POOLING AND SERVICING AGREEMENT

Pooling and Servicing Agreement

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MASTR ASSET BACKED SECURITIES TRUST 2005-OPT1 | WELLS FARGO BANK, N.A. | OPTION ONE MORTGAGE CORPORATION | MORTGAGE ASSET SECURITIZATION TRANSACTIONS, INC.

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Title: POOLING AND SERVICING AGREEMENT
Governing Law: New York Date: 5/27/2005

POOLING AND SERVICING AGREEMENT

, Parties: mastr asset backed securities trust 2005-opt1 , wells fargo bank n.a. , option one mortgage corporation , mortgage asset securitization transactions inc.

MORTGAGE ASSET SECURITIZATION TRANSACTIONS, INC.

Depositor

OPTION ONE MORTGAGE CORPORATION

Master Servicer

and

WELLS FARGO BANK, N.A.

Trustee

POOLING AND SERVICING AGREEMENT

Dated as of May 1, 2005

MASTR Asset Backed Securities Trust 2005-OPT1

Mortgage Pass-Through Certificates

Series 2005-OPT1

TABLE OF CONTENTS

ARTICLE I DEFINITIONS

Section 1.01.	Defined Terms.
Section 1.02.	Allocation of Certain Interest Shortfalls.
Section 1.03.	Rights of the NIMS Insurer.

ARTICLE II CONVEYANCE OF MORTGAGE LOANS; ORIGINAL ISSUANCE OF CERTIFICATES

Section 2.01.	Conveyance of the Mortgage Loans.
Section 2.02.	Acceptance of REMIC I by Trustee.
Section 2.03.	Repurchase or Substitution of Mortgage Loans by the Originator or the Seller.
Section 2.04.	Reserved.
Section 2.05.	Representations, Warranties and Covenants of the Master Servicer.
Section 2.06.	Issuance of the REMIC I Regular Interests and the Class R-I Interest.
Section 2.07.	Conveyance of REMIC Regular Interests and Acceptance of REMIC I, REMIC II, REMIC III and REMIC IV by the Trustee.
Section 2.08.	Issuance of Class R Certificates and the Class R-X Certificates.

ARTICLE III ADMINISTRATION AND SERVICING OF THE MORTGAGE LOANS

Section 3.01.

Master Servicer to Act as Master Servicer.

Section 3.02.

Sub-Servicing Agreements Between Master Servicer and Sub-Servicers.

Section 3.03.

Successor Sub-Servicers.

Section 3.04.

Liability of the Master Servicer.

Section 3.05.

No Contractual Relationship Between Sub-Servicers and the NIMS Insurer, the Trustee or Certificateholders.

Section 3.06.

Assumption or Termination of Sub-Servicing Agreements by Trustee.

Section 3.07.

Collection of Certain Mortgage Loan Payments.

Section 3.08.

Sub-Servicing Accounts.

Section 3.09.

Collection of Taxes, Assessments and Similar Items; Servicing Accounts.

Section 3.10.

Collection Account and Distribution Account.

Section 3.11.

Withdrawals from the Collection Account and Distribution Account.

Section 3.12.

Investment of Funds in the Collection Account and the Distribution Account.

Section 3.13.

[Reserved].

Section 3.14.

Maintenance of Hazard Insurance and Errors and Omissions and Fidelity Coverage.

Section 3.15.

Enforcement of Due-On-Sale Clauses; Assumption Agreements.

Section 3.16.

Realization Upon Defaulted Mortgage Loans.

Section 3.17.

Trustee to Cooperate; Release of Mortgage Files.

Section 3.18.

Servicing Compensation.

Section 3.19.

Reports to the Trustee; Collection Account Statements.

Section 3.20.

Statement as to Compliance.

Section 3.21.

Independent Public Accountants’ Servicing Report.

Section 3.22.

Access to Certain Documentation.

Section 3.23.

Title, Management and Disposition of REO Property.

Section 3.24.

Obligations of the Master Servicer in Respect of Prepayment Interest Shortfalls.

Section 3.25.

[Reserved].

Section 3.26.	Obligations of the Master Servicer in Respect of Mortgage Rates and Monthly Payments.
Section 3.27.	Solicitations.
Section 3.28.	Net WAC Rate Carryover Reserve Account.
Section 3.29.	Advance Facility
Section 3.30.	PMI Policies; Claims under the PMI Policies.

ARTICLE IV PAYMENTS TO CERTIFICATEHOLDERS

Section 4.01.	Distributions.
Section 4.02.	Statements to Certificateholders.
Section 4.03.	Remittance Reports; Advances.
Section 4.04.	Allocation of Realized Losses.
Section 4.05.	Compliance with Withholding Requirements.
Section 4.06.	Exchange Commission; Additional Information.

ARTICLE V THE CERTIFICATES

Section 5.01.	The Certificates.
Section 5.02.	Registration of Transfer and Exchange of Certificates.
Section 5.03.	Mutilated, Destroyed, Lost or Stolen Certificates.
Section 5.04.	Persons Deemed Owners.
Section 5.05.	Certain Available Information.

ARTICLE VI THE DEPOSITOR AND THE MASTER SERVICER

Section 6.01.	Liability of the Depositor and the Master Servicer.
Section 6.02.	Merger or Consolidation of the Depositor or the Master Servicer.
Section 6.03.	Limitation on Liability of the Depositor, the Master Servicer and Others.
Section 6.04.	Limitation on Resignation of the Master Servicer.
Section 6.05.	Rights of the Depositor in Respect of the Master Servicer.
Section 6.06.	[Reserved].

ARTICLE VII DEFAULT

Section 7.01.	Master Servicer Events of Default.
Section 7.02.	Trustee to Act; Appointment of Successor.
Section 7.03.	Notification to Certificateholders.
Section 7.04.	Waiver of Master Servicer Events of Default.
Section 7.05.	Survivability of Master Servicer Liabilities.

ARTICLE VIII CONCERNING THE TRUSTEE

Section 8.01.	Duties of Trustee.
Section 8.02.	Certain Matters Affecting the Trustee.
Section 8.03.	Trustee not Liable for Certificates or Mortgage Loans.
Section 8.04.	Trustee May Own Certificates.
Section 8.05.	Trustee’s Fees and Expenses.
Section 8.06.	Eligibility Requirements for Trustee.
Section 8.07.	Resignation and Removal of the Trustee.
Section 8.08.	Successor Trustee.
Section 8.09.	Merger or Consolidation of Trustee.

Section 8.10.	Appointment of Co-Trustee or Separate Trustee.
Section 8.11.	Appointment of Office or Agency.
Section 8.12.	Representations and Warranties.

ARTICLE IX TERMINATION

Section 9.01.	Termination Upon Repurchase or Liquidation of All Mortgage Loans.
Section 9.02.	Additional Termination Requirements.

ARTICLE X REMIC PROVISIONS

Section 10.01.	REMIC Administration.
Section 10.02.	Prohibited Transactions and Activities.
Section 10.03.	Master Servicer and Trustee Indemnification.

ARTICLE XI MISCELLANEOUS PROVISIONS

Section 11.01.	Amendment.
Section 11.02.	Recordation of Agreement; Counterparts.
Section 11.03.	Limitation on Rights of Certificateholders.
Section 11.04.	Governing Law.
Section 11.05.	Notices.
Section 11.06.	Severability of Provisions.
Section 11.07.	Notice to Rating Agencies and the NIMS Insurer.
Section 11.08.	Article and Section References.
Section 11.09.	Grant of Security Interest.
Section 11.10.	Third Party Rights.

Exhibits

Exhibit A-1

Form of Class A-1 Certificate

Exhibit A-2

Form of Class A-2 Certificate

Exhibit A-3

Form of Class A-3 Certificate

Exhibit A-4

Form of Class A-4 Certificate

Exhibit A-5

Form of Class A-5 Certificate

Exhibit A-6

Form of Class M-1 Certificate

Exhibit A-7

Form of Class M-2 Certificate

Exhibit A-8

Form of Class M-3 Certificate

Exhibit A-9

Form of Class M-4 Certificate

Exhibit A-10

Form of Class M-5 Certificate

Exhibit A-11

Form of Class M-6 Certificate

Exhibit A-12

Form of Class M-7 Certificate

Exhibit A-13

Form of Class M-8 Certificate

Exhibit A-14

Form of Class M-9 Certificate

Exhibit A-15

Form of Class M-10 Certificate

Exhibit A-16

Form of Class M-11 Certificate

Exhibit A-17

Form of Class CE Certificate

Exhibit A-18

Form of Class P Certificate

Exhibit A-19

Form of Class R Certificate

Exhibit A-20

Form of Class R-X Certificate

Exhibit B

[Reserved]

Exhibit C-1

Form of Trustee’s Initial Certification

Exhibit C-2

Form of Trustee’s Final Certification

Exhibit C-3

Form of Trustee’s Receipt of Mortgage Notes

Exhibit D

Form of Mortgage Loan Purchase Agreement

Exhibit E

Request for Release

Exhibit F-1

Form of Transferor Representation Letter and Form of Transferee Representation Letter in Connection with Transfer of the Class CE Certificates, Class P Certificates or Residual Certificates Pursuant to Rule 144A Under the 1933 Act

Exhibit F-2

Form of Transfer Affidavit and Agreement and Form of Transferor Affidavit in Connection with Transfer of Residual Certificates

Exhibit G

Form of Certification with respect to ERISA and the Code

Exhibit H

Form of Report Pursuant to Section 4.06

Exhibit I

Form of Lost Note Affidavit

Exhibit J-1

Form of Certification to Be Provided by the Master Servicer with Form 10-K

Exhibit J-2

Form of Certification to Be Provided by the Trustee with Form 10-K

Exhibit K

[Reserved]

Exhibit L

Form of Cap Contracts

Schedule 1

Mortgage Loan Schedule

Schedule 2

Prepayment Charge Schedule

Schedule 3

PMI Mortgage Loans

This Pooling and Servicing Agreement, is dated and effective as of May 1, 2005, among MORTGAGE ASSET SECURITIZATION TRANSACTIONS, INC. as Depositor, OPTION ONE MORTGAGE CORPORATION as Master Servicer and WELLS FARGO BANK, N.A. as Trustee.

PRELIMINARY STATEMENT:

The Depositor intends to sell pass-through certificates to be issued hereunder in multiple classes, which in the aggregate will evidence the entire beneficial ownership interest in each REMIC (as defined herein) created hereunder. The Trust Fund will consist of a segregated pool of assets comprised of the Mortgage Loans and certain other related assets subject to this Agreement.

REMIC I

As provided herein, the Trustee will elect to treat the segregated pool of assets consisting of the Mortgage Loans and certain other related assets (other than the Master Servicer Prepayment Charge Payment Amount, the Net WAC Rate Carryover Reserve Account and the Cap Contracts) subject to this Agreement as a REMIC for federal income tax purposes, and such segregated pool of assets will be designated as “REMIC I.” The Class R-I Interest will be the sole class of “residual interests” in REMIC I for purposes of the REMIC Provisions (as defined herein). The following table irrevocably sets forth the designation, the REMIC I Remittance Rate, the initial Uncertificated Balance and, for purposes of satisfying Treasury regulation section 1.860G-1(a)(4)(iii), the “latest possible maturity date” for each of the REMIC I Regular Interests (as defined herein). None of the REMIC I Regular Interests will be certificated.

Designation	REMIC I Remittance Rate	Initial Uncertificated Balance ($)	Latest Possible Maturity Date ⁽¹⁾
I-LTAA	Variable ⁽²⁾	785,171,068.17	March 25, 2035
I-LTA1	Variable ⁽²⁾	3,334,050.00	March 25, 2035
I-LTA2	Variable ⁽²⁾	370,455.00	March 25, 2035
I-LTA3	Variable ⁽²⁾	1,583,060.00	March 25, 2035
I-LTA4	Variable ⁽²⁾	1,238,450.00	March 25, 2035
I-LTA5	Variable ⁽²⁾	228,060.00	March 25, 2035
I-LTM1	Variable ⁽²⁾	232,345.00	March 25, 2035
I-LTM2	Variable ⁽²⁾	188,280.00	March 25, 2035
I-LTM3	Variable ⁽²⁾	124,185.00	March 25, 2035
I-LTM4	Variable ⁽²⁾	196,295.00	March 25, 2035
I-LTM5	Variable ⁽²⁾	68,100.00	March 25, 2035
I-LTM6	Variable ⁽²⁾	76,115.00	March 25, 2035
I-LTM7	Variable ⁽²⁾	92,135.00	March 25, 2035
I-LTM8	Variable ⁽²⁾	72,110.00	March 25, 2035
I-LTM9	Variable ⁽²⁾	76,115.00	March 25, 2035
I-LTM10	Variable ⁽²⁾	40,060.00	March 25, 2035
I-LTM11	Variable ⁽²⁾	36,055.00	March 25, 2035
I-LTP	Variable ⁽²⁾	100.00	March 25, 2035
I-LTZZ	Variable ⁽²⁾	8,068,029.35	March 25, 2035
I-1SUB	Variable ⁽²⁾	13,798.51	March 25, 2035
I-1GRP	Variable ⁽²⁾	87,888.62	March 25, 2035
I-2SUB	Variable ⁽²⁾	11,358.98	March 25, 2035
I-2GRP	Variable ⁽²⁾	72,350.38	March 25, 2035
I-XX	Variable ⁽²⁾	801,009,571.02	March 25, 2035

________________

⁽¹⁾	For purposes of Section 1.860G-1(a)(4)(iii) of the Treasury regulations, the Distribution Date immediately following the maturity date for the Mortgage Loan with the latest maturity date has been designated as the “latest possible maturity date” for each REMIC I Regular Interest.
⁽²⁾	Calculated in accordance with the definition of “REMIC I Remittance Rate” herein.

REMIC II

As provided herein, the Trustee will elect to treat the segregated pool of assets consisting of the REMIC I Regular Interests as a REMIC for federal income tax purposes, and such segregated pool of assets will be designated as “REMIC II.” The Class R-II Interest will evidence the sole class of “residual interests” in REMIC II for purposes of the REMIC Provisions under federal income tax law. The following table irrevocably sets forth the designation, the Pass-Through Rate, the initial aggregate Certificate Principal Balance and, for purposes of satisfying Treasury regulation section 1.860G-1(a)(4)(iii), the “latest possible maturity date” for the indicated Classes of Certificates.

Designation	Pass-Through Rate	Initial Aggregate Certificate Principal Balance ($)	Latest Possible Maturity Date ⁽¹⁾
Class A-1	Variable ⁽²⁾	666,810,000.00	March 25, 2035
Class A-2	Variable ⁽²⁾	74,091,000.00	March 25, 2035
Class A-3	Variable ⁽²⁾	316,612,000.00	March 25, 2035
Class A-4	Variable ⁽²⁾	247,690,000.00	March 25, 2035
Class A-5	Variable ⁽²⁾	45,612,000.00	March 25, 2035
Class M-1	Variable ⁽²⁾	46,469,000.00	March 25, 2035
Class M-2	Variable ⁽²⁾	37,656,000.00	March 25, 2035
Class M-3	Variable ⁽²⁾	24,837,000.00	March 25, 2035
Class M-4	Variable ⁽²⁾	39,259,000.00	March 25, 2035
Class M-5	Variable ⁽²⁾	13,620,000.00	March 25, 2035
Class M-6	Variable ⁽²⁾	15,223,000.00	March 25, 2035
Class M-7	Variable ⁽²⁾	18,427,000.00	March 25, 2035
Class M-8	Variable ⁽²⁾	14,422,000.00	March 25, 2035
Class M-9	Variable ⁽²⁾	15,223,000.00	March 25, 2035
Class M-10	Variable ⁽²⁾	8,012,000.00	March 25, 2035
Class M-11	Variable ⁽²⁾	7,211,000.00	March 25, 2035
Class CE Interest	Variable ⁽²⁾	11,215,935.04	March 25, 2035
Class P Interest	N/A ⁽⁴⁾	100.00	March 25, 2035

_______________

⁽¹⁾	For purposes of Section 1.860G-1(a)(4)(iii) of the Treasury regulations, the Distribution Date immediately following the maturity date for the Mortgage Loans with the latest maturity date has been designated as the “latest possible maturity date” for each Class of Certificates.
⁽²⁾	Calculated in accordance with the definition of “Pass-Through Rate” herein.
⁽³⁾	The Class CE Interest will accrue interest at their variable Pass-Through Rate on the Notional Amount of the Class CE Certificates outstanding from time to time which shall equal the Uncertificated Balance of the REMIC I Regular Interests (other than REMIC I Regular Interest I-LTP). The Class CE Interest will not accrue interest on their Certificate Principal Balance.
⁽⁴⁾	The Class P Interest will not accrue interest.

REMIC III

As provided herein, the Trustee shall make an election to treat the segregated pool of assets consisting of the Class CE Interest as a REMIC for federal income tax purposes, and such segregated pool of assets will be designated as “REMIC III.” The Class R-III Interest represents the sole class of “residual interests” in REMIC III for purposes of the REMIC Provisions.

The following table sets forth (or describes) the Class designation, Pass-Through Rate and initial aggregate Certificate Principal Balance for the indicated Class of Certificates that represents a “regular interest” in REMIC III created hereunder:

Class Designation	Pass-Through Rate	Initial Aggregate Certificate Principal Balance	Latest Possible Maturity Date ⁽¹⁾
Class CE Certificates	Variable ⁽²⁾	$11,215,935.04	March 25, 2035

_______________

⁽¹⁾	For purposes of Section 1.860G-1(a)(4)(iii) of the Treasury regulations, the Distribution Date immediately following the maturity date for the Mortgage Loans with the latest maturity date has been designated as the “latest possible maturity date” for the Class CE Certificates.
⁽²⁾	The Class CE Certificates will receive 100% of amounts received in respect of the Class CE Interest.

REMIC IV

As provided herein, the Trustee shall make an election to treat the segregated pool of assets consisting of the Class P Interest as a REMIC for federal income tax purposes, and such segregated pool of assets will be designated as “REMIC IV.” The Class R-IV Interest represents the sole class of “residual interests” in REMIC IV for purposes of the REMIC Provisions.

Class Designation	Pass-Through Rate	Initial Aggregate Certificate Principal Balance	Latest Possible Maturity Date ⁽¹⁾
Class P Certificates	Variable ⁽²⁾	$100.00	March 25, 2035

_______________

⁽¹⁾	For purposes of Section 1.860G-1(a)(4)(iii) of the Treasury regulations, the Distribution Date immediately following the maturity date for the Mortgage Loans with the latest maturity date has been designated as the “latest possible maturity date” for the Class P Certificates.
⁽²⁾	The Class P Certificates will receive 100% of amounts received in respect of the Class P Interest.

As of the Cut-off Date, the Original Mortgage Loans had an aggregate Principal Balance equal to $1,602,390,035.04. As of the Cut-off Date, the Group I Mortgage Loans had an Aggregate Principal Balance equal to $878,886,199.51 and the Group II Mortgage Loans had an Aggregate Principal Balance equal to $723,503,835.53.

In consideration of the mutual agreements herein contained, the Depositor, the Master Servicer and the Trustee agree as follows:

ARTICLE I

DEFINITIONS

Section 1.01.

Defined Terms .

Whenever used in this Agreement, including, without limitation, in the Preliminary Statement hereto, the following words and phrases, unless the context otherwise requires, shall have the meanings specified in this Article. Unless otherwise specified, all calculations described herein shall be made on the basis of a 360-day year consisting of twelve 30-day months.

“Accepted Servicing Practices”: The servicing standards set forth in Section 3.01.

“Accrual Period”: With respect to the Class A Certificates and the Mezzanine Certificates and each Distribution Date, the period commencing on the preceding Distribution Date (or in the case of the first such Accrual Period, commencing on the Closing Date) and ending on the day preceding the current Distribution Date. With respect to the Class CE Certificates and the REMIC I Regular Interests and each Distribution Date, the calendar month prior to the month of such Distribution Date.

“Adjustable-Rate Mortgage Loan”: Each of the Mortgage Loans identified in the Mortgage Loan Schedule as having a Mortgage Rate that is subject to adjustment.

“Adjusted Net Maximum Mortgage Rate”: With respect to any Mortgage Loan (or the related REO Property), as of any date of determination, a per annum rate of interest equal to the applicable Maximum Mortgage Rate for such Mortgage Loan (or the Mortgage Rate in the case of any Fixed-Rate Mortgage Loan) as of the first day of the month preceding the month in which the related Distribution Date occurs minus the sum of (i) the Trustee Fee Rate, (ii) the Servicing Fee Rate and (iii) the related PMI Insurer Fee Rate, if applicable.

“Adjusted Net Mortgage Rate”: With respect to any Mortgage Loan (or the related REO Property), as of any date of determination, a per annum rate of interest equal to the applicable Mortgage Rate for such Mortgage Loan as of the first day of the month preceding the month in which the related Distribution Date occurs minus the sum of (i) the Trustee Fee Rate, (ii) the Servicing Fee Rate and (iii) the related PMI Insurer Fee Rate, if applicable.

“Adjustment Date”: With respect to each Adjustable-Rate Mortgage Loan, the first day of the month in which the Mortgage Rate of such Mortgage Loan changes pursuant to the related Mortgage Note. The first Adjustment Date following the Cut-off Date as to each Adjustable-Rate Mortgage Loan is set forth in the Mortgage Loan Schedule.

“Advance”: As to any Mortgage Loan or REO Property, any advance made by the Master Servicer in respect of any Distribution Date pursuant to Section 4.03.

“Advance Facility”: As defined in Section 3.29 hereof.

“Advancing Person”: As defined in Section 3.29 hereof.

“Affiliate”: With respect to any specified Person, any other Person controlling or controlled by or under common control with such specified Person. For the purposes of this definition, “control” when used with respect to any specified Person means the power to direct the management and policies of such Person, directly or indirectly, whether through the ownership of voting securities, by contract or otherwise, and the terms “controlling” and “controlled” have meanings correlative to the foregoing.

“Aggregate Loss Severity Percentage”: With respect to any Distribution Date, the percentage equivalent of a fraction, the numerator of which is the aggregate amount of Realized Losses incurred on any Mortgage Loans from the Cut-off Date to the last day of the preceding calendar month and the denominator of which is the aggregate principal balance of such Mortgage Loans immediately prior to the liquidation of such Mortgage Loans.

“Agreement”: This Pooling and Servicing Agreement and all amendments hereof and supplements hereto.

“Allocated Realized Loss Amount”: With respect to any Distribution Date and any Class of Mezzanine Certificates, the sum of (i) any Realized Losses allocated to such Class of Certificates on such Distribution Date and (ii) the amount of any Allocated Realized Loss Amount for such Class of Certificates remaining unpaid from the previous Distribution Date and reduced by the amount of any Subsequent Recoveries added to the Certificate Principal Balance of such Class of Certificates.

“Assignment”: An assignment of Mortgage, notice of transfer or equivalent instrument, in recordable form (excepting therefrom, if applicable, the mortgage recordation information which has not been required pursuant to Section 2.01 hereof or returned by the applicable recorder’s office), which is sufficient under the laws of the jurisdiction wherein the related Mortgaged Property is located to reflect of record the sale of the Mortgage, which assignment, notice of transfer or equivalent instrument may be in the form of one or more blanket assignments covering Mortgages secured by Mortgaged Properties located in the same county, if permitted by law.

