POOLING AND SERVICING AGREEMENT

Pooling and Servicing Agreement

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WELLS FARGO ASSET SECURITIES CORPORATION | WELLS FARGO BANK, N.A. | WACHOVIA BANK, NATIONAL ASSOCIATION

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Title: POOLING AND SERVICING AGREEMENT
Governing Law: New York Date: 6/21/2005

POOLING AND SERVICING AGREEMENT, Parties: wells fargo asset securities corporation , wells fargo bank n.a. , wachovia bank national association

EXHIBIT 4

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WELLS FARGO ASSET SECURITIES CORPORATION

(Seller)

and

WELLS FARGO BANK, N.A.

(Master Servicer)

and

WACHOVIA BANK, NATIONAL ASSOCIATION

(Trustee)

POOLING AND SERVICING AGREEMENT

Dated as of May 27, 2005

$1,500,693,806.75

Mortgage Pass-Through Certificates

Series 2005-AR13

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<PAGE>

TABLE OF CONTENTS

ARTICLE I

DEFINITIONS

Section 1.01 Definitions..............................................

Section 1.02 Acts of Holders..........................................

Section 1.03 Effect of Headings and Table of Contents.................

Section 1.04 Benefits of Agreement....................................

ARTICLE II

CONVEYANCE OF MORTGAGE LOANS;

ORIGINAL ISSUANCE OF THE CERTIFICATES

Section 2.01 Conveyance of Mortgage Loans.............................

Section 2.02 Acceptance by Custodian..................................

Section 2.03 Representations and Warranties of the Master Servicer and

the Seller...............................................

Section 2.04 Execution and Delivery of Certificates...................

Section 2.05 Designation of Certificates; Designation of Startup Day

and Latest Possible Maturity Date.......................

Section 2.06 Optional Substitution of Mortgage Loans..................

ARTICLE III

ADMINISTRATION OF THE TRUST ESTATE; SERVICING

OF THE MORTGAGE LOANS

Section 3.01 Certificate Account......................................

Section 3.02 Permitted Withdrawals from the Certificate Account.......

Section 3.03 Advances by Master Servicer and Trustee..................

Section 3.04 Custodian to Cooperate; Release of Owner Mortgage Loan

Files and Retained Mortgage Loan Files..................

Section 3.05 Reports to the Trustee; Annual Compliance Statements.....

Section 3.06 Title, Management and Disposition of Any REO Mortgage

Loan....................................................

Section 3.07 Amendments to Servicing Agreements,

Modification of Standard Provisions.....................

Section 3.08 Oversight of Servicing...................................

Section 3.09 Termination and Substitution of Servicing Agreements.....

Section 3.10 Application of Net Liquidation Proceeds..................

Section 3.11 Exchange Act Reports.....................................

ARTICLE IV

DISTRIBUTIONS IN RESPECT OF CERTIFICATES;

PAYMENTS TO CERTIFICATEHOLDERS;

STATEMENTS AND REPORTS

Section 4.01 Distributions............................................

Section 4.02 Allocation of Realized Losses............................

Section 4.03 Paying Agent.............................................

Section 4.04 Statements to Certificateholders;

Reports to the Trustee and the Seller...................

Section 4.05 Reports to Mortgagors and the Internal Revenue Service...

Section 4.06 Calculation of Amounts; Binding Effect of

Interpretations and Actions of Master Servicer..........

Section 4.07 Determination of LIBOR...................................

Section 4.08 Reserve Funds............................................

ARTICLE V

THE CERTIFICATES

Section 5.01 The Certificates.........................................

Section 5.02 Registration of Certificates.............................

Section 5.03 Mutilated, Destroyed, Lost or Stolen Certificates........

Section 5.04 Persons Deemed Owners....................................

Section 5.05 Access to List of Certificateholders' Names and Addresses

Section 5.06 Maintenance of Office or Agency..........................

Section 5.07 Definitive Certificates..................................

Section 5.08 Notices to Clearing Agency...............................

ARTICLE VI

THE SELLER AND THE MASTER SERVICER

Section 6.01 Liability of the Seller and the Master Servicer..........

Section 6.02 Merger or Consolidation of the Seller or the Master

Servicer................................................

Section 6.03 Limitation on Liability of the Seller, the Master

Servicer and Others.....................................

Section 6.04 Resignation of the Master Servicer.......................

Section 6.05 Compensation to the Master Servicer......................

Section 6.06 Assignment or Delegation of Duties by Master Servicer....

Section 6.07 Indemnification of Trustee and Seller by Master Servicer.

ARTICLE VII

DEFAULT

Section 7.01 Events of Default........................................

Section 7.02 Other Remedies of Trustee................................

Section 7.03 Directions by Certificateholders and

Duties of Trustee During Event of Default...............

Section 7.04 Action upon Certain Failures of the

Master Servicer and upon Event of Default...............

Section 7.05 Trustee to Act; Appointment of Successor.................

Section 7.06 Notification to Certificateholders.......................

ARTICLE VIII

CONCERNING THE TRUSTEE

Section 8.01 Duties of Trustee........................................

Section 8.02 Certain Matters Affecting the Trustee....................

Section 8.03 Trustee Not Required to Make Investigation...............

Section 8.04 Trustee Not Liable for Certificates or Mortgage Loans....

Section 8.05 Trustee May Own Certificates.............................

Section 8.06 The Master Servicer to Pay Fees and Expenses.............

Section 8.07 Eligibility Requirements.................................

Section 8.08 Resignation and Removal..................................

Section 8.09 Successor................................................

Section 8.10 Merger or Consolidation..................................

Section 8.11 Authenticating Agent.....................................

Section 8.12 Separate Trustees and Co-Trustees........................

Section 8.13 Tax Matters; Compliance with REMIC Provisions............

Section 8.14 Monthly Advances.........................................

ARTICLE IX

TERMINATION

Section 9.01 Termination upon Purchase by the

Seller or Liquidation of All Mortgage Loans.............

Section 9.02 Additional Termination Requirements......................

ARTICLE X

MISCELLANEOUS PROVISIONS

Section 10.01 Amendment................................................

Section 10.02 Recordation of Agreement.................................

Section 10.03 Limitation on Rights of Certificateholders...............

Section 10.04 Governing Law; Jurisdiction..............................

Section 10.05 Notices..................................................

Section 10.06 Severability of Provisions...............................

Section 10.07 Special Notices to Rating Agencies.......................

Section 10.08 Covenant of Seller.......................................

Section 10.09 Recharacterization.......................................

ARTICLE XI

TERMS FOR CERTIFICATES

Section 11.01 Cut-Off Date.............................................

Section 11.02 Cut-Off Date Aggregate Principal Balance.................

Section 11.03 Original Group Percentage................................

Section 11.04 Original Principal Balances of the Classes of Class A

Certificates and Components.............................

Section 11.05 Original Notional Amount.................................

Section 11.05 (a) Original Class I-A-2 Notional Amount. ...............

Section 11.05 (b) Original Class I-A-4 Notional Amount. ...............

Section 11.05 (c) Original Class I-A-4 Notional Amount. ...............

Section 11.05 (d) Original Class II-A-2 Notional Amount. ..............

Section 11.06 Original Aggregate Subordinated Percentage...............

Section 11.07 Original Class B Principal Balance.......................

Section 11.08 Original Principal Balances of the Classes of Class B

Certificates. ...........................................

Section 11.09 Original Class B-1 Fractional Interest...................

Section 11.10 Original Class B-2 Fractional Interest...................

Section 11.11 Original Class B-3 Fractional Interest...................

Section 11.12 Original Class B-4 Fractional Interest...................

