POOLING AND SERVICING AGREEMENT

Pooling and Servicing Agreement

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Bank of New York, New York | Certificate Insurer, Financial Security Assurance Inc | CLAYTON FIXED INCOME SERVICES INC | Custodian, Wells Fargo Bank, NA | Depositor, Mortgage Asset Securitization Transactions, Inc | Master Servicer, Wells Fargo Bank, NA | Transferor, UBS Real Estate Securities Inc | US BANK NATIONAL ASSOCIATION

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Title: POOLING AND SERVICING AGREEMENT
Governing Law: New York Date: 11/30/2006

POOLING AND SERVICING AGREEMENT, Parties: bank of new york new york , certificate insurer financial security assurance inc , clayton fixed income services inc , custodian wells fargo bank na , depositor mortgage asset securitization transactions inc , master servicer wells fargo bank na , transferor ubs real estate securities inc , us bank national association

EXECUTION COPY

MORTGAGE ASSET SECURITIZATION TRANSACTIONS, INC.,
Depositor

UBS REAL ESTATE SECURITIES INC.,
Transferor

WELLS FARGO BANK, N.A.,
Master Servicer, Trust Administrator and Custodian

U.S. BANK NATIONAL ASSOCIATION,
Trustee

CLAYTON FIXED INCOME SERVICES INC.,

Credit Risk Manager

POOLING AND SERVICING AGREEMENT
Dated as of October 1, 2006

MASTR ADJUSTABLE RATE MORTGAGES TRUST 2006-OA2

MORTGAGE PASS-THROUGH CERTIFICATES, Series 2006-OA2

TABLE OF CONTENTS

ARTICLE I DEFINITIONS

Section 1.01. Definitions.

Section 1.02. Certain Calculations.

Section 1.03. Rights of the NIMS Insurer.

ARTICLE II CONVEYANCE OF MORTGAGE LOANS; REPRESENTATIONS AND

WARRANTIES

Section 2.01. Conveyance of Mortgage Loans.

Section 2.02. Acceptance by Trustee of the Mortgage Loans.

Section 2.03. Remedies for Breaches of Representations and Warranties.

Section 2.04. Representations and Warranties of the Depositor as to the Mortgage Loans.

Section 2.05. [Reserved].

Section 2.06. Execution and Delivery of Certificates.

Section 2.07. REMIC Matters.

Section 2.08. Covenants of the Master Servicer.

Section 2.09. Representations and Warranties of the Master Servicer.

Section 2.10. Representations and Warranties of the Custodian.

ARTICLE III ADMINISTRATION AND MASTER SERVICING OF MORTGAGE LOANS

Section 3.01. Master Servicing of Mortgage Loans.

Section 3.02. Monitoring of Servicers.

Section 3.03. [Reserved].

Section 3.04. Rights of the Depositor and the Trustee in Respect of the Master Servicer.

Section 3.05. Trustee to Act as Master Servicer.

Section 3.06. Protected Accounts.

Section 3.07. Collection of Mortgage Loan Payments; Collection Account; Distribution Account;

Carryover Reserve Fund; Cap Account; Mezzanine Cap Account; Class P Reserve

Fund.

Section 3.08. Collection of Taxes, Assessments and Similar Items; Escrow Accounts.

Section 3.09. Access to Certain Documentation and Information Regarding the Mortgage Loans.

Section 3.10. Permitted Withdrawals from the Collection Account, the Distribution Account, the

Carryover Reserve Fund, the Cap Account, the Mezzanine Cap Account and the

Class P Reserve Fund.

Section 3.11. Maintenance of Hazard Insurance.

Section 3.12. Presentment of Claims and Collection of Proceeds.

Section 3.13. Maintenance of the Primary Insurance Policies.

Section 3.14. Realization upon Defaulted Mortgage Loans.

Section 3.15. REO Property.

Section 3.16. Due on Sale Clauses; Assumption Agreements.

Section 3.17. Trustee to Cooperate; Release of Mortgage Files.

Section 3.18. Documents, Records and Funds in Possession of the Master Servicer and the

Custodian to Be Held for the Trustee.

Section 3.19. Master Servicing Compensation.

Section 3.20. Access to Certain Documentation.

Section 3.21. Annual Statement as to Compliance.

Section 3.22. Report on Assessment of Compliance and Attestation.

Section 3.23. Errors and Omissions Insurance; Fidelity Bonds.

Section 3.24. Cap Contract.

Section 3.25. Mezzanine Cap Contract.

Section 3.26. Duties of the Credit Risk Manager; Termination.

Section 3.27. Limitation Upon Liability of the Credit Risk Manager.

ARTICLE IV DISTRIBUTIONS AND SERVICING ADVANCES

Section 4.01. Advances.

Section 4.02. Priorities of Distributions on the Certificates.

Section 4.03. [Reserved].

104

Section 4.04. Distribution Date Statements to Certificateholders.

104

Section 4.05. [Reserved].

107

Section 4.06. Supplemental Interest Trust.

107

Section 4.07. Distributions from the Cap Account.

107

Section 4.08. Distributions from the Mezzanine Cap Account.

109

Section 4.09. Determination of MTA

110

Section 4.10. Determination of LIBOR.

110

Section 4.11. Determination of COFI

111

ARTICLE V THE CERTIFICATES

112

Section 5.01. The Certificates.

112

Section 5.02. Certificate Register; Registration of Transfer and Exchange of Certificates.

113

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

119

Section 5.04. Persons Deemed Owners.

119

Section 5.05. Access to List of Certificateholders’ Names and Addresses.

119

Section 5.06. Maintenance of Office or Agency.

120

ARTICLE VI THE DEPOSITOR, THE MASTER SERVICER AND THE CUSTODIAN

120

Section 6.01. Respective Liabilities of the Depositor, the Master Servicer and the Custodian.

120

Section 6.02. Merger or Consolidation of the Depositor, the Master Servicer and the Custodian.

120

Section 6.03. Limitation on Liability of the Depositor, the NIMS Insurer, the Certificate Insurer, the

Transferor, the Master Servicer, the Custodian and Others.

121

Section 6.04. Limitation on Resignation of Master Servicer.

122

Section 6.05. Sale and Assignment of Master Servicing Rights.

122

Section 6.06. Fees of the Custodian.

122

ARTICLE VII DEFAULT

123

Section 7.01. Events of Default.

123

Section 7.02. Trustee to Act; Appointment of Successor.

125

Section 7.03. Notification to Certificateholders.

126

ARTICLE VIII CONCERNING THE TRUSTEE AND THE MASTER SERVICER

126

Section 8.01. Duties of Trustee.

126

Section 8.02. Certain Matters Affecting the Trustee.

128

Section 8.03. Trustee Not Liable for Certificates or Mortgage Loans.

130

Section 8.04. Trustee May Own Certificates.

130

Section 8.05. Trustee’s Fees and Expenses.

130

Section 8.06. Eligibility Requirements for Trustee.

131

Section 8.07. Resignation and Removal of Trustee.

131

Section 8.08. Successor Trustee.

132

Section 8.09. Merger or Consolidation of Trustee.

133

Section 8.10. Appointment of Co-Trustee or Separate Trustee.

133

ARTICLE IX CONCERNING THE TRUST ADMINISTRATOR

134

Section 9.01. Duties of Trust Administrator.

134

Section 9.02. Certain Matters Affecting the Trust Administrator.

135

Section 9.03. Trust Administrator Not Liable for Certificates or Mortgage Loans.

137

Section 9.04. Trust Administrator May Own Certificates.

138

Section 9.05. Trust Administrator’s Fees and Expenses.

138

Section 9.06. Eligibility Requirements for Trust Administrator.

139

Section 9.07. Resignation and Removal of Trust Administrator.

139

Section 9.08. Successor Trust Administrator.

141

Section 9.09. Merger or Consolidation of Trust Administrator.

141

Section 9.10. [Reserved].

142

Section 9.11. Tax Matters.

142

Section 9.12. Periodic Filing.

145

ARTICLE X TERMINATION

152

Section 10.01. Termination upon Liquidation or Purchase of Mortgage Loans

152

Section 10.02. Additional Termination Requirements.

156

ARTICLE XI MISCELLANEOUS PROVISIONS

157

Section 11.01. Amendment.

157

Section 11.02. Recordation of Agreement; Counterparts.

159

Section 11.03. Governing Law.

159

Section 11.04. Intention of Parties.

159

Section 11.05. Notices.

160

Section 11.06. Severability of Provisions.

161

Section 11.07. Assignment.

161

Section 11.08. Limitation on Rights of Certificateholders.

162

Section 11.09. Inspection and Audit Rights.

163

Section 11.10. Certificates Nonassessable and Fully Paid.

163

Section 11.11. Compliance With Regulation AB

163

Section 11.12. Third Party Rights.

163

ARTICLE XII CERTAIN MATTERS REGARDING THE CERTIFICATE INSURER

164

Section 12.01. Exercise of Voting Rights of Holder of the Insured Certificates.

164

Section 12.02. Trustee and Trust Administrator to Act Solely with Consent of Certificate Insurer.

164

Section 12.03. Trust Fund and Accounts Held for Benefit of Certificate Insurer.

164

Section 12.04. Claims Upon the Certificate Insurance Policy; Policy Payments Account.

165

Section 12.05. Effect of Payments by Certificate Insurer; Subrogation.

168

Section 12.06. Trust Administrator to Hold the Certificate Insurance Policy.

169

Section 12.07. Termination of Certain of Certificate Insurer’s Rights.

169

Section 12.08. Survival of Indemnification.

169

SCHEDULES

Schedule I

Mortgage Loan Schedule

Schedule II

Representations and Warranties as to the Mortgage Loans

Schedule III

Cap Contract Schedule

Schedule IV

Mezzanine Cap Contract Schedule

Schedule V

Class P Prepayment Charges Mortgage Loan Schedule

EXHIBITS

Exhibit A:

Form of Senior Certificate

A-1

Exhibit B:

Form of Mezzanine Certificate

B-1

Exhibit C:

Form of Class X Certificate

C-1

Exhibit D-1:

Form of Class C Certificate

D-1-1

Exhibit D-2:

Form of Class P Certificate

D-2-1

Exhibit D-3:

Form of Class R Certificate

D-3-1

Exhibit E-1:

[Reserved]

E-1-1

Exhibit E-2:

[Reserved]

E-2-1

Exhibit F:

Form of Reverse of Certificates

F-1

Exhibit G:

Form of Initial Certification of Custodian

G-1

Exhibit H:

Form of Final Certification of Custodian

H-1

Exhibit I:

Form of Class R Transfer Affidavit

I-1

Exhibit J:

Form of Transferor Certificate

J-1

Exhibit K:

Form of Investment Letter (Non Rule 144A)

K-1

Exhibit L:

Form of Rule 144A Letter

L-1

Exhibit M:

Form of Request for Release of Documents

M-1

Exhibit N:

Form of Sarbanes-Oxley Certification

N-1

Exhibit O:

Form of Cap Contract

O-1

Exhibit P:

Form of Mezzanine Cap Contract

P-1

Exhibit Q:

Form of Assessment of Compliance

Q-1

Exhibit R:

[Reserved]

R-1

Exhibit S:

Additional Disclosure Notification

S-1

Exhibit T:

Additional Form 10-D Disclosure

T-1

Exhibit U:

Additional Form 10-K Disclosure

U-1

Exhibit V:

Form 8-K Disclosure Information

V-1

Exhibit W:

[Reserved]

W-1

Exhibit X:

Assessments of Compliance and Attestation Reports Servicing Criteria

X-1

THIS POOLING AND SERVICING AGREEMENT, dated as of October 1, 2006, among MORTGAGE ASSET SECURITIZATION TRANSACTIONS, INC., a Delaware corporation, as depositor (the “Depositor”), UBS REAL ESTATE SECURITIES INC., a Delaware corporation, as transferor (the “Transferor”), WELLS FARGO BANK, N.A., a national banking association (“Wells Fargo”), as master servicer (in such capacity, the “Master Servicer”), as trust administrator (in such capacity, the “Trust Administrator”) and as custodian (in such capacity, “Custodian”), U.S. BANK NATIONAL ASSOCIATION, a national banking association organized under the laws of the United States, as trustee (in such capacity, the “Trustee”) and CLAYTON FIXED INCOME SERVICES INC., a Colorado corporation, as credit risk manager (the “Credit Risk Manager”).

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

In consideration of the mutual agreements herein contained, the parties hereto agree as follows:

PRELIMINARY STATEMENT

The Depositor is the owner of the Trust Fund that is hereby conveyed to the Trustee in return for the Certificates. The Trust Fund is being conveyed to the Trustee to create a trust for the benefit of the Certificateholders. As provided herein, an election shall be made that the Trust Fund (exclusive of (i) the right to receive and the obligation to pay Net Rate Carryover Amounts to the extent such amounts would result in the payment of interest reflecting an interest rate exceeding the REMIC Maximum Rate, (ii) the Carryover Reserve Fund, (iii) the Cap Contract (iv) the Cap Account, (v) the Mezzanine Cap Contract, (vi) the Mezzanine Cap Account and (vii) the Supplemental Interest Trust (collectively, the “Excluded Trust Assets”)) be treated for federal income tax purposes as comprising four real estate mortgage investment conduits under Section 860D of the Code (each a “REMIC” or, in the alternative the “Subsidiary REMIC,” the “Middle REMIC 1,” the “Middle REMIC 2” and the “Master REMIC”). Any inconsistencies or ambiguities in this Agreement or in the administration of this Agreement shall be resolved in a manner that preserves the validity of such REMIC elections.

Each Certificate, other than the Class R Certificates, represents ownership of a regular interest in the Master REMIC for purposes of the REMIC Provisions. In addition, each Certificate, other than the Class X-1, Class X-2, Class R, Class P and Class C Certificates, represents the right to receive certain payments reflecting an interest rate greater than the REMIC Maximum Rate to the extent provided herein. The Class R Certificate represents ownership of the sole Class of residual interest in each of the Subsidiary REMIC, Middle REMIC 1, Middle REMIC 2 and the Master REMIC for purposes of the REMIC Provisions.

The Master REMIC shall hold as its assets the Class P Reserve Fund and the uncertificated interests in Middle REMIC 2, other than the MT2-R interest, and each such interest is hereby designated as a regular interest in Middle REMIC 2 for purposes of the REMIC Provisions. Middle REMIC 2 shall hold as its assets the uncertificated interests in Middle REMIC 1, other than the MT1-R interest, and each such interest is hereby designated as a regular interest in Middle REMIC 1. Middle REMIC 1 shall hold as its assets the uncertificated interests in the Subsidiary REMIC, other than the LT-R interest, and each such interest is hereby designated as a regular interest in the Subsidiary REMIC. The Subsidiary REMIC shall hold as its assets the property of the Trust Fund other than the interests in the Subsidiary REMIC, Middle REMIC 1 and Middle REMIC 2, and the Excluded Trust Assets.