“Available Funds”: With respect to any Distribution Date, an amount equal to the excess of (i) the sum of (a) the aggregate of the related Monthly Payments received on the Mortgage Loans on or prior to the related Determination Date, (b) Net Liquidation Proceeds, Insurance Proceeds, Principal Prepayments, proceeds from repurchases of and substitutions for such Mortgage Loans and other unscheduled recoveries of principal and interest in respect of the Mortgage Loans received during the related Prepayment Period, (c) the aggregate of any amounts received in respect of a related REO Property withdrawn from any REO Account and deposited in the Collection Account for such Distribution Date, (d) the aggregate of any amounts deposited in the Collection Account by the Master Servicer in respect of related Prepayment Interest Shortfalls for such Distribution Date, (e) the aggregate of any Advances made by the Master Servicer for such Distribution Date in respect of the Mortgage Loans and (f) the aggregate of any related advances made by the Trustee in respect of the Mortgage Loans for such Distribution Date pursuant to Section 7.02 over (ii) the sum of (a) amounts reimbursable or payable to the Master Servicer pursuant to Section 3.11(a), (b) Extraordinary Trust Fund Expenses reimbursable to the Trustee pursuant to Section 3.11(b), (c) amounts deposited in the

Collection Account or the Distribution Account pursuant to clauses (a) through (f) above, as the case may be, in error, (d) the amount of any Prepayment Charges collected by the Master Servicer in connection with the full or partial prepayment of any of the Mortgage Loans and any Master Servicer Prepayment Charge Payment Amount, (e) the Trustee Fee and any indemnification amounts owed to the Trustee payable from the Distribution Account pursuant to Section 8.05 and (f) the PMI Insurer Fee payable to each PMI Insurer from the Distribution Account.

“Balloon Mortgage Loan”: A Mortgage Loan that provides for the payment of the unamortized principal balance of such Mortgage Loan in a single payment at the maturity of such Mortgage Loan that is substantially greater than the preceding monthly payment.

“Balloon Payment”: A payment of the unamortized principal balance of a Mortgage Loan in a single payment at the maturity of such Mortgage Loan that is substantially greater than the preceding Monthly Payment.

“Bankruptcy Code”: The Bankruptcy Reform Act of 1978 (Title 11 of the United States Code), as amended.

“Book-Entry Certificate”: The Class A Certificates and the Mezzanine Certificates for so long as the Certificates of such Class shall be registered in the name of the Depository or its nominee.

“Book-Entry Custodian”: The custodian appointed pursuant to Section 5.01.

“Business Day”: Any day other than a Saturday, a Sunday or a day on which banking or savings and loan institutions in the State of California, the State of New York, the Commonwealth of Pennsylvania, or in the cities in which the Corporate Trust Office of the Trustee is located, are authorized or obligated by law or executive order to be closed.

“Cap Contracts”: The Group I Cap Contract, the Group II Cap Contract and the Mezzanine Cap Contract between the Trustee on behalf of the Trust Fund and the counterparty thereunder, for the benefit of the Holders of the Offered Certificates, in the form annexed hereto as Exhibit L.

“Certificate”: Any one of the Mortgage Pass-Through Certificates, Series 2005-OPT1, Class A-1, Class A-2, Class A-3, Class A-4, Class A-5, Class M-1, Class M-2, Class M-3, Class M-4, Class M-5, Class M-6, Class M-7, Class M-8, Class M-9, Class M-10, Class M-11, Class CE, Class P, Class R or Class R-X, issued under this Agreement.

“Certificate Factor”: With respect to any Class of Regular Certificates as of any Distribution Date, a fraction, expressed as a decimal carried to six places, the numerator of which is the aggregate Certificate Principal Balance (or the Notional Amount, in the case of the Class CE Certificates) of such Class of Certificates on such Distribution Date (after giving effect to any distributions of principal and allocations of Realized Losses in reduction of the Certificate Principal Balance (or the Notional Amount, in the case of the Class CE Certificates) of such Class of Certificates to be made on such Distribution Date), and the denominator of which is the

initial aggregate Certificate Principal Balance (or the Notional Amount, in the case of the Class CE Certificates) of such Class of Certificates as of the Closing Date.

“Certificate Margin”: With respect to the Class A-1 Certificates and REMIC I Regular Interest I-LTA1, 0.305% in the case of each Distribution Date through and including the Distribution Date on which the aggregate Principal Balance of the Mortgage Loans (and properties acquired in respect thereof) remaining in the Trust Fund is reduced to less than 10% of the aggregate Cut-off Date Principal Balance of the Mortgage Loans and 0.610% in the case of each Distribution Date thereafter.

With respect to the Class A-2 Certificates and REMIC I Regular Interest I-LTA2, 0.260% in the case of each Distribution Date through and including the Distribution Date on which the aggregate Principal Balance of the Mortgage Loans (and properties acquired in respect thereof) remaining in the Trust Fund is reduced to less than 10% of the aggregate Cut-off Date Principal Balance of the Mortgage Loans and 0.520% in the case of each Distribution Date thereafter.

With respect to the Class A-3 Certificates and REMIC I Regular Interest I-LTA3, 0.090% in the case of each Distribution Date through and including the Distribution Date on which the aggregate Principal Balance of the Mortgage Loans (and properties acquired in respect thereof) remaining in the Trust Fund is reduced to less than 10% of the aggregate Cut-off Date Principal Balance of the Mortgage Loans and 0.180% in the case of each Distribution Date thereafter.

With respect to the Class A-4 Certificates and REMIC I Regular Interest I-LTA4, 0.180% in the case of each Distribution Date through and including the Distribution Date on which the aggregate Principal Balance of the Mortgage Loans (and properties acquired in respect thereof) remaining in the Trust Fund is reduced to less than 10% of the aggregate Cut-off Date Principal Balance of the Mortgage Loans and 0.360% in the case of each Distribution Date thereafter.

With respect to the Class A-5 Certificates and REMIC I Regular Interest I-LTA5, 0.310% in the case of each Distribution Date through and including the Distribution Date on which the aggregate Principal Balance of the Mortgage Loans (and properties acquired in respect thereof) remaining in the Trust Fund is reduced to less than 10% of the aggregate Cut-off Date Principal Balance of the Mortgage Loans and 0.620% in the case of each Distribution Date thereafter.

With respect to the Class M-1 Certificates and REMIC I Regular Interest I-LTM1, 0.400% in the case of each Distribution Date through and including the Distribution Date on which the aggregate Principal Balance of the Mortgage Loans (and properties acquired in respect thereof) remaining in the Trust Fund is reduced to less than 10% of the aggregate Cut-off Date Principal Balance of the Mortgage Loans and 0.600% in the case of each Distribution Date thereafter.

With respect to the Class M-2 Certificates and REMIC I Regular Interest I-LTM2, 0.420% in the case of each Distribution Date through and including the Distribution Date on

which the aggregate Principal Balance of the Mortgage Loans (and properties acquired in respect thereof) remaining in the Trust Fund is reduced to less than 10% of the aggregate Cut-off Date Principal Balance of the Mortgage Loans and 0.630% in the case of each Distribution Date thereafter.

With respect to the Class M-3 Certificates and REMIC I Regular Interest I-LTM3, 0.460% in the case of each Distribution Date through and including the Distribution Date on which the aggregate Principal Balance of the Mortgage Loans (and properties acquired in respect thereof) remaining in the Trust Fund is reduced to less than 10% of the aggregate Cut-off Date Principal Balance of the Mortgage Loans and 0.690% in the case of each Distribution Date thereafter.

With respect to the Class M-4 Certificates and REMIC I Regular Interest I-LTM4, 0.500% in the case of each Distribution Date through and including the Distribution Date on which the aggregate Principal Balance of the Mortgage Loans (and properties acquired in respect thereof) remaining in the Trust Fund is reduced to less than 10% of the aggregate Cut-off Date Principal Balance of the Mortgage Loans and 0.750% in the case of each Distribution Date thereafter.

With respect to the Class M-5 Certificates and REMIC I Regular Interest I-LTM5, 0.600% in the case of each Distribution Date through and including the Distribution Date on which the aggregate Principal Balance of the Mortgage Loans (and properties acquired in respect thereof) remaining in the Trust Fund is reduced to less than 10% of the aggregate Cut-off Date Principal Balance of the Mortgage Loans and 0.900% in the case of each Distribution Date thereafter.

With respect to the Class M-6 Certificates and REMIC I Regular Interest I-LTM6, 0.680% in the case of each Distribution Date through and including the Distribution Date on which the aggregate Principal Balance of the Mortgage Loans (and properties acquired in respect thereof) remaining in the Trust Fund is reduced to less than 10% of the aggregate Cut-off Date Principal Balance of the Mortgage Loans and 1.020% in the case of each Distribution Date thereafter.

With respect to the Class M-7 Certificates and REMIC I Regular Interest I-LTM7, 0.920% in the case of each Distribution Date through and including the Distribution Date on which the aggregate Principal Balance of the Mortgage Loans (and properties acquired in respect thereof) remaining in the Trust Fund is reduced to less than 10% of the aggregate Cut-off Date Principal Balance of the Mortgage Loans and 1.380% in the case of each Distribution Date thereafter.

With respect to the Class M-8 Certificates and REMIC I Regular Interest I-LTM8, 1.000% in the case of each Distribution Date through and including the Distribution Date on which the aggregate Principal Balance of the Mortgage Loans (and properties acquired in respect thereof) remaining in the Trust Fund is reduced to less than 10% of the aggregate Cut-off Date Principal Balance of the Mortgage Loans and 1.500% in the case of each Distribution Date thereafter.

With respect to the Class M-9 Certificates and REMIC I Regular Interest I-LTM9, 1.750% in the case of each Distribution Date through and including the Distribution Date on which the aggregate Principal Balance of the Mortgage Loans (and properties acquired in respect thereof) remaining in the Trust Fund is reduced to less than 10% of the aggregate Cut-off Date Principal Balance of the Mortgage Loans and 2.625% in the case of each Distribution Date thereafter.

With respect to the Class M-10 Certificates and REMIC I Regular Interest I-LTM10, 2.500% in the case of each Distribution Date through and including the Distribution Date on which the aggregate Principal Balance of the Mortgage Loans (and properties acquired in respect thereof) remaining in the Trust Fund is reduced to less than 10% of the aggregate Cut-off Date Principal Balance of the Mortgage Loans and 3.750% in the case of each Distribution Date thereafter.

With respect to the Class M-11 Certificates and REMIC I Regular Interest I-LTM11, 3.500% in the case of each Distribution Date through and including the Distribution Date on which the aggregate Principal Balance of the Mortgage Loans (and properties acquired in respect thereof) remaining in the Trust Fund is reduced to less than 10% of the aggregate Cut-off Date Principal Balance of the Mortgage Loans and 5.250% in the case of each Distribution Date thereafter.

“Certificateholder” or “Holder”: The Person in whose name a Certificate is registered in the Certificate Register, except that a Disqualified Organization or a Non-United States Person shall not be a Holder of a Residual Certificate for any purposes hereof and, solely for the purposes of giving any consent pursuant to this Agreement, any Certificate registered in the name of the Depositor or the Master Servicer or any Affiliate thereof shall be deemed not to be outstanding and the Voting Rights to which it is entitled shall not be taken into account in determining whether the requisite percentage of Voting Rights necessary to effect any such consent has been obtained, except as otherwise provided in Section 11.01. The Trustee and the NIMS Insurer may conclusively rely upon a certificate of the Depositor or the Master Servicer in determining whether a Certificate is held by an Affiliate thereof. All references herein to “Holders” or “Certificateholders” shall reflect the rights of Certificate Owners as they may indirectly exercise such rights through the Depository and participating members thereof, except as otherwise specified herein; provided, however, that the Trustee and the NIMS Insurer shall be required to recognize as a “Holder” or “Certificateholder” only the Person in whose name a Certificate is registered in the Certificate Register.

“Certificate Owner”: With respect to a Book-Entry Certificate, the Person who is the beneficial owner of such Certificate as reflected on the books of the Depository or on the books of a Depository Participant or on the books of an indirect participating brokerage firm for which a Depository Participant acts as agent.

“Certificate Principal Balance”: With respect to each Class A Certificate, Mezzanine Certificate or Class P Certificate as of any date of determination plus any Subsequent Recoveries added to the Certificate Principal Balance of such Certificate pursuant to Section 4.01, the Certificate Principal Balance of such Certificate on the Distribution Date immediately prior to such date of determination, minus all distributions allocable to principal made thereon

and Realized Losses allocated thereto on such immediately prior Distribution Date (or, in the case of any date of determination up to and including the first Distribution Date, the initial Certificate Principal Balance of such Certificate, as stated on the face thereof). With respect to each Class CE Certificate as of any date of determination, an amount equal to the Percentage Interest evidenced by such Certificate times the excess, if any, of (A) the then aggregate Uncertificated Balances of the REMIC I Regular Interests over (B) the then aggregate Certificate Principal Balances of the Class A Certificates, the Mezzanine Certificates and the Class P Certificates then outstanding.

“Certificate Register”: The register maintained pursuant to Section 5.02.

“Class”: Collectively, all of the Certificates bearing the same class designation.

“Class A Certificates”: Any Class A-1 Certificate, Class A-2 Certificate, Class A-3 Certificate, Class A-4 Certificate or Class A-5 Certificate.

“Class A Principal Distribution Amount”: With respect to any Distribution Date, the sum of (i) the Senior Group I Principal Distribution Amount and (ii) the Senior Group II Principal Distribution Amount.

“Class A-1 Certificate”: Any one of the Class A-1 Certificates executed, authenticated and delivered by the Trustee, substantially in the form annexed hereto as Exhibit A-1 and evidencing a Regular Interest in REMIC II for purposes of the REMIC Provisions.

“Class A-2 Certificate”: Any one of the Class A-2 Certificates executed, authenticated and delivered by the Trustee, substantially in the form annexed hereto as Exhibit A-2 and evidencing a Regular Interest in REMIC II for purposes of the REMIC Provisions.

Class A-3 Certificate”: Any one of the Class A-3 Certificates executed, authenticated and delivered by the Trustee, substantially in the form annexed hereto as Exhibit A-3 and evidencing a Regular Interest in REMIC II for purposes of the REMIC Provisions.

Class A-4 Certificate”: Any one of the Class A-4 Certificates executed, authenticated and delivered by the Trustee, substantially in the form annexed hereto as Exhibit A-4 and evidencing a Regular Interest in REMIC II for purposes of the REMIC Provisions.

Class A-5 Certificate”: Any one of the Class A-5 Certificates executed, authenticated and delivered by the Trustee, substantially in the form annexed hereto as Exhibit A-5 and evidencing a Regular Interest in REMIC II for purposes of the REMIC Provisions.

“Class CE Certificate”: Any one of the Class CE Certificates executed, authenticated and delivered by the Trustee, substantially in the form annexed hereto as Exhibit A-17 and evidencing a Regular Interest in REMIC III for purposes of the REMIC Provisions.

“Class CE Interest”: An uncertificated interest in the Trust Fund held by the Trustee on behalf of the Holders of the Class CE Certificates, evidencing a Regular Interest in REMIC II for purposes of the REMIC Provisions.

“Class M-1 Certificate”: Any one of the Class M-1 Certificates executed, authenticated and delivered by the Trustee, substantially in the form annexed hereto as Exhibit A-6 and evidencing a Regular Interest in REMIC II for purposes of the REMIC Provisions.

“Class M-1 Principal Distribution Amount”: The excess of (x) the sum of (i) the aggregate Certificate Principal Balance of the Class A Certificates (after taking into account the distribution of the Class A Principal Distribution Amount on such Distribution Date) and (ii) the Certificate Principal Balance of the Class M-1 Certificates immediately prior to such Distribution Date over (y) the lesser of (A) the product of (i) 74.40% and (ii) the aggregate Stated Principal Balance of the Mortgage Loans as of the last day of the related Due Period (after giving effect to scheduled payments of principal due during the related Due Period, to the extent received or advanced, and unscheduled collections of principal received during the related Prepayment Period) and (B) the excess of the aggregate Stated Principal Balance of the Mortgage Loans as of the last day of the related Due Period (after giving effect to scheduled payments of principal due during the related Due Period, to the extent received or advanced, and unscheduled collections of principal received during the related Prepayment Period) over $8,011,950.18.

“Class M-2 Certificate”: Any one of the Class M-2 Certificates executed, authenticated and delivered by the Trustee, substantially in the form annexed hereto as Exhibit A-7 and evidencing a Regular Interest in REMIC II for purposes of the REMIC Provisions.

“Class M-2 Principal Distribution Amount”: The excess of (x) the sum of (i) the aggregate Certificate Principal Balance of the Class A Certificates (after taking into account the distribution of the Class A Principal Distribution Amount on such Distribution Date), (ii) the Certificate Principal Balance of the Class M-1 Certificates (after taking into account the distribution of the Class M-1 Principal Distribution Amount on such Distribution Date) and (iii) the Certificate Principal Balance of the Class M-2 Certificates immediately prior to such Distribution Date over (y) the lesser of (A) the product of (i) 79.10% and (ii) the aggregate Stated Principal Balance of the Mortgage Loans as of the last day of the related Due Period (after giving effect to scheduled payments of principal due during the related Due Period, to the extent received or advanced, and unscheduled collections of principal received during the related Prepayment Period) and (B) the excess of the aggregate Stated Principal Balance of the Mortgage Loans as of the last day of the related Due Period (after giving effect to scheduled payments of principal due during the related Due Period, to the extent received or advanced, and unscheduled collections of principal received during the related Prepayment Period) over $8,011,950.18.

“Class M-3 Certificate”: Any one of the Class M-3 Certificates executed, authenticated and delivered by the Trustee, substantially in the form annexed hereto as Exhibit A-8 and evidencing a Regular Interest in REMIC II for purposes of the REMIC Provisions.

“Class M-3 Principal Distribution Amount”: With respect to any Distribution Date, the excess of (x) the sum of (i) the aggregate Certificate Principal Balance of the Class A Certificates (after taking into account the distribution of the Class A Principal Distribution Amount on such Distribution Date), (ii) the Certificate Principal Balance of the Class M-1 Certificates (after taking into account the distribution of the Class M-1 Principal Distribution Amount on such Distribution Date), (iii) the Certificate Principal Balance of the Class M-2

Certificates (after taking into account the distribution of the Class M-2 Principal Distribution Amount on such Distribution Date) and (iv) the Certificate Principal Balance of the Class M-3 Certificates immediately prior to such Distribution Date over (y) the lesser of (A) the product of (i) 82.20% and (ii) the aggregate Stated Principal Balance of the Mortgage Loans as of the last day of the related Due Period (after giving effect to scheduled payments of principal due during the related Due Period, to the extent received or advanced, and unscheduled collections of principal received during the related Prepayment Period) and (B) the excess of the aggregate Stated Principal Balance of the Mortgage Loans as of the last day of the related Due Period (after giving effect to scheduled payments of principal due during the related Due Period, to the extent received or advanced, and unscheduled collections of principal received during the related Prepayment Period) over $8,011,950.18.

“Class M-4 Certificate”: Any one of the Class M-4 Certificates executed, authenticated and delivered by the Trustee, substantially in the form annexed hereto as Exhibit A-9 and evidencing a Regular Interest in REMIC II for purposes of the REMIC Provisions.

“Class M-4 Principal Distribution Amount”: With respect to any Distribution Date, the excess of (x) the sum of (i) the aggregate Certificate Principal Balance of the Class A Certificates (after taking into account the distribution of the Class A Principal Distribution Amount on such Distribution Date), (ii) the Certificate Principal Balance of the Class M-1 Certificates (after taking into account the distribution of the Class M-1 Principal Distribution Amount on such Distribution Date), (iii) the Certificate Principal Balance of the Class M-2 Certificates (after taking into account the distribution of the Class M-2 Principal Distribution Amount on such Distribution Date), (iv) the Certificate Principal Balance of the Class M-3 Certificates (after taking into account the distribution of the Class M-3 Principal Distribution Amount on such Distribution Date) and (v) the Certificate Principal Balance of the Class M-4 Certificates immediately prior to such Distribution Date over (y) the lesser of (A) the product of (i) 87.10% and (ii) the aggregate Stated Principal Balance of the Mortgage Loans as of the last day of the related Due Period (after giving effect to scheduled payments of principal due during the related Due Period, to the extent received or advanced, and unscheduled collections of principal received during the related Prepayment Period) and (B) the excess of the aggregate Stated Principal Balance of the Mortgage Loans as of the last day of the related Due Period (after giving effect to scheduled payments of principal due during the related Due Period, to the extent received or advanced, and unscheduled collections of principal received during the related Prepayment Period) over $8,011,950.18.

“Class M-5 Certificate”: Any one of the Class M-5 Certificates executed, authenticated and delivered by the Trustee, substantially in the form annexed hereto as Exhibit A-10 and evidencing a Regular Interest in REMIC II for purposes of the REMIC Provisions.

“Class M-5 Principal Distribution Amount”: With respect to any Distribution Date, the excess of (x) the sum of (i) the aggregate Certificate Principal Balance of the Class A Certificates (after taking into account the distribution of the Class A Principal Distribution Amount on such Distribution Date), (ii) the Certificate Principal Balance of the Class M-1 Certificates (after taking into account the distribution of the Class M-1 Principal Distribution Amount on such Distribution Date), (iii) the Certificate Principal Balance of the Class M-2 Certificates (after taking into account the distribution of the Class M-2 Principal Distribution

Amount on such Distribution Date), (iv) the Certificate Principal Balance of the Class M-3 Certificates (after taking into account the distribution of the Class M-3 Principal Distribution Amount on such Distribution Date), (v) the Certificate Principal Balance of the Class M-4 Certificates (after taking into account the distribution of the Class M-4 Principal Distribution Amount on such Distribution Date) and (vi) the Certificate Principal Balance of the Class M-5 Certificates immediately prior to such Distribution Date over (y) the lesser of (A) the product of (i) 88.80% and (ii) the aggregate Stated Principal Balance of the Mortgage Loans as of the last day of the related Due Period (after giving effect to scheduled payments of principal due during the related Due Period, to the extent received or advanced, and unscheduled collections of principal received during the related Prepayment Period) and (B) the excess of the aggregate Stated Principal Balance of the Mortgage Loans as of the last day of the related Due Period (after giving effect to scheduled payments of principal due during the related Due Period, to the extent received or advanced, and unscheduled collections of principal received during the related Prepayment Period) over $8,011,950.18.

“Class M-6 Certificate”: Any one of the Class M-6 Certificates executed, authenticated and delivered by the Trustee, substantially in the form annexed hereto as Exhibit A-11 and evidencing a Regular Interest in REMIC II for purposes of the REMIC Provisions.