Section 11.13 Original Class B-5 Fractional Interest...................

Section 11.14 Closing Date.............................................

Section 11.15 Right to Purchase........................................

Section 11.16 Wire Transfer Eligibility................................

Section 11.17 Single Certificate.......................................

Section 11.18 Servicing Fee Rate.......................................

Section 11.19 Master Servicing Fee Rate................................

SCHEDULE I Applicable Unscheduled Principal Receipt Period

<PAGE>

EXHIBITS

EXHIBIT A-I-A-1 - Form of Face of Class I-A-1 Certificate

EXHIBIT A-I-A-2 - Form of Face of Class I-A-2 Certificate

EXHIBIT A-I-A-3 - Form of Face of Class I-A-3 Certificate

EXHIBIT A-I-A-4 - Form of Face of Class I-A-4 Certificate

EXHIBIT A-I-A-5 - Form of Face of Class I-A-5 Certificate

EXHIBIT A-I-A-6 - Form of Face of Class I-A-6 Certificate

EXHIBIT A-I-A-7 - Form of Face of Class I-A-7 Certificate

EXHIBIT A-I-A-R - Form of Face of Class I-A-R Certificate

EXHIBIT A-II-A-1 - Form of Face of Class II-A-1 Certificate

EXHIBIT A-II-A-2 - Form of Face of Class II-A-2 Certificate

EXHIBIT A-III-A-1 - Form of Face of Class III-A-1 Certificate

EXHIBIT A-IV-A-1 - Form of Face of Class IV-A-1 Certificate

EXHIBIT A-1 - Form of Face of Class A-1 Certificate

EXHIBIT A-2 - Form of Face of Class A-2 Certificate

EXHIBIT A-3 - Form of Face of Class A-3 Certificate

EXHIBIT B-1 - Form of Face of Class B-1 Certificate

EXHIBIT B-2 - Form of Face of Class B-2 Certificate

EXHIBIT B-3 - Form of Face of Class B-3 Certificate

EXHIBIT B-4 - Form of Face of Class B-4 Certificate

EXHIBIT B-5 - Form of Face of Class B-5 Certificate

EXHIBIT B-6 - Form of Face of Class B-6 Certificate

EXHIBIT C - Form of Reverse of Series 2005-AR13 Certificates

EXHIBIT D - Reserved

EXHIBIT E - Custodial Agreement

EXHIBIT F-1A - Schedule of Wells Fargo Mortgage Loans in Loan

Group I

EXHIBIT F-1B - Schedule of Wells Fargo Mortgage Loans in Loan

Group II

EXHIBIT F-1C - Schedule of Wells Fargo Mortgage Loans in Loan

Group III

EXHIBIT F-1D - Schedule of Wells Fargo Mortgage Loans in Loan

Group IV

EXHIBIT F-2A - Schedule of Other Servicer Mortgage Loans in Loan

Group I

EXHIBIT F-2B - Schedule of Other Servicer Mortgage Loans in Loan

Group II

EXHIBIT F-2C - Schedule of Other Servicer Mortgage Loans in Loan

Group III

EXHIBIT F-2D - Schedule of Other Servicer Mortgage Loans in Loan

Group IV

EXHIBIT G - Request for Release

EXHIBIT H - Affidavit Pursuant to Section 860E(e)(4) of the

Internal Revenue Code of 1986, as amended, and for

Non-ERISA Investors

EXHIBIT I - Letter from Transferor of Class [I-A-R] Certificate

EXHIBIT J - Transferee's Letter (Class [B-4] [B-5] [B-6]

Certificates)

EXHIBIT K - List of Recordation States

EXHIBIT L - Servicing Agreements

EXHIBIT M - Form of Special Servicing Agreement

EXHIBIT N - Form of Initial Certification of the Custodian

EXHIBIT O - Form of Final Certification of the Custodian

EXHIBIT P - Form of Sarbanes-Oxley Certification

EXHIBIT Q - Form of Yield Maintenance Agreement

<PAGE>

This Pooling and Servicing Agreement, dated as of May 27, 2005

executed by WELLS FARGO ASSET SECURITIES CORPORATION, as Seller, WELLS FARGO

BANK, N.A., as Master Servicer, and WACHOVIA BANK, NATIONAL ASSOCIATION, as

Trustee.

W I T N E S S E T H T H A T:

In consideration of the mutual agreements herein contained, the

Seller, the Master Servicer and the Trustee agree as follows:

ARTICLE I

DEFINITIONS

Section 1.01 Definitions.

Whenever used herein, the following words and phrases, unless the

context otherwise requires, shall have the meanings specified in this Article.

Accepted Master Servicing Practices: Accepted Master Servicing

Practices shall consist of the customary and usual master servicing practices of

prudent master servicing institutions which master service mortgage loans of the

same type as the Mortgage Loans in the jurisdictions in which the related

Mortgaged Properties are located, regardless of the date upon which the related

Mortgage Loans were originated.

Adjusted Principal Balance: As to any Distribution Date and any

Class of Class B Certificates, the greater of (A) zero and (B) (i) the Principal

Balance of such Class with respect to such Distribution Date minus (ii) the

Adjustment Amount for such Distribution Date less the Principal Balances for any

Classes of Class B Certificates with higher numerical designations.

Adjustment Amount: For any Distribution Date, the difference between

(A) the sum of the Aggregate Class A Principal Balance and the Class B Principal

Balance as of the related Determination Date and (B) the sum of (i) the sum of

the Aggregate Class A Principal Balance and the Class B Principal Balance as of

the Determination Date succeeding such Distribution Date and (ii) the aggregate

amount that would have been distributed to all Classes as principal in

accordance with Section 4.01(a)(i) for such Distribution Date without regard to

the provisos in the definitions of Class B-1 Optimal Principal Amount, Class B-2

Optimal Principal Amount, Class B-3 Optimal Principal Amount, Class B-4 Optimal

Principal Amount, Class B-5 Optimal Principal Amount and Class B-6 Optimal

Principal Amount.

Adjustment Date: As to each Mortgage Loan, the Due Date on which

date an adjustment to the Mortgage Interest Rate of such Mortgage Loan becomes

effective under the related Mortgage Note, which Due Date is the date set forth

in the Mortgage Loan Schedule as the first Adjustment Date and each subsequent

anniversary thereof.

Aggregate Adjusted Pool Amount: With respect to any Distribution

Date, the sum of the Group I Adjusted Pool Amount, Group II Adjusted Pool

Amount, Group III Adjusted Pool Amount and Group IV Adjusted Pool Amount.

Aggregate Class A Principal Balance: With respect to any

Determination Date, the sum of the Group I-A Principal Balance, Group II-A

Principal Balance, Group III-A Principal Balance and Group IV-A Principal

Balance.

Aggregate Class A Percentage: With respect to any Distribution Date,

the percentage, the numerator of which is the Aggregate Class A Principal

Balance prior to giving effect to any distributions on such Distribution Date,

and the denominator of which is the sum of the Pool Balances for each Loan Group

on the first day of the month preceding the month of such Distribution Date.

Aggregate Group I-A Unpaid Interest Shortfall: As to any

Distribution Date, an amount equal to the sum of the Class A Unpaid Interest

Shortfalls for the Group I-A Certificates and the Group I-A Components.

Aggregate Group II-A Unpaid Interest Shortfall: As to any

Distribution Date, an amount equal to the sum of the Class A Unpaid Interest

Shortfalls for the Group II-A Certificates and the Group II-A Components.

Aggregate Group III-A Unpaid Interest Shortfall: As to any

Distribution Date, an amount equal to the sum of the Class A Unpaid Interest

Shortfalls for the Group III-A Certificates.