The startup day for each REMIC created hereby for purposes of the REMIC Provisions is the Closing Date. In addition, for purposes of the REMIC Provisions, the latest possible maturity date for each regular interest in each REMIC created hereby is the Latest Possible Maturity Date.

Subsidiary REMIC:

The following table sets forth the designations, principal balances and interest rates for each interest in the Subsidiary REMIC, each of which (other than the LT-R interest) is hereby designated as a regular interest in the Subsidiary REMIC (the “Subsidiary REMIC Regular Interests”):

Class Designation	Interest Rate	Initial Class Principal Amount	Corresponding Class of Certificate(s)
LT-1A1	(1)	(5)	1-A-1, X-1, XW
LT-1A2	(1)	(5)	1-A-2, X-1, XW
LT-1A3	(1)	(5)	1-A-3, X-1, XW
LT-Group 1	(1)	(6)	N/A
LT-2A1	(2)	(5)	2-A-1, X-2, XW
LT-2A2	(2)	(5)	2-A-2, X-2, XW
LT-2A3	(2)	(5)	2-A-3, X-2, XW
LT-Group 2	(2)	(7)	N/A
LT-3A1	(3)	(5)	3-A-1
LT-3A2	(3)	(5)	3-A-2
LT-Group 3	(3)	(8)	N/A
LT-4A1A	(4)	(5)	4-A-1A
LT-4A1B	(4)	(5)	4-A-1B
LT-4A2	(4)	(5)	4-A-2
LT-Group 4	(4)	(9)	N/A
LT-R	(10)	(10)	N/A

(1)

The interest rate with respect to any Distribution Date (and the related Accrual Period) for each of these Subsidiary REMIC Regular Interests is a per annum rate equal to the Net WAC for Loan Group 1.

(2)

(3)

(4)

(5)

This interest shall have an initial principal balance equal to the Class Principal Balance of its Corresponding Class of Certificates.

(6)

This interest shall have an initial principal balance equal to the excess of (i) the aggregate Principal Balance for Loan Group 1 over (ii) the initial aggregate principal balance of the LT-1A1, LT-1A2 and LT-1A3 Interests.

(7)

This interest shall have an initial principal balance equal to the excess of (i) the aggregate Principal Balance for Loan Group 2 over (ii) the initial principal balance of the LT-2A1, LT-2A2 and LT-2A3 Interests.

(8)

This interest shall have an initial principal balance equal to the excess of (i) the aggregate Principal Balance for Loan Group 3 over (ii) the initial aggregate principal balance of the LT-3A1 and LT-3A2 Interests.

(9)

This interest shall have an initial principal balance equal to the excess of (i) the aggregate Principal Balance for Loan Group 4 over (ii) the initial aggregate principal balance of the LT-4A1A, LT-4A1B and LT-4A2 Interests.

(10)

The LT-R interest is the sole class of residual interests in the Subsidiary REMIC. It does not have an interest rate or a principal balance.

On each Distribution Date, Available Funds shall be distributed in payment of principal and interest on the interests in the Subsidiary REMIC as follows:

(i)

first, concurrently to the LT-1A1, LT-1A2, LT-1A3, LT-2A1, LT-2A2, LT-2A3, LT-3A1, LT-3A2, LT-4A1A, LT-4A1B and LT-4A2 Interests until the principal balance of each such Subsidiary REMIC Regular Interest equals the Class Principal Balance of its Corresponding Class of Certificates immediately after such Distribution Date;

(ii)

second, to the LT-Group 1 Interest until the principal balance of such Subsidiary REMIC Regular Interest equals the Subordinated Portion for Loan Group 1 immediately after such Distribution Date;

(iii)

third, to the LT-Group 2 Interest until the principal balance of such Subsidiary REMIC Interest equals the Subordinated Portion for Loan Group 2 immediately after such Distribution Date;

(iv)

fourth, to the LT-Group 3 Interest until the principal balance of such Subsidiary REMIC Regular Interest the Subordinated Portion for Loan Group 3 immediately after such Distribution Date;

(v)

fifth, to the LT-Group 4 Interest until the principal balance of such Subsidiary REMIC Interest equals the Subordinated Portion for Loan Group 4 immediately after such Distribution Date;

(vi)

sixth, to the Subsidiary REMIC Regular Interests, as distributions of interest at the interest rates shown in the table above, pro rata, based on the amounts of interest accrued on each such interest for the related Accrual Period; and

(vii)

finally, to the LT-R interest, any remaining amounts.

On each Distribution Date, Realized Losses shall be allocated among the Subsidiary REMIC Regular Interests in the same manner that principal is distributed among such Subsidiary REMIC Regular Interests.

On each Distribution Date, the Trust Administrator shall distribute the Class P Prepayment Charges with respect to the Group 1 Loans, Group 2 Loans, Group 3 Loans and Group 4 Loans to the LT-Group 1, LT-Group 2, LT-Group 3 and LT-Group 4 Interests, respectively.

Middle REMIC 1:

The following table sets forth the designations, principal balances and interest rates for each interest in Middle REMIC 1, each of which (other than the MT1-R interest) is hereby designated as a regular interest in Middle REMIC 1 (the “Middle REMIC 1 Regular Interests”):

Class Designation	Interest Rate	Initial Class Principal Amount	Corresponding Class of Certificate(s)
MT1-1A1	(1)	(5)	1-A-1, XW
MT1-1A2	(1)	(5)	1-A-2, XW
MT1-1A3	(1)	(5)	1-A-3, XW
MT1-Group 1	(1)	(6)	N/A
MT1-2A1	(2)	(5)	2-A-1, XW
MT1-2A2	(2)	(5)	2-A-2, XW
MT1-2A3	(2)	(5)	2-A-3, XW
MT1-Group 2	(2)	(7)	N/A
MT1-3A1	(3)	(5)	3-A-1
MT1-3A2	(3)	(5)	3-A-2
MT1-Group 3	(3)	(8)	N/A
MT1-4A1A	(4)	(5)	4-A-1A
MT1-4A1B	(4)	(5)	4-A-1B
MT1-4A2	(4)	(5)	4-A-2
MT1-Group 4	(4)	(9)	N/A
MT1-X1	(10)	(10)	X-1
MT1-X2	(11)	(11)	X-2
MT1-R	(12)	(12)	N/A

(1)

The interest rate with respect to any Distribution Date (and the related Accrual Period) for each of these Middle REMIC 1 Regular Interests is a per annum rate equal to the weighted average of each Subsidiary REMIC Regular Interest relating to Loan Group 1, provided that, for this purpose, each of the LT-1A1, LT-1A2 and LT-1A3 Interests shall be treated as bearing interest at a per annum rate equal to the Net WAC for Loan Group 1 minus 0.90%.

(2)

The interest rate with respect to any Distribution Date (and the related Accrual Period) for each of these Middle REMIC 1 Regular Interests is a per annum rate equal to the weighted average of each Subsidiary REMIC Regular Interest relating to Loan Group 2, provided that, for this purpose, each of the LT-2A1, LT-2A2 and LT-2A3 Interests shall be treated as bearing interest at a per annum rate equal to the Net WAC for Loan Group 2 minus 0.90%.

(3)

(4)

(5)

This interest shall have an initial principal balance equal to the Class Principal Balance of its Corresponding Class of Certificates.

(6)

(7)

This interest shall have an initial principal balance equal to the excess of (i) the aggregate Principal Balance for Loan Group 2 over (ii) the initial principal balance of the MT1-2A1, MT1-2A2 and MT1-2A3 Interests.

(8)

(9)

(10)

The Class MT1-X1 is an interest-only interest and does not have a principal balance. The Class MT1-X1 Interest shall be entitled to receive amounts equal to those distributable on the Class X-1 Certificate.

(11)

The Class MT1-X2 is an interest-only interest and does not have a principal balance. The Class MT1-X2 Interest shall be entitled to receive amounts equal to those distributable on the Class X-2 Certificate.

(12)

The MT1-R interest is the sole class of residual interests in Middle REMIC 1. It does not have an interest rate or a principal balance.

On each Distribution Date, Available Funds shall be distributed in payment of principal and interest on the interests in Middle REMIC 1 as follows:

(i)

first, concurrently to the MT1-1A1, MT1-1A2, MT1-1A3, MT1-2A1, MT1-2A2, MT1-2A3, MT1-3A1, MT1-3A2, MT1-4A1A, MT1-4A1B and MT1-4A2 Interests until the principal balance of each such Middle REMIC 1 Regular Interest equals the Class Principal Balance of its Corresponding Class of Certificates immediately after such Distribution Date;

(ii)

second, to the MT1-Group 1 Interest until the principal balance of such Middle REMIC 1 Regular Interest equals the Subordinated Portion for Loan Group 1 immediately after such Distribution Date;

(iii)

third, to the MT1-Group 2 Interest until the principal balance of such Middle REMIC 1 Interest equals the Subordinated Portion for Loan Group 2 immediately after such Distribution Date;

(iv)

fourth, to the MT1-Group 3 Interest until the principal balance of such Middle REMIC 1 Regular Interest the Subordinated Portion for Loan Group 3 immediately after such Distribution Date;

(v)

fifth, to the MT1-Group 4 Interest until the principal balance of such Middle REMIC 1 Interest equals the Subordinated Portion for Loan Group 4 immediately after such Distribution Date;

(vi)

sixth, to the Middle REMIC 1 Regular Interests, as distributions of interest at the interest rates shown in the table above, pro rata, based on the amounts of interest accrued on each such interest for the related Accrual Period; and

(vii)

finally, to the MT1-R interest, any remaining amounts.

On each Distribution Date, Realized Losses shall be allocated among the Middle REMIC 1 Regular Interests in the same manner that principal is distributed among such Middle REMIC 1 Regular Interests.

On each Distribution Date, the Trust Administrator shall be deemed to have distributed the Class P Prepayment Charges with respect to LT-Group 1, LT-Group 2, LT-Group 3 and LT-Group 4 Interests to the MT1-Group 1, MT1-Group 2, MT1-Group 3 and MT1-Group 4 Interests, respectively.

Middle REMIC 2:

The following table sets forth the designations, principal balances and interest rates for each interest in Middle REMIC 2, each of which (other than the Class MT2-R interest) is hereby designated as a regular interest in Middle REMIC 2 (the “Middle REMIC 2 Regular Interests”):

Designation	Interest Rate	Initial Principal Amount	Corresponding Class of Certificates
MT2-Group 1	(1)	(7)	N/A
MT2-SC1	(1)	(6)	N/A
MT2-Group 2	(2)	(9)	N/A
MT2-SC2	(2)	(8)	N/A
MT2-Group 3	(3)	(11)	N/A
MT2-SC3	(3)	(10)	N/A
MT2-Group 4	(4)	(13)	N/A
MT2-SC4	(4)	(12)	N/A
MT2-1A1	(5)	(14)	1-A-1
MT2-1A2	(5)	(14)	1-A-2
MT2-1A3	(5)	(14)	1-A-3
MT2-2A1	(5)	(14)	2-A-1
MT2-2A2	(5)	(14)	2-A-2
MT2-2A3	(5)	(14)	2-A-3
MT2-3A1	(5)	(14)	3-A-1
MT2-3A2	(5)	(14)	3-A-2
MT2-4A1A	(5)	(14)	4-A-1A
MT2-4A1B	(5)	(14)	4-A-1B
MT2-4A2	(5)	(14)	4-A-2
MT2-M1	(5)	(14)	M1
MT2-M2	(5)	(14)	M2
MT2-M3	(5)	(14)	M3
MT2-M4	(5)	(14)	M4
MT2-M5	(5)	(14)	M5
MT2-M6	(5)	(14)	M6
MT2-M7	(5)	(14)	M7
MT2-M8	(5)	(14)	M8
MT2-Q	(5)	(15)	N/A
MT2-X1	(16)	(16)	X-1
MT2-X2	(17)	(17)	X-2
MT2-XW	(18)	(18)	XW
MT2-R	(19)	(19)	N/A

(1)

The interest rate with respect to any Distribution Date (and the related Accrual Period) for each of these Middle REMIC 2 Regular Interests is a per annum rate equal to the weighted average of each Middle REMIC 1 Regular Interest Relating to Loan Group 1, provided that, for this purpose, each of the MT1-1A1, MT1-1A2 and MT1-1A3 Interests shall be treated as bearing interest at a per annum rate equal to the lesser of (i) MTA plus 1.7716% and (ii) the Net WAC for Loan Group 1 minus 0.90%.

(2)

The interest rate with respect to any Distribution Date (and the related Accrual Period) for each of these Middle REMIC 2 Regular Interests is a per annum rate equal to the weighted average of each Middle REMIC 1 Regular Interest Relating to Loan Group 2, provided that, for this purpose, each of the MT1-2A1, MT1-2A2 and MT1-2A3 Interests shall be treated as bearing interest at a per annum rate equal to the lesser of (i) MTA plus 1.7716% and (ii) the Net WAC for Loan Group 2 minus 0.90%.

(3)

The interest rate with respect to any Distribution Date (and the related Accrual Period) for each of these Middle REMIC 2 Regular Interests is a per annum rate equal to the Net WAC for Loan Group 3.

(4)

The interest rate with respect to any Distribution Date (and the related Accrual Period) for each of these Middle REMIC 2 Regular Interests is a per annum rate equal to the Net WAC for Loan Group 4.

(5)

The interest rate with respect to any Distribution Date (and the related Accrual Period) for each of these Middle REMIC 2 Regular Interests is a per annum rate equal to the weighted average of each Middle REMIC 1 Regular Interest, provided that, for this purpose, each of the MT1-1A1, MT1-1A2 and MT1-1A3 Interests shall be treated as bearing interest at a per annum rate equal to the lesser of (i) MTA plus 1.7716% and (ii) the Net WAC for Loan Group 1 minus 0.90% and each of MT1-2A1, MT1-2A2 and MT1-2A3 shall be treated as bearing interest at a per annum rate equal to the lesser of (i) MTA plus 1.7716% and (ii) the Net WAC for Loan Group 2 minus 0.90%.

(6)

This interest shall have an initial principal balance equal to one percent of the Subordinated Portion for Loan Group 1.

(7)

This interest shall have an initial principal balance equal to the excess of (i) one-half of the aggregate Principal Balance for Loan Group 1 over (ii) the initial aggregate principal balance of the Class MT2-SC1, Class MT2-1A1, Class MT2-1A2 and Class MT2-1A3 Interests.

(8)

This interest shall have an initial principal balance equal to one percent of the Subordinated Portion for Loan Group 2.

(9)

This interest shall have an initial principal balance equal to the excess of (i) one-half of the aggregate Principal Balance for Loan Group 2 over (ii) the initial aggregate principal balance of the Class MT2-SC2, Class MT2-2A1, Class MT2-2A2 and Class MT2-2A3 Interests.

(10)

This interest shall have an initial principal balance equal to one percent of the Subordinated Portion for Loan Group 3.

