, “Mortgage Loan” shall include, but not be limited to, the Mortgage Note, Security Agreement, Assignment of Proprietary Lease, Recognition Agreement, Cooperative Stock Certificate and Cooperative Lease, and, with respect to each Mortgage Loan other than a Cooperative Loan, “Mortgage Loan” shall include, but not be limited to the Mortgage Note and the related Mortgage.

Mortgage Note :  The note or other evidence of the indebtedness of a Mortgagor under a Mortgage Loan.

Mortgage Pool :  All of the Mortgage Loans.

Mortgage Pool Assets :  (i) The Mortgage Loans (including all Substitute Mortgage Loans) identified on the Mortgage Loan Schedule, and all rights pertaining thereto, including the related Mortgage Notes, Mortgages, Cooperative Stock Certificates, Cooperative Leases, Security Agreements, Assignments of Proprietary Lease, and Recognition Agreements, and all payments and distributions with respect to the Mortgage Loans payable on and after the Cut-Off Date; (ii) the Certificate Account, the Investment Account, and all money, instruments, investment property, and other property credited thereto, carried therein, or deposited therein (except amounts constituting the Master Servicing Fee or the Servicing Fee); (iii) the Custodial Accounts for P&I, the Custodial Accounts for Reserves, any Buydown Fund Account (to the extent of the amounts on deposit or other property therein attributable to the Mortgage Loans), and all money, instruments, investment property, and other property credited thereto, carried therein, or deposited therein (except amounts constituting the Master Servicing Fee or the Servicing Fee); (iv) all property that secured a Mortgage Loan and that has been acquired by foreclosure or deed in lieu of foreclosure or, in the case of a Cooperative Loan, a similar form of conversion, after the Cut-Off Date; and (v) each FHA insurance policy, Primary Insurance Policy, VA guaranty, and other insurance policy related to any Mortgage Loan, and all amounts paid or payable thereunder and all proceeds thereof.

Mortgaged Property :  With respect to any Mortgage Loan, other than a Cooperative Loan, the real property, together with improvements thereto, and, with respect to any Cooperative Loan, the related Cooperative Stock and Cooperative Lease, securing the indebtedness of the Mortgagor under the related Mortgage Loan.  “Mortgaged Property” shall also refer to property which once secured the indebtedness of a Mortgagor under the related Mortgage Loan but which was acquired by the Trust upon foreclosure or other liquidation of such Mortgage Loan.

Mortgagor :  The obligor on a Mortgage Note.

No-Delay Class A Accrual Period :  For any Distribution Date, the period beginning on the 25 ^th day of the month preceding that Distribution Date (or, in the case of the first Distribution Date, on the Closing Date) and ending on the 24th day of the month of that Distribution Date.

Nonrecoverable Advance :  With respect to any Mortgage Loan, any advance which the Master Servicer shall determine to be a Nonrecoverable Advance pursuant to Section 4.03 and which was, or is proposed to be, made by (i) the Master Servicer or (ii) a Servicer pursuant to its Selling and Servicing Contract.

Non-U.S. Person :  A Person that is not a U.S. Person.

Notice Addresses :  (a) In the case of the Company, 75 North Fairway Drive, Vernon Hills, Illinois 60061, Attention: Master Servicing Department, with a copy to: Washington Mutual Legal Department, 1201 Third Avenue, WMT 1706, Seattle, Washington 98101, Attention: WMMSC, or such other address as may hereafter be furnished to the Trustee in writing by the Company, (b) in the case of the Trustee, at its Corporate Trust Office, or such other address as may hereafter be furnished to the Master Servicer in writing by the Trustee, (c) in the case of the Delaware Trustee, 1011 Centre Road, Suite 200, Wilmington, Delaware 19805-1266, or such other address as may hereafter be furnished to the Master Servicer in writing by the Delaware Trustee, (d) in the case of the Trust, c/o Deutsche Bank National Trust Company, at the Corporate Trust Office, or such other address as may hereafter be furnished to the Master Servicer in writing by the Trustee, (e) in the case of the Certificate Registrar, at its Corporate Trust Office, or such other address as may hereafter be furnished to the Trustee in writing by the Certificate Registrar, (f) in the case of S&P, 55 Water Street, 41st Floor, New York, New York 10041-0003, Attention:  Frank Raiter, or such other address as may hereafter be furnished to the Trustee and Master Servicer in writing by S&P and (g) in the case of Moody’s, 99 Church Street, New York, New York 10007, Attention:  Monitoring, or such other address as may hereafter be furnished to the Trustee and Master Servicer in writing by Moody’s.