Aggregate Group IV-A Unpaid Interest Shortfall: As to any

Distribution Date, an amount equal to the sum of the Class A Unpaid Interest

Shortfalls for the Group IV-A Certificates.

Aggregate Principal Balance: As of any Determination Date, the sum

of the Group I-A Principal Balance, the Group II-A Principal Balance, Group

III-A Principal Balance, the Group IV-A Principal Balance and the Class B

Principal Balance as of such date.

Aggregate Subordinated Percentage: As to any Determination Date, the

difference between 100% and the Aggregate Class A Percentage.

Agreement: This Pooling and Servicing Agreement and all amendments

and supplements hereto.

Applicable Unscheduled Principal Receipt Period: With respect to the

Mortgage Loans serviced by each Servicer and each of the Full Unscheduled

Principal Receipts and Partial Unscheduled Principal Receipts, the Unscheduled

Principal Receipt Period specified on Schedule I hereto.

Apportioned Class B Principal Distribution Amount: As to any

Distribution Date and any Class of Class B Certificates, the product of (i) the

applicable Class B Principal Distribution Amount and (ii) the Apportionment

Fraction for such Class.

Apportionment Fraction: As to any Class of Class B Certificates and

any Distribution Date occurring prior to the Subordination Depletion Date and on

or after the Distribution Date on which the Principal Balance of each Class and

Component of one Group has been reduced to zero, a fraction, the numerator of

which is the portion of the Class B Loan Group Optimal Principal Amounts

represented by clauses (ii) and (iii) of the definition thereof (other than

Liquidation Proceeds that are not partial Liquidation Proceeds) for which the

corresponding Class A Certificates and Components are no longer outstanding and

the denominator of which is the applicable Class B Optimal Principal Amount

without regard to the proviso thereto.

Authenticating Agent: Any authenticating agent appointed by the

Trustee pursuant to Section 8.11. There shall initially be no Authenticating

Agent for the Certificates.

Available Master Servicer Compensation: With respect to any

Distribution Date, the sum of (a) the Master Servicing Fee for such Distribution

Date, (b) interest earned through the business day preceding the applicable

Distribution Date on any Prepayments in Full remitted to the Master Servicer and

Master Servicer pursuant to the related Servicing Agreements.

Bankruptcy Code: The Bankruptcy Code of 1978, as amended.

Bankruptcy Loss: With respect to any Mortgage Loan, a Deficient

Valuation or Debt Service Reduction; provided, however, that a Bankruptcy Loss

shall not be deemed a Bankruptcy Loss hereunder so long as the applicable

Servicer has notified the Master Servicer and the Trustee in writing that such

Servicer is diligently pursuing any remedies that may exist in connection with

the representations and warranties made regarding the related Mortgage Loan and

either (A) the related Mortgage Loan is not in default with regard to payments

due thereunder or (B) delinquent payments of principal and interest under the

related Mortgage Loan and any premiums on any applicable primary hazard

insurance policy and any related escrow payments in respect of such Mortgage

Loan are being advanced on a current basis by such Servicer without giving

effect to any Debt Service Reduction.

Beneficial Owner: With respect to a Book-Entry Certificate, the

Person who is the beneficial owner of such Book-Entry Certificate, as reflected

on the books of the Clearing Agency, or on the books of a Person maintaining an

account with such Clearing Agency (directly or as an indirect participant, in

accordance with the rules of such Clearing Agency), as the case may be.

Book-Entry Certificate: Any one of the Class I-A-1 Certificates,

Class I-A-2 Certificates, Class I-A-3 Certificates, Class I-A-4 Certificates,

Class I-A-5 Certificates, Class I-A-6 Certificates, Class I-A-7 Certificates,

Class II-A-1 Certificates, Class II-A-2 Certificates, Class III-A-1

Certificates, Class IV-A-1 Certificates, Class A-1 Certificates, Class A-2

Certificates, Class A-3 Certificates, Class B-1 Certificates, Class B-2

Certificates and Class B-3 Certificates, beneficial ownership and transfers of

which shall be evidenced by, and made through, book entries by the Clearing

Agency as described in Section 5.01(b).

Business Day: Any day other than (i) a Saturday or a Sunday, or (ii)

a legal holiday in the City of New York, State of Iowa, State of Maryland, State

of Minnesota or State of North Carolina or (iii) a day on which banking

institutions in the City of New York, or the State of Iowa, State of Maryland,

State of Minnesota or State of North Carolina are authorized or obligated by law

or executive order to be closed.

Certificate: Any one of the Class A Certificates or Class B

Certificates.

Certificate Account: The separate trust account established and

maintained by the Master Servicer in the name of the Master Servicer on behalf

of the Trustee pursuant to Section 3.01. The Certificate Account shall be an

Eligible Account.

Certificate Custodian: Initially, Wachovia Bank, National

Association; thereafter any other Certificate Custodian acceptable to The

Depository Trust Company and selected by the Trustee.

Certificate Register and Certificate Registrar: Respectively, the

The initial Certificate Registrar is the Trustee.

Certificateholder or Holder: The Person in whose name a Certificate

is registered in the Certificate Register, except that, solely for the purposes

of the taking of any action under Articles VII or VIII, any Certificate

registered in the name of the Master Servicer, a Servicer or any affiliate

thereof shall be deemed not to be outstanding and the Voting Interest evidenced

thereby shall not be taken into account in determining whether the requisite

percentage of Certificates necessary to effect any such action has been

obtained.

Class: All certificates whose form is identical except for

variations in the Percentage Interest evidenced thereby.

Class I-A-1 Certificate: Any one of the Certificates executed by the

Trustee and authenticated by the Trustee or the Authenticating Agent in

substantially the form set forth in Exhibit A-I-A-1 and Exhibit C hereto.

Class I-A-1 Certificateholder: The registered holder of a Class

I-A-1 Certificate.

Class I-A-1 Counterparty: The Bank of New York.

Class I-A-1 Pass-Through Rate: With respect to the Distribution Date

occurring in June 2005, 3.390% per annum. With respect to each succeeding

Distribution Date, a per annum rate, determined by the Trustee on the applicable

Rate Determination Date, equal to LIBOR plus 0.300%, subject to a minimum rate

of 0.300% and a maximum rate equal to the Net WAC of the Group I Mortgage Loans.

Class I-A-1 Reserve Fund: The trust account created and maintained

by the Trustee pursuant to Section 4.08 which shall be entitled the "Reserve

Account, Wachovia Bank, National Association, as Trustee, in trust for

registered Holders of the Class I-A-1 Certificates of the Wells Fargo Mortgage

Backed Securities 2005-AR13 Trust" and which must be an Eligible Account.

Amounts on deposit in the Class I-A-1 Reserve Account shall not be invested. The

Class I-A-1 Reserve Account shall not be an asset of any REMIC formed under this

Agreement.

Class I-A-I Yield Maintenance Agreement: The yield maintenance

agreement between the Trustee, on behalf of the Trust, and the Class I-A-1

Counterparty, which will be primarily for the benefit of the Class I-A-1

Certificates, substantially in the form attached hereto as Exhibit Q. The Class

I-A-1 Yield Maintenance Agreement shall not be an asset of any REMIC formed

under this Agreement.

Class I-A-1 Yield Maintenance Agreement Payment: For any

Distribution Date (other than the Distribution Date in June 2005) prior to and

including the Distribution Date in September 2009, the amount, if any, required

to be paid by the counterparty to the Trustee under the Yield Maintenance

Agreement.