(11)

This interest shall have an initial principal balance equal to the excess of (i) one-half of the aggregate Principal Balance for Loan Group 3 over (ii) the initial aggregate principal balance of the Class MT2-SC3, Class MT2-3A1 and Class MT2-3A2 Interests.

(12)

This interest shall have an initial principal balance equal to one percent of the Subordinated Portion for Loan Group 4.

(13)

This interest shall have an initial principal balance equal to the excess of (i) one-half of the aggregate Principal Balance for Loan Group 4 over (ii) the initial aggregate principal balance of the Class MT2-SC4, Class MT2-4A1A, Class MT2-4A1B and Class MT2-4A2 Interests.

(14)

This interest shall have an initial principal balance equal to one quarter of the Original Certificate Principal Balance of its Corresponding Class of Certificates.

(15)

This interest shall have an initial principal balance amount equal to the excess of (i) the aggregate Pool Balance as of the Cut-off Date, over (ii) the aggregate initial class principal amount of each other regular interest in Middle REMIC 2.

(16)

The Class MT2-X1 is an interest-only interest and does not have a principal balance. The Class MT2-X1 Interest shall be entitled to receive amounts equal to those distributable on the Class MT1-X1 Interest.

(17)

The Class MT2-X2 is an interest-only interest and does not have a principal balance. The Class MT2-X2 Interest shall be entitled to receive amounts equal to those distributable on the Class MT1-X2 Interest.

(18)

This interest shall be entitled to receive amounts equal to those distributable on the Class XW Certificate.

(19)

The MT2-R Interest is the sole Class of residual interest in Middle REMIC 2. It does not have an interest rate or a principal balance.

On each Distribution Date, interest shall be distributed on the interests in Middle REMIC 2 based on the above-described interest rates, except that interest shall be deferred on the MT2-Q Interest to the extent necessary to make the principal distributions described below .

On each Distribution Date, principal shall be distributed, and Realized Losses shall be allocated, among the interests in Middle REMIC 2 as follows:

(i)

first, to the MT2-SC1 Interest until the principal balance of such Middle REMIC 2 Regular Interest equals one percent of the Subordinated Portion for Loan Group 1 for the next succeeding Distribution Date;

(ii)

second, to the MT2-SC2 Interest until the principal balance of such Middle REMIC 2 Interest equals one percent of the Subordinated Portion for Loan Group 2 for the next succeeding Distribution Date;

(iii)

third, to the MT2-SC3 Interest until the principal balance of such Middle REMIC 2 Regular Interest equals one percent of the Subordinated Portion for Loan Group 3 for the next succeeding Distribution Date;

(iv)

fourth, to the MT2-SC4 Interest until the principal balance of such Middle REMIC 2 Interest equals one percent of the Subordinated Portion for Loan Group 4 for the next succeeding Distribution Date;

(v)

fifth, to the MT2-SC1, MT2-SC2, MT2-SC3, or MT2-SC4 Interest the amount necessary to cause the ratio of the principal balance of each such interest to the principal balance of the remaining three interests to equal the ratio of the Subordinated Portion for the Loan Group related to such interest to the aggregate of the Subordinated Portions for the remaining three Loan Groups for the immediately succeeding Distribution Date;

(vi)

sixth, to the MT2-Group 1, MT2-Group 2, MT2-Group 3, and the MT2-Group 4 Interests concurrently, as follows:

(a)

To the MT2-Group 1 Interest until its principal balance equals the excess, if any, of (I) 50% of the Loan Group Balance for Loan Group 1 for the next Distribution Date, over (II) the aggregate principal balance of the MT2-1A1, MT2-1A2, MT2-1A3, and MT2-SC1 Interests on such Distribution Date, taking into account the distributions under priorities (i) through (v) above;

(b)

To the MT2-Group 2 Interest until its principal balance equals the excess, if any, of (I) 50% of the Loan Group Balance for Loan Group 2 for the next Distribution Date, over (II) the aggregate principal balance of the MT2-2A1, MT2-2A2, MT2-2A3 and MT2-SC2 Interests on such Distribution Date, taking into account the distributions under priorities (i) through (v) above;

(c)

To the MT2-Group 3 Interest until its principal balance equals the excess, if any, of (I) 50% of the Loan Group Balance for Loan Group 3 for the next Distribution Date, over (II) the aggregate principal balance of the MT2-3A1, MT2-3A2, and MT2-SC3 Interests on such Distribution Date, taking into account the distributions under priorities (i) through (v) above;

(d)

To the MT2-Group 4 Interest until its principal balance equals the excess, if any, of (I) 50% of the Loan Group Balance for Loan Group 4 for the next Distribution Date, over (II) the aggregate principal balance of the MT2-4A1A, MT2-4A1B, MT2-4A2 and MT2-SC4 Interests on such Distribution Date, taking into account the distributions under priorities (i) through (v) above;

(vii)

seventh, concurrently to each Middle REMIC 2 Regular Interest with a Corresponding Class of Certificates (other than any interest-only Interest) until the principal balance of each such Middle REMIC 2 Regular Interest equals 25% of the Class Principal Balance of the Corresponding Class of Certificates for immediately after such Distribution Date; and

(viii)

eighth, to the MT2-Q Interest until its principal balance equals the excess, if any, of (I) the aggregate Pool Balance immediately after such Distribution Date over (II) the aggregate of the principal balances of Middle REMIC 2 Regular Interests (other than the MT2-Q Interest or any interest-only Interests) after taking into account distributions on such Distribution Date under priorities (i) through (vii), above.

On each Distribution Date, the Trust Administrator shall be deemed to have distributed the Class P Prepayment Charges with respect to the MT1-Group 1, MT1-Group 2, MT1-Group 3 and MT1-Group 4 Interests to the Class MT2-Q Interest.

Master REMIC

As provided herein, the Trustee shall elect to treat the segregated pool of assets consisting of the Middle REMIC 2 Regular Interests as a REMIC for federal income tax purposes, and such segregated pool of assets shall be designated as the “Master REMIC.” The Master REMIC shall also issue the Class R-IV Interest, which shall evidence the sole class of “residual interests” in the Master REMIC for purposes of the REMIC Provisions under federal income tax law. The following table irrevocably sets forth the designation, the Pass-Through Rate, and the initial aggregate Certificate Principal Balance for the indicated Class of Certificates.

Designation	Pass-Through Rate(16)	Initial Aggregate Certificate Principal Balance	Latest Possible Maturity Date(1)
Class 1-A-1	Variable(2)	$558,331,000	December 25, 2046
Class 1-A-2	Variable(2)	$69,791,000	December 25, 2046
Class 1-A-3	Variable(2)	$69,792,000	December 25, 2046
Class 2-A-1	Variable(2	$361,746,000	December 25, 2046
Class 2-A-2	Variable(2)	$45,218,000	December 25, 2046
Class 2-A-3	Variable(2)	$45,218,000	December 25, 2046
Class 3-A-1	Variable(3)	$92,654,000	December 25, 2046
Class 3-A-2	Variable(3)	$23,164,000	December 25, 2046
Class 4-A-1A	Variable(2)	$244,989,000	December 25, 2046
Class 4-A-1B	Variable(2)	$192,677,000	December 25, 2046
Class 4-A-2	Variable(4)	$109,416,000	December 25, 2046
Class X-1	(5)	(6)	December 25, 2046
Class X-2	(5)	(7)	December 25, 2046
Class XW	(8)	(9)	December 25, 2046
Class M-1	Variable(10)	$46,307,000	December 25, 2046
Class M-2	Variable(10)	$42,279,000	December 25, 2046
Class M-3	Variable(10)	$14,093,000	December 25, 2046
Class M-4	Variable(10)	$31,206,000	December 25, 2046
Class M-5	Variable(10)	$18,120,000	December 25, 2046
Class M-6	Variable(10)	$12,080,000	December 25, 2046
Class M-7	Variable(10)	$11,074,000	December 25, 2046
Class M-8	Variable(10)	$15,099,000	December 25, 2046
Class C	Variable(11)	$10,067,248	December 25, 2046
Class 1-P	N/A(12)	$ 100	December 25, 2046
Class 2-P	N/A(13)	$ 100	December 25, 2046
Class 3-P	N/A(14)	$ 100	December 25, 2046
Class 4-P	N/A(15)	$ 100	December 25, 2046

_______________

(1)

For purposes of Section 1.860G-1(a)(4)(iii) of the Treasury regulations, the Latest Possible Maturity Date has been designated as the “latest possible maturity date” for each Class of Certificates.

(2)

The Pass-Through Rate on any Distribution Date with respect to the Class 1-A-1, Class 1-A-2, Class 1-A-3, Class 2-A-1, Class 2-A-2, Class 2-A-3, Class 4-A-1A and Class 4-A-1B Certificates will be a per annum rate equal to the lesser of (i) One Year MTA for the related Accrual Period plus the related Certificate Margin for that Distribution Date and (ii) the related Net Rate Cap.

(3)

The Pass-Through Rate on any Distribution Date with respect to the Class 3-A-1 and Class 3-A-2 Certificates will be a per annum rate equal to the lesser of (i) COFI for the related Accrual Period plus the related Certificate Margin for that Distribution Date and (ii) the related Net Rate Cap.

(4)

The Pass-Through Rate on any Distribution Date with respect to Class 4-A-2 Certificates will be a per annum rate equal to the lesser of (i) LIBOR for the related Accrual Period plus the related Certificate Margin for that Distribution Date and (ii) the related Net Rate Cap.

(5)

The Pass-Through Rate on any Distribution Date with respect to the Class X-1 and Class X-2 Certificates will be a per annum rate equal to 0.900%.

(6)

The Class X-1 Certificates are Interest Only Certificates, will not be entitled to distributions in respect of principal and will bear interest on the Class X-1 Notional Amount (initially, $697,914,000).

(7)

The Class X-2 Certificates are Interest Only Certificates, will not be entitled to distributions in respect of principal and will bear interest on the Class X-2 Notional Amount (initially, $452,182,00)

(8)

The Pass-Through Rate on any Distribution Date with respect to the Class XW Certificates will be a per annum rate equal to the lesser of (i) the excess, if any of (x) the Aggregate Group 1 and Group 2 Net WAC over (y) the sum of MTA plus 1.7716% and (ii) the related Net Rate Cap.

(9)

The Class XW Certificates are Interest Only Certificates, will not be entitled to distributions in respect of principal and will bear interest on the Class XW Notional Amount (initially, $1,150,096,000).

(10)

The Pass-Through Rate on any Distribution Date with respect to the Class M-1, Class M-2, Class M-3, Class M-4, Class M-5, Class M-6, Class M-7 and Class M-8 Certificates will be a per annum rate equal to the lesser of (i) LIBOR for the related Accrual Period plus the related Certificate Margin for that Distribution Date and (ii) the related Net Rate Cap.

(11)

The Class C Certificates will accrue interest at its variable Pass-Through Rate on the Notional Amount of the Class C Certificates outstanding from time to time. For purposes of the REMIC Provisions, Class C Certificates shall have an initial principal balance of $10,067,248, and the right to receive distributions of such amount represents a regular interest in the Master REMIC. The Class C Certificates shall also comprise a notional component, which represents a regular interest in the Master REMIC. Such component has a notional balance that will at all times equal the aggregate of the Class Principal Amounts of the Middle REMIC 2 Regular Interests, and, for each Distribution Date (and the related Accrual Period) this notional component shall bear interest at a per annum rate equal to the excess, if any, of (i) the weighted average of the interest rates on the Middle REMIC 2 Regular Interests (other than any interest-only regular interest), over (ii) the Adjusted WAC.

(12)

The Class 1-P Certificates will not accrue interest. The Class 1-P Certificates shall be entitled to Class P Prepayment Charges collected with respect to the Group 1 Loans.

(13)

The Class 2-P Certificates will not accrue interest. The Class 2-P Certificates shall be entitled to Class P Prepayment Charges collected with respect to the Group 2 Loans.

(14)

The Class 3-P Certificates will not accrue interest. The Class 3-P Certificates shall be entitled to Class P Prepayment Charges collected with respect to the Group 3 Loans.

(15)

The Class 4-P Certificates will not accrue interest. The Class 4-P Certificates shall be entitled to Class P Prepayment Charges collected with respect to the Group 4 Loans.

(16)

For purposes of the REMIC Provisions, the maximum rate of interest payable on the regular interest evidenced by this Certificate shall not exceed the REMIC Maximum Rate.

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

Set forth below are designations of Classes of Certificates to the categories used herein:

Book-Entry Certificates

All Classes of Offered Certificates.

COFI Certificates

The Group 3 Certificates.

Delay Certificates

The MTA Certificates, COFI Certificates and the Interest Only Certificates.

ERISA-Restricted Certificates

The Offered Certificates (other than the ERISA-Restricted Cap Certificates), any Class of ERISA-Restricted Cap Certificates whose rating has fallen to below AA- or its equivalent upon its acquisition, the Private Certificates, the Residual Certificates and, in general, any Certificates that do not satisfy the applicable ratings requirement under the Underwriter’s Exemption.

ERISA-Restricted Cap

Certificates

The Class 1-A-1, Class 2-A-1, Class 3-A-1, Class 4-A-1A, Class 4-A-1B, Class X-1, Class X-2 and Class XW Certificates

Group 1 Certificates

The Class 1-A-1, Class 1-A-2 and Class 1-A-3 Certificates.

Group 2 Certificates

The Class 2-A-1, Class 2-A-2 and Class 2-A-3 Certificates.

Group 3 Certificates

The Class 3-A-1 and Class 3-A-2 Certificates.

Group 4 Certificates

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

Interest Only Certificates

The Class X-1, Class X-2 and Class XW Certificates.

LIBOR Certificates

The Class 4-A-2 and Mezzanine Certificates.

Mezzanine Certificates

The Class M-1, Class M-2, Class M-3, Class M-4, Class M-5, Class M-6, Class M-7 and Class M-8 Certificates.

MTA Certificates

The Group 1, Group 2, Class 4-A-1A and Class 4-A-1B Certificates.

No Delay Certificates

The LIBOR Certificates.

Offered Certificates

The Senior Certificates and Mezzanine Certificates, except for the Class M-8 Certificates.

Physical Certificates

The Class C Certificates, Class P Certificates and Residual Certificates.

Class P Certificates

The Class 1-P, Class 2-P, Class 3-P and Class 4-P Certificates.

Private Certificates

The Class P Certificates, Class M-8 and Class C Certificates.

Rating Agencies

Moody’s, S&P and Fitch.

Regular Certificates

All Classes of Certificates, other than the Residual Certificates.

Residual Certificates

The Class R Certificates.

Senior Certificates

The Group 1, Group 2, Group 3, Group 4 and Interest Only Certificates.

Subordinate Certificates

The Mezzanine Certificates and the Class C Certificates.

Defined terms and provisions herein relating to statistical rating agencies not designated above as Rating Agencies shall be of no force or effect.