OTS :  The Office of Thrift Supervision, or any successor thereto.

Officer’s Certificate :  A certificate signed by the Chairman of the Board, the President, a Vice President, or the Treasurer of the Master Servicer and delivered to the Trustee or the Delaware Trustee, as applicable.

One-Year CMT :  The weekly average yield on United States Treasury Securities adjusted to a constant maturity of one year, as made available by the Federal Reserve Board, published in Federal Reserve Statistical Release H.15(519) most recently available as of 45 days before the applicable Adjustment Date.

One-Year LIBOR : The average of interbank offered rates for one-year U.S. dollar-denominated deposits in the London market, as published in The Wall Street Journal and most recently available as of the date 45 days before the applicable Adjustment Date.

Opinion of Counsel :  A written opinion of counsel, who shall be reasonably acceptable to the Trustee or the Delaware Trustee, as applicable, and who may be counsel (including in-house counsel) for the Company or the Master Servicer.

Original Trust Agreement :  The Trust Agreement, dated as of March 1, 2005, between the Company and the Delaware Trustee, providing for the creation of the Trust.

Original Value :  With respect to any Mortgage Loan other than a Mortgage Loan originated for the purpose of refinancing an existing mortgage debt, the lesser of (a) the Appraised Value (if any) of the Mortgaged Property at the time the Mortgage Loan was originated or (b) the purchase price paid for the Mortgaged Property by the Mortgagor. With respect to a Mortgage Loan originated for the purpose of refinancing existing mortgage debt, the Original Value shall be equal to the Appraised Value of the Mortgaged Property.

Ownership Interest :  With respect to any Residual Certificate, any ownership or security interest in such Residual Certificate, including any interest in a Residual Certificate as the Holder thereof and any other interest therein whether direct or indirect, legal or beneficial, as owner or as pledgee.

Pass-Through Entity :  Any regulated investment company, real estate investment trust, common trust fund, partnership, trust or estate, and any organization to which Section 1381 of the Code applies.

Pass-Through Rate :  For each Mortgage Loan, the Mortgage Interest Rate for such Mortgage Loan less (i) the Servicing Fee Rate for such Mortgage Loan, (ii) the Master Servicing Fee Rate for such Mortgage Loan and (iii) if such Mortgage Loan was covered by a Special Primary Insurance Policy on the Closing Date (even if no longer so covered), the per annum rate at which the applicable Special Primary Insurance Premium for such Mortgage Loan is calculated. For each Mortgage Loan, any calculation of monthly interest at such rate shall be based upon annual interest at such rate (computed on the basis of a 360-day year of twelve 30-day months) on the unpaid Principal Balance of such Mortgage Loan divided by twelve, and any calculation of interest at such rate by reason of a Payoff shall be based upon annual interest at such rate on the outstanding Principal Balance of such Mortgage Loan multiplied by a fraction, the numerator of which is the number of days elapsed from the Due Date of the last scheduled payment of principal and interest to, but not including, the date of such Payoff, and the denominator of which is (a) for Payoffs received on a Due Date, 360, and (b) for all other Payoffs, 365.

Paying Agent :  Any paying agent appointed by the Trustee pursuant to Section 8.12.

Payoff :  Any Mortgagor payment of principal on a Mortgage Loan equal to the entire outstanding Principal Balance of such Mortgage Loan, if received in advance of the last scheduled Due Date for such Mortgage Loan and accompanied by an amount of interest equal to accrued unpaid interest on the Mortgage Loan to the date of such payment-in-full.  (Prepayment penalties are not payments of principal and hence Payoffs do not include prepayment penalties.)