Class I-A-1 Yield Maintenance Amount: For any Distribution Date

(other than the Distribution Date in June 2005) prior to and including the

Distribution Date in September 2009, an amount equal to the product of (a) the

Principal Balance of the Class I-A-1 Certificates immediately prior to such

Distribution Date, (b) the excess of (i) the lesser of (x) 8.700% and (y) LIBOR

over (ii) 5.010% and (c) one-twelfth.

Class I-A-1 Yield Maintenance Amount Shortfall: For any Distribution

Date, the amount, if any, by which the Class I-A-1 Yield Maintenance Amount for

such Distribution Date exceeds the sum of the Class I-A-1 Yield Maintenance

Agreement Payment for such Distribution Date and any Excess Funds in the Class

I-A-1 Reserve Fund.

Class I-A-2 Certificate: Any one of the Certificates executed by the

Trustee and authenticated by the Trustee or the Authenticating Agent in

substantially the form set forth in Exhibit A-I-A-2 and Exhibit C hereto.

Class I-A-2 Certificateholder: The registered holder of a Class

I-A-2 Certificate.

Class I-A-2 Notional Amount: As to the first Distribution Date, the

Original Class I-A-2 Notional Amount, and, with respect to each Distribution

Date thereafter, an amount equal to the Principal Balance of the Class I-A-1

Certificates.

Class I-A-2 Pass-Through Rate: With respect to the Distribution Date

occurring in June 2005, 2.178% per annum. With respect to each succeeding

Distribution Date, a per annum rate equal to the excess, if any, of (i) the Net

WAC of the Group I Mortgage Loans over (ii) the Class I-A-1 Pass-Through Rate.

Class I-A-3 Certificate: Any one of the Certificates executed by the

Trustee and authenticated by the Trustee or the Authenticating Agent in

substantially the form set forth in Exhibit A-I-A-3 and Exhibit C hereto.

Class I-A-3 Certificateholder: The registered holder of a Class

I-A-3 Certificate.

Class I-A-4 Certificate: Any one of the Certificates executed by the

Trustee and authenticated by the Trustee or the Authenticating Agent in

substantially the form set forth in Exhibit A-I-A-4 and Exhibit C hereto.

Class I-A-4 Certificateholder: The registered holder of a Class

I-A-4 Certificate.

Class I-A-4 Notional Amount: As to the first Distribution Date, the

Original Class I-A-4 Notional Amount, and, with respect to each Distribution

Date thereafter, an amount equal to the Principal Balance of the Class I-A-3

Certificates.

Class I-A-5 Certificate: Any one of the Certificates executed by the

Trustee and authenticated by the Trustee or the Authenticating Agent in

substantially the form set forth in Exhibit A-I-A-5 and Exhibit C hereto.

Class I-A-5 Certificateholder: The registered holder of a Class

I-A-5 Certificate.

Class I-A-6 Certificate: Any one of the Certificates executed by the

Trustee and authenticated by the Trustee or the Authenticating Agent in

substantially the form set forth in Exhibit A-I-A-6 and Exhibit C hereto.

Class I-A-6 Certificateholder: The registered holder of a Class

I-A-6 Certificate.

Class I-A-7 Certificate: Any one of the Certificates executed by the

Trustee and authenticated by the Trustee or the Authenticating Agent in

substantially the form set forth in Exhibit A-I-A-7 and Exhibit C hereto.

Class I-A-7 Certificateholder: The registered holder of a Class

I-A-7 Certificate.

Class I-A-7 Notional Amount: As to the first Distribution Date, the

Original Class I-A-7 Notional Amount, and, with respect to each Distribution

Date thereafter, an amount equal to the Principal Balance of the Class I-A-6

Certificates.

Class I-A-LR Interest: The residual interest in the Lower-Tier

REMIC, beneficial ownership of which is represented by the Class I-A-R

Certificate.

Class I-A-M1 Interest: A regular interest in the Middle-Tier REMIC

which is held as an asset of the Upper-Tier REMIC and is entitled to monthly

distributions as provided in Section 4.01(a)(iii) hereof.

Class I-A-M3 Interest: A regular interest in the Middle-Tier REMIC

which is held as an asset of the Upper-Tier REMIC and is entitled to monthly

distributions as provided in Section 4.01(a)(iii) hereof.

Class I-A-M5 Interest: A regular interest in the Middle-Tier REMIC

which is held as an asset of the Upper-Tier REMIC and is entitled to monthly

distributions as provided in Section 4.01(a)(iii) hereof.

Class I-A-M6 Interest: A regular interest in the Middle-Tier REMIC

which is held as an asset of the Upper-Tier REMIC and is entitled to monthly

distributions as provided in Section 4.01(a)(iii) hereof.

Class I-A-MR Interest: The residual interest in the Middle-Tier

REMIC, beneficial ownership of which is represented by the Class I-A-R

Certificate.

Class I-A-MUR Interest: A regular interest in the Middle-Tier REMIC

which is held as an asset of the Upper-Tier REMIC and is entitled to monthly

distributions as provided in Section 4.01(a)(iii) hereof.

Class I-A-R Certificate: The Certificate executed by the Trustee and

authenticated by the Trustee or the Authenticating Agent in substantially the

form set forth in Exhibit A-I-A-R and Exhibit C hereto.

Class I-A-R Certificateholder: The registered holder of the Class

I-A-R Certificate.

Class I-A-R Interest: The residual interest in the Upper-Tier REMIC,

beneficial ownership of which is evidenced by the Class I-A-R Certificate.

Class I-L Interest: A regular interest in the Lower-Tier REMIC which

is held as an asset of the Middle-Tier REMIC and is entitled to monthly

distributions as provided in Section 4.01(a)(iv) hereof.

Class I-LS Interest: A regular interest in the Lower-Tier REMIC

which is held as an asset of the Middle-Tier REMIC and is entitled to monthly

distributions as provided in Section 4.01(a)(iv) hereof.

Class II-A-1 Certificate: Any one of the Certificates executed by

the Trustee and authenticated by the Trustee or the Authenticating Agent in

substantially the form set forth in Exhibit A-II-A-1 and Exhibit C hereto.

Class II-A-1 Certificateholder: The registered holder of a Class

II-A-1 Certificate.

Class II-A-1 Counterparty: The Bank of New York.

Class II-A-1 Pass-Through Rate: With respect to the Distribution

Date occurring in June 2005, 3.390% per annum. With respect to each succeeding

Distribution Date, a per annum rate, determined by the Trustee on the applicable

Rate Determination Date, equal to LIBOR plus 0.300%, subject to a minimum rate

of 0.300% and a maximum rate equal to the Net WAC of the Group II Mortgage

Loans.

Class II-A-1 Reserve Fund: The trust account created and maintained

by the Trustee pursuant to Section 4.08 which shall be entitled the "Reserve

Account, Wachovia Bank, National Association, as Trustee, in trust for

registered Holders of the Class II-A-1 Certificates of the Wells Fargo Mortgage

Backed Securities 2005-AR13 Trust" and which must be an Eligible Account.

Amounts on deposit in the Class II-A-1 Reserve Account shall not be invested.

The Class II-A-1 Reserve Account shall not be an asset of any REMIC formed under

this Agreement.

Class II-A-1 Yield Maintenance Agreement: The yield maintenance

agreement between the Trustee, on behalf of the Trust, and the Class II-A-1

Counterparty, which will be primarily for the benefit of the Class II-A-1

Certificates, substantially in the form attached hereto as Exhibit Q. The Class

II-A-1 Yield Maintenance Agreement shall not be an asset of any REMIC formed

under this Agreement.

Class II-A-1 Yield Maintenance Agreement Payment: For any

Distribution Date (other than the Distribution Date in June 2005) prior to and

including the Distribution Date in July 2009, the amount, if any, required to be

paid by the counterparty to the Trustee under the Yield Maintenance Agreement.