ARTICLE I

DEFINITIONS

Section 1.01. Definitions.

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

10-K Filing Deadline : As defined in Section 9.12.

Account Property : All amounts and investments held from time to time in a Securities Account (whether in the form of deposit accounts, physical property, book-entry securities, uncertificated securities, securities entitlements, investment property or otherwise), and all proceeds of the foregoing.

Accountant’s Attestation : As defined in Section 3.22(b)(i).

Accrual Period : With respect to any Distribution Date and the Delay Certificates, the calendar month preceding the month in which such Distribution Date occurs (calculated on a 30/360 day basis). With respect to the first Distribution Date and the No Delay Certificates, the period from the Closing Date to (but excluding) November 27, 2006 (calculated on an actual/360 day basis). With respect to each Distribution Date thereafter and the No Delay Certificates, from the prior Distribution Date to (but excluding) the current Distribution Date (calculated on an actual/360 day basis).

Additional Disclosure Notification : As set forth in Exhibit S.

Additional Form 10-D Disclosure : As defined in Section 9.12(a)(1).

Additional Form 10-K Disclosure : As defined in Section 9.12(b)(i).

Adjusted WAC : For any Distribution Date (and the related Accrual Period), an amount equal to (i) four, multiplied by (ii) the weighted average of the interest rates for such Distribution Date for the Middle REMIC 2 Regular Interests (other than any interest only regular interest), weighted in proportion to their class principal amounts as of the beginning of the related Accrual Period and computed by subjecting the rate on each Middle REMIC 2 Regular Interest that does not correspond to a Class of Certificates to a cap of 0.00%, and by subjecting the rate on each remaining such Middle REMIC 2 Regular Interest to a cap that corresponds to the Pass-Through Rate (determined without regard to the Available Funds Rate Cap) for the Corresponding Class of Certificates, provided, however , that for each Class of No Delay Certificates, the Pass-Through Rate shall be multiplied by an amount equal to (a) the actual number of days in the Accrual Period, divided by (b) 30.

Adjustment Date : As to each Mortgage Loan, the date on which the Mortgage Rate is adjusted in accordance with the terms of the related Mortgage Note and Mortgage.

Advance : An advance of principal or interest required to be made by the applicable Servicer pursuant to the related Servicing Agreement or required to be made by the Master Servicer with respect to any Distribution Date pursuant to Section 4.01.

Affiliate : When used with reference to a specified Person, another Person that (i) directly or indirectly controls or is controlled by or is under common control with the specified Person, (ii) is an officer of, partner in or trustee of, or serves in a similar capacity with respect to, the specified Person or of which the specified Person is an officer, partner or trustee, or with respect to which the specified Person serves in a similar capacity, or (iii) directly or indirectly is the beneficial owner of 10% or more of any class of equity securities of the specified Person or of which the specified Person is directly or indirectly the owner of 10% or more of any class of equity securities.

Agreement : This Pooling and Servicing Agreement and all amendments or supplements hereto.

Aggregate Certificate Insurer Reimbursement Amount : With respect to any Distribution Date, the sum of the Class 1-A-3 Certificate Insurer Reimbursement Amount, the Class 2-A-3 Certificate Insurer Reimbursement Amount and the Class 4-A-2 Certificate Insurer Reimbursement Amount.

Aggregate Group 1 and Group 2 Net WAC : With respect to any Distribution Date and Group 1 Loans and Group 2 Loans, the weighted average of the Net Mortgage Rate of each Group 1 Loan and Group 2 Loan weighted on the basis of its Stated Principal Balance as of the Due Date occurring in the month preceding the month of that Distribution Date (after giving effect to Principal Prepayments in the Prepayment Period related to that prior Due Date).

AHM : American Home Mortgage Servicing, Inc., and its successors and assigns, in its capacity as Servicer of the AHM Mortgage Loans.

AHM Mortgage Loans : The Mortgage Loans for which AHM is listed as “Servicer” on the Mortgage Loan Schedule.

AHM Servicing Agreement : Solely with respect to the AHM Mortgage Loans, the Master Loan Purchase and Servicing Agreement, dated as of December 1, 2005, among the Transferor, as initial purchaser, AHM, as seller, and American Home Mortgage Servicing, Inc., as servicer, as the same may be amended from time to time, and any assignments and conveyances related to the AHM Mortgage Loans.

Amount Held for Future Distribution : As to any related Distribution Date and any Mortgage Loan, the aggregate amount held in the Collection Account at the close of business on the related Servicer Remittance Date with respect to such Mortgage Loan at the close of business on the related Servicer Remittance Date on account of (i) Principal Prepayments received after the related Prepayment Period and Liquidation Proceeds and Insurance Proceeds received in the month of such Distribution Date and (ii) all Scheduled Payments due after the related Due Date.

Annual Statement of Compliance : As defined in Section 3.21(a).

Applied Realized Loss Amount: With respect to any Distribution Date, the amount, if any, by which the aggregate Class Principal Balance of all Classes of Certificates (other than the Interest Only Certificates and after all distributions of principal on such Distribution Date) exceeds the aggregate Stated Principal Balance of the Mortgage Loans as of the Due Date in the month of such Distribution Date.

Appraised Value : With respect to any Mortgage Loan, the Appraised Value of the related Mortgaged Property shall be: (i) with respect to a Mortgage Loan other than a Refinancing Mortgage Loan, the lesser of (a) the value of the Mortgaged Property based upon the appraisal made at the time of the origination of such Mortgage Loan and (b) the sales price of the Mortgaged Property at the time of the origination of such Mortgage Loan; and (ii) with respect to a Refinancing Mortgage Loan, the value of the Mortgaged Property based upon the appraisal made at the time of the origination of such Refinancing Mortgage Loan as modified by an updated appraisal.

Assessment of Compliance : As defined in Section 3.22(i)(a).

Assignment : An individual assignment of a Mortgage, notice of transfer or equivalent instrument in recordable form, sufficient under the laws of the jurisdiction wherein the related Mortgaged Property is located to reflect of record the sale or transfer of the Mortgage Loan.

Assignment Agreements : The following Assignment, Assumption and Recognition Agreements, each dated as of November 15, 2006, whereby certain Servicing Agreements solely with respect to the related Mortgage Loans were assigned to the Depositor for the benefit of the Certificateholders:

(a)

The Assignment, Assumption and Recognition Agreement among AHM, as company, American Home Mortgage Servicing, Inc., as servicer, the Transferor and the Depositor;

(b)

The Assignment, Assumption and Recognition Agreement among Countrywide, as company, Countrywide Home Loans Servicing LP, the Trustee, the Transferor and the Depositor;

(c)

The Assignment, Assumption and Recognition Agreement among IndyMac, as company, the Transferor and the Depositor;

(d)

The Assignment, Assumption and Recognition Agreement among GMACM, as company, the Transferor and the Depositor; and

(e)

The Assignment, Assumption and Recognition Agreement among RFC, as company, the Transferor and the Depositor.

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

Auction Initiator : The Class C Certificateholder; provided, that if the Class C Certificateholder has not exercised its rights to initiate an auction under Section 10.01 on any date on which the Class C Certificateholder is entitled to do so, and the Master Servicer has not exercised its termination rights under Section 10.01 on any date on which the Master Servicer is entitled to do so, the Auction Initiator shall be the Certificate Insurer.

Auction Date : As defined in Section 10.01.

Auction Purchaser : As defined in Section 10.01.

Auction Sale Price : As defined in Section 10.01.

Available Funds : As to any Distribution Date and any Loan Group, the sum of (a) the Interest Funds for that Loan Group and Distribution Date and (b) the Principal Funds for that Loan Group and Distribution Date.

Available Funds Rate Cap : For any Distribution Date and the following Classes of Certificates is:

(a)

with respect to the Senior Certificates (other than the Interest Only Certificates) and the Mezzanine Certificates, the product of:

(i)

the excess of:

(1)

the Available Funds for all Loan Groups for that Distribution Date, over

(2)

the Current Interest for the Class X-1, Class X-2 and Class XW Certificates for that Distribution Date, and

(ii)

a fraction, the numerator of which is 12 and the denominator of which is the aggregate Stated Principal Balance of the Loans in all Loan Groups as of the Due Date occurring in the month preceding the month of that Distribution Date (after giving effect to principal prepayments in the Prepayment Period related to that prior Due Date), and

(b)

with respect to the Class XW Certificates, the product of:

(i)

the sum of the Available Funds for Loan Group 1 and Loan Group 2, and

(ii)

a fraction, the numerator of which is 12 and the denominator of which is the aggregate Stated Principal Balance of the Group 1 Loans and the Group 2 Loans as of the Due Date occurring in the month preceding the month of that Distribution Date (after giving effect to principal prepayments in the Prepayment Period related to that prior Due Date).

Bankruptcy Code : The United States Bankruptcy Reform Act of 1978, as amended.

Basic Principal Distribution Amount : With respect to each Distribution Date, the lesser of:

(a)

the aggregate Class Principal Balance of the Senior and Mezzanine Certificates (other than the Interest Only Certificates) immediately prior to such Distribution Date, and

(b)

the excess, if any, of (a) the Principal Funds for such Distribution Date over (b) the Overcollateralization Release Amount for such Distribution Date.

Book-Entry Certificates : As specified in the Preliminary Statement.

Business Day : Any day other than (i) a Saturday or a Sunday or (ii) a day on which banking institutions in the City of New York, New York, Minnesota, Maryland, or any city in which the Corporate Trust Office of the Trustee or Trust Administrator is located are authorized or obligated by law or executive order to be closed.

Cap Account : A segregated trust account established and maintained by the Trust Administrator pursuant to 3.07(i) of this agreement in which payments received from the Cap Provider will be deposited.

Cap Contract : The cap contract between the Cap Provider and the Supplemental Interest Trust Trustee relating to the Certificates in the form attached hereto as Exhibit O.

Cap Contract Termination Date: The Distribution Date in October 2013.

Cap Provider : Swiss Re Financial Products Corporation

Carryover Reserve Fund : The account established and maintained by the Trust Administrator pursuant to Section 3.07(h).

Cenlar : Cenlar, FSB, and its successors and assigns, in its capacity as Servicer of the Cenlar Mortgage Loans.

Cenlar Serviced Mortgage Loans : The Mortgage Loans for which Cenlar is listed as “Servicer” on the Mortgage Loan Schedule.

Cenlar Servicing Agreement : Solely with respect to the Cenlar Serviced Mortgage Loans, the Servicing Agreement, dated as of January 1, 2006 by and among the Master Servicer, UBS Real Estate Securities Inc., as seller, and Cenlar, as servicer, as the same may be amended from time to time.

Certificate : Any one of the Certificates executed by the Trust Administrator on behalf of the Trust and authenticated by the Trust Administrator in substantially the forms attached hereto as Exhibits A through F.

Certificate Factor : With respect to any Class of Regular Certificates as of any Distribution Date, a fraction, expressed as a decimal carried to at least six places, the numerator of which is the aggregate Certificate Principal Balance (or the Notional Amount, in the case of the Class C 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 C 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 C Certificates) of such Class of Certificates as of the Closing Date.

Certificate Group : The Group 1 Certificates, Group 2 Certificates, Group 3 Certificates and Group 4 Certificates, as applicable.

Certificate Insurance Policy : The Financial Guaranty Insurance Policy No. 51776-N issued by the Certificate Insurer in respect of the Insured Certificates, including any endorsements thereto.

Certificate Insurer : Financial Security Assurance Inc., a New York stock insurance company, and its successors in interest.

Certificate Insurer Default : As defined in Section 12.04(j)

Certificate Insurer Fee Rate : 0.065% per annum.

Certificate Margin : The certificate margin with respect to each Class of LIBOR Certificates, MTA Certificates and COFI Certificates will be as set forth below:

	Margin
Class	(1)	(2)
1-A-1	0.800%	0.800%
1-A-2	0.800%	0.800%
1-A-3	0.730%	0.730%
2-A-1	0.800%	0.800%
2-A-2	0.800%	0.800%
2-A-3	0.730%	0.730%
3-A-1	1.500%	1.500%
3-A-2	1.500%	1.500%
4-A-1A	0.850%	0.850%
4-A-1B	1.200%	1.200%
4-A-2	0.190%	0.380%
M-1	0.400%	0.600%
M-2	0.420%	0.630%
M-3	0.440%	0.660%
M-4	0.650%	0.975%
M-5	1.250%	1.875%
M-6	2.600%	3.900%
M-7	6.500%	9.750%
M-8	8.500%	12.750%

(1)

For each Distribution Date through and including the Optional Termination Date.

(2)

For each Distribution Date after the Optional Termination Date.

Certificate Owner : With respect to a Book-Entry Certificate, the Person who is the beneficial owner of such Book-Entry Certificate.

Certificate Principal Balance : With respect to any Certificate (other than the Interest Only Certificates and Class C Certificates) at any date, the maximum dollar amount of principal to which the Holder thereof is then entitled under this Agreement, such amount being equal to the Denomination of that Certificate (A) plus any increase to the Certificate Principal Balance of such Certificate pursuant to Section 4.02 due to the receipt of Subsequent Recoveries and (B) minus the sum of (i) all distributions of principal previously made with respect to that Certificate; provided , however , that solely for purposes of determining the Premium Distribution Amount payable to the Certificate Insurer and the Certificate Insurer’s rights as subrogee to the Holders of the Insured Certificates, the Certificate Principal Balance of any Insured Certificate shall be deemed not to be reduced by any principal amounts paid to the Holder thereof from payments made by the Certificate Insurer under the Certificate Insurance Policy, unless such amounts have been reimbursed to the Certificate Insurer pursuant to Section 4.02, and (ii) any Applied Realized Loss Amounts allocated to such Certificate on previous Distribution Dates pursuant to Section 4.02(c) without duplication; provided , however , that to the extent that any Realized Loss was paid under the Certificate Insurance Policy, any Subsequent Recoveries payable to the Class 1-A-3, Class 2-A-3 and Class 4-A-2 Certificates shall be payable to the Certificate Insurer. With respect to each Class C 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 Balance of the Middle REMIC 2 Regular Interests over (B) the then aggregate Certificate Principal Balance of the Senior Certificates and the Mezzanine Certificates then outstanding.

Certificate Register : The register maintained pursuant to Section 5.02 hereof.

Certificateholder or Holder : The person in whose name a Certificate is registered in the Certificate Register, except that, solely for the purpose of giving any consent pursuant to this Agreement, any Certificate registered in the name of the Master Servicer or the Depositor or any affiliate of the Master Servicer or the Depositor, as applicable, shall be deemed not to be Outstanding and the Percentage Interest evidenced thereby shall not be taken into account in determining whether the requisite amount of Percentage Interests necessary to effect such consent has been obtained; provided , however , that if any such Person (including the Master Servicer or the Depositor) owns 100% of the Percentage Interests evidenced by a Class of Certificates, such Certificates shall be deemed to be Outstanding for purposes of any provision hereof that requires the consent of the Holders of Certificates of a particular Class as a condition to the taking of any action hereunder. The Trust Administrator is entitled to rely conclusively on a certification of the Master Servicer or the Depositor or any affiliate of the Master Servicer or the Depositor, as applicable, in determining which Certificates are registered in the name of an affiliate of the Master Servicer or the Depositor.