“Class M-6 Principal Distribution Amount” is an amount equal to the excess of (x) the sum of (i) the aggregate Certificate Principal Balance of the Class A Certificates (after taking into account the distribution of the Class A Principal Distribution Amount on such Distribution Date), (ii) the Certificate Principal Balance of the Class M-1 Certificates (after taking into account the distribution of the Class M-1 Principal Distribution Amount on such Distribution Date), (iii) the Certificate Principal Balance of the Class M-2 Certificates (after taking into account the distribution of the Class M-2 Principal Distribution Amount on such Distribution Date), (iv) the Certificate Principal Balance of the Class M-3 Certificates (after taking into account the distribution of the Class M-3 Principal Distribution Amount on such Distribution Date), (v) the Certificate Principal Balance of the Class M-4 Certificates (after taking into account the distribution of the Class M-4 Principal Distribution Amount on such Distribution Date), (vi) the Certificate Principal Balance of the Class M-5 Certificates (after taking into account the distribution of the Class M-5 Principal Distribution Amount on such Distribution Date) and (vii) the Certificate Principal Balance of the Class M-6 Certificates immediately prior to such Distribution Date over (y) the lesser of (A) the product of (i) 90.70% and (ii) the aggregate Principal Balance of the Mortgage Loans as of the last day of the related Due Period (after giving effect to scheduled payments of principal due during the related Due Period, to the extent received or advanced, and unscheduled collections of principal received during the related Prepayment Period) and (B) the excess of the aggregate Principal Balance of the Mortgage Loans as of the last day of the related Due Period (after giving effect to scheduled payments of principal due during the related Due Period, to the extent received or advanced, and unscheduled collections of principal received during the related Prepayment Period) over $8,011,950.18.

“Class M-7 Certificate”: Any one of the Class M-7 Certificates executed, authenticated and delivered by the Trustee, substantially in the form annexed hereto as Exhibit A-12 and evidencing a Regular Interest in REMIC II for purposes of the REMIC Provisions.

“Class M-7 Principal Distribution Amount” is an amount equal to the excess of (x) the sum of (i) the aggregate Certificate Principal Balance of the Class A Certificates (after taking into account the distribution of the Class A Principal Distribution Amount on such Distribution Date), (ii) the Certificate Principal Balance of the Class M-1 Certificates (after taking into account the distribution of the Class M-1 Principal Distribution Amount on such Distribution Date), (iii) the Certificate Principal Balance of the Class M-2 Certificates (after taking into account the distribution of the Class M-2 Principal Distribution Amount on such Distribution Date), (iv) the Certificate Principal Balance of the Class M-3 Certificates (after taking into account the distribution of the Class M-3 Principal Distribution Amount on such Distribution Date), (v) the Certificate Principal Balance of the Class M-4 Certificates (after taking into account the distribution of the Class M-4 Principal Distribution Amount on such Distribution Date), (vi) the Certificate Principal Balance of the Class M-5 Certificates (after taking into account the distribution of the Class M-5 Principal Distribution Amount on such Distribution Date), (vii) the Certificate Principal Balance of the Class M-6 Certificates (after taking into account the distribution of the Class M-6 Principal Distribution Amount on such Distribution Date) and (viii) the Certificate Principal Balance of the Class M-7 Certificates immediately prior to such Distribution Date over (y) the lesser of (A) the product of (i) 93.00% and (ii) the aggregate Principal Balance of the Mortgage Loans as of the last day of the related Due Period (after giving effect to scheduled payments of principal due during the related Due Period, to the extent received or advanced, and unscheduled collections of principal received during the related Prepayment Period) and (B) the excess of the aggregate Principal Balance of the Mortgage Loans as of the last day of the related Due Period (after giving effect to scheduled payments of principal due during the related Due Period, to the extent received or advanced, and unscheduled collections of principal received during the related Prepayment Period) over $8,011,950.18.

“Class M-8 Certificate”: Any one of the Class M-8 Certificates executed, authenticated and delivered by the Trustee, substantially in the form annexed hereto as Exhibit A-13 and evidencing a Regular Interest in REMIC II for purposes of the REMIC Provisions.

“Class M-8 Principal Distribution Amount” is an amount equal to the excess of (x) the sum of (i) the aggregate Certificate Principal Balance of the Class A Certificates (after taking into account the distribution of the Class A Principal Distribution Amount on such Distribution Date), (ii) the Certificate Principal Balance of the Class M-1 Certificates (after taking into account the distribution of the Class M-1 Principal Distribution Amount on such Distribution Date), (iii) the Certificate Principal Balance of the Class M-2 Certificates (after taking into account the distribution of the Class M-2 Principal Distribution Amount on such Distribution Date), (iv) the Certificate Principal Balance of the Class M-3 Certificates (after taking into account the distribution of the Class M-3 Principal Distribution Amount on such Distribution Date), (v) the Certificate Principal Balance of the Class M-4 Certificates (after taking into account the distribution of the Class M-4 Principal Distribution Amount on such Distribution Date), (vi) the Certificate Principal Balance of the Class M-5 Certificates (after taking into account the distribution of the Class M-5 Principal Distribution Amount on such Distribution Date), (vii) the Certificate Principal Balance of the Class M-6 Certificates (after taking into account the distribution of the Class M-6 Principal Distribution Amount on such Distribution Date), (viii) the Certificate Principal Balance of the Class M-7 Certificates (after

taking into account the distribution of the Class M-7 Principal Distribution Amount on such Distribution Date) and (ix) the Certificate Principal Balance of the Class M-8 Certificates immediately prior to such Distribution Date over (y) the lesser of (A) the product of (i) 94.80% and (ii) the aggregate Principal Balance of the Mortgage Loans as of the last day of the related Due Period (after giving effect to scheduled payments of principal due during the related Due Period, to the extent received or advanced, and unscheduled collections of principal received during the related Prepayment Period) and (B) the excess of the aggregate Principal Balance of the Mortgage Loans as of the last day of the related Due Period (after giving effect to scheduled payments of principal due during the related Due Period, to the extent received or advanced, and unscheduled collections of principal received during the related Prepayment Period) over $8,011,950.18.

“Class M-9 Certificate”: Any one of the Class M-9 Certificates executed, authenticated and delivered by the Trustee, substantially in the form annexed hereto as Exhibit A-14 and evidencing a Regular Interest in REMIC II for purposes of the REMIC Provisions.

“Class M-9 Principal Distribution Amount” is an amount equal to the excess of (x) the sum of (i) the aggregate Certificate Principal Balance of the Class A Certificates (after taking into account the distribution of the Class A Principal Distribution Amount on such Distribution Date), (ii) the Certificate Principal Balance of the Class M-1 Certificates (after taking into account the distribution of the Class M-1 Principal Distribution Amount on such Distribution Date), (iii) the Certificate Principal Balance of the Class M-2 Certificates (after taking into account the distribution of the Class M-2 Principal Distribution Amount on such Distribution Date), (iv) the Certificate Principal Balance of the Class M-3 Certificates (after taking into account the distribution of the Class M-3 Principal Distribution Amount on such Distribution Date), (v) the Certificate Principal Balance of the Class M-4 Certificates (after taking into account the distribution of the Class M-4 Principal Distribution Amount on such Distribution Date), (vi) the Certificate Principal Balance of the Class M-5 Certificates (after taking into account the distribution of the Class M-5 Principal Distribution Amount on such Distribution Date), (vii) the Certificate Principal Balance of the Class M-6 Certificates (after taking into account the distribution of the Class M-6 Principal Distribution Amount on such Distribution Date), (viii) the Certificate Principal Balance of the Class M-7 Certificates (after taking into account the distribution of the Class M-7 Principal Distribution Amount on such Distribution Date), (ix) the Certificate Principal Balance of the Class M-8 Certificates (after taking into account the distribution of the Class M-8 Principal Distribution Amount on such Distribution Date) and (x) the Certificate Principal Balance of the Class M-9 Certificates immediately prior to such Distribution Date over (y) the lesser of (A) the product of (i) 96.70% and (ii) the aggregate Principal Balance of the Mortgage Loans as of the last day of the related Due Period (after giving effect to scheduled payments of principal due during the related Due Period, to the extent received or advanced, and unscheduled collections of principal received during the related Prepayment Period) and (B) the excess of the aggregate Principal Balance of the Mortgage Loans as of the last day of the related Due Period (after giving effect to scheduled payments of principal due during the related Due Period, to the extent received or advanced, and unscheduled collections of principal received during the related Prepayment Period) over $8,011,950.18.

“Class M-10 Certificate”: Any one of the Class M-10 Certificates executed, authenticated and delivered by the Trustee, substantially in the form annexed hereto as Exhibit A-15 and evidencing a Regular Interest in REMIC II for purposes of the REMIC Provisions.

“Class M-10 Principal Distribution Amount” is an amount equal to the excess of (x) the sum of (i) the aggregate Certificate Principal Balance of the Class A Certificates (after taking into account the distribution of the Class A Principal Distribution Amount on such Distribution Date), (ii) the Certificate Principal Balance of the Class M-1 Certificates (after taking into account the distribution of the Class M-1 Principal Distribution Amount on such Distribution Date), (iii) the Certificate Principal Balance of the Class M-2 Certificates (after taking into account the distribution of the Class M-2 Principal Distribution Amount on such Distribution Date), (iv) the Certificate Principal Balance of the Class M-3 Certificates (after taking into account the distribution of the Class M-3 Principal Distribution Amount on such Distribution Date), (v) the Certificate Principal Balance of the Class M-4 Certificates (after taking into account the distribution of the Class M-4 Principal Distribution Amount on such Distribution Date), (vi) the Certificate Principal Balance of the Class M-5 Certificates (after taking into account the distribution of the Class M-5 Principal Distribution Amount on such Distribution Date), (vii) the Certificate Principal Balance of the Class M-6 Certificates (after taking into account the distribution of the Class M-6 Principal Distribution Amount on such Distribution Date), (viii) the Certificate Principal Balance of the Class M-7 Certificates (after taking into account the distribution of the Class M-7 Principal Distribution Amount on such Distribution Date), (ix) the Certificate Principal Balance of the Class M-8 Certificates (after taking into account the distribution of the Class M-8 Principal Distribution Amount on such Distribution Date), (x) the Certificate Principal Balance of the Class M-9 Certificates (after taking into account the distribution of the Class M-9 Principal Distribution Amount on such Distribution Date) and (xi) the Certificate Principal Balance of the Class M-10 Certificates immediately prior to such Distribution Date over (y) the lesser of (A) the product of (i) 97.70% and (ii) the aggregate Principal Balance of the Mortgage Loans as of the last day of the related Due Period (after giving effect to scheduled payments of principal due during the related Due Period, to the extent received or advanced, and unscheduled collections of principal received during the related Prepayment Period) and (B) the excess of the aggregate Principal Balance of the Mortgage Loans as of the last day of the related Due Period (after giving effect to scheduled payments of principal due during the related Due Period, to the extent received or advanced, and unscheduled collections of principal received during the related Prepayment Period) over $8,011,950.18.

“Class M-11 Principal Distribution Amount” is an amount equal to the excess of (x) the sum of (i) the aggregate Certificate Principal Balance of the Class A Certificates (after taking into account the distribution of the Class A Principal Distribution Amount on such Distribution Date), (ii) the Certificate Principal Balance of the Class M-1 Certificates (after taking into account the distribution of the Class M-1 Principal Distribution Amount on such Distribution Date), (iii) the Certificate Principal Balance of the Class M-2 Certificates (after taking into account the distribution of the Class M-2 Principal Distribution Amount on such Distribution Date), (iv) the Certificate Principal Balance of the Class M-3 Certificates (after taking into account the distribution of the Class M-3 Principal Distribution Amount on such Distribution Date), (v) the Certificate Principal Balance of the Class M-4 Certificates (after

taking into account the distribution of the Class M-4 Principal Distribution Amount on such Distribution Date), (vi) the Certificate Principal Balance of the Class M-5 Certificates (after taking into account the distribution of the Class M-5 Principal Distribution Amount on such Distribution Date), (vii) the Certificate Principal Balance of the Class M-6 Certificates (after taking into account the distribution of the Class M-6 Principal Distribution Amount on such Distribution Date), (viii) the Certificate Principal Balance of the Class M-7 Certificates (after taking into account the distribution of the Class M-7 Principal Distribution Amount on such Distribution Date), (ix) the Certificate Principal Balance of the Class M-8 Certificates (after taking into account the distribution of the Class M-8 Principal Distribution Amount on such Distribution Date), (x) the Certificate Principal Balance of the Class M-9 Certificates (after taking into account the distribution of the Class M-9 Principal Distribution Amount on such Distribution Date), (xi) the Certificate Principal Balance of the Class M-10 Certificates (after taking into account the distribution of the Class M-10 Principal Distribution Amount on such Distribution Date) and (xii) the Certificate Principal Balance of the Class M-11 Certificates immediately prior to such Distribution Date over (y) the lesser of (A) the product of (i) 98.60% and (ii) the aggregate Principal Balance of the Mortgage Loans as of the last day of the related Due Period (after giving effect to scheduled payments of principal due during the related Due Period, to the extent received or advanced, and unscheduled collections of principal received during the related Prepayment Period) and (B) the excess of the aggregate Principal Balance of the Mortgage Loans as of the last day of the related Due Period (after giving effect to scheduled payments of principal due during the related Due Period, to the extent received or advanced, and unscheduled collections of principal received during the related Prepayment Period) over $8,011,950.18.

“Class P Certificate”: Any one of the Class P Certificates executed, authenticated and delivered by the Trustee, substantially in the form annexed hereto as Exhibit A-18 and evidencing a Regular Interest in REMIC IV for purposes of the REMIC Provisions.

“Class P Interest”: An uncertificated interest in the Trust Fund held by the Trustee on behalf of the Holders of the Class P Certificates, evidencing a Regular Interest in REMIC II for purposes of the REMIC Provisions.

“Class R Certificate”: Any one of the Class R Certificates executed, authenticated and delivered by the Trustee, substantially in the form annexed hereto as Exhibit A-19 and evidencing the ownership of the Class R-I Interest and the Class R-II Interest.

“Class R-X Certificate”: Any one of the Class R-X Certificates executed, authenticated and delivered by the Trustee, substantially in the form annexed hereto as Exhibit A-20 and evidencing the ownership of the Class R-III Interest and the Class R-IV Interest.

“Class R-I Interest”: The uncertificated Residual Interest in REMIC I.

“Class R-II Interest”: The uncertificated Residual Interest in REMIC II.

“Class R-III Interest”: The uncertificated Residual Interest in REMIC III.

“Class R-IV Interest”: The uncertificated Residual Interest in REMIC IV.

“Closing Date”: May 12, 2005.

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

“Collection Account”: The segregated account or accounts created and maintained, or caused to be created and maintained, by the Master Servicer pursuant to Section 3.10(a), which shall be entitled “Option One Mortgage Corporation, as Master Servicer for Wells Fargo Bank, N.A., as Trustee, in trust for the registered holders of MASTR Asset Backed Securities Trust 2005-OPT1, Mortgage Pass-Through Certificates.” The Collection Account must be an Eligible Account.

“Commission”: The Securities and Exchange Commission.

“Compensating Interest”: As defined in Section 3.24 hereof.

“Corporate Trust Office”: The principal corporate trust office of the Trustee at which at any particular time its corporate trust business in connection with this Agreement shall be administered, which office, at the date of the execution of this instrument is located (i) for Certificate transfer purposes, at Sixth Street and Marquette Avenue, Minneapolis, Minnesota 55479-0113, Attention: Corporate Trust Services – MASTR Series 2005-OPT1 and (ii) for all other purposes, at 9062 Old Annapolis Road, Columbia, Maryland 21045, Attention: MASTR Series 2005-OPT1, or at such other address as the Trustee may designate from time to time by notice to the Certificateholders, the Depositor and the Master Servicer.

“Corresponding Certificate”: With respect to (i) REMIC I Regular Interest I-LTA1, (ii) REMIC I Regular Interest I-LTA2, (iii) REMIC I Regular Interest I-LTA3, (iv) REMIC I Regular Interest I-LTA4, (v) REMIC I Regular Interest I-LTA5, (vi) REMIC I Regular Interest I-LTM1, (vii) REMIC I Regular Interest I-LTM2, (viii) REMIC I Regular Interest I-LTM3, (ix) REMIC I Regular Interest I-LTM4, (x) REMIC I Regular Interest I-LTM5, (xi) REMIC I Regular Interest I-LTM6, (xii) REMIC I Regular Interest I-LTM7, (xiii) REMIC I Regular Interest I-LTM8, (xiv) REMIC I Regular Interest I-LTM9, (xv) REMIC I Regular Interest I-LTM10, (xvi) REMIC I Regular Interest I-LTM11 and (xvii) REMIC I Regular Interest I-LTP, (i) the Class A-1 Certificates, (ii) the Class A-2 Certificates, (iii) the Class A-3 Certificates, (iv) the Class A-4 Certificates, (v) the Class A-5 Certificates, (vi) the Class M-1 Certificates, (vii) the Class M-2 Certificates, (viii) the Class M-3 Certificates, (ix) the Class M-4 Certificates, (x) the Class M-5 Certificates, (xi) the Class M-6 Certificates, (xii) the Class M-7 Certificates, (xiii) the Class M-8 Certificates, (xiv) the Class M-9 Certificates, (xv) the Class M-10 Certificates, (xvi) the Class M-11 Certificates and (xvii) the Class P Certificates, respectively.

“Credit Enhancement Percentage”: For any Distribution Date, the percentage equivalent of a fraction, the numerator of which is the sum of the aggregate Certificate Principal Balances of the Mezzanine Certificates and the Class CE Certificates, and the denominator of which is the aggregate Stated Principal Balance of the Mortgage Loans, calculated prior to taking into account distributions of principal on the Mortgage Loans and distribution of the Group I Principal Distribution Amount and the Group II Principal Distribution Amount to the Certificates then entitled to distributions of principal on such Distribution Date.

“Cumulative Loss Percentage”: With respect to any Distribution Date, the percentage equivalent of a fraction, the numerator of which is the aggregate amount of Realized Losses incurred from the Cut-off Date to the last day of the preceding calendar month and the denominator of which is the sum of the aggregate Stated Principal Balance of the Mortgage Loans as of the Cut-off Date.

“Cut-off Date”: With respect to each Original Mortgage Loan, May 1, 2005. With respect to all Qualified Substitute Mortgage Loans, their respective dates of substitution. References herein to the “Cut-off Date,” when used with respect to more than one Mortgage Loan, shall be to the respective Cut-off Dates for such Mortgage Loans.

“Cut-off Date Principal Balance”: With respect to any Mortgage Loan, the unpaid principal balance thereof as of the Cut-off Date of such Mortgage Loan (or as of the applicable date of substitution with respect to a Qualified Substitute Mortgage Loan), after giving effect to scheduled payments due on or before the Cut-off Date, whether or not received.

“Debt Service Reduction”: With respect to any Mortgage Loan, a reduction in the scheduled Monthly Payment for such Mortgage Loan by a court of competent jurisdiction in a proceeding under the Bankruptcy Code, except such a reduction resulting from a Deficient Valuation.

“Deficient Valuation”: With respect to any Mortgage Loan, a valuation of the related Mortgaged Property by a court of competent jurisdiction in an amount less than the then outstanding principal balance of the Mortgage Loan, which valuation results from a proceeding initiated under the Bankruptcy Code.

“Definitive Certificates”: As defined in Section 5.01(b).

“Deleted Mortgage Loan”: A Mortgage Loan replaced or to be replaced by a Qualified Substitute Mortgage Loan.

“Delinquency Master Servicer Termination Trigger”: A Delinquency Master Servicer Termination Trigger will have occurred with respect to the Certificates on a Distribution Date if the Three Month Rolling Delinquency Percentage for the Mortgage Loans exceeds 16.00%.

“Delinquency Percentage”: As of the last day of the related Due Period, the percentage equivalent of a fraction, the numerator of which is the aggregate Stated Principal Balance of all Mortgage Loans that, as of the last day of the previous calendar month, are 60 or more days delinquent, are in foreclosure, have been converted to REO Properties or have been discharged by reason of bankruptcy, and the denominator of which is the aggregate Stated Principal Balance of the Mortgage Loans and REO Properties as of the last day of the previous calendar month.

“Depositor”: Mortgage Asset Securitization Transactions, Inc., a Delaware corporation, or its successor in interest.

“Depository”: The Depository Trust Company, or any successor Depository hereafter named. The nominee of the initial Depository, for purposes of registering those Certificates that are to be Book-Entry Certificates, is CEDE & Co. The Depository shall at all times be a “clearing corporation” as defined in Section 8-102(3) of the Uniform Commercial Code of the State of New York and a “clearing agency” registered pursuant to the provisions of Section 17A of the Securities Exchange Act of 1934, as amended.

“Depository Participant”: A broker, dealer, bank or other financial institution or other Person for whom from time to time a Depository effects book-entry transfers and pledges of securities deposited with the Depository.

“Determination Date”: With respect to any Distribution Date, the 15 ^th day of the calendar month in which such Distribution Date occurs or, if such 15 ^th day is not a Business Day, the Business Day immediately preceding such 15 ^th day.

“Directly Operate”: With respect to any REO Property, the furnishing or rendering of services to the tenants thereof, the management or operation of such REO Property, the holding of such REO Property primarily for sale to customers, the performance of any construction work thereon or any use of such REO Property in a trade or business conducted by REMIC I other than through an Independent Contractor; provided, however, that the Trustee (or the Master Servicer on behalf of the Trustee) shall not be considered to Directly Operate an REO Property solely because the Trustee (or the Master Servicer on behalf of the Trustee) establishes rental terms, chooses tenants, enters into or renews leases, deals with taxes and insurance, or makes decisions as to repairs or capital expenditures with respect to such REO Property.

“Disqualified Organization”: Any of the following: (i) the United States, any State or political subdivision thereof, any possession of the United States, or any agency or instrumentality of any of the foregoing (other than an instrumentality which is a corporation if all of its activities are subject to tax and, except for Freddie Mac, a majority of its board of directors is not selected by such governmental unit), (ii) any foreign government, any international organization, or any agency or instrumentality of any of the foregoing, (iii) any organization (other than certain farmers’ cooperatives described in Section 521 of the Code) which is exempt from the tax imposed by Chapter 1 of the Code (including the tax imposed by Section 511 of the Code on unrelated business taxable income), (iv) rural electric and telephone cooperatives described in Section 1381(a)(2)(C) of the Code, (v) an “electing large partnership” and (vi) any other Person so designated by the Trustee based upon an Opinion of Counsel that the holding of an Ownership Interest in a Residual Certificate by such Person may cause any of REMIC I or REMIC II or any Person having an Ownership Interest in any Class of Certificates (other than such Person) to incur a liability for any federal tax imposed under the Code that would not otherwise be imposed but for the Transfer of an Ownership Interest in a Residual Certificate to such Person. The terms “United States,” “State” and “international organization” shall have the meanings set forth in Section 7701 of the Code or successor provisions.

“Distribution Account”: The segregated trust account or accounts created and maintained by the Trustee pursuant to Section 3.10(b), which shall be entitled “Wells Fargo Bank, N.A., as Trustee, in trust for the registered holders of MASTR Asset Backed Securities

Trust 2005-OPT1, Mortgage Pass-Through Certificates.” The Distribution Account must be an Eligible Account.