Class II-A-1 Yield Maintenance Amount: For any Distribution Date

(other than the Distribution Date in June 2005) prior to and including the

Distribution Date in July 2009, an amount equal to the product of (a) the

Principal Balance of the Class II-A-1 Certificates immediately prior to such

Distribution Date, (b) the excess of (i) the lesser of (x) 8.700% and (y) LIBOR

over (ii) 4.949% and (c) one-twelfth.

Class II-A-1 Yield Maintenance Amount Shortfall: For any

Distribution Date, the amount, if any, by which the Class II-A-1 Yield

Maintenance Amount for such Distribution Date exceeds the sum of the Class

II-A-1 Yield Maintenance Agreement Payment for such Distribution Date and any

Excess Funds in the Class II-A-1 Reserve Fund.

Class II-A-2 Certificate: Any one of the Certificates executed by

the Trustee and authenticated by the Trustee or the Authenticating Agent in

substantially the form set forth in Exhibit A-II-A-2 and Exhibit C hereto.

Class II-A-2 Certificateholder: The registered holder of a Class

II-A-2 Certificate.

Class II-A-2 Notional Amount: As to the first Distribution Date, the

Original Class II-A-2 Notional Amount, and, with respect to each Distribution

Date thereafter, an amount equal to the Principal Balance of the Class II-A-1

Certificates.

Class II-A-2 Pass-Through Rate: With respect to the Distribution

Date occurring in June 2005, 2.085% per annum. With respect to each succeeding

Distribution Date, a per annum rate equal to the excess, if any, of (i) the Net

WAC of the Group II Mortgage Loans over (ii) the Class II-A-1 Pass-Through Rate.

Class II-A-M1 Interest: A regular interest in the Middle-Tier REMIC

which is held as an asset of the Upper-Tier REMIC and is entitled to monthly

distributions as provided in Section 4.01(a)(iii) hereof.

Class II-L Interest: A regular interest in the Lower-Tier REMIC

which is held as an asset of the Middle-Tier REMIC and is entitled to monthly

distributions as provided in Section 4.01(a)(iv) hereof.

Class II-LS Interest: A regular interest in the Lower-Tier REMIC

which is held as an asset of the Middle-Tier REMIC and is entitled to monthly

distributions as provided in Section 4.01(a)(iv) hereof.

Class III-A-1 Certificate: Any one of the Certificates executed by

the Trustee and authenticated by the Trustee or the Authenticating Agent in

substantially the form set forth in Exhibit A-III-A-1 and Exhibit C hereto.

Class III-A-1 Certificateholder: The registered holder of a Class

III-A-1 Certificate.

Class III-A-M1 Interest: A regular interest in the Middle-Tier REMIC

which is held as an asset of the Upper-Tier REMIC and is entitled to monthly

distributions as provided in Section 4.01(a)(iii) hereof.

Class III-L Interest: A regular interest in the Lower-Tier REMIC

which is held as an asset of the Middle-Tier REMIC and is entitled to monthly

distributions as provided in Section 4.01(a)(iv) hereof.

Class III-LS Interest: A regular interest in the Lower-Tier REMIC

which is held as an asset of the Middle-Tier REMIC and is entitled to monthly

distributions as provided in Section 4.01(a)(iv) hereof.

Class IV-A-1 Certificate: Any one of the Certificates executed by

the Trustee and authenticated by the Trustee or the Authenticating Agent in

substantially the form set forth in Exhibit A-IV-A-1 and Exhibit C hereto.

Class IV-A-1 Certificateholder: The registered holder of a Class

IV-A-1 Certificate.

Class IV-A-M1 Interest: A regular interest in the Middle-Tier REMIC

which is held as an asset of the Upper-Tier REMIC and is entitled to monthly

distributions as provided in Section 4.01(a)(iii) hereof.

Class IV-L Interest: A regular interest in the Lower-Tier REMIC

which is held as an asset of the Middle-Tier REMIC and is entitled to monthly

distributions as provided in Section 4.01(a)(iv) hereof.

Class IV-LS Interest: A regular interest in the Lower-Tier REMIC

which is held as an asset of the Middle-Tier REMIC and is entitled to monthly

distributions as provided in Section 4.01(a)(iv) hereof.

Class A Certificate: Any of the Group I-A Certificates, Group II-A

Certificates, Group III-A Certificates, Group IV-A Certificates, Class A-1

Certificates, Class A-2 Certificates or Class A-3 Certificates.

Class A Certificateholder: The registered holder of a Class A

Certificate.

Class A Interest Percentage: As to any Distribution Date and any

Class of Class A Certificates (other than the Class A-1, Class A-2 or Class A-3

Certificates) or Class A-1, Class A-2 or Class A-3 Component, the percentage

calculated by dividing the Interest Accrual Amount of such Class or Component

(determined without regard to clause (ii) of the definition thereof) by the sum

of (a) the Group I-A Interest Accrual Amount, (b) the Group II-A Interest

Accrual Amount, (c) the Group III-A Interest Accrual Amount and (b) the Group

IV-A Interest Accrual Amount.

Class A Pass-Through Rate: As to the Class I-A-1, Class I-A-2, Class

II-A-1 and Class II-A-2 Certificates and each Distribution Date, the Class I-A-1

Pass-Through Rate, Class I-A-2 Pass-Through Rate, Class II-A-1 Pass-Through Rate

and Class II-A-2 Pass-Through Rate, respectively. As to the Class I-A-3

Certificates and each Distribution Date, the Class A Pass-Through Rate will be a

per annum rate equal to the Net WAC of the Group I Mortgage Loans minus 0.7419%.

As to the Class I-A-4 Certificates and each Distribution Date, the Class A

Pass-Through Rate will be a per annum rate equal to 0.7419%. As to the Class

I-A-5 and Class I-A-R Certificates and each Distribution Date, the Class A

Pass-Through Rate will be a per annum rate equal to the Net WAC of the Group I

Mortgage Loans. As to the Class I-A-6 Certificates and each Distribution Date,

the Class A Pass-Through Rate will be a per annum rate equal to the Net WAC of

the Group I Mortgage Loans minus 0.5419%. As to the Class I-A-7 Certificates and

each Distribution Date, the Class A Pass-Through Rate will be a per annum rate

equal to 0.5419%. As to the Class III-A-1 Certificates and each Distribution

Date, the Class A Pass-Through Rate will be a per annum rate equal to the Net

WAC of the Group III Mortgage Loans. As to the Class IV-A-1 Certificates and

each Distribution Date, the Class A Pass-Through Rate will be a per annum rate

equal to the Net WAC of the Group IV Mortgage Loans. As to the Class A-1-I,

Class A-2-I and Class A-3-I Components and each Distribution Date, the Class A

Pass-Through Rate will be a per annum rate equal to the Net WAC of the Group I

Mortgage Loans. As to the Class A-1-II, Class A-2-II and Class A-3-II Components

and each Distribution Date, the Class A Pass-Through Rate will be a per annum

rate equal to the Net WAC of the Group II Mortgage Loans.

Class A Unpaid Interest Shortfall: As to any Distribution Date and

Class of Class A Certificates (other than the Class A-1, Class A-2 or Class A-3

Certificates) and Component, the amount, if any, by which the aggregate of the

Group I-A Interest Shortfall Amounts, Group II-A Interest Shortfall Amounts,

Group III-A Interest Shortfall Amounts and Group IV-A Interest Shortfall Amounts

for such Class or Component for prior Distribution Dates is in excess of the

amounts distributed in respect of such Class on prior Distribution Dates

pursuant to Paragraph second of Section 4.01(a)(i).