Certification : As specified in Section 9.12(d).

Certification Parties : As defined in Section 9.12.

Certifying Person : As defined in Section 9.12.

Class : All Certificates bearing the same class designation as set forth in the Preliminary Statement.

Class 1-A-3 Certificate Insurer Reimbursement Amount : With respect to any Distribution Date, any amount owing to the Certificate Insurer under Section 4.02 or 4.07 for reimbursement, with interest, for claims paid with respect to the Class 1-A-3 Certificates under the Certificate Insurance Policy and any amounts with respect to the Class 1-A-3 Certificates owing to the Certificate Insurer and remaining unpaid for such Distribution Date.

Class 2-A-3 Certificate Insurer Reimbursement Amount : With respect to any Distribution Date, any amount owing to the Certificate Insurer under Section 4.02 or 4.07 for reimbursement, with interest, for claims paid with respect to the Class 2-A-3 Certificates under the Certificate Insurance Policy and any amounts with respect to the Class 2-A-3 Certificates owing to the Certificate Insurer and remaining unpaid for such Distribution Date.

Class 4-A-2 Certificate Insurer Reimbursement Amount : With respect to any Distribution Date, any amount owing to the Certificate Insurer under Section 4.02 or 4.07 for reimbursement, with interest, for claims paid with respect to the Class 4-A-2 Certificates under the Certificate Insurance Policy and any amounts with respect to the Class 4-A-2 Certificates owing to the Certificate Insurer and remaining unpaid for such Distribution Date.

Class C Certificate : Any one of the Class C Certificates executed, authenticated and delivered by the Trust Administrator, substantially in the form annexed hereto as Exhibit D-1

Class P Certificate : Any one of the Class P Certificates executed, authenticated and delivered by the Trust Administrator, substantially in the form annexed hereto as Exhibit D-2.

Class P Prepayment Charges : Any prepayment premium, penalty or charge to which the Trust is entitled with respect to the Mortgage Loans identified on Schedule V attached hereto.

Class P Reserve Fund : The account established and maintained by the Trust Administrator pursuant to Section 3.07(k).

Class Principal Balance : With respect to any Class of Certificates (other than the Interest Only Certificates) and as to any date of determination, the aggregate of the Certificate Principal Balances of all Certificates of such Class as of such date. The Interest Only Certificates do not have Class Principal Balances.

Clearstream : Clearstream Banking Luxembourg, formerly known as Cedelbank SA.

Closing Date : November 15, 2006.

Code : The Internal Revenue Code of 1986, including any successor or amendatory provisions.

COFI : As to any Distribution Date, the weighted average cost of funds of depository institutions, headquartered in Arizona, California or Nevada and members of the Eleventh District of the Federal Home Loan Bank System, as computed from statistics tabulated and published by the FHLB of San Francisco, as determined by the Trust Administrator in accordance with Section 4.11.

COFI Determination Date : As to any Distribution Date, other than the first Distribution Date, and any Class of COFI Certificates, the fifteenth calendar day prior to the beginning of the applicable Accrual Period for such Class and such Distribution Date.

Collection Account : The separate Eligible Account or Accounts created and maintained by the Master Servicer pursuant to Section 3.07 with a depository institution in the name of the Master Servicer for the benefit of the Trustee on behalf of Certificateholders and designated “Wells Fargo Bank, N.A., for the benefit of U.S. Bank National Association, in trust for the registered Holders of MASTR Adjustable Rate Mortgages Trust 2006-OA2, Mortgage Pass-Through Certificates, Series 2006-OA2.” The Collection Account may be deemed to be a sub-account of the Distribution Account.

Commission : The U.S. Securities and Exchange Commission.

Compensating Interest : With respect to any Distribution Date and any Servicer, the amount required to be paid by such Servicer under the related Servicing Agreement in connection with Prepayment Interest Shortfalls that occur on Mortgage Loans serviced by such Servicer for the related Distribution Date.

Control Person : As defined in Section 8.05.

Cooperative Corporation : With respect to any Cooperative Mortgage Loan, the cooperative apartment corporation that holds legal title to the related Cooperative Property and grants occupancy rights to units therein to stockholders through Proprietary Leases or similar arrangements.

Cooperative Lien Search : A search for (a) federal tax liens, mechanics’ liens, lis pendens, judgments of record or otherwise against (i) the Cooperative Corporation and (ii) the seller of the Cooperative Unit, (b) filings of Financing Statements and (c) the deed of the Cooperative Property into the Cooperative Corporation.

Cooperative Mortgage Loan : A Mortgage Loan that is secured by a second lien on and a perfected security interest in Cooperative Shares and the related Proprietary Lease granting exclusive rights to occupy the related Cooperative Unit in the building owned by the related Cooperative Corporation.

Cooperative Property : With respect to any Cooperative Mortgage Loan, all real property and improvements thereto and rights therein and thereto owned by a Cooperative Corporation including without limitation the land, separate dwelling units and all common elements.

Cooperative Shares : With respect to any Cooperative Mortgage Loan, the shares of stock issued by a Cooperative Corporation and allocated to a Cooperative Unit and represented by stock certificates.

Cooperative Unit : With respect to any Cooperative Mortgage Loan, a specific unit in a Cooperative Property.

Corporate Trust Office : With respect to the Trustee, the designated office of the Trustee at which at any particular time its corporate trust business with respect to this Agreement shall be administered, which office at the date of execution of this Agreement is located at EP-MN-WS3D, 60 Livingston Avenue, St. Paul, Minnesota 55107, Attention: Structured Finance—MASTR Adjustable Rate Mortgages Trust 2006-OA2, which is the address to which appropriate notices to and correspondence with the Trustee should be directed

With respect to the Trust Administrator, the designated office of the Trust Administrator at which at any particular time its corporate trust business with respect to this Agreement shall be administered, which office at the date of execution of this Agreement is located for certificate transfer purposes at Wells Fargo Center, Sixth Street and Marquette Avenue, Minneapolis, Minnesota 55479, Attention: Corporate Trust Services—MARM 2006-OA2, and for all other purposes at 9062 Old Annapolis Road, Columbia Maryland 21045, Attention: Corporate Trust Services—MARM 2006-OA2.

Corresponding Class: With respect to any interest in Middle REMIC 1 or Middle REMIC 2, the Corresponding Class of Certificates identified in the table for Middle REMIC 1 or Middle REMIC 2, as applicable, in the Preliminary Statement.

Countrywide : Countrywide Home Loans, Inc., and its successors and assigns.

Countrywide Mortgage Loans : The Mortgage Loans for which Countrywide Home Loans Servicing L.P. is listed as “Servicer” on the Mortgage Loan Schedule.

Countrywide Servicing Agreement : Solely with respect to the Countrywide Serviced Mortgage Loans, the Mortgage Loan Purchase and Servicing Agreement, dated as of November 1, 2001, between the Transferor, as purchaser, and Countrywide Home Loans, Inc., as seller and as servicer, as amended by Amendment Reg AB, dated as of March 1, 2006, and any other related amendments thereto, and any assignments and conveyances related to the Countrywide Mortgage Loans (as modified pursuant to the related Assignment Agreement).

Covered Mortgage Loan : A Mortgage Loan categorized as Covered pursuant to Appendix E of Standard & Poor’s Glossary.

Credit Risk Management Agreement : Each agreement between the Credit Risk Manager and the Servicers and the Credit Risk Manager and the Master Servicer, dated as of November 15, 2006.

Credit Risk Manager : Clayton Fixed Income Services Inc., a Colorado corporation, formerly known as The Murrayhill Company.

Credit Risk Manager Fee : For any Distribution Date, an amount equal to one-twelfth of the Credit Risk Manager Fee Rate (without regard to the words “per annum” in the definition thereof) multiplied by the Scheduled Principal Balance of the Mortgage Loans as of the first Business Day of the month in which the Distribution Date occurs.

Credit Risk Manager Fee Rate : 0.009% per annum.

Cumulative Loss Trigger Event : A Cumulative Loss Trigger Event is in effect with respect to a Distribution Date on or after the Stepdown Date if the aggregate amount of Realized Losses on the Mortgage Loans from (and including) the Cut-off Date for each such Mortgage Loan to (and including) the related Due Date (reduced by the aggregate amount of Subsequent Recoveries received from the Cut-off Date through the Prepayment Period related to that Due Date) exceeds the applicable percentage, for such Distribution Date, of the aggregate Stated Principal Balance of the Mortgage Loans as of the Cut-off Date, as set forth below:

Distribution Date	Percentage
November 2008 – October 2009	0.15% with respect to November 2008, plus an additional 1/12 ^th of 0.20% for each month thereafter through October 2009.
November 2009 – October 2010	0.35% with respect to November 2009, plus an additional 1/12 ^th of 0.30% for each month thereafter through October 2010.
November 2010 – October 2011	0.65% with respect to November 2010, plus an additional 1/12 ^th of 0.25% for each month thereafter through October 2011.
November 2011 – October 2012	0.90% with respect to November 2011, plus an additional 1/12 ^th of 0.35% for each month thereafter through October 2012.
November 2012 – October 2013	1.25% with respect to November 2012, plus an additional 1/12 ^th of 0.10% for each month thereafter through October 2013.
November 2013 and thereafter	1.35%.

Current Interest : With respect to each Class of Offered Certificates and each Distribution Date, the interest accrued at the applicable Pass-Through Rate for the applicable Accrual Period on the Class Principal Balance of such Class immediately prior to such Distribution Date, reduced by any Prepayment Interest Shortfalls not covered by Compensating Interest Payments and Relief Act Reductions (allocated to each such Certificate based on its respective entitlements to interest irrespective of any Prepayment Interest Shortfalls and Relief Act Reductions for such Distribution Date).

Custodian : Wells Fargo, in its capacity as custodian hereunder, and its successor and assigns or any successor Custodian hereunder.

Cut-off Date : October 1, 2006.

Cut-off Date Principal Balance : The aggregate Principal Balance of the Mortgage Loans as of the close of business on the Cut-off Date, which amount is equal to $2,013,321,248.

Deferred Interest : With respect to each Mortgage Loan and each related Due Date, the excess, if any, of the amount of interest accrued on such Mortgage Loan from the preceding Due Date to such Due Date over the monthly payment due for such Due Date.

Deficient Valuation : With respect to any Mortgage Loan, a valuation by a court of competent jurisdiction of the Mortgaged Property in an amount less than the then outstanding indebtedness under the Mortgage Loan, or any reduction in the amount of principal to be paid in connection with any Scheduled Payment that results in a permanent forgiveness of principal, which valuation or reduction results from an order of such court which is final and non-appealable in a proceeding under the Bankruptcy Code.

Definitive Certificates : Any Physical Certificate issued pursuant to Section 5.02(e).

Delay Certificates : As specified in the Preliminary Statement.

Deleted Mortgage Loan : Any Mortgage Loan that is replaced or required to be replaced pursuant to Section 2.02 or 2.03.

Delinquency Trigger Event : A Delinquency Trigger Event is in effect with respect to a Distribution Date on or after the Stepdown Date if the Rolling Sixty Day Delinquency Rate for the outstanding Loans equals or exceeds the product of (i) 28.15% and the Senior Enhancement Percentage for any Distribution Date prior to the Distribution Date in November 2011 and (ii) 35.15% and the Senior Enhancement Percentage for any Distribution Date on or after the Distribution Date in November 2011.

Delinquent : With respect to any Mortgage Loan, means that any monthly payment with respect to such Mortgage Loan that is due on a Due Date is not made by the close of business on the next scheduled Due Date for such Mortgage Loan. A Mortgage Loan is “30 days Delinquent” if such monthly payment has not been received by the close of business on the corresponding day of the month immediately succeeding the month in which such monthly payment was due or, if there was no such corresponding day (e.g., as when a 30-day month follows a 31-day month in which a payment was due on the 31st day of such month), then on the last day of such immediately succeeding month; and similarly for “60 days Delinquent” and “90 days Delinquent,” etc. (in each case, 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).

Denomination : With respect to each Certificate, the amount set forth on the face thereof as the “Initial Certificate Principal Balance of this Certificate” or the “Initial Notional Amount of this Certificate” or, if neither of the foregoing, the Percentage Interest appearing on the face thereof.

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

Depository : The initial Depository shall be The Depository Trust Company, the nominee of which is CEDE & Co., as the registered Holder of the Book-Entry Certificates. The Depository shall at all times be a “clearing corporation” as defined in Section 8-102(a)(5) of the Uniform Commercial Code of the State of New York.

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 : The date on which a Servicer is required to determine the amount it is required to advance pursuant to the applicable Servicing Agreement.

Distribution Account : The separate Eligible Account created and maintained by the Trust Administrator pursuant to Section 3.07 in the name of the Trustee for the benefit of the Certificateholders and the Certificate Insurer and designated “U.S. Bank National Association in trust for registered holders of MASTR Adjustable Rate Mortgages Trust 2006-OA2, Mortgage Pass-Through Certificates, Series 2006-OA2.” Funds in the Distribution Account shall be held in trust for the Certificateholders and the Certificate Insurer for the uses and purposes set forth in this Agreement.

Distribution Account Deposit Date : As to any Distribution Date, one Business Day prior to such Distribution Date.

Distribution Date : The first Distribution Date shall be November 27, 2006. Commencing in December 2006, the Distribution Date shall be the 25th day of each calendar month after the initial issuance of the Certificates, or if such 25th day is not a Business Day, the next succeeding Business Day.

Distribution Date Statement : The statement delivered to the Certificateholders pursuant to Section 4.04.

DTC : The Depository Trust Company.

Due Date : With respect to each Mortgage Loan, the date on which the Scheduled Payment is due each month.

Due Period : With respect to each Distribution Date, the period commencing on the second day of the month preceding the month of the Distribution Date and ending on the first day of the month of the Distribution Date.

Eligible Account : Either (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 debt obligations of such holding company) have the highest short term ratings of each of S&P, Moody’s and Fitch at the time any amounts are held on deposit therein, or (ii) an account or accounts in a depository institution or trust company in which such accounts are insured by the FDIC (to the limits established by the FDIC) and the uninsured deposits in which accounts are otherwise secured such that, as evidenced by an Opinion of Counsel delivered to the Trust Administrator, the Certificate Insurer and the NIMS Insurer, the Trust Administrator, the Certificate Insurer and the NIMS Insurer have a claim with respect to the funds in such account that is superior to claims of any other depositors or creditors of the depository institution or trust company in which such account is maintained (provided that the ratings of the Rating Agencies with respect to the Certificates shall not be downgraded or withdrawn) or (iii) a segregated trust account or accounts maintained with the corporate trust department of a federal depository institution or state-chartered depository institution subject to regulations regarding fiduciary funds on deposit similar to Title 12 of the U.S. Code of Federal Regulation Section 9.10(b), which, in either case, has corporate trust powers and is acting in its fiduciary capacity. Eligible Accounts may bear interest and may include, if otherwise qualified under this definition, accounts maintained by the Trust Administrator.