“Distribution Date”: The 25 ^th day of any month, or if such 25 ^th day is not a Business Day, the Business Day immediately following such 25 ^th day, commencing in June 2005.

“Due Date”: With respect to each Distribution Date, the first day of the calendar month in which such Distribution Date occurs, which is generally the day of the month on which the Monthly Payment is due on a Mortgage Loan, exclusive of any days of grace.

“Due Period”: With respect to any Distribution Date, the period commencing on the second day of the month immediately preceding the month in which such Distribution Date occurs and ending on the related Due Date.

“Eligible Account”: Any of (i) an account or accounts maintained with a federal or state chartered depository institution or trust company the short-term unsecured debt obligations of which (or, in the case of a depository institution or trust company that is the principal subsidiary of a holding company, the short-term unsecured debt obligations of such holding company) are rated P-1 by Moody’s, F-1 by Fitch or A-1+ by S&P (or comparable ratings if Moody’s, Fitch and S&P are not the Rating Agencies) at the time any amounts are held on deposit therein, (ii) an account or accounts the deposits in which are fully insured by the FDIC (to the limits established by such corporation), the uninsured deposits in which account are otherwise secured such that, as evidenced by an Opinion of Counsel delivered to the NIMS Insurer, the Trustee and to each Rating Agency, the Certificateholders will have a claim with respect to the funds in such account or a perfected first priority security interest against such collateral (which shall be limited to Permitted Investments) securing such funds that is superior to claims of any other depositors or creditors of the depository institution with which such account is maintained, (iii) a trust account or accounts maintained with the trust department of a federal or state chartered depository institution, national banking association or trust company acting in its fiduciary capacity or (iv) an account otherwise acceptable to the NIMS Insurer and to each Rating Agency without reduction or withdrawal of their then current ratings of the Certificates as evidenced by a letter from each Rating Agency to the Trustee and the NIMS Insurer. Eligible Accounts may bear interest.

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

“Escrow Payments”: The amounts constituting ground rents, taxes, assessments, water rates, fire and hazard insurance premiums and other payments required to be escrowed by the Mortgagor with the mortgagee pursuant to any Mortgage Loan.

“Estate in Real Property”: A fee simple estate in a parcel of land.

“Excess Overcollateralized Amount”: With respect to the Class A Certificates and the Mezzanine Certificates and any Distribution Date, the excess, if any, of (i) the Overcollateralized Amount for such Distribution Date, assuming that 100% of the Principal

Remittance Amount is applied as a principal payment on such Distribution Date over (ii) the Overcollateralization Target Amount for such Distribution Date.

“Extra Principal Distribution Amount”: With respect to any Distribution Date, the lesser of (x) the Monthly Interest Distributable Amount payable on the Class CE Certificates on such Distribution Date as reduced by Realized Losses allocated thereto with respect to such Distribution Date pursuant to Section 4.04 and (y) the Overcollateralization Deficiency Amount for such Distribution Date.

“Extraordinary Trust Fund Expense”: Any amounts reimbursable to the Trustee, or any director, officer, employee or agent of the Trustee from the Trust Fund pursuant to Section 8.05 or Section 10.01(c) and any amounts payable from the Distribution Account in respect of taxes pursuant to Section 10.01(g)(iii).

“Fannie Mae”: Fannie Mae, formally known as the Federal National Mortgage Association, or any successor thereto.

“FDIC”: Federal Deposit Insurance Corporation or any successor thereto.

“Final Recovery Determination”: With respect to any defaulted Mortgage Loan or any REO Property (other than a Mortgage Loan or REO Property purchased by the Originator, the Seller, the Depositor or the Master Servicer pursuant to or as contemplated by Section 2.03, Section 3.16(c) or Section 9.01), a determination made by the Master Servicer that all Insurance Proceeds, Liquidation Proceeds and other payments or recoveries which the Master Servicer, in its reasonable good faith judgment, expects to be finally recoverable in respect thereof have been so recovered. The Master Servicer shall maintain records, prepared by a Servicing Officer, of each Final Recovery Determination made thereby.

“Fitch”: Fitch Ratings, or its successor in interest.

“Fixed-Rate Mortgage Loan”: Each of the Mortgage Loans identified in the Mortgage Loan Schedule as having a Mortgage Rate that is fixed.

“Formula Rate”: For any Distribution Date and the Offered Certificates, the lesser of (i) One-Month LIBOR plus the related Certificate Margin and (ii) the Maximum Cap Rate.

“Freddie Mac”: Freddie Mac, formally known as the Federal Home Loan Mortgage Corporation, or any successor thereto.

“Gross Margin”: With respect to each Adjustable-Rate Mortgage Loan, the fixed percentage set forth in the related Mortgage Note that is added to the Index on each Adjustment Date in accordance with the terms of the related Mortgage Note used to determine the Mortgage Rate for such Adjustable-Rate Mortgage Loan.

“Group I Allocation Percentage”: With respect to any Distribution Date, the percentage equivalent of a fraction, the numerator of which is (i) the Group I Principal

Remittance Amount for such Distribution Date, and the denominator of which is (ii) the Principal Remittance Amount for such Distribution Date.

“Group I Basic Principal Distribution Amount”: With respect to any Distribution Date, the excess of (i) the Group I Principal Remittance Amount for such Distribution Date over (ii)(a) the Overcollateralization Release Amount, if any, for such Distribution Date multiplied by (b) the Group I Allocation Percentage.

“Group I Cap Contract”: The Cap Contract between the Trustee on behalf of the Trust Fund and the counterparty thereunder, for the benefit of the Holders of the Group I Certificates.

“Group I Certificates”: The Class A-1 Certificates and the Class A-2 Certificates.

“Group I Interest Remittance Amount”: With respect to any Distribution Date, that portion of the Available Funds for such Distribution Date attributable to interest received or advanced with respect to the Group I Mortgage Loans.

“Group I Mortgage Loan”: A Mortgage Loan assigned to Loan Group I with a principal balance that conforms to Fannie Mae and Freddie Mac loan limits.

“Group I Principal Distribution Amount”: With respect to any Distribution Date, the sum of (i) the Group I Basic Principal Distribution Amount for such Distribution Date and (ii)(a) the Extra Principal Distribution Amount for such Distribution Date multiplied by (b) the Group I Allocation Percentage.

“Group I Principal Remittance Amount”: With respect to any Distribution Date, the sum of (i) each scheduled payment of principal collected or advanced on the Group I Mortgage Loans by the Master Servicer that were due during the related Due Period, (ii) the principal portion of all partial and full principal prepayments of the Group I Mortgage Loans applied by the Master Servicer during the related Prepayment Period, (iii) the principal portion of all related Net Liquidation Proceeds, Insurance Proceeds and Subsequent Recoveries received during such Prepayment Period with respect to the Group I Mortgage Loans, (iv) that portion of the Purchase Price, representing principal of any repurchased Group I Mortgage Loan, deposited to the Collection Account during such Prepayment Period, (v) the principal portion of any related Substitution Adjustment Amounts deposited in the Collection Account during such Prepayment Period with respect to the Group I Mortgage Loans and (vi) on the Distribution Date on which the Trust Fund is to be terminated pursuant to Section 9.01, that portion of the Termination Price, in respect of principal on the Group I Mortgage Loans.

“Group II Allocation Percentage”: With respect to any Distribution Date, the percentage equivalent of a fraction, the numerator of which is (i) the Group II Principal Remittance Amount for such Distribution Date, and the denominator of which is (ii) the Principal Remittance Amount for such Distribution Date.

“Group II Basic Principal Distribution Amount”: With respect to any Distribution Date, the excess of (i) the Group II Principal Remittance Amount for such Distribution Date over

(ii)(a) the Overcollateralization Release Amount, if any, for such Distribution Date multiplied by (b) the Group II Allocation Percentage.

“Group II Cap Contract”: The Cap Contract between the Trustee on behalf of the Trust Fund and the counterparty thereunder, for the benefit of the Holders of the Group II Certificates.

“Group II Certificates”: The Class A-3 Certificates, the Class A-4 Certificates and the Class A-5 Certificates.

“Group II Interest Remittance Amount”: With respect to any Distribution Date, that portion of the Available Funds for such Distribution Date attributable to interest received or advanced with respect to the Group II Mortgage Loans.

“Group II Mortgage Loan”: A Mortgage Loan assigned to Loan Group II with a principal balance that may or may not conform to Fannie Mae and Freddie Mac loan limits.

“Group II Principal Distribution Amount”: With respect to any Distribution Date, the sum of (i) the Group II Basic Principal Distribution Amount for such Distribution Date and (ii)(a) the Extra Principal Distribution Amount for such Distribution Date multiplied by (b) the Group II Allocation Percentage.

“Group II Principal Remittance Amount”: With respect to any Distribution Date, the sum of (i) each scheduled payment of principal collected or advanced on the Group II Mortgage Loans by the Master Servicer that were due during the related Due Period, (ii) the principal portion of all partial and full principal prepayments of the Group II Mortgage Loans applied by the Master Servicer during the related Prepayment Period, (iii) the principal portion of all related Net Liquidation Proceeds, Insurance Proceeds and Subsequent Recoveries received during such Prepayment Period with respect to the Group II Mortgage Loans, (iv) that portion of the Purchase Price, representing principal of any repurchased Group II Mortgage Loan, deposited to the Collection Account during such Prepayment Period, (v) the principal portion of any related Substitution Adjustment Amounts deposited in the Collection Account during such Prepayment Period with respect to the Group II Mortgage Loans and (vi) on the Distribution Date on which the Trust Fund is to be terminated pursuant to Section 9.01, that portion of the Termination Price, in respect of principal on the Group II Mortgage Loans.

“Highest Priority”: As of any date of determination, the Class of Mezzanine Certificates then outstanding with a Certificate Principal Balance greater than zero, with the highest priority for payments pursuant to Section 4.01, in the following order: Class M-1, Class M-2, Class M-3, Class M-4, Class M-5, Class M-6, Class M-7, Class M-8, Class M-9, Class M-10 and Class M-11 Certificates.

“Indenture”: An indenture relating to the issuance of notes secured by the Class CE Certificates, the Class P Certificates and/or the Class R Certificates (or any portion thereof) which may or may not be guaranteed by the NIMS Insurer.

“Independent”: When used with respect to any specified Person, any such Person who (a) is in fact independent of the Depositor, the Seller, the Master Servicer, the Originator and their respective Affiliates, (b) does not have any direct financial interest in or any material indirect financial interest in the Depositor, the Seller, the Originator, the Master Servicer or any Affiliate thereof, and (c) is not connected with the Depositor, the Seller, the Originator, the Master Servicer or any Affiliate thereof as an officer, employee, promoter, underwriter, trustee, partner, director or Person performing similar functions; provided, however, that a Person shall not fail to be Independent of the Depositor, the Seller, the Originator, the Master Servicer or any Affiliate thereof merely because such Person is the beneficial owner of 1% or less of any class of securities issued by the Depositor, the Seller, the Originator, the Master Servicer or any Affiliate thereof, as the case may be.

“Independent Contractor”: Either (i) any Person (other than the Master Servicer) that would be an “independent contractor” with respect to REMIC I within the meaning of Section 856(d)(3) of the Code if REMIC I were a real estate investment trust (except that the ownership tests set forth in that section shall be considered to be met by any Person that owns, directly or indirectly, 35% or more of any Class of Certificates), so long as REMIC I does not receive or derive any income from such Person and provided that the relationship between such Person and REMIC I is at arm’s length, all within the meaning of Treasury Regulation Section 1.856-4(b)(5), or (ii) any other Person (including the Master Servicer) if the Trustee has received an Opinion of Counsel to the effect that the taking of any action in respect of any REO Property by such Person, subject to any conditions therein specified, that is otherwise herein contemplated to be taken by an Independent Contractor will not cause such REO Property to cease to qualify as “foreclosure property” within the meaning of Section 860G(a)(8) of the Code (determined without regard to the exception applicable for purposes of Section 860D(a) of the Code), or cause any income realized in respect of such REO Property to fail to qualify as Rents from Real Property.

“Index”: With respect to each Adjustable Rate Mortgage Loan and with respect to each related Adjustment Date, the index as specified in the related Mortgage Note.

“Insurance Proceeds”: Proceeds of any title policy, hazard policy or other insurance policy, including each PMI Policy, covering a Mortgage Loan, to the extent such proceeds are not to be applied to the restoration of the related Mortgaged Property or released to the Mortgagor in accordance with the procedures that the Master Servicer would follow in servicing mortgage loans held for its own account, subject to the terms and conditions of the related Mortgage Note and Mortgage.

“Interest Determination Date”: With respect to the Class A Certificates, the Mezzanine Certificates, REMIC I Regular Interest I-LTA1, REMIC I Regular Interest I-LTA2, REMIC I Regular Interest I-LTA3, REMIC I Regular Interest I-LTA4, REMIC I Regular Interest I-LTA5, REMIC I Regular Interest I-LTM1, REMIC I Regular Interest I-LTM2, REMIC I Regular Interest I-LTM3, REMIC I Regular Interest I-LTM4, REMIC I Regular Interest I-LTM5, REMIC I Regular Interest I-LTM6, REMIC I Regular Interest I-LTM7, REMIC I Regular Interest I-LTM8, REMIC I Regular Interest I-LTM9, REMIC I Regular Interest I-LTM10 and REMIC I Regular Interest I-LTM11 and any Accrual Period therefor, the second LIBOR Business Day preceding the commencement of such Accrual Period.

“Late Collections”: With respect to any Mortgage Loan and any Due Period, all amounts received subsequent to the Determination Date immediately following such Due Period, whether as late payments of Monthly Payments or as Insurance Proceeds, Liquidation Proceeds or otherwise, which represent late payments or collections of principal and/or interest due (without regard to any acceleration of payments under the related Mortgage and Mortgage Note) but delinquent for such Due Period and not previously recovered.

“LIBOR Business Day”: Any day on which banks are open for dealing in foreign currency and exchange in London and New York City.

“Liquidated Mortgage Loan”: As to any Distribution Date, any Mortgage Loan in respect of which the Master Servicer has determined, in accordance with the servicing procedures specified herein, as of the end of the related Prepayment Period, that all Liquidation Proceeds which it expects to recover with respect to the liquidation of the Mortgage Loan or disposition of the related REO Property have been recovered.

“Liquidation Event”: With respect to any Mortgage Loan, any of the following events: (i) such Mortgage Loan is paid in full; (ii) a Final Recovery Determination is made as to such Mortgage Loan; or (iii) such Mortgage Loan is removed from REMIC I by reason of its being purchased, sold or replaced pursuant to or as contemplated by Section 2.03, Section 3.16(c) or Section 9.01. With respect to any REO Property, either of the following events: (i) a Final Recovery Determination is made as to such REO Property; or (ii) such REO Property is removed from REMIC I by reason of its being purchased pursuant to Section 9.01.

“Liquidation Proceeds”: The amount (other than amounts received in respect of the rental of any REO Property prior to REO Disposition) received by the Master Servicer in connection with (i) the taking of all or a part of a Mortgaged Property by exercise of the power of eminent domain or condemnation, (ii) the liquidation of a defaulted Mortgage Loan through a trustee’s sale, foreclosure sale or otherwise, or (iii) the repurchase, substitution or sale of a Mortgage Loan or an REO Property pursuant to or as contemplated by Section 2.03, Section 3.16(c), Section 3.23 or Section 9.01.

“Loan-to-Value Ratio”: As of any date of determination, the fraction, expressed as a percentage, the numerator of which is the principal balance of the related Mortgage Loan at such date and the denominator of which is the Value of the related Mortgaged Property.

“Loan Group”: Any of Loan Group I or Loan Group II, as the context requires.

“Loan Group I”: The group of Mortgage Loans identified in the Mortgage Loan Schedule as having been assigned to Loan Group I.

“Loan Group II”: The group of Mortgage Loans identified in the Mortgage Loan Schedule as having been assigned to Loan Group II.

“Loss Severity Percentage”: With respect to any Distribution Date, the percentage equivalent of a fraction, the numerator of which is the amount of Realized Losses incurred on a

Mortgage Loan and the denominator of which is the principal balance of such Mortgage Loan immediately prior to the liquidation of such Mortgage Loan.

“Marker Rate”: With respect to the Class CE Interest and any Distribution Date, a per annum rate equal to two (2) times the weighted average of the REMIC I Remittance Rate for each of REMIC I Regular Interests I-LTA1, I-LTA2, I-LTA3, I-LTA4, I-LTA5, I-LTM1, I-LTM2, I-LTM3, I-LTM4, I-LTM5, I-LTM6, I-LTM7, I-LTM8, I-LTM9, I-LTM10, I-LTM11 and I-LTZZ, with the rate on each such REMIC I Regular Interest (other than the REMIC I Regular Interest I-LTZZ) subject to a cap equal to the lesser of (a) One-Month LIBOR plus the related Certificate Margin for the corresponding Certificate and (b) the related Net WAC Cap rate for the purpose of this calculation for such Distribution Date and with the rate on REMIC I Regular Interest I-LTZZ subject to a cap of zero for the purpose of this calculation; provided, however, that solely for this purpose, calculations of the REMIC I Remittance Rate and the related caps with respect to such REMIC I Regular Interests (other than REMIC I Regular Interest I-LTZZ) shall be multiplied by a fraction, the numerator of which is the actual number of days in the Accrual Period and the denominator of which is 30.

“Master Servicer”: Option One Mortgage Corporation or any successor master servicer appointed as herein provided, in its capacity as Master Servicer hereunder.

“Master Servicer Event of Default”: One or more of the events described in Section 7.01.

“Master Servicer Prepayment Charge Payment Amount”: The amounts payable by the Master Servicer in respect of any Prepayment Charges pursuant to Section 2.05 or Section 3.01.

“Master Servicer Remittance Date”: With respect to any Distribution Date, by 1:00 p.m. New York time the Business Day immediately preceding the related Distribution Date.

“Maximum Cap Rate”: For any Distribution Date with respect to the Offered Certificates, a per annum rate equal to the weighted average of the Adjusted Net Maximum Mortgage Rates of the Mortgage Loans multiplied by a fraction, the numerator of which is 30 and the denominator of which is the actual number of days elapsed in the related Accrual Period.

“Maximum I-LTZZ Uncertificated Interest Deferral Amount”: With respect to any Distribution Date, the excess of (i) accrued interest at the REMIC I Remittance Rate applicable to REMIC I Regular Interest I-LTZZ for such Distribution Date on a balance equal to the Uncertificated Balance of REMIC I Regular Interest I-LTZZ minus the REMIC I Overcollateralization Amount, in each case for such Distribution Date, over (ii) Uncertificated Interest on REMIC I Regular Interest I-LTA1, REMIC I Regular Interest I-LTA2, REMIC I Regular Interest I-LTA3, REMIC I Regular Interest I-LTA4, REMIC I Regular Interest I-LTA5, REMIC I Regular Interest I-LTM1, REMIC I Regular Interest I-LTM2, REMIC I Regular Interest I-LTM3, REMIC I Regular Interest I-LTM4, REMIC I Regular Interest I-LTM5, REMIC I Regular Interest I-LTM6, REMIC I Regular Interest I-LTM7, REMIC I Regular Interest I-LTM8, REMIC I Regular Interest I-LTM9, REMIC I Regular Interest I-LTM10 and

REMIC I Regular Interest I-LTM11 for such Distribution Date, with the rate on REMIC I Regular Interest I-LTA1, REMIC I Regular Interest I-LTA2, REMIC I Regular Interest I-LTA3, REMIC I Regular Interest I-LTA4, REMIC I Regular Interest I-LTA5, REMIC I Regular Interest I-LTM1, REMIC I Regular Interest I-LTM2, REMIC I Regular Interest I-LTM3, REMIC I Regular Interest I-LTM4, REMIC I Regular Interest I-LTM5, REMIC I Regular Interest I-LTM6, REMIC I Regular Interest I-LTM7, REMIC I Regular Interest I-LTM8, REMIC I Regular Interest I-LTM9, REMIC I Regular Interest I-LTM10 and REMIC I Regular Interest I-LTM11 subject to a cap equal to the lesser of (i) One-Month LIBOR plus the related Certificate Margin for the corresponding Certificate and (ii) the related Net WAC Cap Rate; provided, however, each cap shall be multiplied by a fraction, the numerator of which is the actual number of days in the related Accrual Period and the denominator of which is 30.

“Maximum Mortgage Rate”: With respect to each Adjustable-Rate Mortgage Loan, the percentage set forth in the related Mortgage Note as the maximum Mortgage Rate thereunder.

“Mezzanine Cap Contract”: The Cap Contract between the Trustee on behalf of the Trust Fund and the counterparty thereunder, for the benefit of the Holders of the Mezzanine Certificates.

“Mezzanine Certificate”: Any Class M-1 Certificate, Class M-2 Certificate, Class M-3 Certificate, Class M-4 Certificate, Class M-5 Certificate, Class M-6 Certificate, Class M-7 Certificate, Class M-8 Certificate, Class M-9 Certificate or Class M-10 Certificate.

“Minimum Mortgage Rate”: With respect to each Adjustable-Rate Mortgage Loan, the percentage set forth in the related Mortgage Note as the minimum Mortgage Rate thereunder.

“Monthly Interest Distributable Amount”: With respect to the Class A Certificates, the Mezzanine Certificates and the Class CE Certificates and any Distribution Date, the amount of interest accrued during the related Accrual Period at the related Pass-Through Rate on the Certificate Principal Balance (or Notional Amount in the case of the Class CE Certificates) of such Class immediately prior to such Distribution Date, reduced by any Prepayment Interest Shortfalls (to the extent not covered by payments made by the Master Servicer pursuant to Section 3.24) and Relief Act Interest Shortfalls (allocated to such Certificate based on its respective entitlements to interest irrespective of any Prepayment Interest Shortfalls and Relief Act Interest Shortfalls for such Distribution Date). The Monthly Interest Distributable Amount will be calculated for the Class A Certificates and the Mezzanine Certificates on the basis of the actual number of days in the related Accrual Period, based on a 360-day year.

“Monthly Payment”: With respect to any Mortgage Loan, the scheduled monthly payment of principal and interest on such Mortgage Loan which is payable by the related Mortgagor from time to time under the related Mortgage Note, determined: (a) after giving effect to (i) any Deficient Valuation and/or Debt Service Reduction with respect to such Mortgage Loan and (ii) any reduction in the amount of interest collectible from the related Mortgagor pursuant to the Relief Act; (b) without giving effect to any extension granted or agreed to by the

Master Servicer pursuant to Section 3.07 and (c) on the assumption that all other amounts, if any, due under such Mortgage Loan are paid when due.

“Monthly Statement”: The statement prepared by the Trustee pursuant to Section 4.02.

“Moody’s”: Moody’s Investors Service, Inc. or its successor in interest.

“Mortgage”: The mortgage, deed of trust or other instrument creating a first or second lien on, or first or second priority security interest in, a Mortgaged Property securing a Mortgage Note.