Class A-1 Certificate: Any one of the Certificates executed by the

Trustee and authenticated by the Trustee or the Authenticating Agent in

substantially the form set forth in Exhibit A-1 and Exhibit C hereto.

Class A-1 Certificateholder: The registered holder of a Class A-1

Certificate.

Class A-1 Component: Either of the Class A-1-I or Class A-1-II

Component.

Class A-1 Interest Accrual Amount: The sum of the Interest Accrual

Amounts for the Class A-1 Components.

Class A-1-I Component: One of the components of the Class A-1

Certificates.

Class A-1-I Interest Accrual Amount: As to any Distribution Date,

(i) the product of (a) 1/12th of the Class A Pass-Through Rate for the Class

A-1-I Component and (b) the Principal Balance of the Class A-1-I Component as of

such Distribution Date minus (ii) the sum of (A) the Group I-A Interest

Percentage of the Class A-1-I Component of the interest portion of any Realized

Losses on the Group I Mortgage Loans on or after the Subordination Depletion

Date pursuant to Section 4.02(c) and (B) the Class A Interest Percentage of the

Class A-1-I Component of any Non-Supported Interest Shortfall or Relief Act

Shortfall allocated to the Class A Certificates with respect to such

Distribution Date.

Class A-1-I-M1 Interest: A regular interest in the Middle-Tier REMIC

which is held as an asset of the Upper-Tier REMIC and is entitled to monthly

distributions as provided in Section 4.01(a)(iii) hereof.

Class A-1-I / Class A-2-I Priority Amount: For any Distribution

Date, the lesser of (i) the sum of the Principal Balances of the Class A-1-I and

Class A-2-I Components and (ii) the product of (1) the Class A-1-I / Class A-2-I

Priority Percentage, (2) the Shift Percentage and (3) the Group I-A Principal

Distribution Amount remaining after the payment of amounts in accordance with

priorities first and second as set forth in Section 4.01(b)(i).

Class A-1-I / Class A-2-I Priority Percentage: The sum of

$167,633,100 and the Principal Balances of the Class A-1-I and Class A-2-I

Components divided by the Group I-A Principal Balance (minus the Principal

Balance of the Class A-3-I Component).

Class A-1-II Component: One of the components of the Class A-1

Certificates.

Class A-1-II Interest Accrual Amount: As to any Distribution Date,

(i) the product of (a) 1/12th of the Class A Pass-Through Rate for the Class

A-1-II Component and (b) the Principal Balance of the Class A-1-II Component as

of such Distribution Date minus (ii) the sum of (A) the Group II-A Interest

Percentage of the Class A-1-II Component of the interest portion of any Realized

Losses on the Group II Mortgage Loans on or after the Subordination Depletion

Date pursuant to Section 4.02(c) and (B) the Class A Interest Percentage of the

Class A-1-II Component of any Non-Supported Interest Shortfall or Relief Act

Shortfall allocated to the Class A Certificates with respect to such

Distribution Date.

Class A-1-II-M1 Interest: A regular interest in the Middle-Tier

REMIC which is held as an asset of the Upper-Tier REMIC and is entitled to

monthly distributions as provided in Section 4.01(a)(iii) hereof.

Class A-1-II / Class A-2-II Priority Amount: For any Distribution

Date, the lesser of (i) the sum of the Principal Balances of the Class A-1-II

and Class A-2-II Components and (ii) the product of (1) the Class A-1-II / Class

A-2-II Priority Percentage, (2) the Shift Percentage and (3) the Group II-A

Principal Distribution Amount remaining after the payment of amounts in

accordance with priority first as set forth in Section 4.01(b)(ii).

Class A-1-II / Class A-2-II Priority Percentage: The sum of

$22,485,600 and the Principal Balances of the Class A-1-II and Class A-2-II

Components divided by the Group II-A Principal Balance (minus the Principal

Balance of the Class A-3-II Component).

Class A-2 Certificate: Any one of the Certificates executed by the

Trustee and authenticated by the Trustee or the Authenticating Agent in

substantially the form set forth in Exhibit A-2 and Exhibit C hereto.

Class A-2 Certificateholder: The registered holder of a Class A-2

Certificate.

Class A-2 Component: Either of the Class A-2-I or Class A-2-II

Component.

Class A-2 Interest Accrual Amount: The sum of the Interest Accrual

Amounts for the Class A-2 Components.

Class A-2-I Component: One of the components of the Class A-2

Certificates.

Class A-2-I Interest Accrual Amount: As to any Distribution Date,

(i) the product of (a) 1/12th of the Class A Pass-Through Rate for the Class

A-2-I Component and (b) the Principal Balance of the Class A-2-I Component as of

such Distribution Date minus (ii) the sum of (A) the Group I-A Interest

Percentage of the Class A-2-I Component of the interest portion of any Realized

Losses on the Group I Mortgage Loans on or after the Subordination Depletion

Date pursuant to Section 4.02(c) and (B) the Class A Interest Percentage of the

Class A-2-I Component of any Non-Supported Interest Shortfall or Relief Act

Shortfall allocated to the Class A Certificates with respect to such

Distribution Date.

Class A-2-I-M1 Interest: A regular interest in the Middle-Tier REMIC

which is held as an asset of the Upper-Tier REMIC and is entitled to monthly

distributions as provided in Section 4.01(a)(iii) hereof.

Class A-2-II Component: One of the components of the Class A-2

Certificates.

Class A-2-II Interest Accrual Amount: As to any Distribution Date,

(i) the product of (a) 1/12th of the Class A Pass-Through Rate for the Class

A-2-II Component and (b) the Principal Balance of the Class A-2-II Component as

of such Distribution Date minus (ii) the sum of (A) the Group II-A Interest

Percentage of the Class A-2-II Component of the interest portion of any Realized

Losses on the Group II Mortgage Loans on or after the Subordination Depletion

Date pursuant to Section 4.02(c) and (B) the Class A Interest Percentage of the

Class A-2-II Component of any Non-Supported Interest Shortfall or Relief Act

Shortfall allocated to the Class A Certificates with respect to such

Distribution Date.

Class A-2-II-M1 Interest: A regular interest in the Middle-Tier

REMIC which is held as an asset of the Upper-Tier REMIC and is entitled to

monthly distributions as provided in Section 4.01(a)(iii) hereof.

Class A-3 Certificate: Any one of the Certificates executed by the

Trustee and authenticated by the Trustee or the Authenticating Agent in

substantially the form set forth in Exhibit A-3 and Exhibit C hereto.

Class A-3 Certificateholder: The registered holder of a Class A-3

Certificate.

Class A-3 Component: Either of the Class A-3-I or Class A-3-II

Component.

Class A-3 Interest Accrual Amount: The sum of the Interest Accrual

Amounts for the Class A-3 Components.

Class A-3-I Component: One of the components of the Class A-3

Certificates.

Class A-3-I Interest Accrual Amount: As to any Distribution Date,

(i) the product of (a) 1/12th of the Class A Pass-Through Rate for the Class

A-3-I Component and (b) the Principal Balance of the Class A-3-I Component as of

such Distribution Date minus (ii) the sum of (A) the Group I-A Interest

Percentage of the Class A-3-I Component of the interest portion of any Realized

Losses on the Group I Mortgage Loans on or after the Subordination Depletion

Date pursuant to Section 4.02(c) and (B) the Class A Interest Percentage of the

Class A-3-I Component of any Non-Supported Interest Shortfall or Relief Act

Shortfall allocated to the Class A Certificates with respect to such

Distribution Date.

Class A-3-I-M1 Interest: A regular interest in the Middle-Tier REMIC

which is held as an asset of the Upper-Tier REMIC and is entitled to monthly

distributions as provided in Section 4.01(a)(iii) hereof.

