POOLING AND SERVICING AGREEMENT

Pooling and Servicing Agreement

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Washington Mutual Mortgage Securities Corp. | WASHINGTON MUTUAL MORTGAGE SECURITIES CORP., | WASHINGTON MUTUAL BANK, | LASALLE BANK NATIONAL ASSOCIATION, | CHRISTIANA BANK & TRUST COMPANY,

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Title: POOLING AND SERVICING AGREEMENT
Governing Law: Delaware Date: 6/9/2005

POOLING AND SERVICING AGREEMENT, Parties: washington mutual mortgage securities corp. , washington mutual mortgage securities corp. , washington mutual bank , lasalle bank national association , christiana bank & trust company

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EXHIBIT 4.1

EXECUTION VERSION

WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.,

as Depositor

and

WASHINGTON MUTUAL BANK,

as Servicer

and

LASALLE BANK NATIONAL ASSOCIATION,

as Trustee

and

CHRISTIANA BANK & TRUST COMPANY,

as Delaware Trustee

POOLING AND SERVICING AGREEMENT

$1,077,859,139.11

Washington Mutual Mortgage Securities Corp.

Washington Mutual Mortgage Pass-Through Certificates

WMALT Series 2005-4

Cut-Off Date: May 1, 2005

TABLE OF CONTENTS

	Page
ARTICLE I	8
Section 1.01. Definitions	8
Aggregate Certificate Principal Balance	8
Appraised Value	8
Assignment of Proprietary Lease	8
Authenticating Agent	8
Authorized Denomination	8
Bankruptcy Loss	8
Beneficial Holder	9
Benefit Plan Opinion	9
Book-Entry Certificates	9
Business Day	9
Buydown Agreement	9
Buydown Fund	9
Buydown Fund Account	9
Buydown Loan	10
Cap Counterparty	10
Carry-Forward Subsequent Recoveries Amount	10
Certificate	10
Certificate Account	10
Certificate Group	10
Certificateholder or Holder	11
Certificate Insurance Policy	11
Certificate Insurer	11
Certificate Insurer Default	11
Certificate Insurer Premium	12
Certificate Interest Rate	12
Certificate of Trust	12
Certificate Principal Balance	12
Certificate Register and Certificate Registrar	12
Class	12
Class 1-P Fraction	13
Class 1-P Mortgage Loan	13
Class 2-CB Certificates	13
Class 2-CB-L Regular Interest	13
Class 2-P Fraction	13
Class 2-P Mortgage Loan	13
Class 3-CB Certificates	13
Class 3-CB-L Regular Interest	13
Class 4-A-1 Certificates	13
Class 4-A-1-L Regular Interest	13
Class 4-A-2 Certificates	13
Class 4-A-2-L Regular Interest	13
Class 4-P Fraction	14
Class 4-P Mortgage Loan	14
Class 5-A-1 Certificates	14
Class 5-A-1-L Regular Interest	14
Class 5-A-2 Certificates	14
Class 5-A-2-L Regular Interest	14
Class 5-A-2-M Regular Interest	14
Class 5-A-3 Certificates	14
Class 5-A-3 Notional Amount	14
Class 5-A-4 Certificates	14
Class 5-A-4-L Regular Interest	14
Class 5-A-5 Certificates	14
Class 5-A-5-L Regular Interest	14
Class 5-A-5-M Regular Interest	14
Class 5-A-6 Certificates	15
Class 5-A-6 Notional Amount	15
Class 5-A-7 Certificates	15
Class 5-A-7-L Regular Interest	15
Class 5-A-8 Certificates	15
Class 5-A-8-L Regular Interest	15
Class 5-A-9 Certificates	15
Class 5-A-9-L Regular Interest	15
Class 5-A-10 Certificates	15
Class 5-A-10-L Regular Interest	15
Class 5-P Fraction	15
Class 5-P Mortgage Loan	15
Class A Certificates	15
Class A-L Regular Interests	15
Class B Certificates	16
Class B Percentage	16
Class B-L Regular Interests	16
Class B-1 Certificates	16
Class B-1-L Regular Interest	16
Class B-2 Certificates	16
Class B-2-L Regular Interest	16
Class B-3 Certificates	16
Class B-3-L Regular Interest	16
Class B-4 Certificates	16
Class B-4-L Regular Interest	16
Class B-5 Certificates	16
Class B-5-L Regular Interest	16
Class B-6 Certificates	16
Class B-6-L Regular Interest	17
Class CB-1 Certificates	17
Class CB-1-L Regular Interest	17
Class CB-1-M Regular Interest	17
Class CB-2 Certificates	17
Class CB-2 Notional Amount	17
Class CB-3 Certificates	17
Class CB-3 Fraction	17
Class CB-3-L Regular Interest	17
Class CB-3-M Regular Interest	17
Class CB-4 Certificates	17
Class CB-4 Notional Amount	17
Class CB-5 Certificates	17
Class CB-5-L Regular Interest	17
Class CB-6 and Class CB-15 Priority Amount	18
Class CB-6 Certificates	18