Payoff Earnings :  For any Distribution Date with respect to each Mortgage Loan on which a Payoff was received by the Master Servicer during the Payoff Period, the aggregate of the interest earned by the Master Servicer from investment of each such Payoff from the date of receipt of such Payoff until the Business Day immediately preceding the related Distribution Date (net of investment losses).

Payoff Interest :  For any Distribution Date with respect to a Mortgage Loan for which a Payoff was received on or after the first calendar day of the month of such Distribution Date and before the 15th calendar day of such month, an amount of interest thereon at the applicable Pass-Through Rate from the first day of the month of distribution through the day of receipt thereof; to the extent (together with Payoff Earnings and the aggregate Master Servicing Fee) not required to be distributed as Compensating Interest on such Distribution Date, Payoff Interest shall be payable to the Master Servicer as additional servicing compensation.

Payoff Period :  For the first Distribution Date, the period from the Cut-Off Date through April 14, 2005, inclusive; and for any Distribution Date thereafter, the period from the 15th day of the Prior Period through the 14th day of the month of such Distribution Date, inclusive.

Percentage Interest :  (a)  With respect to the right of each Certificate of a particular Class in the distributions allocated to such Class, “Percentage Interest” shall mean the percentage equal to:

(i)         with respect to any Certificate (other than the Class X and Residual Certificates), its Certificate Principal Balance divided by the applicable Class Principal Balance;

(ii)        with respect to any Class X Certificate, the portion of the Class X Notional Amount evidenced by such Certificate divided by the Class X Notional Amount; and

(iii)       with respect to any Residual Certificate, the percentage set forth on the face of such Certificate.

(b)        With respect to the rights of each Certificate in connection with Sections 5.09, 7.01, 8.01(c), 8.02, 8.07, 10.01 and 10.03, “Percentage Interest” shall mean the percentage equal to:

(i)         with respect to any Certificate (other than the Class X and Residual Certificates), the product of (x) ninety-nine percent (99%) and (y) its Certificate Principal Balance divided by the Aggregate Certificate Principal Balance of the Certificates; provided, however, that the percentage in clause (x) above shall be increased by one percent (1%) upon the retirement of the Class X Certificates;

(ii)        with respect to any Class X Certificate, one percent (1%) of such Certificate’s Percentage Interest as calculated by paragraph (a)(ii) of this definition; and

(iii)       with respect to any Residual Certificate, zero.

Periodic Cap :  For each Mortgage Loan, any applicable limit on adjustment of the Mortgage Interest Rate for each Adjustment Date specified in the applicable Mortgage Note and designated as such in the Mortgage Loan Schedule.

Permitted Transferee :  With respect to the holding or ownership of any Residual Certificate, any Person other than (i) the United States, a State or any political subdivision thereof, or any agency or instrumentality of any of the foregoing, (ii) a foreign government, International Organization or any agency or instrumentality of either of the foregoing, (iii) an organization (except certain farmers’ cooperatives described in Code Section 521) which is exempt from the taxes imposed by Chapter 1 of the Code (unless such organization is subject to the tax imposed by Section 511 of the Code on unrelated business taxable income), (iv) rural electric and telephone cooperatives described in Code Section 1381(a)(2)(C), (v) any “electing large partnership” as defined in Section 775(a) of the Code, (vi) any Person from whom the Trustee has not received an affidavit to the effect that it is not a “disqualified organization” within the meaning of Section 860E(e)(5) of the Code, and (vii) any other Person so designated by the Company based upon an Opinion of Counsel that the transfer of an Ownership Interest in a Residual Certificate to such Person may cause REMIC I or REMIC II to fail to qualify as a REMIC at any time that the Certificates are outstanding. The terms “United States,” “State” and “International Organization” shall have the meanings set forth in Code Section 7701 or successor provisions. A corporation shall not be treated as an instrumentality of the United States or of any State or political subdivision thereof if all of its activities are subject to tax, and, with the exception of the Freddie Mac, a majority of its board of directors is not selected by such governmental unit.

Person :  Any individual, corporation, limited liability company, partnership, joint venture, association, joint-stock company, trust, unincorporated organization or government or any agency or political subdivision thereof.