Class A-3-I Priority Amount: For any Distribution Date, the lesser

of (i) the Principal Balances of the Class A-3-I Component and (ii) the product

of (1) the Class A-3-I Priority Percentage, (2) the Shift Percentage and (3) the

Group I-A Principal Distribution Amount.

Class A-3-I Priority Percentage: The Principal Balance of the Class

A-3-I Component divided by the Group I-A Principal Balance.

Class A-3-II Component: One of the components of the Class A-3

Certificates.

Class A-3-II Interest Accrual Amount: As to any Distribution Date,

(i) the product of (a) 1/12th of the Class A Pass-Through Rate for the Class

A-3-II Component and (b) the Principal Balance of the Class A-3-II Component as

of such Distribution Date minus (ii) the sum of (A) the Group II-A Interest

Percentage of the Class A-3-II Component of the interest portion of any Realized

Losses on the Group II Mortgage Loans on or after the Subordination Depletion

Date pursuant to Section 4.02(c) and (B) the Class A Interest Percentage of the

Class A-3-II Component of any Non-Supported Interest Shortfall or Relief Act

Shortfall allocated to the Class A Certificates with respect to such

Distribution Date.

Class A-3-II-M1 Interest: A regular interest in the Middle-Tier

REMIC which is held as an asset of the Upper-Tier REMIC and is entitled to

monthly distributions as provided in Section 4.01(a)(iii) hereof.

Class A-3-II Priority Amount: For any Distribution Date, the lesser

of (i) the Principal Balances of the Class A-3-II Component and (ii) the product

of (1) the Class A-3-II Priority Percentage, (2) the Shift Percentage and (3)

the Group II-A Principal Distribution Amount.

Class A-3-II Priority Percentage: The Principal Balance of the Class

A-3-II Component divided by the Group II-A Principal Balance.

Class B Certificate: Any one of the Class B-1 Certificates, Class

B-2 Certificates, Class B-3 Certificates, Class B-4 Certificates, Class B-5

Certificates or Class B-6 Certificates.

Class B Certificateholder: The registered holder of a Class B

Certificate.

Class B Distribution Amount: Any of the Class B-1 Distribution

Amount, Class B-2 Distribution Amount, Class B-3 Distribution Amount, Class B-4

Distribution Amount, Class B-5 Distribution Amount or Class B-6 Distribution

Amount.

Class B Interest Accrual Amount: With respect to any Distribution

Date, the sum of the Interest Accrual Amounts for the Classes of Class B

Certificates with respect to such Distribution Date.

Class B Interest Percentage: With respect to any Distribution Date

and any Class of Class B Certificates, the percentage calculated by dividing the

Interest Accrual Amount of such Class (determined without regard to clause (ii)

of the definition thereof) by the Class B Interest Accrual Amount (determined

without regard to clause (ii) of the definition of each Interest Accrual

Amount).

Class B Interest Shortfall Amount: Any of the Class B-1 Interest

Shortfall Amount, Class B-2 Interest Shortfall Amount, Class B-3 Interest

Shortfall Amount, Class B-4 Interest Shortfall Amount, Class B-5 Interest

Shortfall Amount or Class B-6 Interest Shortfall Amount.

Class B Loan Group I Optimal Principal Amount: Any of the Class B-1,

Class B-2, Class B-3, Class B-4, Class B-5 or Class B-6 Loan Group I Optimal

Principal Amounts.

Class B Loan Group II Optimal Principal Amount: Any of the Class

B-1, Class B-2, Class B-3, Class B-4, Class B-5 or Class B-6 Loan Group II

Optimal Principal Amounts.

Class B Loan Group III Optimal Principal Amount: Any of the Class

B-1, Class B-2, Class B-3, Class B-4, Class B-5 or Class B-6 Loan Group III

Optimal Principal Amounts.

Class B Loan Group IV Optimal Principal Amount: Any of the Class

B-1, Class B-2, Class B-3, Class B-4, Class B-5 or Class B-6 Loan Group IV

Optimal Principal Amounts.

Class B Loan Group Optimal Principal Amount: Any of the Class B Loan

Group I Optimal Principal Amount, Class B Loan Group II Optimal Principal

Amount, Class B Loan Group III Optimal Principal Amount or Class B Loan Group IV

Optimal Principal Amount.

Class B Loss Percentage: With respect to any Determination Date and

any Class of Class B Certificates then outstanding, the percentage calculated by

dividing the Principal Balance of such Class by the Class B Principal Balance

(determined without regard to any Principal Balance of any Class of Class B

Certificates not then outstanding), in each case determined as of the preceding

Determination Date.

Class B Optimal Principal Amount: Any of the Class B-1 Optimal

Principal Amount, Class B-2 Optimal Principal Amount, Class B-3 Optimal

Principal Amount, Class B-4 Optimal Principal Amount, Class B-5 Optimal

Principal Amount or Class B-6 Optimal Principal Amount.

Class B Pass-Through Rate: As to any Distribution Date, the Class B

Pass-Through Rate will be a per annum rate equal to the weighted average (based

on the Group Subordinate Amount for each Loan Group) of the Net WACs of the Loan

Groups.

Class B Principal Balance: As of any date, an amount equal to the

sum of the Class B-1 Principal Balance, Class B-2 Principal Balance, Class B-3

Principal Balance, Class B-4 Principal Balance, Class B-5 Principal Balance and

Class B-6 Principal Balance.

Class B Principal Distribution Amount: Any of the Class B-1

Principal Distribution Amount, Class B-2 Principal Distribution Amount, Class

B-3 Principal Distribution Amount, Class B-4 Principal Distribution Amount,

Class B-5 Principal Distribution Amount or Class B-6 Principal Distribution

Amount.

Class B Unpaid Interest Shortfall: Any of the Class B-1 Unpaid

Interest Shortfall, Class B-2 Unpaid Interest Shortfall, Class B-3 Unpaid

Interest Shortfall, Class B-4 Unpaid Interest Shortfall, Class B-5 Unpaid

Interest Shortfall or Class B-6 Unpaid Interest Shortfall.

Class B-1 Certificate: Any one of the Certificates executed by the

Trustee and authenticated by the Trustee or the Authenticating Agent in

substantially the form set forth in Exhibit B-1 and Exhibit C hereto.

Class B-1 Certificateholder: The registered holder of a Class B-1

Certificate.

Class B-1 Distribution Amount: As to any Distribution Date, any

amount distributable to the Holders of the Class B-1 Certificates pursuant to

Paragraphs first, second and third of Section 4.01(a)(ii).

Class B-1 Interest Shortfall Amount: As to any Distribution Date,

any amount by which the Interest Accrual Amount of the Class B-1 Certificates

with respect to such Distribution Date exceeds the amount distributed in respect

of the Class B-1 Certificates on such Distribution Date pursuant to Paragraph

first of Section 4.01(a)(ii).

Class B-1 Loan Group I Optimal Principal Amount: As to any

Distribution Date, the Class B-1 Optimal Principal Amount calculated only with

respect to Group I Mortgage Loans and without regard to the proviso thereto.

Class B-1 Loan Group II Optimal Principal Amount: As to any

Distribution Date, the Class B-1 Optimal Principal Amount calculated only with

respect to Group II Mortgage Loans and without regard to the proviso thereto.

Class B-1 Loan Group III Optimal Principal Amount: As to any

Distribution Date, the Class B-1 Optimal Principal Amount calculated only with

respect to Group III Mortgage Loans and without regard to the proviso thereto.