Class CB-6-L Regular Interest	18
Class CB-6 Rounding Account	18
Class CB-7 Certificates	18
Class CB-7-L Regular Interest	18
Class CB-8 Certificates	18
Class CB-8-L Regular Interest	18
Class CB-9 Certificates	18
Class CB-9-L Regular Interest	18
Class CB-9-M Regular Interest	18
Class CB-10 Certificates	18
Class CB-10 Notional Amount	18
Class CB-11 Certificates	19
Class CB-11-L Regular Interest	19
Class CB-12 Certificates	19
Class CB-12-L Regular Interest	19
Class CB-13 Certificates	19
Class CB-13-L Regular Interest	19
Class CB-13-M Regular Interest	19
Class CB-14 Certificates	19
Class CB-14 Notional Amount	19
Class CB-15 Additional Reimbursement Amount	19
Class CB-15 Available Funds	19
Class CB-15 Certificates	19
Class CB-15 Covered Payoff Shortfall Amount	19
Class CB-15 Reimbursement Amount	20
Class CB-15 Required Distributions	20
Class CB-15 Reserve Fund	20
Class CB-15-L Regular Interest	20
Class CB-15 Rounding Account	20
Class CB-16 Certificates	20
Class CB-16 Notional Amount	20
Class C-P Certificates	20
Class C-P-L Regular Interest	20
Class C-P-M Regular Interest	21
Class C-X Certificates	21
Class C-X Notional Amount	21
Class C-X-L Regular Interest	21
Class C-X-M Regular Interest	21
Class C-Y Principal Reduction Amounts	21
Class C-Y Regular Interests	21
Class C-Y-1 Principal Distribution Amount	21
Class C-Y-1 Regular Interest	21
Class C-Y-2 Principal Distribution Amount	21
Class C-Y-2 Regular Interest	21
Class C-Z Principal Reduction Amounts	21
Class C-Z Regular Interests	22
Class C-Z-1 Principal Distribution Amount	22
Class C-Z-1 Regular Interest	22
Class C-Z-2 Principal Distribution Amount	22
Class C-Z-2 Regular Interest	22
Class D-P Certificates	22
Class D-P-L Regular Interest	22
Class D-P-M Regular Interest	22
Class D-X Certificates	22
Class D-X Notional Amount	22
Class D-X-L Regular Interest	23
Class D-X-M Regular Interest	23
Class Notional Amount	23
Class P Certificates	23
Class P Fraction	23
Class P Mortgage Loan	23
Class P-L Regular Interests	23
Class P-M Regular Interests	23
Class Principal Balance	23
Class R Certificates	24
Class R Residual Interests	24
Class R-1 Residual Interest	25
Class R-2 Residual Interest	25
Class R-3 Residual Interest	25
Class X Certificates	25
Class X-L Regular Interests	25
Class X-M Regular Interests	25
Clean-Up Call Percentage	25
Clearing Agency	25
Closing Date	25
Closing Date Loan-to-Value Ratio	25
Code	25
Company	25
Compensating Interest	25
Cooperative	26
Cooperative Apartment	26
Cooperative Lease	26
Cooperative Loans	26
Cooperative Stock	26
Cooperative Stock Certificate	26
Corporate Trust Office	26
Corporation	26
Corresponding Class	26
Credit Support Depletion Date	27
Cumulative Carry-Forward Subsequent Recoveries Amount	27
Curtailment	27
Curtailment Shortfall	27
Custodial Account for P&I	28
Custodial Account for Reserves	28
Custodial Agreement	28
Custodian	28
Cut-Off Date	29
Deceased Holder	29
Deficiency Amount	29
Definitive Certificates	29
Delaware Trustee	29
Depositary Agreement	29
Destroyed Mortgage Note	29
Determination Date	29
Disqualified Organization	29
Distribution Date	29
DTC	29
DTC Participant	30
Due Date	30
Eligible Institution	30
Eligible Investments	30
ERISA	31
ERISA Restricted Certificate	31
Event of Default	31
Excess Liquidation Proceeds	31
Excess Subsequent Recoveries	32
Fannie Mae	32
FDIC	32
FHA	32
Final Maturity Date	32
Final Yield Maintenance Payment Date	32
Fitch	32
Freddie Mac	32
Group 1 Certificates	32
Group 1 Loans	32
Group 1 Lockout Adjusted Percentage	32
Group 1 Lockout Liquidation Amount	32
Group 1 Lockout Percentage	33
Group 1 Lockout Prepayment Percentage	33
Group 1 Lockout Priority Amount	33
Group 1 Premium Rate Mortgage Loans	33
Group 1 Senior Liquidation Amount	33
Group 1 Senior Percentage	33
Group 1 Senior Prepayment Percentage, Group 2 Senior Prepayment Percentage, Group 3 Senior Prepayment Percentage, Group 4 Senior Prepayment Percentage or Group 5 Senior Prepayment Percentage	33
Group 1 Senior Principal Distribution Amount	36
Group 1 Subordinate Percentage	37