Prepaid Monthly Payment :  Any Monthly Payment received prior to its scheduled Due Date, which is intended to be applied to a Mortgage Loan on its scheduled Due Date and held in the related Custodial Account for P&I until the Withdrawal Date following its scheduled Due Date.

Primary Insurance Policy :  A policy of mortgage guaranty insurance, if any, on an individual Mortgage Loan or on pools of mortgage loans that include an individual Mortgage Loan, providing coverage as required by Section 2.08(xi) (including any Special Primary Insurance Policy).

Principal Balance :  Except as used in Sections 2.07, 3.09 and 9.01 and for purposes of the definition of Purchase Price, at the time of any determination, the principal balance of a Mortgage Loan remaining to be paid at the close of business on the Cut‑Off Date, after application of all scheduled principal payments due on or before the Cut‑Off Date, whether or not received, reduced by all amounts distributed or (except when such determination occurs earlier in the month than the Distribution Date) to be distributed to Certificateholders through the Distribution Date in the month of determination that are reported as allocable to principal of such Mortgage Loan.

For purposes of the definition of Purchase Price and as used in Sections 2.07, 3.09 and 9.01, at the time of any determination, the principal balance of a Mortgage Loan remaining to be paid at the close of business on the Cut-Off Date, after deduction of all scheduled principal payments due on or before the Cut-Off Date, whether or not received, reduced by all amounts distributed or to be distributed to Certificateholders through the Distribution Date in the month of determination that are reported as allocable to principal of such Mortgage Loan.

In the case of a Substitute Mortgage Loan, “Principal Balance” shall mean, at the time of any determination, the principal balance of such Substitute Mortgage Loan transferred to the Trust, on the date of substitution, reduced by all amounts distributed or to be distributed to Certificateholders through the Distribution Date in the month of determination that are reported as allocable to principal of such Substitute Mortgage Loan.

The Principal Balance of a Mortgage Loan (including a Substitute Mortgage Loan) shall not be adjusted solely by reason of any bankruptcy or similar proceeding or any moratorium or similar waiver or grace period. Whenever a Realized Loss has been incurred with respect to a Mortgage Loan during a calendar month, the Principal Balance of such Mortgage Loan shall be reduced by the amount of such Realized Loss as of the Due Date next following the end of such calendar month.

Principal Payment :  Any payment of principal on a Mortgage Loan other than a Principal Prepayment.

Principal Payment Amount :  For any Distribution Date, the sum of (i) the scheduled principal payments (if any) on the Mortgage Loans due on the related Due Date, (ii) the principal portion of proceeds received with respect to any Mortgage Loan which was purchased or repurchased pursuant to a Purchase Obligation or as permitted by this Agreement during the Prior Period and (iii) any other unscheduled payments of principal which were received with respect to any Mortgage Loan during the Prior Period, other than Payoffs, Curtailments, Liquidation Principal and Subsequent Recoveries.

Principal Prepayment :  Any payment of principal on a Mortgage Loan which constitutes a Payoff or a Curtailment.

Principal Prepayment Amount :  For any Distribution Date, the sum of (i) Curtailments received during the Prior Period from the Mortgage Loans and (ii) Payoffs received during the Payoff Period from the Mortgage Loans.

Prior Period :  With respect to any Distribution Date, the calendar month immediately preceding such Distribution Date.

Prospectus :   The Prospectus, dated March 21, 2005, and the Prospectus Supplement, dated March 21, 2005, of the Company.

Purchase Obligation :  An obligation of the Company to repurchase Mortgage Loans under the circumstances and in the manner provided in Section 2.07 or Section 2.08.