Eligible Substitute Mortgage Loan : With respect to a Mortgage Loan substituted by the Transferor for a Deleted Mortgage Loan, a Mortgage Loan which must, on the date of such substitution, (i) have a Principal Balance, (or, in the case of a substitution of more than one mortgage loan for a Deleted Mortgage Loan, an aggregate Principal Balance), not in excess of, and not more than 10% less than the Principal Balance of the Deleted Mortgage Loan; (ii) be accruing interest at a rate no lower than and not more than 1% per annum higher than, that of the Deleted Mortgage Loan; (iii) have a Loan-to-Value Ratio no higher than that of the Deleted Mortgage Loan; (iv) have a remaining term to maturity no greater than (and not more than one year less than that of) the Deleted Mortgage Loan; (v) comply with each representation and warranty set forth in Section 2.03 hereof; (vi) be the same credit grade category as the Deleted Mortgage Loan; (vii) have the same prepayment penalty term; and (viii) not be a Cooperative Mortgage Loan unless the Deleted Mortgage Loan was a Cooperative Mortgage Loan.

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

ERISA Qualifying Underwriting : A best efforts or firm commitment underwriting or private placement that meets the requirements (without regard to the ratings requirements) of an Underwriter’s Exemption.

ERISA-Restricted Certificate : As specified in the Preliminary Statement.

Euroclear: The Euroclear System.

Excess Proceeds : With respect to any Liquidated Mortgage Loan, the amount, if any, by which the sum of any Liquidation Proceeds of such Mortgage Loan received in the calendar month in which such Mortgage Loan became a Liquidated Mortgage Loan, exceeds (i) the Principal Balance of such Liquidated Mortgage Loan as of the Due Date in the month in which such Mortgage Loan became a Liquidated Mortgage Loan plus (ii) accrued interest at the Mortgage Rate from the Due Date as to which interest was last paid or advanced (and not reimbursed) to Certificateholders up to the Due Date applicable to the Distribution Date immediately following the calendar month during which such liquidation occurred.

Exchange Act : The Securities Exchange Act of 1934, as amended from time to time, and the rules and regulations thereunder.

Excluded Interest Payments : The excess of the amount of interest that accrues on the No-Delay Certificates for the first Accrual Period over the amount of interest that would have accrued on such Certificates had the first Accrual Period started on the Closing Date.

Fannie Mae : Fannie Mae, a federally chartered and privately owned corporation organized and existing under the Federal National Mortgage Association Charter Act, or any successor thereto.

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

Final Certification : With respect to the Custodian, the certification required to be delivered by the Custodian not later than 90 days after the Closing Date to the Depositor, the Trustee and the Transferor in the form annexed hereto as Exhibit H pursuant to Section 2.02 of this Agreement.

Financing Statement : A financing statement in the form of a UCC-1 or UCC-3, as applicable, filed pursuant to the Uniform Commercial Code to perfect a security interest in the Cooperative Shares and Pledge Instruments.

Fitch : Fitch, Inc., or any successor thereto. If Fitch is designated as a Rating Agency in the Preliminary Statement, for purposes of Section 11.05(b), the address for notices to Fitch shall be One State Street Plaza, New York, NY 10004, Attention: MBS Monitoring MASTR Adjustable Rate Mortgages Trust 2006-OA2, or such other address as Fitch may hereafter furnish to each party to this Agreement.

Form 8-K Disclosure Information : As defined in Section 9.12(c)(i).

Freddie Mac : Freddie Mac, a corporate instrumentality of the United States created and existing under Title III of the Emergency Home Finance Act of 1970, as amended, or any successor thereto.

GMACM : GMAC Mortgage, LLC, a Delaware limited liability company formerly known as GMAC Mortgage Corporation, and its successors and assigns, in its capacity as Servicer of the GMACM Serviced Loans.

GMACM Serviced Mortgage Loans : The Mortgage Loans for which GMACM is listed as “Servicer” on the Mortgage Loan Schedule.

GMACM Servicing Agreement : Solely with respect to the GMACM Serviced Mortgage Loans, Servicing Agreement, dated as of November 1, 2001, as amended by Amendment Number One, dated as of January 1, 2003, as further amended by Amendment Number Two, dated as of July 1, 2006, each between the Transferor, as owner, and GMACM, as servicer, as the same may be amended from time to time, and any assignments and conveyances related to the GMACM Mortgage Loans (as modified pursuant to the related Assignment Agreement).

Group : With respect to the Certificates, the related Certificate Group and with respect to the Mortgage Loans, the related Loan Group.

Group 1 Certificates : As specified in the Preliminary Statement.

Group 1 Loans : Those Mortgage Loans identified on the Mortgage Loan Schedule as Group 1 Loans.

Group 1 Principal Distribution Amount : With respect to each Distribution Date, the product of (i) the Principal Distribution Amount and (ii) a fraction, the numerator of which is the Principal Remittance Amount for Loan Group 1 for that Distribution Date and the denominator of which is the aggregate Principal Remittance Amount for all of the Loan Groups for that Distribution Date.

Group 1 Senior Principal Distribution Amount : With respect to each Distribution Date, the product of (i) the Senior Principal Distribution Amount and (ii) a fraction, the numerator of which is the Principal Remittance Amount for Loan Group 1 for that Distribution Date and the denominator of which is the aggregate Principal Remittance Amount for all of the Loan Groups for that Distribution Date.

Group 1 XW Amount : With respect to each Distribution Date, an amount equal to (i) the Current Interest for the Class XW Certificates for that Distribution Date multiplied by (ii) the sum of the Class Principal Balances of the Group 1 Certificates divided by the Class XW Notional Amount, in each case, as of immediately prior to that Distribution Date.

Group 2 Certificates : As specified in the Preliminary Statement.

Group 2 Loans : Those Mortgage Loans identified on the Mortgage Loan Schedule as Group 2 Loans.

Group 2 Principal Distribution Amount : With respect to each Distribution Date, the product of (i) the Principal Distribution Amount and (ii) a fraction, the numerator of which is the Principal Remittance Amount for Loan Group 2 for that Distribution Date and the denominator of which is the aggregate Principal Remittance Amount for all of the Loan Groups for that Distribution Date.

Group 2 Senior Principal Distribution Amount : With respect to each Distribution Date, the product of (i) the Senior Principal Distribution Amount and (ii) a fraction, the numerator of which is the Principal Remittance Amount for Loan Group 2 for that Distribution Date and the denominator of which is the aggregate Principal Remittance Amount for all of the Loan Groups for that Distribution Date.

Group 2 XW Amount : With respect to each Distribution Date, an amount equal to (i) the Current Interest for the Class XW Certificates for that Distribution Date multiplied by (ii) the sum of the Class Principal Balances of the Group 2 Certificates divided by the Class XW Notional Amount, in each case, as of immediately prior to that Distribution Date.

Group 3 Certificates : As specified in the Preliminary Statement.

Group 3 Loans : Those Mortgage Loans identified on the Mortgage Loan Schedule as Group 3 Loans.

Group 3 Principal Distribution Amount : With respect to each Distribution Date, the product of (i) the Principal Distribution Amount and (ii) a fraction, the numerator of which is the Principal Remittance Amount for Loan Group 3 for that Distribution Date and the denominator of which is the aggregate Principal Remittance Amount for all of the Loan Groups for that Distribution Date.

Group 3 Senior Principal Distribution Amount : With respect to each Distribution Date, the product of (i) the Senior Principal Distribution Amount and (ii) a fraction, the numerator of which is the Principal Remittance Amount for Loan Group 3 for that Distribution Date and the denominator of which is the aggregate Principal Remittance Amount for all of the Loan Groups for that Distribution Date.

Group 4 Certificates : As specified in the Preliminary Statement.

Group 4 Loans : Those Mortgage Loans identified on the Mortgage Loan Schedule as Group 4 Loans.

Group 4 Principal Distribution Amount : With respect to each Distribution Date, the product of (i) the Principal Distribution Amount and (ii) a fraction, the numerator of which is the Principal Remittance Amount for Loan Group 4 for that Distribution Date and the denominator of which is the aggregate Principal Remittance Amount for all of the Loan Groups for that Distribution Date.

Group 4 Senior Principal Distribution Amount : With respect to each Distribution Date, the product of (i) the Senior Principal Distribution Amount and (ii) a fraction, the numerator of which is the Principal Remittance Amount for Loan Group 4 for that Distribution Date and the denominator of which is the aggregate Principal Remittance Amount for all of the Loan Groups for that Distribution Date.

Group Net WAC Cap : For each Distribution Date and:

(a)

with respect to the Group 1 Certificates, the Net WAC for Loan Group 1 for that Distribution Date minus (1) the sum of Current Interest for the Class X-1 Certificates and the Group 1 XW Amount for that Distribution Date, (2) multiplied by 12, (3) divided by the Stated Principal Balance of the Mortgage Loans in Loan Group 1;

(b)

with respect to the Group 2 Certificates, the Net WAC for Loan Group 2 for that Distribution Date minus (1) the sum of Current Interest for the Class X-2 Certificates and the Group 2 XW Amount for that Distribution Date, (2) multiplied by 12, (3) divided by the Stated Principal Balance of the Mortgage Loans in Loan Group 2; and

(c)

with respect to the Group 3 and Group 4 Certificates, the related Net WAC.

Group Principal Distribution Amount: Any of the Group 1 Principal Distribution Amount, the Group 2 Principal Distribution Amount, the Group 3 Principal Distribution Amount and the Group 4 Principal Distribution Amount, as applicable.

Group Senior Principal Distribution Amount : Any of the Group 1 Senior Principal Distribution Amount, the Group 2 Senior Principal Distribution Amount, the Group 3 Senior Principal Distribution Amount and the Group 4 Senior Principal Distribution Amount, as applicable.

High Cost Mortgage Loan : A Mortgage Loan classified as (a) a “high cost” loan under the Home Ownership and Equity Protection Act of 1994, (b) a “high cost home,” “threshold,” “covered,” (excluding New Jersey “Covered Home Mortgage Loans” as that term is defined in clause (1) of the definition of that term in the New Jersey Home Ownership Security Act of 2002), “high risk home,” “predatory” or similar loan under any other applicable state, federal or local law (or a similarly classified loan using different terminology under a law imposing heightened regulatory scrutiny or additional legal liability for residential mortgage loans having high interest rates, points and/or fees) or (c) a Mortgage Loan categorized as High Cost pursuant to Appendix E of Standard and Poor’s Glossary.

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

Home Loan : A Mortgage Loan categorized as a Home Loan pursuant to Appendix E of Standard & Poor’s Glossary.

Homeownership Act : The federal Truth-in-Lending Act as amended by the Home Ownership and Equity Protection Act of 1994.

Independent : When used with respect to any accountants, a Person who is “independent” within the meaning of Rule 2-01(B) of the Commission’s Regulation S-X. Independent means when used with respect to any other Person, a Person who (a) is in fact independent of another specified Person and any affiliate of such other Person, (b) does not have any material direct or indirect financial interest in such other Person or any affiliate of such other Person, (c) is not connected with such other Person or any affiliate of such other Person as an officer, employee, promoter, underwriter, trust administrator, trustee, partner, director or Person performing similar functions and (d) is not a member of the immediate family of a Person defined clause (b) or (c) above.

Indirect Participant : A broker, dealer, bank or other financial institution or other Person that clears through or maintains a custodial relationship with a Depository Participant.

IndyMac : IndyMac Bank, F.S.B., and its successors and assigns, in its capacity as Servicer of the IndyMac Serviced Loans

IndyMac Serviced Mortgage Loans : The Mortgage Loans for which IndyMac is listed as “Servicer” on the Mortgage Loan Schedule.

IndyMac Servicing Agreement : Solely with respect to the IndyMac Serviced Mortgage Loans, the Master Loan Purchase and Servicing Agreement, dated as of September 1, 2006, by and between the Transferor, as initial purchaser, and IndyMac, as seller and as servicer, as the same may be amended from time to time (as modified pursuant to the related Assignment Agreement).

Initial Certification : With respect to the Custodian, the certification required to be executed by the Custodian and delivered on the Closing Date to the Depositor and the Trustee in the form annexed hereto as Exhibit G pursuant to Section 2.02 of this Agreement.

Initial COFI Rate : 4.177% per annum.

Initial LIBOR Rate : 5.320% per annum.

Initial MTA Rate : 4.664% per annum.

Insolvency Proceeding : With respect to any Person: (i) any case, action, or proceeding with respect to such Person before any court or other governmental authority relating to bankruptcy, reorganization, insolvency, liquidation, receivership, dissolution, winding up, or relief of debtors; or (ii) any general assignment for the benefit of creditors, composition, marshaling of assets for creditors, or other, similar arrangement in respect of the creditors generally of such Person or any substantial portion of such Person’s creditors, in any case undertaken under federal, state or foreign law, including the Bankruptcy Code.

Insurance Policy : With respect to any Mortgage Loan included in the Trust Fund, any insurance policy, including all riders and endorsements thereto in effect, including any replacement policy or policies for any Insurance Policies.

Insurance Proceeds : Proceeds paid by an insurer pursuant to any title policy, hazard policy or other Insurance 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 related 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.

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

Insured Expenses : Expenses covered by an Insurance Policy or any other insurance policy with respect to the Mortgage Loans.

Interest Carry Forward Amount : With respect to each Class of Senior Certificates and Mezzanine Certificates and each Distribution Date, the excess of (i) the Current Interest for such Class with respect to prior Distribution Dates over (ii) the amount actually distributed to such Class with respect to interest on such prior Distribution Dates.

Interest Funds : With respect to any Distribution Date and Loan Group, the sum of (i) the Interest Remittance Amount for such Loan Group for such Distribution Date and (ii) the Deferred Interest for all Mortgage Loans in such Loan Group for the related Due Date up to the Principal Remittance Amount for such Loan Group for such Distribution Date.

Interest Only Certificates : As defined in the Preliminary Statement.

Interest Remittance Amount : With respect to the Mortgage Loans in a Loan Group and any Distribution Date, (x) the sum, without duplication, of (i) all scheduled interest on the Mortgage Loans in that Loan Group due on the related Due Date and received on or prior to the related Determination Date, less the related Servicing Fees, Credit Risk Manager Fees and any payments made in respect of premiums on lender paid insurance mortgage loans, (ii) all interest on Principal Prepayments on the Mortgage Loans in that Loan Group, other than Prepayment Interest Excess, (iii) all Advances relating to interest with respect to the Mortgage Loans in that Loan Group, (iv) all Compensating Interest with respect to such Mortgage Loans in that Loan Group and (v) Liquidation Proceeds with respect to the Mortgage Loans in that Loan Group during the related Prepayment Period (to the extent such Liquidation Proceeds relate to interest), less (y) all reimbursements to the Master Servicer since the immediately preceding Due Date for Nonrecoverable Advances of interest previously made allocable to such Loan Group.