Group 1 Subordinate Prepayment Percentage	37
Group 1 Super Lockout Priority Amount	37
Group 1-A Certificates	37
Group 1-A-L Regular Interests	37
Group 1-L Regular Interests	37
Group 2 Certificates	37
Group 2 Loans	37
Group 2 Premium Rate Mortgage Loans	37
Group 2 Senior Liquidation Amount	37
Group 2 Senior Percentage	37
Group 2 Senior Prepayment Percentage	38
Group 2 Senior Principal Distribution Amount	38
Group 2 Subordinate Percentage	38
Group 2 Subordinate Prepayment Percentage	38
Group 2-A Certificates	38
Group 2-A-L Regular Interest	38
Group 2-L Regular Interest	38
Group 3 Certificates	38
Group 3 Loans	38
Group 3 Premium Rate Mortgage Loans	38
Group 3 Senior Liquidation Amount	38
Group 3 Senior Percentage	38
Group 3 Senior Prepayment Percentage	39
Group 3 Senior Principal Distribution Amount	39
Group 3 Subordinate Percentage	39
Group 3 Subordinate Prepayment Percentage	39
Group 3-A Certificates	39
Group 3-A-L Regular Interest	39
Group 3-L Regular Interest	39
Group 4 Certificates	39
Group 4 Loans	39
Group 4 Premium Rate Mortgage Loans	39
Group 4 Senior Liquidation Amount	39
Group 4 Senior Percentage	39
Group 4 Senior Prepayment Percentage	39
Group 4 Senior Principal Distribution Amount	40
Group 4 Subordinate Percentage	40
Group 4 Subordinate Prepayment Percentage	40
Group 4-A Certificates	40
Group 4-A-L Regular Interests	40
Group 4-L Regular Interests	40
Group 5 Certificates	40
Group 5 Loans	40
Group 5 Lockout Adjusted Percentage	40
Group 5 Lockout Liquidation Amount	40
Group 5 Lockout Percentage	40
Group 5 Lockout Prepayment Percentage	40
Group 5 Lockout Priority Amount	41
Group 5 Premium Rate Mortgage Loans	41
Group 5 Senior Liquidation Amount	41
Group 5 Senior Percentage	41
Group 5 Senior Prepayment Percentage	41
Group 5 Senior Principal Distribution Amount	41
Group 5 Subordinate Percentage	41
Group 5 Subordinate Prepayment Percentage	41
Group 5 Super Lockout Priority Amount	41
Group 5-A Certificates	42
Group 5-A-L Regular Interests	42
Group 5-L Regular Interests	42
Group I Subordinate Balance	42
Group II Subordinate Balance	42
Indirect DTC Participants	42
Initial Custodial Agreement	42
Initial Custodian	42
Insurance Proceeds	42
Insured Amount	42
Insured Certificates	43
Interest Distribution Amount	43
Interest Transfer Amount	43
Investment Account	43
Investment Depository	43
Junior Subordinate Certificates	43
Last Scheduled Distribution Date	43
Lender	43
LIBOR	43
LIBOR Determination Date	43
Living Holder	44
Liquidated Mortgage Loan	44
Liquidation Principal	44
Liquidation Proceeds	44
Loan Group	44
Loan Group 1	44
Loan Group 2	44
Loan Group 3	44
Loan Group 4	44
Loan Group 5	44
Loan-to-Value Ratio	44
Lowest Class B Owner	44
MERS	44
MERS Loan	45
MERS® System	45
MIN	45
MOM Loan	45
Monthly P&I Advance	45
Monthly Payment	45
Moody’s	45
Mortgage	45
Mortgage File	45
Mortgage Interest Rate	48
Mortgage Loan Schedule	48
Mortgage Loans	48
Mortgage Note	48
Mortgage Pool	48
Mortgage Pool Assets	49
Mortgaged Property	49
Mortgagor	49
Nonrecoverable Advance	49
Non-U.S. Person	49
Notice Addresses	49
Notice of Claim	50
OTS	50
Officer’s Certificate	50
Opinion of Counsel	50
Order	50
Original Trust Agreement	50
Original Value	50
Overcollateralized Group	50
Ownership Interest	50
Pass-Through Entity	51
Pass-Through Rate	51
Paying Agent	51
Payoff	51
Payoff Earnings	51
Payoff Interest	51
Payoff Period	51
Percentage Interest	52
Permitted Transferee	52
Person	53
Preference Amount	53
Premium Letter	53
Prepaid Monthly Payment	53
Primary Insurance Policy	53
Principal Balance	53
Principal Payment	54
Principal Payment Amount	54
Principal Prepayment	54
Principal Prepayment Amount	54
Principal Transfer Amount	54
Prior Period	54
Prospectus	54
Purchase Obligation	54
Purchase Price	55
Random Lot	55
Rating Agency	55
Ratings	55
Realized Loss	55
Recognition Agreement	58
Record Date	58
Reference Banks	58
Regular Interest Group	58
Regular Interests	59
Relief Act Shortfall	59
REMIC	59
REMIC Provisions	59
REMIC I	59
REMIC I Assets	59
REMIC I Available Distribution Amount	59
REMIC I Distribution Amount	60