“Mortgage File”: The mortgage documents listed in Section 2.01 pertaining to a particular Mortgage Loan and any additional documents required to be added to the Mortgage File pursuant to this Agreement.

“Mortgage Loan”: Each mortgage loan transferred and assigned to the Trustee and delivered to the Trustee pursuant to Section 2.01 or Section 2.03(b) of this Agreement, as held from time to time as a part of the Trust, the Mortgage Loans so held being identified in the Mortgage Loan Schedule.

“Mortgage Loan Purchase Agreement”: The agreement among the Seller, the Originator and the Depositor, regarding the sale of the Mortgage Loans by the Seller to the Depositor, substantially in the form of Exhibit D annexed hereto.

“Mortgage Loan Schedule”: As of any date, the list of Mortgage Loans included in REMIC I on such date, attached hereto as Schedule 1. The Mortgage Loan Schedule shall set forth the following information with respect to each Mortgage Loan:

(1)	the Mortgage Loan identifying number;
(2)	[reserved];
(3)	the state and zip code of the Mortgaged Property;

(4) a code indicating whether the Mortgaged Property was represented by the borrower, at the time of origination, as being owner-occupied;

(5)	the type of Residential Dwelling constituting the Mortgaged Property;
(6)	the original months to maturity;

(7) the stated remaining months to maturity from the Cut-off Date based on the original amortization schedule;

(8)	the Loan-to-Value Ratio at origination;
(9)	the Mortgage Rate in effect immediately following the Cut-off Date;

(10) the date on which the first Monthly Payment was due on the Mortgage Loan;

(11)	the stated maturity date;
(12)	the amount of the Monthly Payment at origination;

(13) the amount of the Monthly Payment due on the first Due Date after the Cut-off Date;

(14) the last Due Date on which a Monthly Payment was actually applied to the unpaid Stated Principal Balance;

(15)	the original principal amount of the Mortgage Loan;

(16) the Stated Principal Balance of the Mortgage Loan as of the close of business on the Cut-off Date;

(17) a code indicating the purpose of the Mortgage Loan ( i.e. , purchase financing, rate/term refinancing, cash-out refinancing);

(18)	the Mortgage Rate at origination;

(19) a code indicating the documentation program ( i.e. , full documentation, limited documentation, stated income documentation);

(20)	the risk grade;
(21)	the Value of the Mortgaged Property;
(22)	the sale price of the Mortgaged Property, if applicable;

(23) the actual unpaid principal balance of the Mortgage Loan as of the Cut-off Date;

(24)	the type and term of the related Prepayment Charge;
(25)	the rounding code;
(26)	the program code;
(27)	a code indicating the lien priority for Mortgage Loans;

(28) with respect to each Adjustable Rate Mortgage Loan, the Minimum Mortgage Rate;

(29) with respect to each Adjustable Rate Mortgage Loan, the Maximum Mortgage Rate;

(30)	with respect to each Adjustable Rate Mortgage Loan, the Gross Margin;

(31) with respect to each Adjustable Rate Mortgage Loan, the next Adjustment Date;

(32) with respect to each Adjustable Rate Mortgage Loan, the Periodic Rate Cap;

(33)	whether such Mortgage Loan is covered under one of the PMI Policies;
(34)	the credit score (“FICO”) of such Mortgage Loan; and
(35)	the total amount of points and fees charged such Mortgage Loan.

The Mortgage Loan Schedule shall set forth the following information with respect to the Mortgage Loans in the aggregate and for each Loan Group as of the Cut-off Date: (1) the number of Mortgage Loans (separately identifying the number of Fixed-Rate Mortgage Loans and the number of Adjustable-Rate Mortgage Loans); (2) the current Principal Balance of the Mortgage Loans; (3) the weighted average Mortgage Rate of the Mortgage Loans and (4) the weighted average maturity of the Mortgage Loans. The Mortgage Loan Schedule shall be amended from time to time by the Depositor in accordance with the provisions of this Agreement. With respect to any Qualified Substitute Mortgage Loan, the Cut-off Date shall refer to the related Cut-off Date for such Mortgage Loan, determined in accordance with the definition of Cut-off Date herein.

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

“Mortgage Pool”: The pool of Mortgage Loans, identified on Schedule 1 and existing from time to time thereafter, and any REO Properties acquired in respect thereof.

“Mortgage Rate”: With respect to each Mortgage Loan, the annual rate at which interest accrues on such Mortgage Loan from time to time in accordance with the provisions of the related Mortgage Note, which rate with respect to the Adjustable-Rate Mortgage Loans, (A) as of any date of determination until the first Adjustment Date following the Cut-off Date shall be the rate set forth in the Mortgage Loan Schedule as the Mortgage Rate in effect immediately following the Cut-off Date and (B) as of any date of determination thereafter shall be the rate as adjusted on the most recent Adjustment Date equal to the sum, rounded to the nearest or next highest 0.125% as provided in the Mortgage Note, of the Index, as most recently available as of a date prior to the Adjustment Date as set forth in the related Mortgage Note, plus the related Gross Margin; provided that the Mortgage Rate on such Adjustable-Rate Mortgage Loan on any Adjustment Date shall never be more than the lesser of (i) the sum of the Mortgage Rate in effect immediately prior to the Adjustment Date plus the related Periodic Rate Cap, if any, and (ii) the related Maximum Mortgage Rate, and shall never be less than the greater of (i) the Mortgage Rate in effect immediately prior to the Adjustment Date less the Periodic Rate Cap, if any, and (ii) the related Minimum Mortgage Rate. With respect to each Mortgage Loan that becomes an REO Property, as of any date of determination, the annual rate determined in accordance with

the immediately preceding sentence as of the date such Mortgage Loan became an REO Property.

“Mortgaged Property”: The underlying property securing a Mortgage Loan, including any REO Property, consisting of an Estate in Real Property improved by a Residential Dwelling.

“Mortgagor”: The obligor on a Mortgage Note.

“Net Liquidation Proceeds”: With respect to any Liquidated Mortgage Loan or any other disposition of related Mortgaged Property (including REO Property) the related Liquidation Proceeds and Insurance Proceeds net of Advances, Servicing Advances, Servicing Fees and any other accrued and unpaid servicing fees received and retained in connection with the liquidation of such Mortgage Loan or Mortgaged Property.

“Net Monthly Excess Cashflow”: With respect to each Distribution Date, the sum of (a) any Overcollateralization Release Amount for such Distribution Date and (b) the excess of (x) Available Funds for such Distribution Date over (y) the sum for such Distribution Date of (A) the Monthly Interest Distributable Amounts for the Class A Certificates and the Mezzanine Certificates, (B) the Unpaid Interest Shortfall Amounts for the Class A Certificates and (C) the Principal Remittance Amount.

“Net Mortgage Rate”: With respect to any Mortgage Loan (or the related REO Property) as of any date of determination, a per annum rate of interest equal to the then applicable Mortgage Rate for such Mortgage Loan minus the Servicing Fee Rate.

“Net WAC Rate”: For any Distribution Date with respect to the Group I Certificates, a per annum rate equal to the product of (x) the weighted average of the Adjusted Net Mortgage Rates of the Group I Mortgage Loans, weighted based on their outstanding Principal Balances as of the first day of the calendar month preceding the month in which the Distribution Date occurs and (y) a fraction, the numerator of which is 30 and the denominator of which is the actual number of days elapsed in the related Accrual Period. For federal income tax purposes, the economic equivalent of such rate shall be expressed as the weighted average of the REMIC I Remittance Rate on REMIC I Regular Interest I-LT1GRP, weighted on the basis of the Uncertificated Balance of such REMIC I Regular Interest.

For any Distribution Date with respect to the Group II Certificates, a per annum rate equal to the product of (x) the weighted average of the Adjusted Net Mortgage Rates of the Group II Mortgage Loans, weighted based on their outstanding Principal Balances as of the first day of the calendar month preceding the month in which the Distribution Date occurs and (y) a fraction, the numerator of which is 30 and the denominator of which is the actual number of days elapsed in the related Accrual Period. For federal income tax purposes, the economic equivalent of such rate shall be expressed as the weighted average of the REMIC I Remittance Rate on REMIC I Regular Interest I-LT2GRP, weighted on the basis of the Uncertificated Balance of such REMIC I Regular Interest.

For any Distribution Date with respect to the Mezzanine Certificates, a per annum rate equal to the product of (x) the weighted average of the Adjusted Net Mortgage Rates of the Group I Mortgage Loans and the Group II Mortgage Loans, weighted in proportion to the results of subtracting from the aggregate Stated Principal Balance of each Loan Group the Certificate Principal Balance of the related Class of Class A Certificates and (y) for each Class of Mezzanine Certificates a fraction, the numerator of which is 30 and the denominator of which is the actual number of days elapsed in the related Accrual Period. For federal income tax purposes, the economic equivalent of such rate shall be expressed as the weighted average of the REMIC I Remittance Rates on (a) REMIC I Regular Interest I-LT1SUB, subject to a cap and a floor equal to the Adjusted Net Mortgage Rates of the Group I Mortgage Loans and (b) REMIC I Regular Interest I-LT2SUB, subject to a cap and a floor equal to the Adjusted Net Mortgage Rates of the Group II Mortgage Loans, weighted, in each case, on the basis of the Uncertificated Balance of each such REMIC I Regular Interest.

“Net WAC Rate Carryover Amount”: With respect to the Class A Certificates and the Mezzanine Certificates and any Distribution Date, the sum of (A) the positive excess of (i) the amount of interest accrued on such Class of Certificates on such Distribution Date calculated at the related Formula Rate, over (ii) the amount of interest accrued on such Class of Certificates at the related Net WAC Rate for such Distribution Date and (B) the Net WAC Rate Carryover Amount for the previous Distribution Date not previously paid, together with interest thereon at a rate equal to the Formula Rate for such Class of Certificates for such Distribution Date and for such Accrual Period.

“Net WAC Rate Carryover Reserve Account”: The account established and maintained pursuant to Section 3.28.

“New Lease”: Any lease of REO Property entered into on behalf of REMIC I, including any lease renewed or extended on behalf of REMIC I, if REMIC I has the right to renegotiate the terms of such lease.

“NIMS Insurer”: Any insurer that is guaranteeing certain payments under notes secured by collateral which includes all or a portion of the Class CE Certificates, the Class P Certificates and/or the Class R Certificates.

“Nonrecoverable Advance”: Any Advance previously made or proposed to be made in respect of a Mortgage Loan or REO Property that, in the good faith business judgment of the Master Servicer, will not or, in the case of a proposed Advance, would not be ultimately recoverable from related Late Collections, Insurance Proceeds or Liquidation Proceeds on such Mortgage Loan or REO Property as provided herein.

“Nonrecoverable Servicing Advance”: Any Servicing Advance previously made or proposed to be made in respect of a Mortgage Loan or REO Property that, in the good faith business judgment of the Master Servicer, will not or, in the case of a proposed Servicing Advance, would not be ultimately recoverable from related Late Collections, Insurance Proceeds or Liquidation Proceeds on such Mortgage Loan or REO Property as provided herein.

“Non-United States Person”: Any Person other than a United States Person.

“Notional Amount”: With respect to the Class CE Interest and any Distribution Date, the Uncertificated Balance of the REMIC I Regular Interests (other than REMIC I Regular Interest I-LTP) for such Distribution Date.

“Offered Certificates”: The Class A Certificates and the Mezzanine Certificates.

“Officers’ Certificate”: A certificate signed by the Chairman of the Board, the Vice Chairman of the Board, the President or a vice president (however denominated), and by the Treasurer, the Secretary, or one of the assistant treasurers or assistant secretaries of the Master Servicer, the Originator, the Seller or the Depositor, as applicable.

“One-Month LIBOR”: With respect to the Class A Certificates, the Mezzanine Certificates, REMIC I Regular Interest I-LTA1, REMIC I Regular Interest I-LTA2, REMIC I Regular Interest I-LTA3, REMIC I Regular Interest I-LTA4, REMIC I Regular Interest I-LTA5, REMIC I Regular Interest I-LTM1, REMIC I Regular Interest I-LTM2, REMIC I Regular Interest I-LTM3, REMIC I Regular Interest I-LTM4, REMIC I Regular Interest I-LTM5, REMIC I Regular Interest I-LTM6, REMIC I Regular Interest I-LTM7, REMIC I Regular Interest I-LTM8, REMIC I Regular Interest I-LTM9, REMIC I Regular Interest I-LTM10 and REMIC I Regular Interest I-LTM11 and any Accrual Period therefor, the rate determined by the Trustee on the related Interest Determination Date on the basis of the offered rate for one-month U.S. dollar deposits, as such rate appears on Telerate Page 3750 as of 11:00 a.m. (London time) on such Interest Determination Date; provided that if such rate does not appear on Telerate Page 3750, the rate for such date will be determined on the basis of the offered rates of the Reference Banks for one-month U.S. dollar deposits, as of 11:00 a.m. (London time) on such Interest Determination Date. In such event, the Trustee will request the principal London office of each of the Reference Banks to provide a quotation of its rate. If on such Interest Determination Date, two or more Reference Banks provide such offered quotations, One-Month LIBOR for the related Accrual Period shall be the arithmetic mean of such offered quotations (rounded upwards if necessary to the nearest whole multiple of 1/16%). If on such Interest Determination Date, fewer than two Reference Banks provide such offered quotations, One-Month LIBOR for the related Accrual Period shall be the higher of (i) LIBOR as determined on the previous Interest Determination Date and (ii) the Reserve Interest Rate. Notwithstanding the foregoing, if, under the priorities described above, LIBOR for an Interest Determination Date would be based on LIBOR for the previous Interest Determination Date for the third consecutive Interest Determination Date, the Trustee shall select, after consultation with the NIMS Insurer, an alternative comparable index (over which the Trustee has no control), used for determining one-month Eurodollar lending rates that is calculated and published (or otherwise made available) by an independent party.

“Opinion of Counsel”: A written opinion of counsel, who may, without limitation, be salaried counsel for the Depositor or the Master Servicer, acceptable to the Trustee, except that any opinion of counsel relating to (a) the qualification of any of Trust REMIC as a REMIC or (b) compliance with the REMIC Provisions must be an opinion of Independent counsel.

“Original Mortgage Loan”: Any of the Mortgage Loans included in REMIC I as of the Closing Date.

“Originator”: Option One Mortgage Corporation.

“Overcollateralization Deficiency Amount”: With respect to any Distribution Date, the amount, if any, by which the Overcollateralization Target Amount exceeds the Overcollateralized Amount on such Distribution Date (after giving effect to distributions in respect of the Group I Basic Principal Distribution Amount and the Group II Basic Principal Distribution Amount on such Distribution Date).

“Overcollateralization Release Amount”: With respect to any Distribution Date, the lesser of (x) the Principal Remittance Amount for such Distribution Date and (y) the Excess Overcollateralized Amount.

“Overcollateralization Target Amount”: With respect to any Distribution Date, (i) prior to the Stepdown Date, an amount equal to 0.70% of the aggregate Stated Principal Balance of the Mortgage Loans as of the Cut-off Date, (ii) on or after the Stepdown Date provided a Trigger Event is not in effect, the greater of (x) 1.40% of the aggregate Stated Principal Balance of the Mortgage Loans as of the last day of the related Due Period (after giving effect to scheduled payments of principal due during the related Due Period, to the extent received or advanced, and unscheduled collections of principal received during the related Prepayment Period) and (y) $8,011,950.18 or (iii) on or after the Stepdown Date and if a Trigger Event is in effect, the Overcollateralization Target Amount for the immediately preceding Distribution Date.

“Overcollateralized Amount”: For any Distribution Date, the amount equal to (i) the aggregate Principal Balance of the Mortgage Loans as of the last day of the related Due Period (after giving effect to scheduled payments of principal due during the related Due Period, to the extent received or advanced, and unscheduled collections of principal received during the related Prepayment Period) as of the related Determination Date minus (ii) the sum of the aggregate Certificate Principal Balance of the Class A Certificates, the Mezzanine Certificates and the Class P Certificates as of such Distribution Date after giving effect to distributions to be made on such Distribution Date.

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

“Pass-Through Rate”: With respect to the Class A Certificates and the Mezzanine Certificates and any Distribution Date, a rate per annum equal to the lesser of (i) the related Formula Rate for such Distribution Date and (ii) the Net WAC Rate for such Distribution Date.

With respect to the Class CE Interest and any Distribution Date, a rate per annum equal to the percentage equivalent of a fraction, the numerator of which is the sum of the amounts calculated pursuant to clauses (A) through (S) below, and the denominator of which is the aggregate Uncertificated Balance of REMIC I Regular Interest I-LTAA, I-LTA1, I-LTA2, I-LTA3, I-LTA4, I-LTA5, I-LTM1, I-LTM2, I-LTM3, I-LTM4, I-LTM5, I-LTM6, I-LTM7, I-LTM8, I-LTM9, I-LTM10, I-LTM11 and I-LTZZ. For purposes of calculating the Pass-Through Rate for the Class CE Interest, the numerator is equal to the sum of the following components:

(A) the REMIC I Remittance Rate for REMIC I Regular Interest I-LTAA minus the Marker Rate, applied to an amount equal to the Uncertificated Balance of REMIC I Regular Interest I-LTAA;

(B) the REMIC I Remittance Rate for REMIC I Regular Interest I-LTA1 minus the Marker Rate, applied to an amount equal to the Uncertificated Balance of REMIC I Regular Interest I-LTA1;

(C) the REMIC I Remittance Rate for REMIC I Regular Interest I-LTA2 minus the Marker Rate, applied to an amount equal to the Uncertificated Balance of REMIC I Regular Interest I-LTA2;

(D) the REMIC I Remittance Rate for REMIC I Regular Interest I-LTA3 minus the Marker Rate, applied to an amount equal to the Uncertificated Balance of REMIC I Regular Interest I-LTA3;

(E) the REMIC I Remittance Rate for REMIC I Regular Interest I-LTA4 minus the Marker Rate, applied to an amount equal to the Uncertificated Balance of REMIC I Regular Interest I-LTA4;

(F) the REMIC I Remittance Rate for REMIC I Regular Interest I-LTA5 minus the Marker Rate, applied to an amount equal to the Uncertificated Balance of REMIC I Regular Interest I-LTA5;

(G) the REMIC I Remittance Rate for REMIC I Regular Interest I-LTM1 minus the Marker Rate, applied to an amount equal to the Uncertificated Balance of REMIC I Regular Interest I-LTM1;

(H) the REMIC I Remittance Rate for REMIC I Regular Interest I-LTM2 minus the Marker Rate, applied to an amount equal to the Uncertificated Balance of REMIC I Regular Interest I-LTM2;

(I) the REMIC I Remittance Rate for REMIC I Regular Interest I-LTM3 minus the Marker Rate, applied to an amount equal to the Uncertificated Balance of REMIC I Regular Interest I-LTM3;

(J) the REMIC I Remittance Rate for REMIC I Regular Interest I-LTM4 minus the Marker Rate, applied to an amount equal to the Uncertificated Balance of REMIC I Regular Interest I-LTM4;

(K) the REMIC I Remittance Rate for REMIC I Regular Interest I-LTMV5 minus the Marker Rate, applied to an amount equal to the Uncertificated Balance of REMIC I Regular Interest I-LTM5;

(L) the REMIC I Remittance Rate for REMIC I Regular Interest I-LTMV6 minus the Marker Rate, applied to an amount equal to the Uncertificated Balance of REMIC I Regular Interest I-LTM6;

(M) the REMIC I Remittance Rate for REMIC I Regular Interest I-LTM7 minus the Marker Rate, applied to an amount equal to the Uncertificated Balance of REMIC I Regular Interest I-LTM7;

(N) the REMIC I Remittance Rate for REMIC I Regular Interest I-LTM8 minus the Marker Rate, applied to an amount equal to the Uncertificated Balance of REMIC I Regular Interest I-LTM8;

(O) the REMIC I Remittance Rate for REMIC I Regular Interest I-LTM9 minus the Marker Rate, applied to an amount equal to the Uncertificated Balance of REMIC I Regular Interest I-LTM9;

(P) the REMIC I Remittance Rate for REMIC I Regular Interest I-LTM10 minus the Marker Rate, applied to an amount equal to the Uncertificated Balance of REMIC I Regular Interest I-LTM10;

(Q) the REMIC I Remittance Rate for REMIC I Regular Interest I-LTM11 minus the Marker Rate, applied to an amount equal to the Uncertificated Balance of REMIC I Regular Interest I-LTM11;

(R) the REMIC I Remittance Rate for REMIC I Regular Interest I-LTZZ minus the Marker Rate, applied to an amount equal to the Uncertificated Balance of REMIC I Regular Interest I-LTZZ; and

(S)	100% of the interest on REMIC I Regular Interest I-LTP.

With respect to the Class CE Certificates, 100% of the interest distributable to the Class CE Interest, expressed as a per annum rate.

“Percentage Interest”: With respect to any Class of Certificates (other than the Residual Certificates), the undivided percentage ownership in such Class evidenced by such Certificate, expressed as a percentage, the numerator of which is the initial Certificate Principal Balance or Notional Amount represented by such Certificate and the denominator of which is the aggregate initial Certificate Principal Balance or Notional Amount of all of the Certificates of such Class. The Class A Certificates and the Mezzanine Certificates are issuable only in minimum Percentage Interests corresponding to minimum initial Certificate Principal Balances of $25,000 and integral multiples of $1.00 in excess thereof. The Class P Certificates are issuable only in Percentage Interests corresponding to initial Certificate Principal Balances of $20 and integral multiples thereof. The Class CE Certificates are issuable only in minimum Percentage Interests corresponding to minimum initial Certificate Principal Balances of $10,000 and integral multiples of $1.00 in excess thereof; provided, however, that a single Certificate of each such Class of Certificates may be issued having a Percentage Interest corresponding to the remainder of the aggregate initial Certificate Principal Balance or Notional Amount of such Class or to an otherwise authorized denomination for such Class plus such remainder. With respect to any Residual Certificate, the undivided percentage ownership in such Class evidenced by such Certificate, as set forth on the face of such Certificate. The Residual Certificates are issuable in Percentage Interests of 20% and multiples thereof.

“Periodic Rate Cap”: With respect to each Adjustable-Rate Mortgage Loan and any Adjustment Date therefor, the fixed percentage set forth in the related Mortgage Note, which is the maximum amount by which the Mortgage Rate for such Mortgage Loan may increase or decrease (without regard to the Maximum Mortgage Rate or the Minimum Mortgage Rate) on such Adjustment Date from the Mortgage Rate in effect immediately prior to such Adjustment Date.