Issuing Entity : As defined in Section 2.01(c).

Late Payment Rate : The lesser of (a) the greater of (i) the per annum rate of interest publicly announced from time to time by JPMorgan Chase Bank, N.A. as its prime or base lending rate (any change in such rate of interest to be effective on the date such change is announced by JPMorgan Chase Bank, N.A.) plus 2.00%, and (ii) the then applicable highest rate of interest on the Insured Notes and (b) the maximum rate permissible under applicable usury or similar laws limiting interest rates as determined by the Class A Note Insurer. The Late Payment Rate shall be computed on the basis of the actual number of days elapsed over a year of 360 days.

Latest Possible Maturity Date : The Distribution Date following the third anniversary of the scheduled maturity date of the Mortgage Loan having the latest scheduled maturity date as of the Cut-off Date.

LIBOR : As to any Distribution Date, the arithmetic mean of the London Interbank offered rate quotations for one month U.S. Dollar deposits, as determined by the Trust Administrator in accordance with Section 4.10.

LIBOR Business Day: Any day other than (i) a Saturday or a Sunday or (ii) a day on which banking institutions in the State of New York or in the City of London, England are required or authorized by law to be closed.

LIBOR Determination Date : As to any Distribution Date, other than the first Distribution Date, and any Class of LIBOR Certificates, the second LIBOR Business Day prior to the beginning of the applicable Accrual Period for such Class and such Distribution Date.

Liquidated Mortgage Loan : With respect to any Distribution Date, (i) a defaulted Mortgage Loan (including any REO Property) which was liquidated in the calendar month preceding the month of such Distribution Date and as to which the applicable Servicer or the Master Servicer, as the case may be, has determined (in accordance with the applicable Servicing Agreement and this Agreement) that it has received all amounts it expects to receive in connection with the liquidation of such Mortgage Loan, including the final disposition of an REO Property or (ii) any Mortgage Loan that becomes 180 days or more delinquent in the calendar month preceding the month of such Distribution Date.

Liquidation Proceeds : Amounts, including Insurance Proceeds, received in connection with the partial or complete liquidation of defaulted Mortgage Loans, whether through trustee’s sale, foreclosure sale or otherwise or amounts received in connection with any condemnation or partial release of a Mortgaged Property and any other proceeds received in connection with an REO Property, less the sum of related unreimbursed Servicing Fees and Servicing Advances.

Loan-to-Value Ratio : With respect to any Mortgage Loan and as to 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 of determination and the denominator of which is the Appraised Value of the related Mortgaged Property. For purposes of representation (xxxi) of Schedule II, the Loan-to-Value Ratio will be the loan-to-value ratio calculated in accordance with applicable state laws regarding primary mortgage insurance.

Loan Group : Any of the Group 1 Loans, the Group 2 Loans, the Group 3 Loans or the Group 4 Loans, as applicable.

Loan Seller : With respect to any Mortgage Loan, the entity that sold such Mortgage Loan to the Transferor.

Lost Mortgage Note : Any Mortgage Note the original of which was permanently lost or destroyed and has not been replaced.

Majority Holder : As to any Class of Regular Certificates, the Holder of Certificates of such Class evidencing, in the aggregate, at least 51% of the Percentage Interests evidenced by all Certificates of such Class.

Majority in Interest : As to any Class of Regular Certificates, the Holders of Certificates of such Class evidencing, in the aggregate, at least 51% of the Percentage Interests evidenced by all Certificates of such Class.

Master REMIC : As specified in the Preliminary Statement.

Master Servicer : Wells Fargo Bank, N.A., a national banking association, and its successors and assigns, in its capacity as Master Servicer hereunder, or any successor Master Servicer hereunder.

Master Servicer Event of Termination : As defined in Section 7.01 hereof.

Master Servicer Compensation : All investment earnings on amounts on deposit in the Collection Account.

Master Servicing Officer : Any officer of the Master Servicer involved in, or responsible for, the administration and master servicing of the Mortgage Loans.

MERS : As defined in Section 2.01.

Mezzanine Cap Account : A segregated trust account established and maintained by the Trust Administrator pursuant to 3.07(j) of this agreement in which payments received from the Mezzanine Cap Provider will be deposited.

Mezzanine Cap Contract : The cap contract between the Mezzanine Cap Provider and the Supplemental Interest Trust Trustee relating to the Certificates in the form attached hereto as Exhibit P.

Mezzanine Cap Contract Termination Date: The Distribution Date in February 2015.

Mezzanine Cap Provider : Swiss Re Financial Products Corporation

Mezzanine Certificates : As defined in the Preliminary Statement.

Mezzanine Principal Distribution Amount: For any Class of Mezzanine Certificates and Distribution Date, the excess of:

(a)

the sum of:

(i)

the aggregate Class Principal Balance of the Senior Certificates, other than the Interest Only Certificates (after taking into account the distribution of the Senior Principal Distribution Amount for such Distribution Date),

(ii)

the aggregate Class Principal Balance of any Class(es) of Mezzanine Certificates that are senior to the subject Class (in each case, after taking into account the distribution of the applicable Mezzanine Principal Distribution Amount(s) for such more senior Class(es) of Certificates for such Distribution Date), and

(iii)

the Class Principal Balance of such Class of Mezzanine Certificates immediately prior to such Distribution Date, over

(b)

the lesser of (a) the product of (x) 100% minus the applicable Stepdown Target Subordination Percentage for the subject Class of Mezzanine Certificates for that Distribution Date and (y) the aggregate Stated Principal Balance of the Mortgage Loans as of the Due Date in the month of that Distribution Date (after giving effect to principal prepayments received in the related Prepayment Period) and (b) the aggregate Stated Principal Balance of the Mortgage Loans as of the Due Date in the month of that Distribution Date (after giving effect to principal prepayments received in the related Prepayment Period) minus the OC Floor; provided, however, that if the Class Principal Balance of each Class of Senior Certificates has been reduced to zero, and such Class of Mezzanine Certificates is the only Class of Mezzanine Certificates outstanding on such Distribution Date, that Class will be entitled to receive the entire remaining Principal Distribution Amount until its Class Principal Balance is reduced to zero.

Middle REMIC 1 : As specified in the Preliminary Statement.

Middle REMIC 1 Regular Interest : As specified in the Preliminary Statement.

Middle REMIC 2 : As specified in the Preliminary Statement.

Middle REMIC 2 Regular Interest : As specified in the Preliminary Statement.

Moody’s: Moody’s Investors Service, Inc., or any successor thereto. If Moody’s is designated as a Rating Agency in the Preliminary Statement, for purposes of Section 11.05(b), the address for notices to Moody’s shall be Moody’s Investors Service, Inc., 99 Church Street, New York, New York 10007, Attention: Residential Mortgage Monitoring Group, or such other address as Moody’s may hereafter furnish to each other party to this Agreement.

Mortgage : The mortgage, deed of trust or other instrument creating a second lien on an estate in fee simple or leasehold interest in real property securing a Mortgage Note.

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

Mortgage Loan Purchase Agreement : The Mortgage Loan Purchase Agreement, dated as of October 1, 2006, between the Transferor and the Depositor.

Mortgage Loan Schedule : The list of Mortgage Loans (as from time to time amended by the Custodian to reflect the addition of Eligible Substitute Mortgage Loans and the deletion of Deleted Mortgage Loans pursuant to the provisions of this Agreement) transferred to the Trustee as part of the Trust Fund and from time to time subject to this Agreement, attached hereto as Schedule I, setting forth the following information with respect to each Mortgage Loan: (1) the Mortgage Loan identifying number; (2) the Mortgagor’s first and last name; (3) the street address of the Mortgaged Property including the city, state and zip code; (4) the original principal balance of the Mortgage Loan; (5) the Scheduled Principal Balance of the Mortgage Loan as of the close of business on the Cut-off Date; (6) the unpaid principal balance of the Mortgage Loan as of the close of business on the Cut-off Date; (7) the last scheduled Due Date on which a Scheduled Payment was applied to the Scheduled Principal Balance; (8) the last Due Date on which a Scheduled Payment was actually applied to the unpaid principal balance; (9) the Mortgage Rate in effect immediately following origination; (10) the Mortgage Rate in effect immediately following the Cut-off Date (if different from (9)); (11) the amount of the Scheduled Payment at origination; (12) the amount of the Scheduled Payment as of the Cut-off Date (if different from (11)); (13) a code indicating whether the Mortgaged Property is owner occupied, a second home or an investor property; (14) a code indicating whether the Mortgaged Property is a single family residence, a two-family residence, a three-family residence, a four-family residence, a planned-unit development, a condominium or a Cooperative Unit; (15) a code indicating the loan purpose (i.e., purchase, rate/term refinance, cash-out refinance); (16) the stated maturity date; (17) the original months to maturity; (18) the remaining months to maturity from the Cut-off Date based on the original amortization Schedule and, if different, the remaining months to maturity expressed in the same manner but based on the actual amortization schedule; (19) the origination date of the Mortgage Loan; (20) the Loan-to-Value Ratio at origination; (21) the date on which the first Scheduled Payment was due on the Mortgage Loan after the origination date; (22) a code indicating the documentation style of the Mortgage Loan; (23) a code indicating if the Mortgage Loan is subject to a Primary Insurance Policy and, if so, the name of the Qualified Mortgage Insurer, the certificate number and the coverage amount of the Primary Insurance Policy; (24) the Servicing Fee Rate, and if such rate is subject to change, the date such rate will change and the Servicing Fee Rate applicable thereafter; (25) a code indicating whether the Mortgage Loan is subject to a prepayment penalty and, if so, the term of such prepayment penalty and whether the same shall be a Class P Prepayment Charge; (26) the credit score (or mortgage score) of the Mortgagor; (27) the debt-to-income ratio of the Mortgage Loan; (28) the next Adjustment Date; (29) the lifetime mortgage rate cap; (30) the Periodic Rate Cap; (31) the maximum interest rate; (32) the minimum interest rate; (33) [reserved]; (34) the date on which the Mortgage Loan was transferred to the Transferor; (35) a code indicating the Loan Group such Mortgage Loan is included in; (36) the initial Servicer; (37) a code indicating the originator of the Mortgage Loan; (38) a code indicating whether the Mortgage Loan is a Cooperative Loan; (39) a code indicating the Custodian; and (40) a code indicating whether such Mortgage Loan is a Home Loan.

Mortgage Loans : Such of the mortgage loans and cooperative loans transferred and assigned to the Trustee pursuant to the provisions hereof as from time to time are held as a part of the Trust Fund (including any REO Property), the mortgage loans so held being identified in the Mortgage Loan Schedule, notwithstanding foreclosure or other acquisition of title of the related Mortgaged Property. With respect to each Mortgage Loan that is a Cooperative Mortgage Loan, if any, “Mortgage Loan” shall include, but not be limited to, the related Mortgage Note, Security Agreement, Assignment of Proprietary Lease, Recognition Agreement, Cooperative Shares and Proprietary Lease and, with respect to each Mortgage Loan other than a Cooperative Mortgage Loan, “Mortgage Loan” shall include, but not be limited to the related Mortgage and the related Mortgage Note.

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 included in the Trust.

Mortgage Rate : With respect to any Mortgage Loan, the per annum interest rate at which such Mortgage Loan accrues interest.

Mortgaged Property : The property securing a Mortgage Loan which will consist of one- to four-family residential properties consisting of attached or detached one- to four-family dwelling units and individual condominium units.

Mortgagor : Each obligor on a Mortgage Note.

MTA : As to any Distribution Date, the twelve-month moving average monthly yield on United States Treasury Securities adjusted to a constant maturity of one year as published by the Federal Reserve Board in the Federal Reserve Statistical Release “Selected Interest Rates (H.15)”, determined by averaging the monthly yields for the most recent twelve months, as determined by the Trust Administrator in accordance with Section 4.09.

MTA Determination Date : As to any Distribution Date, other than the first Distribution Date, and any Class of MTA Certificates, the fifteenth calendar day prior to the beginning of the applicable Accrual Period for such Class and such Distribution Date.

Net Monthly Excess Cashflow : With respect to any Distribution Date, the sum for such Distribution Date of (a) any Overcollateralization Release Amount and (b) the excess of (x) the aggregate Available Funds for all of the Loan Groups for such Distribution Date over (y) the sum for such Distribution Date of (A) the Current Interest for the Senior Certificates and Mezzanine Certificates, (B) the Interest Carry Forward Amount for the Senior Certificates, (C) the Principal Distribution Amount and (D) the Premium Distribution Amount.

Net Mortgage Rate : As to each Mortgage Loan, the applicable Mortgage Rate thereof minus the related Servicing Fee Rate, the Credit Risk Manager Fee Rate and any lender paid mortgage insurance premiums for such Loan (expressed as a per annum percentage of its Stated Principal Balance).

Net Rate Cap : For each Distribution Date and the following Classes of Certificates is:

(a)

with respect to the Class 1-A-1, Class 1-A-2, Class 2-A-1, Class 2-A-2, Class 4-A-1A and Class 4-A-1B Certificates, and the Group 3 Certificates, the lesser of:

(i)

the related Group Net WAC Cap, and

(ii)

the related Available Funds Rate Cap,

(b)

with respect to the Class 1-A-3 and Class 2-A-3 Certificates, the excess of:

(i)

the lesser of

(1)

the related Group Net WAC Cap, and

(2)

the related Available Funds Rate Cap, over

(ii)

(x) with respect to the first Distribution Date, the Certificate Insurer Fee Rate multiplied by a fraction, the numerator of which is 12 and the denominator of which is 30; or (y) with respect to each Distribution Date thereafter, the Certificate Insurer Fee Rate;

(c)

with respect to the Class 4-A-2 Certificates,

(i)

the excess of:

(1)

the lesser of:

(A)

the related Group Net WAC Cap, and

(B)

the related Available Funds Rate Cap, over

(2)

(ii)

multiplied by a fraction, the numerator of which is 30, and the denominator of which is the actual number of days that elapsed in the related Accrual Period,

(d)

with respect to the Mezzanine Certificates, the product of:

(i)

the lesser of:

(1)

the sum of: for each Loan Group the product of:

(A)

the related Group Net WAC Cap, and

(B)

a fraction:

the numerator of which is the related Subordinated Portion immediately prior to that Distribution Date; and

the denominator of which is the greater of:

such Subordinated Portion; and

the excess of:

the aggregate Stated Principal Balance of all of the Loans as of the Due Date in the prior month (after giving effect to principal prepayments in the Prepayment Period related to that prior Due Date), over

ii.

the aggregate Class Principal Balance of the Senior Certificates (other than the Interest Only Certificates) immediately prior to that Distribution Date; and

(2)

the related Available Funds Rate Cap, and

(ii)

a fraction, the numerator of which is 30, and the denominator of which is the actual number of days that elapsed in the related Accrual Period, and

(e)

with respect to the Class XW Certificates, the excess, if any of:

(i)

the lesser of:

(1)

the Aggregate Group 1 and Group 2 Net WAC, and

(2)

the Available Funds Rate Cap for the Class XW Certificates, over

(ii)

the sum of MTA plus 1.7716%.