REMIC I Regular Interests	63
REMIC II	63
REMIC II Assets	63
REMIC II Available Distribution Amount	63
REMIC II Distribution Amount	63
REMIC II Regular Interests	77
REMIC III	77
REMIC III Assets	77
REMIC III Available Distribution Amount	77
REMIC III Distribution Amount	78
REMIC III Regular Interests	80
Residual Certificates	81
Residual Distribution Amount	81
Responsible Officer	81
Rounding Accounts	81
Rounding Amount	81
ROV Mortgage Loan	82
S&P	82
Secretary of State	82
Securities Act	82
Security Agreement	82
Selling and Servicing Contract	82
Senior Regular Interests	82
Senior Subordinate Certificates	82
Servicer	82
Servicer Business Day	82
Servicing Fee	82
Servicing Fee Rate	82
Servicing Officer	83
Special Primary Insurance Policy	83
Special Primary Insurance Premium	83
Special Retail Certificates	83
Statutory Trust Statute	83
Step Down Percentage	83
Streamlined Mortgage Loan	83
Stripped Interest Rate	83
Subordinate Certificates	83
Subordinate Component Balance	83
Subordinate Liquidation Amount	84
Subordinate Percentage	84
Subordinate Principal Distribution Amount	84
Subordinate Principal Prepayments Distribution Amount	85
Subordination Level	85
Subsequent Recoveries	86
Substitute Mortgage Loan	86
Tax Matters Person	86
Termination Date	86
Termination Payment	86
Total Transfer Amount	86
Transfer	86
Transferee	86
Transferee Affidavit and Agreement	86
Trust	86
Trustee	87
Uncollected Interest	87
Uncompensated Interest Shortfall	87
Undercollateralized Group	88
Underwriter	88
Underwriting Standards	88
Uninsured Cause	88
U.S. Person	88
VA	89
Withdrawal Date	89
Yield Maintenance Account	89
Yield Maintenance Agreements	89
Yield Maintenance Notional Balance	89
Yield Maintenance Payment Amount	89
ARTICLE II Creation of the Trust; Conveyance of the Mortgage Pool Assets, REMIC I Regular Interests, REMIC II Regular Interests and REMIC III Regular Interests; REMIC Election and Designations; Original Issuance of Certificates	91
Section 2.01. Creation of the Trust	91
Section 2.02. Restrictions on Activities of the Trust	92
Section 2.03. Separateness Requirements	92
Section 2.04. Conveyance of Mortgage Pool Assets; Security Interest	94
Section 2.05. Delivery of Mortgage Files	95
Section 2.06. REMIC Election for REMIC I	97
Section 2.07. Acceptance by Trustee	98
Section 2.08. Representations and Warranties of the Company Concerning the Mortgage Loans	100
Section 2.09. Acknowledgment of Transfer of Mortgage Pool Assets	106
Section 2.10. Conveyance of REMIC II Assets; Security Interest	106
Section 2.11. REMIC Election for REMIC II	107
Section 2.12. Acknowledgement of Transfer of REMIC II Assets	108
Section 2.13. Conveyance of REMIC III Assets; Security Interest	108
Section 2.14. REMIC Election for REMIC III	109
Section 2.15. Acknowledgement of Transfer of REMIC III Assets; Authentication of Certificates	110
Section 2.16. Legal Title	110
Section 2.17. Compliance with ERISA Requirements	110
Section 2.18. Additional Representation of the Company Concerning the Mortgage Loans	111
ARTICLE III Administration and Servicing of Mortgage Loans	111
Section 3.01. The Servicer	111
Section 3.02. Custodial Accounts and Buydown Fund Accounts	113
Section 3.03. The Investment Account; Eligible Investments	114
Section 3.04. The Certificate Account	115
Section 3.05. Permitted Withdrawals from the Certificate Account, the Investment Account, Custodial Accounts for P&I and Custodial Accounts for Reserves and of Buydown Funds from the Buydown Fund Accounts	116
Section 3.06. Maintenance of Primary Insurance Policies; Collections Thereunder	117
Section 3.07. Maintenance of Hazard Insurance	118
Section 3.08. Enforcement of Due-on-Sale Clauses; Assumption Agreements	118
Section 3.09. Realization Upon Defaulted Mortgage Loans	119
Section 3.10. Trustee to Cooperate; Release of Mortgage Files	121
Section 3.11. Compensation to the Servicer	122
Section 3.12. Reports to the Trustee; Certificate Account Statement	122
Section 3.13. Annual Statement as to Compliance	122