Class B-1 Loan Group IV Optimal Principal Amount: As to any

Distribution Date, the Class B-1 Optimal Principal Amount calculated only with

respect to Group IV Mortgage Loans and without regard to the proviso thereto.

Class B-1 Optimal Principal Amount: As to any Distribution Date and

each Outstanding Mortgage Loan, an amount equal to the sum of

(I) the sum of:

(i) the Group I Class B-1 Percentage (with respect to each such

Group I Mortgage Loan), Group II Class B-1 Percentage (with respect to

each such Group II Mortgage Loan), Group III Class B-1 Percentage (with

respect to each such Group III Mortgage Loan) or Group IV Class B-1

Percentage (with respect to each such Group IV Mortgage Loan) of the

principal portion of the Monthly Payment due on the Due Date occurring in

the month of such Distribution Date on such Mortgage Loan;

(ii) the Group I Class B-1 Prepayment Percentage (with respect to

each such Group I Mortgage Loan), Group II Class B-1 Prepayment Percentage

(with respect to each such Group II Mortgage Loan), Group III Class B-1

Prepayment Percentage (with respect to each such Group III Mortgage Loan)

or Group IV Class B-1 Prepayment Percentage (with respect to each such

Group IV Mortgage Loan) of all Unscheduled Principal Receipts (other than

Recoveries) that were received by a Servicer with respect to such Mortgage

Loan during the Applicable Unscheduled Principal Receipt Period relating

to such Distribution Date for each applicable type of Unscheduled

Principal Receipt;

(iii) the Group I Class B-1 Prepayment Percentage (with respect to

each such Group I Mortgage Loan), Group II Class B-1 Prepayment Percentage

(with respect to each such Group II Mortgage Loan), Group III Class B-1

Prepayment Percentage (with respect to each such Group III Mortgage Loan)

or Group IV Class B-1 Prepayment Percentage (with respect to each such

Group IV Mortgage Loan) of the Scheduled Principal Balance of such

Mortgage Loan which, during the one month period ending on the day

preceding the Determination Date for such Distribution Date, was

repurchased by the Seller pursuant to Section 2.02, 2.03 or 3.08; and

(iv) the Group I Class B-1 Percentage (with respect to each such

Group I Mortgage Loan), Group II Class B-1 Percentage (with respect to

each such Group II Mortgage Loan), Group III Class B-1 Percentage (with

respect to each such Group III Mortgage Loan) or Group IV Class B-1

Percentage (with respect to each such Group IV Mortgage Loan) of the

excess of the unpaid principal balance of such Mortgage Loan substituted

for a Mortgage Loan during the one month period ending on the day

preceding the Determination Date for such Distribution Date over the

unpaid principal balance of such Mortgage Loan, less the amount allocable

to the principal portion of any unreimbursed Periodic Advances previously

made by the applicable Servicer, the Master Servicer or the Trustee in

respect of such Mortgage Loan; and

(II) the Group I Class B-1 Prepayment Percentage, Group II Class B-1 Prepayment

Percentage, Group III Class B-1 Prepayment Percentage or Group IV Class B-1

Prepayment Percentage, as applicable, of the Recovery for each Loan Group for

such Distribution Date;

provided, however, that if an Optimal Adjustment Event occurs with respect to

such Class and such Distribution Date, the Class B-1 Optimal Principal Amount

will equal the lesser of (A) the Class B-1 Optimal Principal Amount calculated

as described in the preceding provisions and (B) the Adjusted Principal Balance

for the Class B-1 Certificates.

Class B-1 Principal Balance: As to the first Determination Date, the

Original Class B-1 Principal Balance. As of any subsequent Determination Date,

the Original Class B-1 Principal Balance less the sum of all amounts previously

distributed in respect of the Class B-1 Certificates on prior Distribution Dates

(A) pursuant to Paragraph third of Section 4.01(a)(ii) and (B) as a result of a

Principal Adjustment; provided, however, if the Class B-1 Certificates are the

most subordinate Certificates outstanding, the Class B-1 Principal Balance will

equal the difference, if any, between the Aggregate Adjusted Pool Amount as of

the preceding Distribution Date less the Aggregate Class A Principal Balance as

of such Determination Date.

Class B-1 Principal Distribution Amount: As to any Distribution

Date, any amount distributable to the Holders of the Class B-1 Certificates

pursuant to Paragraph third of Section 4.01(a)(ii).

Class B-1 Unpaid Interest Shortfall: As to any Distribution Date,

the amount, if any, by which the aggregate of the Class B-1 Interest Shortfall

Amounts for prior Distribution Dates is in excess of the amounts distributed in

respect of the Class B-1 Certificates on prior Distribution Dates pursuant to

Paragraph second of Section 4.01(a)(ii).

Class B-2 Certificate: Any one of the Certificates executed by the

Trustee and authenticated by the Trustee or the Authenticating Agent in

substantially the form set forth in Exhibit B-2 and Exhibit C hereto.

Class B-2 Certificateholder: The registered holder of a Class B-2

Certificate.

Class B-2 Distribution Amount: As to any Distribution Date, any

amount distributable to the Holders of the Class B-2 Certificates pursuant to

Paragraphs fourth, fifth and sixth of Section 4.01(a)(ii).

Class B-2 Interest Shortfall Amount: As to any Distribution Date,

any amount by which the Interest Accrual Amount of the Class B-2 Certificates

with respect to such Distribution Date exceeds the amount distributed in respect

of the Class B-2 Certificates on such Distribution Date pursuant to Paragraph

fourth of Section 4.01(a)(ii).

Class B-2 Loan Group I Optimal Principal Amount: As to any

Distribution Date, the Class B-2 Optimal Principal Amount calculated only with

respect to Group I Mortgage Loans and without regard to the proviso thereto.

Class B-2 Loan Group II Optimal Principal Amount: As to any

Distribution Date, the Class B-2 Optimal Principal Amount calculated only with

respect to Group II Mortgage Loans and without regard to the proviso thereto.

Class B-2 Loan Group III Optimal Principal Amount: As to any

Distribution Date, the Class B-2 Optimal Principal Amount calculated only with

respect to Group III Mortgage Loans and without regard to the proviso thereto.

Class B-2 Loan Group IV Optimal Principal Amount: As to any

Distribution Date, the Class B-2 Optimal Principal Amount calculated only with

respect to Group IV Mortgage Loans and without regard to the proviso thereto.

Class B-2 Optimal Principal Amount: As to any Distribution Date and

each Outstanding Mortgage Loan, an amount equal to the sum of

(I) the sum of:

(i) the Group I Class B-2 Percentage (with respect to each such

Group I Mortgage Loan), Group II Class B-2 Percentage (with respect to

each such Group II Mortgage Loan), Group III Class B-2 Percentage (with

respect to each such Group III Mortgage Loan) or Group IV Class B-2

Percentage (with respect to each such Group IV Mortgage Loan) of the

principal portion of the Monthly Payment due on the Due Date occurring in

the month of such Distribution Date on such Mortgage Loan;

(ii) the Group I Class B-2 Prepayment Percentage (with respect to

each such Group I Mortgage Loan), Group II Class B-2 Prepayment Percentage

(with respect to each such Group II Mortgage Loan), Group III Class B-2

Prepayment Percentage (with respect to each such Group III Mortgage Loan)

or Group IV Class B-2 Prepayment Percentage (with respect to each such

Group IV Mortgage Loan) of all Unscheduled Principal Receipts (other than

Recoveries) that were received by a Servicer with respect to such Mortgage

Loan during the Applicable Unscheduled Principal Receipt Period relating

to such Distribution Date for each applicable type of Unscheduled

Principal Receipt;

(iii) the Group I Class B-2 Prepayment Percentage (with respect to