“Permitted Investments”: Any one or more of the following obligations or securities acquired at a purchase price of not greater than par, regardless of whether issued or managed by the Depositor, the Master Servicer, the NIMS Insurer, the Trustee or any of their respective Affiliates or for which an Affiliate of the NIMS Insurer or Trustee serves as an advisor:

(i) direct obligations of, or obligations fully guaranteed as to timely payment of principal and interest by, the United States or any agency or instrumentality thereof, provided such obligations are backed by the full faith and credit of the United States;

(ii) (A) demand and time deposits in, certificates of deposit of, bankers’ acceptances issued by or federal funds sold by any depository institution or trust company (including the Trustee or its agent acting in their respective commercial capacities) incorporated under the laws of the United States of America or any state thereof and subject to supervision and examination by federal and/or state authorities, so long as, at the time of such investment or contractual commitment providing for such investment, such depository institution or trust company (or, if the only Rating Agency is S&P, in the case of the principal depository institution in a depository institution holding company, debt obligations of the depository institution holding company) or its ultimate parent has a short-term uninsured debt rating in the highest available rating category of Moody’s, Fitch and S&P and provided that each such investment has an original maturity of no more than 365 days; and provided further that, if the only Rating Agency is S&P and if the depository or trust company is a principal subsidiary of a bank holding company and the debt obligations of such subsidiary are not separately rated, the applicable rating shall be that of the bank holding company; and, provided further that, if the original maturity of such short-term obligations of a domestic branch of a foreign depository institution or trust company shall exceed 30 days, the short-term rating of such institution shall be A-1+ in the case of S&P if S&P is the Rating Agency; and (B) any other demand or time deposit or deposit which is fully insured by the FDIC;

(iii) repurchase obligations with a term not to exceed 30 days with respect to any security described in clause (i) above and entered into with a depository institution or trust company (acting as principal) rated A-1+ or higher by S&P, F-1+ or higher by Fitch and A2 or higher by Moody’s, provided, however, that collateral transferred pursuant to such repurchase obligation must be of the type described in clause (i) above and must (A) be valued daily at current market prices plus accrued interest, (B) pursuant to such valuation, be equal, at all times, to 105% of the cash transferred by the Trustee in exchange for such collateral and (C) be delivered to the Trustee or, if the Trustee is supplying the collateral, an agent for the Trustee, in such a manner as to accomplish perfection of a security interest in the collateral by possession of certificated securities;

(iv) securities bearing interest or sold at a discount that are issued by any corporation incorporated under the laws of the United States of America or any State thereof and that are rated by a Rating Agency in its highest long-term unsecured rating category at the time of such investment or contractual commitment providing for such investment;

(v) commercial paper (including both non-interest-bearing discount obligations and interest-bearing obligations payable on demand or on a specified date not more than 30 days after the date of acquisition thereof) that is rated by a Rating Agency in its highest short-term unsecured debt rating available at the time of such investment;

(vi) units of money market funds, including those managed or advised by the Trustee or its Affiliates, that have been rated “AAA” by S&P, “AAA” by Fitch (if so rated by Fitch) and “Aaa” by Moody’s; and

(vii) if previously confirmed in writing to the Trustee and consented to by the NIMS Insurer, any other demand, money market or time deposit, or any other obligation, security or investment, as may be acceptable to the Rating Agencies in writing as a permitted investment of funds backing securities having ratings equivalent to its highest initial rating of the Class A Certificates;

provided, that no instrument described hereunder shall evidence either the right to receive (a) only interest with respect to the obligations underlying such instrument or (b) both principal and interest payments derived from obligations underlying such instrument and the interest and principal payments with respect to such instrument provide a yield to maturity at par greater than 120% of the yield to maturity at par of the underlying obligations.

“Permitted Transferee”: Any Transferee of a Residual Certificate other than a Disqualified Organization or Non-United States Person.

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

“Plan”: Any employee benefit plan or certain other retirement plans and arrangements, including individual retirement accounts and annuities, Keogh plans and bank collective investment funds and insurance company general or separate accounts in which such plans, accounts or arrangements are invested, that are subject to ERISA or Section 4975 of the Code.

“PMI Insurers”: Mortgage Guaranty Insurance Corporation, a Wisconsin stock insurance corporation, and Radian Guaranty Inc., a Pennsylvania corporation, or either of their successors in interest.

“PMI Insurer Fee”: The amount payable to each PMI Insurer on each Distribution Date, which amount shall equal (a) one twelfth of the product of (i) the related PMI Insurer Fee Rate, multiplied by (ii) the aggregate Principal Balance of the related PMI Mortgage Loans and any

related REO Properties as of the first day of the related Due Period (after giving effect to scheduled payments of principal due during the Due Period relating to the previous Distribution Date, to the extent received or advanced) plus (b) any taxes on related PMI Mortgage Loans located in West Virginia and Kentucky.

“PMI Insurer Fee Rate”: With respect to each PMI Mortgage Loan covered by the PMI Policy issued by Mortgage Guaranty Insurance Corporation, 1.09% per annum and with respect to each PMI Mortgage Loan that is covered by the PMI Policy issued by Radian Guaranty Inc., 0.90% per annum.

“PMI Mortgage Loans”: The list of Mortgage Loans insured by each of the PMI Insurer attached hereto as Schedule 3.

“PMI Policy”: With respect to the PMI Policy issued by Mortgage Guaranty Insurance Corporation, the primary mortgage insurance policy no. 22-400-4-3229 with respect to the related PMI Mortgage Loans, including all endorsements thereto dated the Closing Date, issued by Mortgage Guaranty Insurance Corporation and the Commitment Letter, dated May 10, 2005, among Mortgage Guaranty Insurance Corporation, the Seller and the Trustee.

With respect to the PMI Policy issued by Radian Guaranty Inc., the primary mortgage insurance policy no. 61368 (policy reference number: #05-998027) with respect to the related PMI Mortgage Loans, including all endorsements thereto dated the Closing Date, issued by Radian Guaranty Inc. and the Commitment Letter, dated May 12, 2005, between Radian Guaranty Inc. and the Seller.

“Prepayment Assumption”: As defined in the Prospectus Supplement.

“Prepayment Charge”: With respect to any Prepayment Period, any prepayment premium, fee, penalty or charge payable by a Mortgagor in connection with any full or partial Principal Prepayment on a Mortgage Loan pursuant to the terms of the related Mortgage Note (other than any Master Servicer Prepayment Charge Payment Amount).

“Prepayment Charge Schedule”: As of any date, the list of Prepayment Charges on the Mortgage Loans included in REMIC I on such date, attached hereto as Schedule 2 (including the Prepayment Charge Summary attached thereto). The Prepayment Charge Schedule shall set forth the following information with respect to each related Mortgage Loan:

(i)	the Mortgage Loan identifying number;
(ii)	a code indicating the type of Prepayment Charge;
(iii)	the state of origination of the related Mortgage Loan;

(iv) the date on which the first monthly payment was due on the related Mortgage Loan;

(v)	the term of the related Mortgage Loan; and

(vi)	the principal balance of the related Mortgage Loan as of the Cut-off Date.

The Prepayment Charge Schedule shall be amended from time to time by the Depositor in accordance with the provisions of this Agreement and a copy of such amended Prepayment Charge Schedule shall be furnished by the Master Servicer to the NIMS Insurer.

“Prepayment Interest Excess”: With respect to any Distribution Date, for each Mortgage Loan that was the subject of a Principal Prepayment in full during the portion of the related Prepayment Period occurring between the first day and the Determination Date of the calendar month in which such Distribution Date occurs, an amount equal to interest (to the extent received) at the applicable Net Mortgage Rate on the amount of such Principal Prepayment for the number of days commencing on the first day of the calendar month in which such Distribution Date occurs and ending on the date on which such prepayment is so applied.

“Prepayment Interest Shortfall”: With respect to any Distribution Date, for each Mortgage Loan that was the subject of a Principal Prepayment in full during the portion of the related Prepayment Period occurring between the first day of the related Prepayment Period and the last day of the calendar month preceding the month in which such Distribution Date occurs, an amount equal to interest at the applicable Net Mortgage Rate on the amount of such Principal Prepayment for the number of days commencing on the date on which the prepayment is applied and ending on the last day of the calendar month preceding the month in which such Distribution Date occurs. The obligations of the Master Servicer in respect of any Prepayment Interest Shortfall are set forth in Section 3.24.

“Prepayment Period”: With respect to any Distribution Date, the period commencing on the day after the Determination Date in the calendar month preceding the calendar month in which such Distribution Date occurs (or, in the case of the first Distribution Date, commencing on May 1, 2005) and ending on the Determination Date of the calendar month in which such Distribution Date occurs.

“Principal Balance”: As to any Mortgage Loan other than a Liquidated Mortgage Loan, and any day, the related Cut-off Date Principal Balance, minus all collections credited against the Cut-off Date Principal Balance of any such Mortgage Loan. For purposes of this definition, a Liquidated Mortgage Loan shall be deemed to have a Principal Balance equal to the Principal Balance of the related Mortgage Loan as of the final recovery of related Liquidation Proceeds and a Principal Balance of zero thereafter. As to any REO Property and any day, the Principal Balance of the related Mortgage Loan immediately prior to such Mortgage Loan becoming REO Property.

“Principal Prepayment”: Any payment of principal made by the Mortgagor on a Mortgage Loan which is received in advance of its scheduled Due Date and which is not accompanied by an amount of interest representing the full amount of scheduled interest due on any Due Date in any month or months subsequent to the month of prepayment.

“Principal Remittance Amount”: With respect to any Distribution Date, the sum of the Group I Principal Remittance Amount and the Group II Principal Remittance Amount.

“Prospectus Supplement”: That certain Prospectus Supplement dated May 10, 2005 relating to the public offering of the Class A Certificates and the Mezzanine Certificates.

“PTCE”: A Prohibited Transaction Class Exemption issued by the United States Department of Labor which provides that exemptive relief is available to any party to any transaction which satisfies the conditions of the exemption.

“Purchase Price”: With respect to any Mortgage Loan or REO Property to be purchased pursuant to or as contemplated by Section 2.03, Section 3.16(c) or Section 9.01, and as confirmed by an Officer’s Certificate from the Master Servicer and to the Trustee an amount equal to the sum of (i) 100% of the Stated Principal Balance thereof as of the date of purchase (or such other price as provided in Section 9.01), (ii) in the case of (x) a Mortgage Loan, accrued interest on such Stated Principal Balance at the applicable Net Mortgage Rate in effect from time to time from the Due Date as to which interest was last covered by a payment by the Mortgagor or an advance by the Master Servicer, which payment or advance had as of the date of purchase been distributed pursuant to Section 4.01, through the end of the calendar month in which the purchase is to be effected and (y) an REO Property, the sum of (1) accrued interest on such Stated Principal Balance at the applicable Net Mortgage Rate in effect from time to time from the Due Date as to which interest was last covered by a payment by the Mortgagor or an advance by the Master Servicer through the end of the calendar month immediately preceding the calendar month in which such REO Property was acquired, plus (2) REO Imputed Interest for such REO Property for each calendar month commencing with the calendar month in which such REO Property was acquired and ending with the calendar month in which such purchase is to be effected, net of the total of all net rental income, Insurance Proceeds, Liquidation Proceeds and Advances that as of the date of purchase had been distributed as or to cover REO Imputed Interest pursuant to Section 4.01, (iii) any unreimbursed Servicing Advances and Advances (including Nonrecoverable Advances and Nonrecoverable Servicing Advances) and any unpaid Servicing Fees allocable to such Mortgage Loan or REO Property, (iv) any amounts previously withdrawn from the Collection Account in respect of such Mortgage Loan or REO Property pursuant to Section 3.11(a)(ix) and Section 3.16(b), and (v) in the case of a Mortgage Loan required to be purchased pursuant to Section 2.03, expenses reasonably incurred or to be incurred by the Master Servicer, the NIMS Insurer or the Trustee in respect of the breach or defect giving rise to the purchase obligation including any costs and damages incurred by the Trust in connection with any violation by such loan of any predatory or abusive lending law.

“Qualified Substitute Mortgage Loan”: A mortgage loan substituted for a Deleted Mortgage Loan pursuant to the terms of this Agreement which must, on the date of such substitution, (i) have an outstanding Principal Balance, after application of all scheduled payments of principal and interest due during or prior to the month of substitution, not in excess of the Principal Balance of the Deleted Mortgage Loan as of the Due Date in the calendar month during which the substitution occurs, (ii) have a Mortgage Rate not less than (and not more than one percentage point in excess of) the Mortgage Rate of the Deleted Mortgage Loan, (iii) with respect to any Adjustable-Rate Mortgage Loan, have a Maximum Mortgage Rate not less than the Maximum Mortgage Rate on the Deleted Mortgage Loan, (iv) with respect to any Adjustable-Rate Mortgage Loan, have a Minimum Mortgage Rate not less than the Minimum Mortgage Rate of the Deleted Mortgage Loan, (v) with respect to any Adjustable-Rate Mortgage Loan, have a Gross Margin equal to the Gross Margin of the Deleted Mortgage Loan, (vi) with

respect to any Adjustable-Rate Mortgage Loan, have a next Adjustment Date not more than two months later than the next Adjustment Date on the Deleted Mortgage Loan, (vii) have a remaining term to maturity not greater than (and not more than one year less than) that of the Deleted Mortgage Loan, (viii) have the same Due Date as the Due Date on the Deleted Mortgage Loan, (ix) have a Loan-to-Value Ratio as of the date of substitution equal to or lower than the Loan-to-Value Ratio of the Deleted Mortgage Loan as of such date, (x) have a risk grading determined by the Originator at least equal to the risk grading assigned on the Deleted Mortgage Loan, (xi) have a Prepayment Charge provision at least equal to the Prepayment Charge provision in the Deleted Mortgage Loan, (xii) be covered by a PMI Policy if the Deleted Mortgage Loan was covered by a PMI Policy and (xiii) conform to each representation and warranty set forth in Section 6 of the Mortgage Loan Purchase Agreement applicable to the Deleted Mortgage Loan. In the event that one or more mortgage loans are substituted for one or more Deleted Mortgage Loans, the amounts described in clause (i) hereof shall be determined on the basis of aggregate principal balances, the Mortgage Rates described in clause (ii) hereof shall be determined on the basis of weighted average Mortgage Rates, the terms described in clause (vii) hereof shall be determined on the basis of weighted average remaining term to maturity, the Loan-to-Value Ratios described in clause (ix) hereof shall be satisfied as to each such mortgage loan, the risk gradings described in clause (x) hereof shall be satisfied as to each such mortgage loan and, except to the extent otherwise provided in this sentence, the representations and warranties described in clause (xiii) hereof must be satisfied as to each Qualified Substitute Mortgage Loan or in the aggregate, as the case may be.

“Rating Agency or Rating Agencies”: Fitch, Moody’s and S&P or their successors. If such agencies or their successors are no longer in existence, “Rating Agencies” shall be such nationally recognized statistical rating agencies, or other comparable Persons, designated by the Depositor, notice of which designation shall be given to the Trustee and the Master Servicer.

“Realized Loss”: With respect to each Mortgage Loan as to which a Final Recovery Determination has been made, an amount (not less than zero) equal to (i) the unpaid Principal Balance of such Mortgage Loan as of the commencement of the calendar month in which the Final Recovery Determination was made, plus (ii) accrued interest from the Due Date as to which interest was last paid by the Mortgagor through the end of the calendar month in which such Final Recovery Determination was made, calculated in the case of each calendar month during such period (A) at an annual rate equal to the annual rate at which interest was then accruing on such Mortgage Loan and (B) on a principal amount equal to the Stated Principal Balance of such Mortgage Loan as of the close of business on the Distribution Date during such calendar month, plus (iii) any amounts previously withdrawn from the Collection Account in respect of such Mortgage Loan pursuant to Section 3.11(a)(ix) and Section 3.16(b), minus (iv) the proceeds, if any, received in respect of such Mortgage Loan during the calendar month in which such Final Recovery Determination was made, net of amounts that are payable therefrom to the Master Servicer with respect to such Mortgage Loan pursuant to Section 3.11(a)(iii).

With respect to any REO Property as to which a Final Recovery Determination has been made, an amount (not less than zero) equal to (i) the unpaid principal balance of the related Mortgage Loan as of the date of acquisition of such REO Property on behalf of REMIC I, plus (ii) accrued interest from the Due Date as to which interest was last paid by the Mortgagor

in respect of the related Mortgage Loan through the end of the calendar month immediately preceding the calendar month in which such REO Property was acquired, calculated in the case of each calendar month during such period (A) at an annual rate equal to the annual rate at which interest was then accruing on the related Mortgage Loan and (B) on a principal amount equal to the Stated Principal Balance of the related Mortgage Loan as of the close of business on the Distribution Date during such calendar month, plus (iii) REO Imputed Interest for such REO Property for each calendar month commencing with the calendar month in which such REO Property was acquired and ending with the calendar month in which such Final Recovery Determination was made, plus (iv) any amounts previously withdrawn from the Collection Account in respect of the related Mortgage Loan pursuant to Section 3.11(a)(ix) and Section 3.16(b), minus (v) the aggregate of all Advances and Servicing Advances (in the case of Servicing Advances, without duplication of amounts netted out of the rental income, Insurance Proceeds and Liquidation Proceeds described in clause (vi) below) made by the Master Servicer in respect of such REO Property or the related Mortgage Loan for which the Master Servicer has been or, in connection with such Final Recovery Determination, will be reimbursed pursuant to Section 3.23 out of rental income, Insurance Proceeds and Liquidation Proceeds received in respect of such REO Property, minus (vi) the total of all net rental income, Insurance Proceeds and Liquidation Proceeds received in respect of such REO Property that has been, or in connection with such Final Recovery Determination, will be transferred to the Distribution Account pursuant to Section 3.23.

With respect to each Mortgage Loan which has become the subject of a Deficient Valuation, the difference between the principal balance of the Mortgage Loan outstanding immediately prior to such Deficient Valuation and the principal balance of the Mortgage Loan as reduced by the Deficient Valuation.

With respect to each Mortgage Loan which has become the subject of a Debt Service Reduction, the portion, if any, of the reduction in each affected Monthly Payment attributable to a reduction in the Mortgage Rate imposed by a court of competent jurisdiction. Each such Realized Loss shall be deemed to have been incurred on the Due Date for each affected Monthly Payment.

If the Master Servicer receives Subsequent Recoveries with respect to any Mortgage Loan, the amount of the Realized Loss with respect to that Mortgage Loan will be reduced to the extent such recoveries are applied to principal distributions on any Distribution Date.

“Record Date”: With respect to each Distribution Date and any Book-Entry Certificate, the Business Day immediately preceding such Distribution Date. With respect to each Distribution Date and any other Certificates and any Definitive Certificates, the last Business Day of the month immediately preceding the month in which such Distribution Date occurs.

“Reference Banks”: Deutsche Bank AG, Barclay’s Bank PLC, The Tokyo Mitsubishi Bank and National Westminster Bank PLC and their successors in interest; provided, however, that if any of the foregoing banks are not suitable to serve as a Reference Bank, then any leading banks selected by the Trustee (after consultation with the NIMS Insurer) which are

engaged in transactions in Eurodollar deposits in the international Eurocurrency market (i) with an established place of business in London, (ii) not controlling, under the control of or under common control with the Depositor or any Affiliate thereof and (iii) which have been designated as such by the Trustee.

“Refinanced Mortgage Loan”: A Mortgage Loan the proceeds of which were not used to purchase the related Mortgaged Property.

“Regular Certificate”: Any Class A Certificate, Mezzanine Certificate, Class CE Certificate or Class P Certificate.

“Regular Interest”: A “regular interest” in a REMIC within the meaning of Section 860G(a)(1) of the Code.

“Relief Act”: The Servicemembers Civil Relief Act.

“Relief Act Interest Shortfall”: With respect to any Distribution Date and any Mortgage Loan, any reduction in the amount of interest collectible on such Mortgage Loan for the most recently ended calendar month as a result of the application of the Relief Act.

“REMIC”: A “real estate mortgage investment conduit” within the meaning of Section 860D of the Code.

“REMIC I”: The segregated pool of assets subject hereto, constituting the primary trust created hereby and to be administered hereunder, with respect to which a REMIC election is to be made, consisting of: (i) such Mortgage Loans and Prepayment Charges as from time to time are subject to this Agreement, together with the Mortgage Files relating thereto, and together with all collections thereon and proceeds thereof; (ii) any REO Property, together with all collections thereon and proceeds thereof; (iii) the Trustee’s rights with respect to the Mortgage Loans under all insurance policies, including the PMI Policies, required to be maintained pursuant to this Agreement and any proceeds thereof; (iv) the Depositor’s rights under the Mortgage Loan Purchase Agreement (including any security interest created thereby); (v) the Collection Account (other than any amounts representing any Master Servicer Prepayment Charge Payment Amount), the Distribution Account (other than any amounts representing any Master Servicer Prepayment Charge Payment Amount) and any REO Account, and such assets that are deposited therein from time to time and any investments thereof, together with any and all income, proceeds and payments with respect thereto. Notwithstanding the foregoing, however, REMIC I specifically excludes the Net WAC Rate Carryover Reserve Account, the Cap Contracts, the Master Servicer Prepayment Charge Payment Amounts, all payments and other collections of principal and interest due on the Mortgage Loans on or before the Cut-off Date and all Prepayment Charges payable in connection with Principal Prepayments made before the Cut-off Date.

“REMIC I Interest Loss Allocation Amount”: With respect to any Distribution Date, an amount (subject to adjustment based on the actual number of days elapsed in the respective Accrual Periods for the indicated Regular Interests for such Distribution Date) equal to (a) the product of (i) 50% of the aggregate Stated Principal Balance of the Mortgage Loans

and REO Properties then outstanding and (ii) the REMIC I Remittance Rate for REMIC I Regular Interest I-LTAA minus the Marker Rate, divided by (b) 12.

“REMIC I Marker Allocation Percentage”: 50% of any amount payable or loss attributable from the Mortgage Loans, which shall be allocated to REMIC I Regular Interest I-LTAA, REMIC I Regular Interest I-LTA1, REMIC I Regular Interest I-LTA2, REMIC I Regular Interest I-LTA3, REMIC I Regular Interest I-LTA4, REMIC I Regular Interest I-LTA5, REMIC I Regular Interest I-LTM1, REMIC I Regular Interest I-LTM2, REMIC I Regular Interest I-LTM3, REMIC I Regular Interest I-LTM4, REMIC I Regular Interest I-LTM5, REMIC I Regular Interest I-LTM6, REMIC I Regular Interest I-LTM7, REMIC I Regular Interest I-LTM8, REMIC I Regular Interest I-LTM9, REMIC I Regular Interest I-LTM10, REMIC I Regular Interest I-LTM11, REMIC I Regular Interest I-LTZZ and REMIC I Regular Interest I-LTP.

“REMIC I Overcollateralized Amount”: With respect to any date of determination, (i) 0.50% of the aggregate Uncertificated Balances of the REMIC I Regular Interests minus (ii) the aggregate of the Uncertificated Balances of REMIC I Regular Interest I-LTA1, REMIC I Regular Interest I-LTA2, REMIC I Regular Interest I-LTA3, REMIC I Regular Interest I-LTA4, REMIC I Regular Interest I-LTA5, REMIC I Regular Interest I-LTM1, REMIC I Regular Interest I-LTM2, REMIC I Regular Interest I-LTM3, REMIC I Regular Interest I-LTM4, REMIC I Regular Interest I-LTM5, REMIC I Regular Interest I-LTM6, REMIC I Regular Interest I-LTM7, REMIC I Regular Interest I-LTM8, REMIC I Regular Interest I-LTM9, REMIC I Regular Interest I-LTM10 and REMIC I Regular Interest I-LTM11, in each case as of such date of determination.