Section 3.14. Access to Certain Documentation and Information Regarding the Mortgage Loans	123
Section 3.15. Annual Independent Public Accountants’ Servicing Report	123
Section 3.16. Yield Maintenance Account.	123
Section 3.17. Maintenance of the Class CB-15 Reserve Fund. 124
Section 3.18. [Reserved.]	125
Section 3.19. Determination of LIBOR by Servicer 125
Section 3.20. [Reserved.]	126
Section 3.21. Maintenance of the Certificate Insurance Policy; Collections Thereunder 126
Section 3.22. Maintenance of the Rounding Accounts; Collections Thereunder.	128
ARTICLE IV Payments to Certificateholders; Payment of Expenses	129
Section 4.01. Distributions to Holders of REMIC I Regular Interests and Class R-1 Residual Interest	129
Section 4.02. Advances by the Servicer; Distribution Reports to the Trustee	129
Section 4.03. Nonrecoverable Advances	130
Section 4.04. Distributions to Holders of REMIC II Regular Interests and Class R-2 Residual Interest; Payments to Certificate Insurer	131
Section 4.05. Distributions to Certificateholders; Payment of Special Primary Insurance Premiums	132
Section 4.06. Statements to Certificateholders	133
Section 4.07. Principal Distributions on the Special Retail Certificates	134
ARTICLE V The Certificates	138
Section 5.01. The Certificates	138
Section 5.02. Certificates Issuable in Classes; Distributions of Principal and Interest; Authorized Denominations	144
Section 5.03. Registration of Transfer and Exchange of Certificates	145
Section 5.04. Mutilated, Destroyed, Lost or Stolen Certificates	145
Section 5.05. Persons Deemed Owners	146
Section 5.06. Temporary Certificates	146
Section 5.07. Book-Entry for Book-Entry Certificates	147
Section 5.08. Notices to Clearing Agency	148
Section 5.09. Definitive Certificates	148
Section 5.10. Office for Transfer of Certificates	148
Section 5.11. Nature of Certificates	148
ARTICLE VI The Company and the Servicer	149
Section 6.01. Liability of the Company and the Servicer	149
Section 6.02. Merger or Consolidation of the Company or the Servicer	149
Section 6.03. Limitation on Liability of the Company, the Servicer and Others	149
Section 6.04. Neither the Company nor the Servicer may Resign	150
Section 6.05. Trustee and Certificate Insurer Access 150
ARTICLE VII Default	151
Section 7.01. Events of Default	151
Section 7.02. Trustee to Act; Appointment of Successor	153
Section 7.03. Notification to Certificateholders and the Certificate Insurer	154
ARTICLE VIII Concerning the Trustees	154
Section 8.01. Duties of Trustees	154
Section 8.02. Certain Matters Affecting the Trustees	156
Section 8.03. Trustees Not Liable for Certificates or Mortgage Loans	157
Section 8.04. Trustees May Own Certificates	157
Section 8.05. The Servicer to Pay Trustees’ Fees and Expenses	157
Section 8.06. Eligibility Requirements for Trustees	158
Section 8.07. Resignation and Removal of Trustees	158
Section 8.08. Successor Trustee	159
Section 8.09. Merger or Consolidation of Trustee	159
Section 8.10. Appointment of Co-Trustee or Separate Trustee	160
Section 8.11. Authenticating Agents	161
Section 8.12. Paying Agents	161
Section 8.13. Duties of Delaware Trustee	162
Section 8.14. Amendment to Certificate of Trust	163
Section 8.15. Limitation of Liability	163
Section 8.16. Yield Maintenance Agreements; the Premium Letter	163
ARTICLE IX Termination	163
Section 9.01. Termination Upon Purchase by the Servicer or Liquidation of All Mortgage Loans	163
Section 9.02. Additional Termination Requirements	165
Section 9.03. Trust Irrevocable	166
ARTICLE X Miscellaneous Provisions	166
Section 10.01. Amendment	166
Section 10.02. Recordation of Agreement	168
Section 10.03. Limitation on Rights of Certificateholders	168
Section 10.04. Access to List of Certificateholders	169
Section 10.05. Governing Law	169
Section 10.06. Notices	169
Section 10.07. Severability of Provisions	170
Section 10.08 Counterpart Signatures	170
Section 10.09 Benefits of Agreement	170
Section 10.10 Notices and Copies to Rating Agencies and the Certificate Insurer	170
Section 10.11 Certificate Insurer Rights	171