Purchase Price :  With respect to any Mortgage Loan to be purchased pursuant to a Purchase Obligation, an amount equal to the sum of (i) the Principal Balance thereof, (ii) unpaid accrued interest thereon, if any, during the calendar month in which the date of purchase occurs to the last day of such month at a rate equal to the applicable Pass-Through Rate and (iii) with respect to any Mortgage Loan to be purchased pursuant to Section 2.08, any costs and damages incurred by the Trust in connection with any violation by such Mortgage Loan of any predatory and abusive lending laws, to the extent such costs and damages result from a breach of the representation and warranty made by the Company pursuant to clause (viii) of Section 2.08; provided, however , that to the extent that such costs and damages constitute a set-off against the principal balance of the Mortgage Loan, such costs and damages will not be paid pursuant to this clause (iii), and the amount paid pursuant to clause (i) above will be calculated without regard to such set-off; provided, further, that no Mortgage Loan shall be purchased or required to be purchased pursuant to Section 2.08, or more than two years after the Closing Date under Section 2.07, unless (a) the Mortgage Loan to be purchased is in default, or default is in the judgment of the Company reasonably imminent, or (b) the Company, at its expense, delivers to the Trustee an Opinion of Counsel addressed to the Trust and the Trustee to the effect that the purchase of such Mortgage Loan will not give rise to a tax on a prohibited transaction, as defined in Section 860F(a) of the Code.

Qualified Insurer :  A mortgage guaranty insurance company duly qualified as such under the laws of the states in which the Mortgaged Properties are located if such qualification is necessary to issue the applicable insurance policy or bond, duly authorized and licensed in such states to transact the applicable insurance business and to write the insurance provided by the Primary Insurance Policies and approved as an insurer by the Master Servicer. A Qualified Insurer must have the rating required by the Rating Agencies.

Rate Ceiling :  The maximum per annum Mortgage Interest Rate permitted under the related Mortgage Note.

Rate Floor :  The minimum per annum Mortgage Interest Rate permitted under the related Mortgage Note.

Rating Agency :  Initially, each of S&P and Moody’s and thereafter, each nationally recognized statistical rating organization that has rated the Certificates at the request of the Company, or their respective successors in interest.

Ratings :  As of any date of determination, the ratings, if any, of the Certificates as assigned by the applicable Rating Agencies.

Realized Loss :  For any Distribution Date, with respect to any Mortgage Loan which became a Liquidated Mortgage Loan during the related Prior Period, the sum of (i) the principal balance of such Mortgage Loan remaining outstanding and the principal portion of Nonrecoverable Advances actually reimbursed with respect to such Mortgage Loan (the principal portion of such Realized Loss), and (ii) the accrued interest on such Mortgage Loan remaining unpaid and the interest portion of Nonrecoverable Advances actually reimbursed with respect to such Mortgage Loan (the interest portion of such Realized Loss); provided , however , that for purposes of allocating Realized Losses to the Certificates and the REMIC I Regular Interests pursuant to this definition of “Realized Loss,” the aggregate principal portion of Realized Losses for any Distribution Date shall be reduced by the Cumulative Carry-Forward Subsequent Recoveries Amount for such Distribution Date. For any Distribution Date, with respect to any Mortgage Loan which is not a Liquidated Mortgage Loan, the amount of the Bankruptcy Loss incurred with respect to such Mortgage Loan as of the related Due Date.

Realized Losses shall be allocated among the REMIC I Regular Interests (i) for Realized Losses allocable to principal (a) first, to the Class B-6-L Regular Interest, until the Class B-6-L Principal Balance has been reduced to zero, (b) second, to the Class B-5-L Regular Interest, until the Class B-5-L Principal Balance has been reduced to zero, (c) third, to the Class B-4-L Regular Interest, until the Class B-4-L Principal Balance has been reduced to zero, (d) fourth, to the Class B-3-L Regular Interest, until the Class B-3-L Principal Balance has been reduced to zero, (e) fifth, to the Class B-2-L Regular Interest, until the Class B-2-L Principal Balance has been reduced to zero, (f) sixth, to the Class B-1-L Regular Interest, until the Class B-1-L Principal Balance has been reduced to zero and (g) seventh, to the Class A-L Regular Interests, pro rata according to the Class Principal Balances thereof, in reduction thereof; and (ii) for Realized Losses allocable to interest (a) first, to the Class B-6-L Regular Interest, in reduction of accrued but unpaid interest thereon and then in reduction of the Class B-6-L Principal Balance, (b) second, to the Class B-5-L Regular Interest, in reduction of accrued but unpaid interest thereon and then in reduction of the Class B-5-L Principal Balance, (c) third, to the Class B-4-L Regular Interest, in reduction of accrued but unpaid interest thereon and then in reduction of the Class B-4-L Principal Balance, (d) fourth, to the Class B-3-L Regular Interest, in reduction of accrued but unpaid interest thereon and then in reduction of the Class B-3-L Principal Balance, (e) fifth, to the Class B-2-L Regular Interest, in reduction of accrued but unpaid interest thereon and then in reduction of the Class B-2-L Principal Balance, (f) sixth, to the Class B-1-L Regular Interest, in reduction of accrued but unpaid interest thereon and then in reduction of the Class B-1-L Principal Balance and (g) seventh, to the Class A-L Regular Interests, pro rata according to accrued but unpaid interest on such Classes, in reduction thereof, and then to such Classes, pro rata according to the Class Principal Balances thereof, in reduction thereof.