“REMIC I Principal Loss Allocation Amount”: With respect to any Distribution Date, an amount equal to the product of (i) 50% of the aggregate Stated Principal Balance of the Mortgage Loans and REO Properties then outstanding and (ii) 1 minus a fraction, the numerator of which is two times the aggregate of the Uncertificated Balances of REMIC I Regular Interest I-LTA1, REMIC I Regular Interest I-LTA2, REMIC I Regular Interest I-LTA3, REMIC I Regular Interest I-LTA4, REMIC I Regular Interest I-LTA5, REMIC I Regular Interest I-LTM1, REMIC I Regular Interest I-LTM2, REMIC I Regular Interest I-LTM3, REMIC I Regular Interest I-LTM4, REMIC I Regular Interest I-LTM5, REMIC I Regular Interest I-LTM6, REMIC I Regular Interest I-LTM7, REMIC I Regular Interest I-LTM8, REMIC I Regular Interest I-LTM9, REMIC I Regular Interest I-LTM10 and REMIC I Regular Interest I-LTM11 and the denominator of which is the aggregate of the Uncertificated Balances of REMIC I Regular Interest I-LTA1, REMIC I Regular Interest I-LTA2, REMIC I Regular Interest I-LTA3, REMIC I Regular Interest I-LTA4, REMIC I Regular Interest I-LTA5, REMIC I Regular Interest I-LTM1, REMIC I Regular Interest I-LTM2, REMIC I Regular Interest I-LTM3, REMIC I Regular Interest I-LTM4, REMIC I Regular Interest I-LTM5, REMIC I Regular Interest I-LTM6, REMIC I Regular Interest I-LTM7, REMIC I Regular Interest I-LTM8, REMIC I Regular Interest I-LTM9, REMIC I Regular Interest I-LTM10, REMIC I Regular Interest I-LTM11 and REMIC I Regular Interest I-LTZZ.

“REMIC I Regular Interest”: Any of the separate non-certificated beneficial ownership interests in REMIC I issued hereunder and designated as a “regular interest” in REMIC I. Each REMIC I Regular Interest shall accrue interest at the related REMIC I

Remittance Rate in effect from time to time, and shall be entitled to distributions of principal, subject to the terms and conditions hereof, in an aggregate amount equal to its initial Uncertificated Balance as set forth in the Preliminary Statement hereto. The designations for the respective REMIC I Regular Interests are set forth in the Preliminary Statement hereto.

“REMIC I Regular Interest I-LTAA”: One of the separate non-certificated beneficial ownership interests in REMIC I issued hereunder and designated as a Regular Interest in REMIC I. REMIC I Regular Interest I-LTAA shall accrue interest at the related REMIC I Remittance Rate in effect from time to time, and shall be entitled to distributions of principal, subject to the terms and conditions hereof, in an aggregate amount equal to its initial Uncertificated Balance as set forth in the Preliminary Statement hereto.

“REMIC I Regular Interest I-LTA1”: One of the separate non-certificated beneficial ownership interests in REMIC I issued hereunder and designated as a Regular Interest in REMIC I. REMIC I Regular Interest I-LTA1 shall accrue interest at the related REMIC I Remittance Rate in effect from time to time, and shall be entitled to distributions of principal, subject to the terms and conditions hereof, in an aggregate amount equal to its initial Uncertificated Balance as set forth in the Preliminary Statement hereto.

“REMIC I Regular Interest I-LTA2”: One of the separate non-certificated beneficial ownership interests in REMIC I issued hereunder and designated as a Regular Interest in REMIC I. REMIC I Regular Interest I-LTA2 shall accrue interest at the related REMIC I Remittance Rate in effect from time to time, and shall be entitled to distributions of principal, subject to the terms and conditions hereof, in an aggregate amount equal to its initial Uncertificated Balance as set forth in the Preliminary Statement hereto.

“REMIC I Regular Interest I-LTA3”: One of the separate non-certificated beneficial ownership interests in REMIC I issued hereunder and designated as a Regular Interest in REMIC I. REMIC I Regular Interest I-LTA3 shall accrue interest at the related REMIC I Remittance Rate in effect from time to time, and shall be entitled to distributions of principal, subject to the terms and conditions hereof, in an aggregate amount equal to its initial Uncertificated Balance as set forth in the Preliminary Statement hereto.

“REMIC I Regular Interest I-LTA4”: One of the separate non-certificated beneficial ownership interests in REMIC I issued hereunder and designated as a Regular Interest in REMIC I. REMIC I Regular Interest I-LTA4 shall accrue interest at the related REMIC I Remittance Rate in effect from time to time, and shall be entitled to distributions of principal, subject to the terms and conditions hereof, in an aggregate amount equal to its initial Uncertificated Balance as set forth in the Preliminary Statement hereto.

“REMIC I Regular Interest I-LTA5”: One of the separate non-certificated beneficial ownership interests in REMIC I issued hereunder and designated as a Regular Interest in REMIC I. REMIC I Regular Interest I-LTA5 shall accrue interest at the related REMIC I Remittance Rate in effect from time to time, and shall be entitled to distributions of principal, subject to the terms and conditions hereof, in an aggregate amount equal to its initial Uncertificated Balance as set forth in the Preliminary Statement hereto.

“REMIC I Regular Interest I-LTM1”: One of the separate non-certificated beneficial ownership interests in REMIC I issued hereunder and designated as a Regular Interest in REMIC I. REMIC I Regular Interest I-LTM1 shall accrue interest at the related REMIC I Remittance Rate in effect from time to time, and shall be entitled to distributions of principal, subject to the terms and conditions hereof, in an aggregate amount equal to its initial Uncertificated Balance as set forth in the Preliminary Statement hereto.

“REMIC I Regular Interest I-LTM2”: One of the separate non-certificated beneficial ownership interests in REMIC I issued hereunder and designated as a Regular Interest in REMIC I. REMIC I Regular Interest I-LTM2 shall accrue interest at the related REMIC I Remittance Rate in effect from time to time, and shall be entitled to distributions of principal, subject to the terms and conditions hereof, in an aggregate amount equal to its initial Uncertificated Balance as set forth in the Preliminary Statement hereto.

“REMIC I Regular Interest I-LTM3”: One of the separate non-certificated beneficial ownership interests in REMIC I issued hereunder and designated as a Regular Interest in REMIC I. REMIC I Regular Interest I-LTM3 shall accrue interest at the related REMIC I Remittance Rate in effect from time to time, and shall be entitled to distributions of principal, subject to the terms and conditions hereof, in an aggregate amount equal to its initial Uncertificated Balance as set forth in the Preliminary Statement hereto.

“REMIC I Regular Interest I-LTM4”: One of the separate non-certificated beneficial ownership interests in REMIC I issued hereunder and designated as a Regular Interest in REMIC I. REMIC I Regular Interest I-LTM4 shall accrue interest at the related REMIC I Remittance Rate in effect from time to time, and shall be entitled to distributions of principal, subject to the terms and conditions hereof, in an aggregate amount equal to its initial Uncertificated Balance as set forth in the Preliminary Statement hereto.

“REMIC I Regular Interest I-LTM5”: One of the separate non-certificated beneficial ownership interests in REMIC I issued hereunder and designated as a Regular Interest in REMIC I. REMIC I Regular Interest I-LTM5 shall accrue interest at the related REMIC I Remittance Rate in effect from time to time, and shall be entitled to distributions of principal, subject to the terms and conditions hereof, in an aggregate amount equal to its initial Uncertificated Balance as set forth in the Preliminary Statement hereto.

“REMIC I Regular Interest I-LTM6”: One of the separate non-certificated beneficial ownership interests in REMIC I issued hereunder and designated as a Regular Interest in REMIC I. REMIC I Regular Interest I-LTM6 shall accrue interest at the related REMIC I Remittance Rate in effect from time to time, and shall be entitled to distributions of principal, subject to the terms and conditions hereof, in an aggregate amount equal to its initial Uncertificated Balance as set forth in the Preliminary Statement hereto.

“REMIC I Regular Interest I-LTM7”: One of the separate non-certificated beneficial ownership interests in REMIC I issued hereunder and designated as a Regular Interest in REMIC I. REMIC I Regular Interest I-LTM7 shall accrue interest at the related REMIC I Remittance Rate in effect from time to time, and shall be entitled to distributions of principal,

subject to the terms and conditions hereof, in an aggregate amount equal to its initial Uncertificated Balance as set forth in the Preliminary Statement hereto.

“REMIC I Regular Interest I-LTM8”: One of the separate non-certificated beneficial ownership interests in REMIC I issued hereunder and designated as a Regular Interest in REMIC I. REMIC I Regular Interest I-LTM8 shall accrue interest at the related REMIC I Remittance Rate in effect from time to time, and shall be entitled to distributions of principal, subject to the terms and conditions hereof, in an aggregate amount equal to its initial Uncertificated Balance as set forth in the Preliminary Statement hereto.

“REMIC I Regular Interest I-LTM9”: One of the separate non-certificated beneficial ownership interests in REMIC I issued hereunder and designated as a Regular Interest in REMIC I. REMIC I Regular Interest I-LTM9 shall accrue interest at the related REMIC I Remittance Rate in effect from time to time, and shall be entitled to distributions of principal, subject to the terms and conditions hereof, in an aggregate amount equal to its initial Uncertificated Balance as set forth in the Preliminary Statement hereto.

“REMIC I Regular Interest I-LTM10”: One of the separate non-certificated beneficial ownership interests in REMIC I issued hereunder and designated as a Regular Interest in REMIC I. REMIC I Regular Interest I-LTM10 shall accrue interest at the related REMIC I Remittance Rate in effect from time to time, and shall be entitled to distributions of principal, subject to the terms and conditions hereof, in an aggregate amount equal to its initial Uncertificated Balance as set forth in the Preliminary Statement hereto.

“REMIC I Regular Interest I-LTM11”: One of the separate non-certificated beneficial ownership interests in REMIC I issued hereunder and designated as a Regular Interest in REMIC I. REMIC I Regular Interest I-LTM11 shall accrue interest at the related REMIC I Remittance Rate in effect from time to time, and shall be entitled to distributions of principal, subject to the terms and conditions hereof, in an aggregate amount equal to its initial Uncertificated Balance as set forth in the Preliminary Statement hereto.

“REMIC I Regular Interest I-LTP”: One of the separate non-certificated beneficial ownership interests in REMIC I issued hereunder and designated as a Regular Interest in REMIC I. REMIC I Regular Interest I-LTP shall be entitled to any Prepayment Charges collected by the Master Servicer and to a distribution of principal, subject to the terms and conditions hereof, in an aggregate amount equal to its initial Uncertificated Balance as set forth in the Preliminary Statement hereto.

“REMIC I Regular Interest I-LTZZ”: One of the separate non-certificated beneficial ownership interests in REMIC I issued hereunder and designated as a Regular Interest in REMIC I. REMIC I Regular Interest I-LTZZ shall accrue interest at the related REMIC I Remittance Rate in effect from time to time, and shall be entitled to distributions of principal, subject to the terms and conditions hereof, in an aggregate amount equal to its initial Uncertificated Balance as set forth in the Preliminary Statement hereto.

“REMIC I Regular Interest I-LT1SUB”: One of the separate non-certificated beneficial ownership interests in REMIC I issued hereunder and designated as a Regular Interest

in REMIC I. REMIC I Regular Interest I-LT1SUB shall accrue interest at the related REMIC I Remittance Rate in effect from time to time, and shall be entitled to distributions of principal, subject to the terms and conditions hereof, in an aggregate amount equal to its initial Uncertificated Balance as set forth in the Preliminary Statement hereto.

“REMIC I Regular Interest I-LT1GRP”: One of the separate non-certificated beneficial ownership interests in REMIC I issued hereunder and designated as a Regular Interest in REMIC I. REMIC I Regular Interest I-LT1GRP shall accrue interest at the related REMIC I Remittance Rate in effect from time to time, and shall be entitled to distributions of principal, subject to the terms and conditions hereof, in an aggregate amount equal to its initial Uncertificated Balance as set forth in the Preliminary Statement hereto.

“REMIC I Regular Interest I-LT2SUB”: One of the separate non-certificated beneficial ownership interests in REMIC I issued hereunder and designated as a Regular Interest in REMIC I. REMIC I Regular Interest I-LT2SUB shall accrue interest at the related REMIC I Remittance Rate in effect from time to time, and shall be entitled to distributions of principal, subject to the terms and conditions hereof, in an aggregate amount equal to its initial Uncertificated Balance as set forth in the Preliminary Statement hereto.

“REMIC I Regular Interest I-LT2GRP”: One of the separate non-certificated beneficial ownership interests in REMIC I issued hereunder and designated as a Regular Interest in REMIC I. REMIC I Regular Interest I-LT2GRP shall accrue interest at the related REMIC I Remittance Rate in effect from time to time, and shall be entitled to distributions of principal, subject to the terms and conditions hereof, in an aggregate amount equal to its initial Uncertificated Balance as set forth in the Preliminary Statement hereto.

“REMIC I Regular Interest I-LTXX”: One of the separate non-certificated beneficial ownership interests in REMIC I issued hereunder and designated as a Regular Interest in REMIC I. REMIC I Regular Interest I-LTXX shall accrue interest at the related REMIC I Remittance Rate in effect from time to time, and shall be entitled to distributions of principal, subject to the terms and conditions hereof, in an aggregate amount equal to its initial Uncertificated Balance as set forth in the Preliminary Statement hereto.

“REMIC I Remittance Rate”: With respect to REMIC I Regular Interest I-LTAA, REMIC I Regular Interest I-LTA1, REMIC I Regular Interest I-LTA2, REMIC I Regular Interest I-LTA3, REMIC I Regular Interest I-LTA4, REMIC I Regular Interest I-LTA5, REMIC I Regular Interest I-LTM1, REMIC I Regular Interest I-LTM2, REMIC I Regular Interest I-LTM3, REMIC I Regular Interest I-LTM4, REMIC I Regular Interest I-LTM5, REMIC I Regular Interest I-LTM6, REMIC I Regular Interest I-LTM7, REMIC I Regular Interest I-LTM8, REMIC I Regular Interest I-LTM9, REMIC I Regular Interest I-LTM10, REMIC I Regular Interest I-LTM11, REMIC I Regular Interest I-LTZZ, REMIC I Regular Interest I-LTP, REMIC I Regular Interest I-LT1SUB, REMIC I Regular Interest I-LT2SUB and REMIC I Regular Interest I-LTXX, the weighted average of the Adjusted Net Mortgage Rates of the Mortgage Loans. With respect to REMIC I Regular Interest I-LT1GRP, the weighted average of the Adjusted Net Mortgage Rates of the Group I Mortgage Loans and with respect REMIC I Regular Interest I-LT2GRP, the weighted average of the Adjusted Net Mortgage Rates of the Group II Mortgage Loans.

“REMIC I Subordinated Balance Ratio”: The ratio among the Uncertificated Balances of each REMIC I Regular Interest ending with the designation “SUB,”, equal to the ratio among, with respect to each such REMIC I Regular Interest, the excess of (x) the aggregate Stated Principal Balance of the Mortgage Loans in the related Loan Group over (y) the Current Principal Amount of the Class A Certificates in the related Loan Group.

“REMIC I Sub WAC Allocation Percentage”: 50% of any amount payable from or loss attributable to the Mortgage Loans, which shall be allocated to REMIC I Regular Interest I-LT1SUB, REMIC I Regular Interest I-LT1GRP, REMIC I Regular Interest I-LT2SUB, REMIC I Regular Interest I-LT2GRP and REMIC I Regular Interest I-LTXX.

“REMIC I Required Overcollateralized Amount”: 0.50% of the Overcollateralization Target Amount.

“REMIC II”: The segregated pool of assets consisting of all of the REMIC I Regular Interests conveyed in trust to the Trustee, for the benefit of the REMIC II Certificateholders pursuant to Section 2.07, and all amounts deposited therein, with respect to which a separate REMIC election is to be made.

“REMIC II Certificate”: Any Regular Certificate (other than the Class CE Certificates or Class P Certificates) or Class R Certificate.

“REMIC II Certificateholder”: The Holder of any REMIC II Certificate.

“REMIC II Regular Interest”: Any Class A Certificate, Mezzanine Certificate, the Class CE Interest or the Class P Interest.

“REMIC III”: The segregated pool of assets consisting of all of the Class CE Interest conveyed in trust to the Trustee, for the benefit of the Holders of the Regular Certificates and the Class R-X Certificate (in respect of the Class R-III Interest), pursuant to Article II hereunder, and all amounts deposited therein, with respect to which a separate REMIC election is to be made.

“REMIC IV”: The segregated pool of assets consisting of all of the Class P Interest conveyed in trust to the Trustee, for the benefit of the Holders of the Regular Certificates and the Class R-X Certificate (in respect of the Class R-IV Interest), pursuant to Article II hereunder, and all amounts deposited therein, with respect to which a separate REMIC election is to be made.

“REMIC Provisions”: Provisions of the federal income tax law relating to real estate mortgage investment conduits, which appear at Section 860A through 860G of the Code, and related provisions, and proposed, temporary and final regulations and published rulings, notices and announcements promulgated thereunder, as the foregoing may be in effect from time to time.

“REMIC Regular Interests”: The REMIC 1 Regular Interests, the REMIC 2 Regular Interests, the Class CE Interest and the Class P Interest.

“Remittance Report”: A report prepared by the Master Servicer and delivered to the Trustee and the NIMS Insurer pursuant to Section 4.03.

“Rents from Real Property”: With respect to any REO Property, gross income of the character described in Section 856(d) of the Code as being included in the term “rents from real property.”

“REO Account”: The account or accounts maintained, or caused to be maintained, by the Master Servicer in respect of an REO Property pursuant to Section 3.23.

“REO Disposition”: The sale or other disposition of an REO Property on behalf of REMIC I.

“REO Imputed Interest”: As to any REO Property, for any calendar month during which such REO Property was at any time part of REMIC I, one month’s interest at the applicable Net Mortgage Rate on the Stated Principal Balance of such REO Property (or, in the case of the first such calendar month, of the related Mortgage Loan, if appropriate) as of the close of business on the Distribution Date in such calendar month.

“REO Property”: A Mortgaged Property acquired by the Master Servicer on behalf of REMIC I through foreclosure or deed-in-lieu of foreclosure, as described in Section 3.23.

“Request for Release”: A release signed by a Servicing Officer, in the form of Exhibit E attached hereto.

“Reserve Interest Rate”: With respect to any Interest Determination Date, the rate per annum that the Trustee determines to be either (i) the arithmetic mean (rounded upwards if necessary to the nearest whole multiple of 1/16%) of the one-month U.S. dollar lending rates which New York City banks selected by the Trustee are quoting on the relevant Interest Determination Date to the principal London offices of leading banks in the London interbank market or (ii) in the event that the Trustee can determine no such arithmetic mean, the lowest one-month U.S. dollar lending rate which New York City banks selected by the Trustee are quoting on such Interest Determination Date to leading European banks.

“Residential Dwelling”: Any one of the following: (i) a detached one-family dwelling, (ii) a detached two- to four-family dwelling, (iii) a one-family dwelling unit in a Fannie Mae eligible condominium project, (iv) a manufactured home, or (v) a detached one-family dwelling in a planned unit development, none of which is a co-operative or mobile home.

“Residual Certificate”: Any one of the Class R Certificates or the Class R-X Certificates.

“Residual Interest”: The sole class of “residual interests” in a REMIC within the meaning of Section 860G(a)(2) of the Code.

“Responsible Officer”: When used with respect to the Trustee, the Chairman or Vice Chairman of the Board of Directors or Trustees, the Chairman or Vice Chairman of the

Executive or Standing Committee of the Board of Directors or Trustees, the President, the Chairman of the Committee on Trust Matters, any vice president, any assistant vice president, the Secretary, any assistant secretary, the Treasurer, any assistant treasurer, the Cashier, any assistant cashier, any trust officer or assistant trust officer, the Controller and any assistant controller or any other officer of the Trustee, customarily performing functions similar to those performed by any of the above designated officers and, with respect to a particular matter, to whom such matter is referred because of such officer’s knowledge of and familiarity with the particular subject.

“S&P”: Standard & Poor’s Ratings Services, a division of The McGraw-Hill Companies, Inc., or its successor in interest.

“Seller”: UBS Real Estate Securities Inc. or its successor in interest, in its capacity as seller under the Mortgage Loan Purchase Agreement.

“Senior Group I Principal Distribution Amount”: The excess of (x) the aggregate Certificate Principal Balance of the Group I Certificates immediately prior to such Distribution Date over (y) the lesser of (A) the product of (i) 68.60% and (ii) the aggregate Stated Principal Balance of the Group I Mortgage Loans as of the last day of the related Due Period (after giving effect to scheduled payments of principal due during the related Due Period, to the extent received or advanced, and unscheduled collections of principal received during the related Prepayment Period) and (B) the excess of the aggregate Stated Principal Balance of the Group I Mortgage Loans as of the last day of the related Due Period (after giving effect to scheduled payments of principal due during the related Due Period, to the extent received or advanced, and unscheduled collections of principal received during the related Prepayment Period) over $4.394,431.00.

“Senior Group II Principal Distribution Amount”: The excess of (x) the aggregate Certificate Principal Balance of the Group II Certificates immediately prior to such Distribution Date over (y) the lesser of (A) the product of (i) 68.60% and (ii) the aggregate Stated Principal Balance of the Group II Mortgage Loans as of the last day of the related Due Period (after giving effect to scheduled payments of principal due during the related Due Period, to the extent received or advanced, and unscheduled collections of principal received during the related Prepayment Period) and (B) the excess of the aggregate Stated Principal Balance of the Group II Mortgage Loans as of the last day of the related Due Period (after giving effect to scheduled payments of principal due during the related Due Period, to the extent received or advanced, and unscheduled collections of principal received during the related Prepayment Period) over $3,617,519.18.

“Sequential Trigger Event”: A Sequential Trigger Event will be in effect if, with respect to any Distribution Date before the 37 ^th Distribution Date, the aggregate amount of Realized Losses incurred since the Cut-off Date through the last day of the related Due Period (reduced by Subsequent Recoveries received through the last day of such Due Period) divided by the aggregate Stated Principal Balance of the Mortgage Loans as of the Cut-off Date exceeds 2.00%, or if, on or after the 37 ^th Distribution Date, a Trigger Event is in effect.

“Servicing Account”: The account or accounts created and maintained pursuant to Section 3.09.

“Servicing Advances”: All customary, reasonable and necessary “out of pocket” costs and expenses (including reasonable attorneys’ fees and expenses) incurred by the Master Servicer in the performance of its servicing obligations, including, but not limited to, the cost of (i) the preservation, restoration, inspection and protection of the Mortgaged Property, (ii) any enforcement or judicial proceedings, including foreclosures, (iii) the management and liquidation of the REO Property and (iv) compliance with the obligations under Sections 3.01, 3.09, 3.16, and 3.23.