Schedule 1             Exceptions to Section 2.08(iv) Representations
Exhibit A                Form of Certificates (other than Class R Certificates)
Exhibit B                Form of Class R Certificates
Exhibit C                Anti-Predatory Lending Categorization
Exhibit D                Mortgage Loan Schedule
Exhibit E                 [Reserved]
Exhibit F                 Form of Transferor Certificate For Junior Subordinate Certificates
Exhibit G                Form of Transferee’s Agreement For Junior Subordinate Certificates
Exhibit H                Form of Additional Matter Incorporated Into the Certificates
Exhibit I                 Transferor Certificate
Exhibit J                 Transferee Affidavit And Agreement
Exhibit K                Form of Certificate Insurance Policy
Exhibit L                 Form of Investment Letter
Exhibit M               Form of Trustee’s Certification Pursuant to Section 2.07
Exhibit N                Officer’s Certificate With Respect to ERISA Matters Pursuant to Section 5.01(d)
Exhibit O                Officer’s Certificate With Respect to ERISA Matters Pursuant to Section 5.01(g)

This Pooling and Servicing Agreement, dated and effective as of May 1, 2005 (this “ Agreement ”), is executed by and among Washington Mutual Mortgage Securities Corp., as depositor (the “ Company ”), Washington Mutual Bank, as Servicer (the “ Servicer ”), LaSalle Bank National Association, a national banking association with a corporate trust office at 135 South LaSalle Street, Suite 1625, Chicago, Illinois 60603, as Trustee (the “ Trustee ”), and Christiana Bank & Trust Company, 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 REMIC II Regular Interests 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 REMIC II Regular Interests. Thereafter on the Closing Date, the Company will acquire the Certificates (other than the Class R-1 and Class R-2 Residual Interests) and the Class R-3 Residual Interest from the Trust as consideration for its transfer to the Trust of the REMIC II 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, (iv) the issuance to the Company of the REMIC II Regular Interests and the Class R-2 Residual Interest representing in the aggregate the entire beneficial interest in REMIC II, (v) the conveyance to the Trust of the REMIC II Regular Interests and (vi) 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 and Class R-2 Residual Interests) representing in the aggregate the entire beneficial interest in REMIC III. The Company and the Servicer are 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 April 20, 2005, and a Prospectus Supplement, dated May 23, 2005, of the Company (together, the “ Prospectus ”). The Junior Subordinate Certificates have been offered for sale pursuant to a Private Placement Memorandum, dated May 25, 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 REMIC II Regular Interests, the Class R Residual Interests and the Certificates:

REMIC I Interests

Class Designation for each REMIC I Regular Interest and the Class R-1 Residual Interest	Type of Interest	Certificate Interest Rate (1)	Initial Class Principal Balance	Final Maturity Date*
Class C-Y-1	Regular	5.500%	$ 519,238.48	June 2035
Class C-Y-2	Regular	5.000%	15,051.76	June 2020
Class C-Z-1	Regular	5.500%	1,042,473,982.96	June 2035
Class C-Z-2	Regular	5.000%	30,088,458.91	June 2020
Class C-X-M	Regular	5.500%(2)	-----	June 2035
Class D-X-M	Regular	5.500%(2)	-----	June 2020
Class C-P-M	Regular	(3)	2,742,845.36	June 2035
Class D-P-M	Regular	(3)	2,019,462.42	June 2020
Class R-1†	Residual	5.500%	100.00	June 2035

* The Distribution Date in the specified month, which is the month following the month the latest maturing Mortgage Loan in the related Loan Group (or Loan Groups, as applicable) matures. For federal income tax purposes, for each Class of REMIC I Regular and Residual Interests, the “latest possible maturity date” shall be the Final Maturity Date.
† The Class R-1 Residual Interest is entitled to receive the applicable Residual Distribution Amount and any Excess Liquidation Proceeds.
(1) Interest distributed to the REMIC I Regular Interests (other than the Class P-M Regular Interests, which shall not be entitled to receive any distributions of interest) and the Class R-1 Residual Interest on each Distribution Date will have accrued at the applicable per annum Certificate Interest Rate on the applicable Class Principal Balance or Class Notional Amount outstanding immediately before such Distribution Date.
(2) Each Class of the Class X-M Regular Interests shall accrue interest on the related Class Notional Amount. The Class X-M Regular Interests shall not be entitled to receive any distributions of principal.
(3) The Class P-M Regular Interests shall not be entitled to receive any distributions of interest.

As provided herein, with respect to REMIC I, the Servicer 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