Realized Losses allocated to any Class of REMIC I Regular Interests pursuant to this definition of “Realized Loss” in reduction of the Class Principal Balance thereof shall also be allocated to the Corresponding Class of Certificates in reduction of the Class Principal Balance thereof by the same amount.

The aggregate of Realized Losses allocable to interest allocated to the Class A-L Regular Interests pursuant to the second or third paragraph, as applicable, of this definition of “Realized Loss” in reduction of accrued but unpaid interest thereon shall be allocated among the Class A and Class X Certificates pro rata according to accrued but unpaid interest on such Classes, in reduction thereof.

On each Distribution Date, after giving effect to the principal distributions and allocations of losses as provided in this Agreement (without regard to this paragraph), if the aggregate Class Principal Balance of all outstanding Classes of REMIC I Regular Interests and the Class R-1 Residual Interest (plus any Cumulative Carry-Forward Subsequent Recoveries Amount for such Distribution Date) exceeds the aggregate principal balance of the Mortgage Loans remaining to be paid at the close of business on the Cut-Off Date, after deduction of (i) all principal payments due on or before the Cut-Off Date in respect of each Mortgage Loan whether or not paid, and (ii) all amounts of principal in respect of each Mortgage Loan that have been received or advanced and included in the REMIC I Available Distribution Amount and all losses in respect of each Mortgage Loan that have been allocated to the REMIC I Regular Interests on such Distribution Date or prior Distribution Dates, then such excess will be deemed a principal loss and will be allocated to the most junior Class of Class B-L Regular Interests, in reduction of the Class Principal Balance thereof.

Recognition Agreement :  With respect to a Cooperative Loan, the recognition agreement between the Cooperative and the originator of such Cooperative Loan.

Record Date :  The last Business Day of the month immediately preceding the month of the related Distribution Date.

Regular Interests :  (i) With respect to REMIC I, the REMIC I Regular Interests and (ii) with respect to REMIC II, the REMIC II Regular Interests.

Relief Act Shortfall :  For any Distribution Date for any Mortgage Loan with respect to which the Servicemembers Civil Relief Act, formerly known as the Soldiers’ and Sailors’ Civil Relief Act of 1940, or any comparable state legislation (collectively, the “ Relief Act ”), limits the amount of interest payable by the related Mortgagor, an amount equal to one month’s interest on such Mortgage Loan at an annual interest rate equal to the excess, if any, of (i) the annual interest rate otherwise payable by the Mortgagor on the related Due Date under the terms of the related Mortgage Note over (ii) the annual interest rate payable by the Mortgagor on the related Due Date by application of the Relief Act.

REMIC :  A real estate mortgage investment conduit, as such term is defined in the Code.

REMIC Provisions :  Sections 860A through 860G of the Code, related Code provisions and regulations promulgated thereunder, as the foregoing may be in effect from time to time.

REMIC I :  The segregated pool of assets of the Trust consisting of the REMIC I Assets, which shall be a REMIC pursuant to the Code, with respect to which a separate REMIC election is to be made and the beneficial interests in which shall be the REMIC I Regular Interests and the Class R-1 Residual Interest.

REMIC I Assets :  All of the Mortgage Pool Assets.

REMIC I Available Distribution Amount :  For any Distribution Date, the sum of the following amounts with respect to the Mortgage Loans:

(1)  &nb