“Servicing Fee”: With respect to each Mortgage Loan and for any calendar month, an amount equal to one month’s interest (or in the event of any payment of interest which accompanies a Principal Prepayment in full or in part made by the Mortgagor during such calendar month, interest for the number of days covered by such payment of interest) at the Servicing Fee Rate on the same principal amount on which interest on such Mortgage Loan accrues for such calendar month. A portion of such Servicing Fee may be retained by any Sub-Servicer as its servicing compensation.

“Servicing Fee Rate”: 0.30% per annum for the first 10 Due Periods, 0.40% per annum for the 11 ^th through 30 ^th Due Periods and 0.65% per annum for all Due Periods thereafter, in each case, on the Principal Balance of each Mortgage Loan.

“Servicing Officer”: Any representative of the Master Servicer involved in, or responsible for, the administration and servicing of Mortgage Loans, whose name and specimen signature appear on a list of Servicing Officers furnished by the Master Servicer to the Trustee and the Depositor on the Closing Date, as such list may from time to time be amended.

“Servicing Standard”: Shall mean the standards set forth in Section 3.01.

“Servicing Transfer Costs”: Shall mean all reasonable costs and expenses incurred by the Trustee in connection with the transfer of servicing from a predecessor servicer, including, without limitation, any reasonable costs or expenses associated with the complete transfer of all servicing data and the completion, correction or manipulation of such servicing data as may be required by the Trustee to correct any errors or insufficiencies in the servicing data or otherwise to enable the Trustee to service the Mortgage Loans properly and effectively.

“Single Certificate”: With respect to any Class of Certificates (other than the Class P Certificates and the Residual Certificates), a hypothetical Certificate of such Class evidencing a Percentage Interest for such Class corresponding to an initial Certificate Principal Balance of $1,000. With respect to the Class P Certificates and the Residual Certificates, a hypothetical Certificate of such Class evidencing a 100% Percentage Interest in such Class.

“Startup Day”: With respect to each Trust REMIC, the day designated as such pursuant to Section 10.01(b) hereof.

“Stated Principal Balance”: With respect to any Mortgage Loan: (a) as of any date of determination up to but not including the Distribution Date on which the proceeds, if any, of a Liquidation Event with respect to such Mortgage Loan would be distributed, the Cut-off Date Principal Balance of such Mortgage Loan, as shown in the Mortgage Loan Schedule, minus the sum of (i) the principal portion of each Monthly Payment due on a Due Date subsequent to the Cut-off Date, to the extent received from the Mortgagor or advanced by the Master Servicer and distributed pursuant to Section 4.01 on or before such date of determination, (ii) all Principal Prepayments received after the Cut-off Date, to the extent distributed pursuant to Section 4.01 on or before such date of determination, (iii) all Liquidation Proceeds and Insurance Proceeds applied by the Master Servicer as recoveries of principal in accordance with the provisions of Section 3.16, to the extent distributed pursuant to Section 4.01 on or before such date of determination, and (iv) any Realized Loss incurred with respect thereto as a result of a Deficient Valuation made during or prior to the Prepayment Period for the most recent Distribution Date coinciding with or preceding such date of determination; and (b) as of any date of determination coinciding with or subsequent to the Distribution Date on which the proceeds, if any, of a Liquidation Event with respect to such Mortgage Loan would be distributed, zero. With respect to any REO Property: (a) as of any date of determination up to but not including the Distribution Date on which the proceeds, if any, of a Liquidation Event with respect to such REO Property would be distributed, an amount (not less than zero) equal to the Stated Principal Balance of the related Mortgage Loan as of the date on which such REO Property was acquired on behalf of REMIC I, minus if such REO Property was acquired before the Distribution Date in any calendar month, the principal portion of the Monthly Payment due on the Due Date in the calendar month of acquisition, to the extent advanced by the Master Servicer and distributed pursuant to Section 4.01 on or before such date of determination; and (b) as of any date of determination coinciding with or subsequent to the Distribution Date on which the proceeds, if any, of a Liquidation Event with respect to such REO Property would be distributed, zero.

“Stepdown Date”: The earlier to occur of (i) the Distribution Date on which the aggregate Certificate Principal Balance of the Class A Certificates is zero and (ii) the later to occur of (x) the Distribution Date occurring in June 2008 and (y) the first Distribution Date on which the Credit Enhancement Percentage (calculated for this purpose only after taking into account distributions of principal on the Mortgage Loans but prior to distribution of the Group I Principal Distribution Amount and the Group II Principal Distribution Amount to the Holders of the Certificates then entitled to distributions of principal on such Distribution Date) is greater than or equal to 31.40%.

“Sub-Servicer”: Any Person with which the Master Servicer has entered into a Sub-Servicing Agreement and which meets the qualifications of a Sub-Servicer pursuant to Section 3.02.

“Sub-Servicing Account”: An account established by a Sub-Servicer which meets the requirements set forth in Section 3.08 and is otherwise acceptable to the Master Servicer.

“Sub-Servicing Agreement”: The written contract between the Master Servicer and a Sub-Servicer relating to servicing and administration of certain Mortgage Loans as provided in Section 3.02.

“Subsequent Recoveries”: As of any Distribution Date, amounts received by the Servicer (net of any related expenses permitted to be reimbursed pursuant to Section 3.11) specifically related to a Mortgage Loan that was the subject of a liquidation or an REO Disposition prior to the related Prepayment Period that resulted in a Realized Loss.

“Substitution Adjustment Amount”: As defined in Section 2.03(b).

“Tax Returns”: The federal income tax return on Internal Revenue Service Form 1066, U.S. Real Estate Mortgage Investment Conduit Income Tax Return, including Schedule Q thereto, Quarterly Notice to Residual Interest Holders of REMIC Taxable Income or Net Loss Allocation, or any successor forms, to be filed on behalf of the Trust Fund due to the classification of portions thereof as REMICs under the REMIC Provisions, together with any and all other information reports or returns that may be required to be furnished to the Certificateholders or filed with the Internal Revenue Service or any other governmental taxing authority under any applicable provisions of federal, state or local tax laws.

“Telerate Page 3750”: The display designated as page “3750” on the Dow Jones Telerate Capital Markets Report (or such other page as may replace page 3750 on that report for the purpose of displaying London interbank offered rates of major banks).

“Termination Price”: As defined in Section 9.01.

“Terminator”: As defined in Section 9.01.

“Three Month Rolling Delinquency Percentage”: With respect to the Mortgage Loans and any Distribution Date, the average for the three most recent calendar months of the fraction, expressed as a percentage, the numerator of which is (x) the sum (without duplication) of the aggregate of the Principal Balances of all Mortgage Loans that are (i) 60 or more days Delinquent, (ii) in bankruptcy and 60 or more days Delinquent, (iii) in foreclosure and 60 or more days Delinquent or (iv) REO Properties, and the denominator of which is (y) the sum of the Principal Balances of the Mortgage Loans, in the case of both (x) and (y), as of the Close of Business on the last Business Day of each of the three most recent calendar months.

“Transfer”: Any direct or indirect transfer, sale, pledge, hypothecation, or other form of assignment of any Ownership Interest in a Certificate.

“Transferee”: Any Person who is acquiring by Transfer any Ownership Interest in a Certificate.

“Transferor”: Any Person who is disposing by Transfer of any Ownership Interest in a Certificate.

“Trigger Event”: A Trigger Event is in effect with respect to any Distribution Date on or after the Stepdown Date if:

(a) the percentage obtained by dividing (x) the aggregate Stated Principal Balance of Mortgage Loans Delinquent 60 days or more or are in foreclosure, have been converted to REO Properties or have been discharged by reason of bankruptcy by (y) the aggregate Stated Principal

Balance of the Mortgage Loans, in each case, as of the last day of the previous calendar month, exceeds 48.00% of the Credit Enhancement Percentage; or

(b) the aggregate amount of Realized Losses incurred since the Cut-off Date through the last day of the related Due Period (reduced by the aggregate amount of Subsequent Recoveries received since the Cut-off Date through the last day of the related Due Period) divided by the aggregate Principal Balance of the Mortgage Loans as of the Cut-off Date exceeds the applicable percentages set forth below with respect to such Distribution Date:

Distribution Date Occurring In	Percentage
June 2008 through May 2009	2.00% for the first month plus an additional 1/12 ^th of 0.50% each month thereafter.
June 2009 through May 2010	2.50% for the first month plus an additional 1/12 ^th of 0.50% each month thereafter.
June 2010 through May 2011	3.00% for the first month plus an additional 1/12 ^th of 0.50% each month thereafter.
June 2011 and thereafter	3.25% for the first month plus an additional 1/12 ^th of 0.50% each month thereafter.

“Trust”: MASTR Asset Backed Securities Trust 2005-OPT1.

“Trust Fund”: Collectively, all of the assets of REMIC I, REMIC II, REMIC III, REMIC IV, the Net WAC Rate Carryover Reserve Account (including any payments made under the Cap Contracts deposited therein) and the other assets conveyed by the Depositor to the Trustee pursuant to Section 2.01.

“Trust REMIC”: Any of REMIC I, REMIC II, REMIC III or REMIC IV.

“Trustee”: Wells Fargo Bank, N.A., a national banking association, or its successor in interest, or any successor trustee appointed as herein provided.

“Trustee Fee”: The amount payable to the Trustee on each Distribution Date pursuant to Section 8.05 as compensation for all services rendered by it in the execution of the trust hereby created and in the exercise and performance of any of the powers and duties of the Trustee hereunder, which amount shall equal the product of (x) one-twelfth of the Trustee Fee Rate and (y) the aggregate Stated Principal Balance of the Mortgage Loans as of the last day of the related Due Period (or, in the case of the initial Distribution Date, as of the Cut-off Date), calculated on the basis of a 360-day year consisting of twelve 30-day months.

“Trustee Fee Rate”: 0.0035% per annum.

“Uncertificated Balance”: The amount of any REMIC Regular Interest outstanding as of any date of determination. As of the Closing Date, the Uncertificated Balance of each REMIC Regular Interest shall equal the amount set forth in the Preliminary Statement hereto as its initial uncertificated balance. On each Distribution Date, the Uncertificated Balance of each REMIC Regular Interest shall be reduced by all distributions of principal made on such REMIC Regular Interest on such Distribution Date pursuant to Section 4.01 and, if and to the extent necessary and appropriate, shall be further reduced on such Distribution Date by Realized Losses as provided in Section 4.04. The Uncertificated Balance of REMIC I Regular Interest I-LTZZ shall be increased by interest deferrals as provided in Section 4.01(a)(1)(i). The Uncertificated Balance of each REMIC Regular Interest shall never be less than zero. With respect to the Class CE Interest as of any date of determination, an amount equal to the excess, if

any, of (A) the then aggregate Uncertificated Principal Balances of the REMIC I Regular Interests over (B) the then aggregate Certificate Principal Balances of the Class A Certificates, Mezzanine Certificates and the Class P Interest then outstanding.

“Uncertificated Interest”: With respect to any REMIC Regular Interest for any Distribution Date, one month’s interest at the REMIC Remittance Rate applicable to such REMIC I Regular Interest for such Distribution Date, accrued on the Uncertificated Balance thereof immediately prior to such Distribution Date. Uncertificated Interest in respect of any REMIC I Regular Interest shall accrue on the basis of a 360-day year consisting of twelve 30-day months. Uncertificated Interest with respect to each Distribution Date, as to any REMIC Regular Interest, shall be reduced by an amount equal to the sum of (a) the aggregate Prepayment Interest Shortfall, if any, for such Distribution Date to the extent not covered by payments pursuant to Section 3.24 and (b) the aggregate amount of any Relief Act Interest Shortfall, if any allocated, in each case, to such REMIC Regular Interest pursuant to Section 1.02. In addition, Uncertificated Interest with respect to each Distribution Date, as to any REMIC Regular Interest shall be reduced by Realized Losses, if any, allocated to such REMIC Regular Interest pursuant to Section 1.02 and Section 4.04.

“Underwriters’ Exemption”: As defined in the Prospectus Supplement.

“Uninsured Cause”: Any cause of damage to a Mortgaged Property such that the complete restoration of such property is not fully reimbursable by the hazard insurance policies required to be maintained pursuant to Section 3.14.

“United States Person”: A citizen or resident of the United States, a corporation, partnership or other entity created or organized in, or under the laws of, the United States, any state thereof or, District of Columbia (except, in the case of a partnership, to the extent provided in regulations) provided that, for purposes solely of the restrictions on the transfer of Class R Certificates, no partnership or other entity treated as a partnership for United States federal income tax purposes shall be treated as a United States Person unless all persons that own an interest in such partnership either directly or through any entity that is not a corporation for United States federal income tax purposes are required by the applicable operative agreement to be United States Persons or an estate whose income is subject to United States federal income tax regardless of its source, or a trust if a court within the United States is able to exercise primary supervision over the administration of the trust and one or more United States persons have the authority to control all substantial decisions of the trust. To the extent prescribed in regulations by the Secretary of the Treasury, a trust which was in existence on August 20, 1996 (other than a trust treated as owned by the grantor under subpart E of part I of subchapter J of chapter 1 of the Code), and which was treated as a United States person on August 20, 1996 may elect to continue to be treated as a United States person notwithstanding the previous sentence. The term “United States” shall have the meaning set forth in Section 7701 of the Code.

“Unpaid Interest Shortfall Amount”: With respect to the Class A Certificates and the Mezzanine Certificates and (i) the first Distribution Date, zero, and (ii) any Distribution Date after the first Distribution Date, the amount, if any, by which (a) the sum of (1) the Monthly Interest Distributable Amount for such Class for the immediately preceding Distribution Date and (2) the outstanding Unpaid Interest Shortfall Amount, if any, for such Class for such

preceding Distribution Date exceeds (b) the aggregate amount distributed on such Class in respect of interest pursuant to clause (a) of this definition on such preceding Distribution Date, plus interest on the amount of interest due but not paid on the Certificates of such Class on such preceding Distribution Date, to the extent permitted by law, at the Pass-Through Rate for such Class for the related Accrual Period.

“Value”: With respect to any Mortgage Loan, and the related Mortgaged Property, the lesser of:

	(i)	the lesser of (a) the value thereof as determined by an appraisal made for the originator of the Mortgage Loan at the time of origination of the Mortgage Loan by an appraiser who met the minimum requirements of Fannie Mae and Freddie Mac, and (b) the value thereof as determined by a review appraisal conducted by the Originator in the event any such review appraisal determines an appraised value more than 10% lower than the value thereof, in the case of a Mortgaged Loan with a Loan-to-Value Ratio less than or equal to 80%, or more than 5% lower than the value thereof, in the case of a Mortgage Loan with a Loan-to-Value Ratio greater than 80%, as determined by the appraisal referred to in clause (i)(a) above; and

	(ii)	the purchase price paid for the related Mortgaged Property by the Mortgagor with the proceeds of the Mortgage Loan; provided, however, that in the case of a refinanced Mortgage Loan (which is a Mortgage Loan the proceeds of which were not used to purchase the related Mortgaged Property) or a Mortgage Loan originated in connection with a “lease option purchase” if the “lease option purchase price” was set 12 months or more prior to origination, such value of the Mortgaged Property is based solely upon clause (i) above.

“Voting Rights”: The portion of the voting rights of all of the Certificates which is allocated to any Certificate. With respect to any date of determination, 98% of all Voting Rights will be allocated among the holders of the Class A Certificates, the Mezzanine Certificates and the Class CE Certificates in proportion to the then outstanding Certificate Principal Balances of their respective Certificates, 1% of all Voting Rights will be allocated to the holders of the Class P Certificates and 1% of all Voting Rights will be allocated among the holders of the Residual Certificates. The Voting Rights allocated to each Class of Certificate shall be allocated among Holders of each such Class in accordance with their respective Percentage Interests as of the most recent Record Date.

Section 1.02.

Allocation of Certain Interest Shortfalls .

For purposes of calculating the amount of the Monthly Interest Distributable Amount for the Class A Certificates, the Mezzanine Certificates and the Class CE Certificates for any Distribution Date, (1) the aggregate amount of any Prepayment Interest Shortfalls (to the extent not covered by payments by the Master Servicer pursuant to Section 3.24) and any Relief Act Interest Shortfall incurred in respect of the Mortgage Loans for any Distribution Date shall be allocated first, to the Class CE Certificates based on, and to the extent of, one month’s interest

at the then applicable respective Pass-Through Rate on the respective Notional Amount of each such Certificate and, thereafter, among the Class A Certificates and the Mezzanine Certificates on a pro rata basis based on, and to the extent of, one month’s interest at the then applicable respective Pass-Through Rate on the respective Certificate Principal Balance of each such Certificate and (2) the aggregate amount of any Realized Losses and Net WAC Rate Carryover Amounts incurred for any Distribution Date shall be allocated to the Class CE Certificates based on, and to the extent of, one month’s interest at the then applicable respective Pass-Through Rate on the respective Notional Amount of each such Certificate.

For purposes of calculating the amount of Uncertificated Interest for the REMIC I Regular Interests for any Distribution Date:

	(A)	The REMIC I Marker Allocation Percentage of the aggregate amount of any Prepayment Interest Shortfalls (to the extent not covered by payments by the Master Servicer pursuant to Section 3.24) and the REMIC I Marker Allocation Percentage of the aggregate amount of any Relief Act Interest Shortfalls incurred in respect of the Mortgage Loans for any Distribution Date shall be allocated among REMIC I Regular Interest I-LTA1, REMIC I Regular Interest I-LTA2, REMIC I Regular Interest I-LTA3, REMIC I Regular Interest I-LTA4, REMIC I Regular Interest I-LTA5, REMIC I Regular Interest I-LTM1, REMIC I Regular Interest I-LTM2, REMIC I Regular Interest I-LTM3, REMIC I Regular Interest I-LTM4, REMIC I Regular Interest I-LTM5, REMIC I Regular Interest I-LTM6, REMIC I Regular Interest I-LTM7, REMIC I Regular Interest I-LTM8, REMIC I Regular Interest I-LTM9, REMIC I Regular Interest I-LTM10, REMIC I Regular Interest I-LTM11 and REMIC I Regular Interest I-LTZZ pro rata based on, and to the extent of, one month’s interest at the then applicable respective Pass-Through Rate on the respective Uncertificated Balance of each such REMIC I Regular Interest; and

	(B)	The REMIC I Sub WAC Allocation Percentage of the aggregate amount of any Prepayment Interest Shortfalls (to the extent not covered by payments by the Master Servicer pursuant to Section 3.24) and the REMIC I Sub WAC Allocation Percentage of the aggregate amount of any Relief Act Interest Shortfalls incurred in respect of the Mortgage Loans for any Distribution Date shall be allocated first, to Uncertificated Interest payable to REMIC I Regular Interest I-LT1SUB, REMIC I Regular Interest I-LT1GRP, REMIC I Regular Interest I-LT2SUB, REMIC I Regular Interest I-LT2GRP and REMIC I Regular Interest I-LTXX, pro rata based on, and to the extent of, one month’s interest at the then applicable respective Pass-Through Rate on the respective Uncertificated Balance of each such REMIC I Regular Interest.

Section 1.03.

Rights of the NIMS Insurer .

Each of the rights of the NIMS Insurer set forth in this Agreement shall exist so long as (i) the NIMS Insurer has undertaken to guarantee certain payments of notes issued pursuant to the Indenture and (ii) the notes issued pursuant to the Indenture remain outstanding or the NIMS Insurer is owed amounts in respect of its guarantee of payment on such notes; provided, however, the NIMS Insurer shall not have any rights hereunder (except pursuant to Section 11.01 and any rights to indemnification hereunder in the case of clause (ii) below) so long as (i) the NIMS Insurer has not undertaken to guarantee certain payments of notes issued pursuant to the Indenture or (ii) any default has occurred and is continuing under the insurance policy issued by the NIMS Insurer with respect to such notes.

ARTICLE II

CONVEYANCE OF MORTGAGE LOANS;

ORIGINAL ISSUANCE OF CERTIFICATES

Section 2.01.

Conveyance of the Mortgage Loans .

The Depositor, concurrently with the execution and delivery hereof, does hereby transfer, assign, set over and otherwise convey to the Trustee without recourse, for the benefit of the Certificateholders, all the right, title and interest of the Depositor, including any security interest therein for the benefit of the Depositor, in and to the Mortgage Loans identified on the Mortgage Loan Schedule, the rights of the Depositor under the Mortgage Loan Purchase Agreement, and all other assets included or to be included in REMIC I. Such assignment includes all interest and principal received by the Depositor or the Master Servicer on or with respect to the Mortgage Loans (other than payments of principal and interest due on such Mortgage Loans on or before the Cut-off Date). The Depositor herewith delivers to the Trustee an executed original Mortgage Loan Purchase Agreement and PMI Policies.

In connection with such transfer and assignment, the Depositor does hereby deliver to, and deposit with, the Trustee the following documents or instruments with respect to each Mortgage Loan so transferred and assigned (a “Mortgage File”):

(i) the original Mortgage Note, endorsed in blank or in the following form: “Pay to the order of Wells Fargo Bank, N.A., as Trustee under the applicable agreement, without recourse,” with all prior and intervening endorsements showing a complete chain of endorsement from the originator to the Person so endorsing to the Trustee;

(ii) the original Mortgage with evidence of recording thereon, and the original recorded power of attorney, if the Mortgage was executed pursuant to a power of attorney, with evidence of recording thereon;

(iii)

an original Assignment in blank;

(iv) the original recorded Assignment or Assignments showing a complete chain of assignment from the originator to the Person assigning the Mortgage to the Trustee as contemplated by the immediately preceding clause (iii);

(v) the original or copies of each assumption, modification, written assurance or substitution agreement, if any; and

(vi) the original lender’s title insurance policy, together with all endorsements or riders that were issued with or subsequent to the issuance of such policy, insuring the priority of the Mortgage as a first or second lien on the Mortgaged Property represented therein as a fee interest vested in the Mortgagor, or in the event such original title policy is unavailable, a written commitment or uniform binder or preliminary report of title issued by the title insurance or escrow company.

With respect to a maximum of approximately 2.00% of the Original Mortgage Loans, by outstanding principal balance of the Original Mortgage Loans as of the Cut-off Date, if any original Mortgage Note referred to in Section 2.01(i) above cannot be located, the obligations of the Depositor to deliver such documents shall be deemed to be satisfied upon delivery to the Trustee of a photocopy of such Mortgage Note, if available, with a lost note affidavit substantially in the form of Exhibit I attached hereto. If any of the original Mortgage Notes for which a lost note affidavit was delivered to the Trustee is subsequently located, such original Mortgage Note shall be delivered to the Trustee within three Business Days.

The Master Servicer, in its capacity as Originator, shall promptly (within sixty Business Days following the later of the Closing Date and the date of receipt by the Trustee of the recording information for a Mortgage, but in no event later than ninety days following the Closing Date) submit or cause to be submitted for recording, at no expense to the Trust Fund, the Trustee or the Depositor, in the appropriate public office for real property records, each Assignment referred to in Sections 2.01(iii) and (iv) above and in connection therewith, the Master Servicer shall cause each original Assignment to be executed in the following for