	Class Designation for each Class of REMIC II Regular Interests and the Class R-2 Residual Interest	Type of Interest	Certificate Interest Rate (1)	Initial Class Principal Balance	Final Maturity Date*
	Class CB-1-L	Regular	5.500%	$ 305,066,700.00	June 2035
	Class CB-3-L	Regular	5.500%	154,500,000.00	June 2035
	Class CB-5-L	Regular	5.500%	3,880,300.00	June 2035
	Class CB-6-L	Regular	5.500%	500,000.00	June 2035
	Class CB-7-L	Regular	5.500%	68,674,000.00	June 2035
	Class CB-8-L	Regular	5.500%	3,576,900.00	June 2035
	Class CB-9-L	Regular	5.500%	30,000,000.00	June 2035
	Class CB-11-L	Regular	5.500%	32,615,000.00	June 2035
	Class CB-12-L	Regular	5.500%	1,698,000.00	June 2035
	Class CB-13-L	Regular	5.500%	107,250,000.00	June 2035
	Class CB-15-L	Regular	5.420%	14,725,000.00	June 2035
	Class 2-CB-L	Regular	5.000%	28,570,000.00	June 2035
	Class 3-CB-L	Regular	5.500%	43,691,000.00	June 2035
	Class 4-A-1-L	Regular	5.500%	28,498,000.00	June 2035
	Class 4-A-2-L	Regular	5.500%	1,484,000.00	June 2035
	Class 5-A-1-L	Regular	5.500%	18,433,000.00	June 2035
	Class 5-A-2-L	Regular	5.500%	15,500,000.00	June 2035
	Class 5-A-4-L	Regular	5.500%	8,555,000.00	June 2035
	Class 5-A-5-L	Regular	5.500%	36,000,000.00	June 2035
	Class 5-A-7-L	Regular	5.500%	108,199,000.00	June 2035
	Class 5-A-8-L	Regular	5.500%	5,841,000.00	June 2035
	Class 5-A-9-L	Regular	5.500%	960,000.00	June 2035
	Class 5-A-10-L	Regular	5.500%	445,000.00	June 2035
	Class C-X-L	Regular	5.500%(2)	-----	June 2035
	Class D-X-L	Regular	5.500%(2)	-----	June 2020
	Class C-P-L	Regular	(3)	2,742,845.00	June 2035
	Class D-P-L	Regular	(3)	2,019,462.00	June 2020
	Class B-1-L	Regular	Variable(4)	24,254,000.00	June 2035
	Class B-2-L	Regular	Variable(4)	10,778,000.00	June 2035
	Class B-3-L	Regular	Variable(4)	5,928,000.00	June 2035
	Class B-4-L	Regular	Variable(4)	5,928,000.00	June 2035
	Class B-5-L	Regular	Variable(4)	4,311,000.00	June 2035
	Class B-6-L	Regular	Variable(4)	3,235,832.11	June 2035
	Class R-2†	Residual	-----	-----	June 2035

* The Distribution Date in the specified month, which is the month following the month the latest maturing Mortgage Loan in the related Loan Group (or Loan Groups, as applicable) matures. For federal income tax purposes, for each Class of REMIC II Regular and Residual Interests, the “latest possible maturity date” shall be the Final Maturity Date.
† The Class R-2 Residual Interest is entitled to receive the applicable Residual Distribution Amount and any Excess Liquidation Proceeds.
(1) Interest distributed on each Distribution Date to the REMIC II Regular Interests (other than the Class P-L Regular Interests, which shall not be entitled to receive any distributions of interest) will have accrued at the applicable per annum Certificate Interest Rate on the applicable Class Principal Balance or Class Notional Amount outstanding immediately before such Distribution Date.
(2) Each Class of the Class X-L Regular Interests shall accrue interest on the related Class Notional Amount. The Class X-L Regular Interests shall not be entitled to receive any distributions of principal.
(3) The Class P-L Regular Interests shall not be entitled to receive any distributions of interest.
(4) The Certificate Interest Rate for each Class of the Class B-L Regular Interests shall equal, on any Distribution Date, the weighted average of the Certificate Interest Rates for the Class C-Y-1and Class C-Y-2 Regular Interests.

As provided herein, with respect to REMIC II, the Servicer will cause an election to be made on behalf of REMIC II to be treated for federal income tax purposes as a REMIC. The REMIC II Regular Interests 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.

REMIC III Interests

Class Designation for each Class of REMIC III Regular Interests and the Class R-3 Residual Interest	Type of Interest	Certificate Interest Rate (1)	Initial Class Principal Balance	Final Maturity Date*
Class CB-1-M	Regular	(2)	$ 305,066,700.00	June 2035
Class CB-2	Regular	(3)	-----	June 2035
Class CB-3-M	Regular	(4)	154,500,000.00	June 2035
Class CB-4	Regular	(5)	-----	June 2035
Class CB-5	Regular	5.500%	3,880,300.00	June 2035
Class CB-6	Regular	5.500%	500,000.00	June 2035
Class CB-7	Regular	5.500%	68,674,000.00	June 2035
Class CB-8	Regular	5.500%	3,576,900.00	June 2035
Class CB-9-M	Regular	(6)	30,000,000.00	June 2035
Class CB-10	Regular	(7)	-----	June 2035
Class CB-11	Regular	5.500%	32,615,000.00	June 2035
Class CB-12	Regular	5.500%	1,698,000.00	June 2035
Class CB-13-M	Regular	(8)