Net Rate Carryover : For each Class of Senior Certificates (other than the Class X-1 and Class X-2 Certificates) and Mezzanine Certificates on any Distribution Date is equal to the sum of:

(a)

the excess, if any, of:

(i)

the amount of interest that such Class would have accrued for such Distribution Date had the Pass-Through Rate for that Class and the related Accrual Period not been calculated based on the related Net Rate Cap, over

(ii)

the amount of interest such Class accrued on such Distribution Date based on the related Net Rate Cap, and

(b)

the unpaid portion of any such excess from prior Distribution Dates (and interest accrued thereon at the then applicable Pass-Through Rate, without giving effect to the related Net Rate Cap).

Net WAC : For any Distribution Date and any Loan Group, the weighted average of the Net Mortgage Rate of each Loan in that Loan Group, weighted on the basis of its Stated Principal Balance as of the Due Date occurring in the month preceding the month of that Distribution Date (after giving effect to principal prepayments in the Prepayment Period related to that prior Due Date).

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

NIMS Insurer Default : The continuance of any failure by the NIMS Insurer, if any, to make a required payment under the policy insuring the net interest margin securities.

No Delay Certificates : As specified in the Preliminary Statement.

Nonrecoverable Advance : Any portion of an Advance previously made or proposed to be made by the applicable Servicer or the Master Servicer, as the case may be, that, in the good faith judgment of the applicable Servicer or the Master Servicer, will not be ultimately recoverable by the applicable Servicer or the Master Servicer from the related Mortgagor, related Liquidation Proceeds or otherwise.

Notice of Final Distribution : The notice to be provided pursuant to Section 10.02 to the effect that final distribution on any of the Certificates shall be made only upon presentation and surrender thereof.

Notional Amount : With respect to the Class X-1 Certificates and any Distribution Date, the aggregate Class Principal Balance of the Group 1 Certificates immediately prior to that Distribution Date.

With respect to the Class X-2 Certificates and any Distribution Date, the aggregate Class Principal Balance of the Group 2 Certificates immediately prior to that Distribution Date.

With respect to the Class XW Certificates and any Distribution Date, the aggregate Class Principal Balance of the Group 1 and Group 2 Certificates immediately prior to that Distribution Date.

With respect to the Class C Certificates and any Distribution Date, the aggregate Uncertificated Balance of the Middle REMIC 2 Regular Interests for such Distribution Date.

OC Floor: An amount equal to 0.50% of the aggregate Stated Principal Balance of the Loans as of the Cut-off Date.

Offered Certificates : As specified in the Preliminary Statement.

Officer’s Certificate : A certificate (i) signed by the Chairman of the Board, the Vice Chairman of the Board, the President, a Managing Director, a Vice President (however denominated), an Assistant Vice President, the Treasurer, the Secretary, or one of the Assistant Treasurers or Assistant Secretaries of the Depositor or the Master Servicer, or (ii) if provided for in this Agreement, signed by a Master Servicing Officer, as the case may be, and delivered to the Depositor, the Trustee and the Trust Administrator, as the case may be, as required by this Agreement.

Opinion of Counsel : A written opinion of counsel, who may be counsel for the Depositor or the Master Servicer, including in house counsel, reasonably acceptable to the Trustee or the Trust Administrator, as applicable; provided, however, that, with respect to the interpretation or application of the REMIC Provisions, such counsel must (i) in fact be independent of the Depositor and the Master Servicer, (ii) not have any direct financial interest in the Depositor or the Master Servicer or in any affiliate of either, and (iii) not be connected with the Depositor or the Master Servicer as an officer, employee, promoter, underwriter, trustee, partner, director or person performing similar functions.

Optional Termination : The termination of the Trust created hereunder in connection with the auction or purchase of the Mortgage Loans pursuant to Section 10.01 hereof.

Optional Termination Date: As specified in Section 10.01(a) hereof.

Order : A final nonappealable order of a court or other body exercising jurisdiction in an Insolvency Proceeding by or against the Trust, to the effect that a Holder or the Trust Administrator is required to return or repay all or a portion of a Preference Amount.

Original Certificate Principal Balance : The Certificate Principal Balance of the Senior Certificates or the Mezzanine Certificates on the Closing Date.

OTS : The Office of Thrift Supervision.

Outstanding : With respect to the Certificates as of any date of determination, all Certificates theretofore executed and authenticated under this Agreement except:

(a)

Certificates theretofore canceled by the Trust Administrator or delivered to the Trust Administrator for cancellation; and

(b)

Certificates in exchange for which or in lieu of which other Certificates have been executed and delivered by the Trust Administrator pursuant to this Agreement.

Outstanding Mortgage Loan : As of any Due Date, a Mortgage Loan with a Principal Balance greater than zero that was not the subject of a Principal Prepayment in Full prior to such Due Date and that did not become a Liquidated Mortgage Loan prior to such Due Date.

Overcollateralization Amount : With respect to any Distribution Date, an amount equal to the excess, if any, of (i) the aggregate Stated Principal Balance of the Mortgage Loans as of the Due Date in the month of that Distribution Date (after giving effect to Principal Prepayments received in the related Prepayment Period) over (ii) the sum of the aggregate Class Principal Balance of the Senior Certificates and the Mezzanine Certificates as of such Distribution Date (after giving effect to distributions of the Principal Distribution Amount to be made on such Distribution Date).

Overcollateralization Deficiency Amount : With respect to any Distribution Date, the amount, if any, by which the Overcollateralization Target Amount for such Distribution Date exceeds the Overcollateralization Amount for such Distribution Date (after giving effect to distributions in respect of the Principal Funds on such Distribution Date but before giving effect to any other distributions on the Certificates in reduction of their respective Class Principal Balances on such Distribution Date).

Overcollateralization Maintenance Amount : With respect to any Distribution Date, the lesser of (a) the Net Monthly Excess Cashflow for such Distribution Date and (b) the Overcollateralization Deficiency Amount for such Distribution Date.

Overcollateralization Release Amount : With respect to any Distribution Date, the lesser of (x) the Principal Funds for such Distribution Date and (y) the excess, if any, of (i) the Overcollateralization Amount for such Distribution Date (assuming that 100% of the Principal Funds is applied as a principal payment on such Distribution Date and without giving effect to any other distributions on the Certificates in reduction of their respective Class Principal Balances on such Distribution Date) over (ii) the Overcollateralization Target Amount for such Distribution Date.

Overcollateralization Target Amount: With respect to any Distribution Date (a) prior to the Stepdown Date, an amount equal to 0.50% of the aggregate Stated Principal Balance of the Loans as of the Cut-off Date and (b) on or after the Stepdown Date, the greater of (i) (x) for any Distribution Date on or after the Stepdown Date but prior to the Distribution Date in November 2012, an amount equal to 1.25% of the aggregate Stated Principal Balance of the Loans as of the Due Date in the month of that Distribution Date (after giving effect to principal prepayments received in the related Prepayment Period) and (y) for any Distribution Date on or after the Stepdown Date and on or after the Distribution Date in November 2012, an amount equal to 1.00% of the aggregate Stated Principal Balance of the Loans as of the Due Date in the month of that Distribution Date (after giving effect to principal prepayments received in the related Prepayment Period) and (ii) the OC Floor; provided, however, that if a Trigger Event is in effect on any Distribution Date, the Overcollateralization Target Amount will be the Overcollateralization Target Amount as in effect for the prior Distribution Date.

Ownership Interest : As to any Residual Certificate, any ownership 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.

Par Value : As defined in Section 10.01.

Pass-Through Rate : For any interest bearing Class of Certificates, the per annum rate set forth or calculated in the manner described in the Preliminary Statement.

PCAOB: The Public Company Accounting Oversight Board.

Percentage Interest : As to any Certificate, the percentage interest evidenced thereby in distributions required to be made on the related Class, such percentage interest being set forth on the face thereof or equal to the percentage obtained by dividing the Denomination of such Certificate by the aggregate of the Denominations of all Certificates of the same Class.

Permitted Investments : At any time, any one or more of the following obligations and securities:

(a)

obligations of the United States or any agency thereof, provided such obligations are backed by the full faith and credit of the United States;

(b)

general obligations of or obligations guaranteed by any state of the United States or the District of Columbia receiving the highest long-term debt rating of each Rating Agency, or such lower rating as will not result in the downgrading or withdrawal of the ratings, by any Rating Agency, then assigned to any of the Certificates;

(c)

commercial or finance company paper which is then receiving the highest commercial or finance company paper rating of any Rating Agency, or such lower rating as will not result in the downgrading or withdrawal of the ratings, by any Rating Agency, then assigned to any of the Certificates;

(d)

certificates of deposit, demand or time deposits, or bankers’ acceptances issued by any depository institution or trust company incorporated under the laws of the United States or of any state thereof and subject to supervision and examination by federal and/or state banking authorities, provided that the commercial paper and/or long term unsecured debt obligations of such depository institution or trust company are then rated in one of the two highest long-term and the highest short-term ratings of each Rating Agency for such securities, or such lower ratings as will not result in the downgrading or withdrawal of the ratings, by any Rating Agency, then assigned to any of the Certificates;

(e)

demand or time deposits or certificates of deposit issued by any bank or trust company or savings institution to the extent that such deposits are fully insured by the FDIC and are then rated in the highest long-term and the highest short-term ratings of each Rating Agency for such securities, or such lower ratings as will not result in the downgrading or withdrawal of the ratings, by any Rating Agency, to any of the Certificates;

(f)

guaranteed reinvestment agreements issued by any bank, insurance company or other corporation containing, at the time of the issuance of such agreements, such terms and conditions as will not result in the downgrading or withdrawal of the ratings, by any Rating Agency, then assigned to any of the Certificates;

(g)

repurchase obligations with respect to any security described in subclauses (a) and (b) above, in either case entered into with a depository institution or trust company (acting as principal) described in subclause (d) above;

(h)

securities (other than stripped bonds, stripped coupons or instruments sold at a purchase price in excess of 115% of the face amount thereof) bearing interest or sold at a discount issued by any corporation incorporated under the laws of the United States or any state thereof which, at the time of such investment, have the highest rating of each Rating Agency, or such lower rating as will not result in the downgrading or withdrawal of the ratings, by any Rating Agency, then assigned to the of the Certificates, as evidenced by a signed writing delivered by each Rating Agency;

(i)

units of a taxable money-market portfolio having the highest available long-term rating assigned by each Rating Agency at the time of such investment and restricted to obligations issued or guaranteed by the United States of America or entities whose obligations are backed by the full faith and credit of the United States of America and repurchase agreements collateralized by such obligations;

(j)

any mutual fund, money market fund, common trust fund or other pooled investment vehicle, the assets of which are limited to instruments that otherwise would constitute Permitted Investments hereunder, including any such fund that is managed by the Trust Administrator or Master Servicer or any Affiliate of the Trust Administrator or Master Servicer or for which the Trust Administrator or Master Servicer or any Affiliate of the Trust Administrator or Master Servicer acts as an adviser as long as such fund is rated in at least the highest rating category by each Rating Agency (if so rated by such Rating Agency); and

(k)

such other investments bearing interest or sold at a discount acceptable to each Rating Agency as will not result in the downgrading or withdrawal of the ratings, by any Rating Agency, then assigned to any of the Certificates, as evidenced by a signed writing delivered by each Rating Agency;

provided that no such instrument shall be a Permitted Investment if such instrument evidences the right to receive interest only payments with respect to the obligations underlying such instrument.

Permitted Transferee : Any Person other than (i) the United States, any State or political subdivision thereof, or any agency or instrumentality of any of the foregoing, (ii) a foreign government, international organization or any agency or instrumentality of either of the foregoing, (iii) an organization (except certain farmers’ cooperatives described in section 521 of the Code) which is exempt from tax imposed by Chapter 1 of the Code (including the tax imposed by section 511 of the Code on unrelated business taxable income) on any excess inclusions (as defined in section 860E(c)(l) of the Code) with respect to any Residual Certificate, (iv) rural electric and telephone cooperatives described in section 1381(a)(2)(C) of the Code, (v) a Person that is not a citizen or resident of the United States, a corporation, partnership (except as provided in applicable Treasury Regulations), or other entity created or organized in or under the laws of the United States, any state thereof or the District of Columbia, 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 Persons described in this clause (v) have the authority to control all substantial decisions of the Trust (or, to the extent provided in applicable Treasury Regulations, certain trusts in existence on August 20, 1996 which are eligible to elect to be treated as United States persons) unless such Person has furnished the transferor and the Trust Administrator with a duly completed Internal Revenue Service Form W-8ECI or any applicable successor form, (vi) any Person with respect to whom income on any Residual Certificate is attributable to a foreign permanent establishment or fixed base, within the meaning of an applicable income tax treaty, of such Person or any other Person and (vii) any other Person so designated by the Depositor based upon an Opinion of Counsel that the Transfer of an Ownership Interest in a Residual Certificate to such Person may cause any REMIC hereunder to fail to qualify as a REMIC at any time that the Certificates are outstanding. The terms “United States,” “State” and “international organization” shall have the meanings set forth in section 7701 of the Code or successor provisions. A corporation will not be treated as an instrumentality of the United States or of any State or political subdivision thereof for these purposes if all of its activities are subject to tax and, with the exception of Freddie Mac, a majority of its board of directors is not selected by such government unit.

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.

Physical Certificate : As specified in the Preliminary Statement.

Pledge Instruments : With respect to each Cooperative Mortgage Loan, the Stock Power, the Assignment of Proprietary Lease and the Security Agreement.

Policy Payments Account : The account created and maintained by the Trust Administrator pursuant to Section 12.04 hereof, which shall be entitled “U.S. Bank National Association in trust for registered holders of MASTR Adjustable Rate Mortgages Trust 2006-OA2, Mortgage Pass-Through Certificates, Series 2006-OA2, Class 1-A-3, Class 2-A-3 and Class 4-A-2 Certificates.” The Policy Payments Account must be an Eligible Account.

Pool Balance : The aggregate of the Principal Balances of the Mortgage Loans.

Premium Distribution Amount : With respect to any Distribution Date, the sum of (A) the product of (x) the Certificate Insurer Fee Rate multiplied by (y) the aggregate Class Principal Balance of the Insured Certificates immediately preceding such Distribution Date, not taking into account any payments made under the Certificate Insurance Policy, multiplied by (a) 12 for the first Distribution Date, or (b) for each Distribution Date thereafter, the number of days that elapsed in the related Accrual Period on a 30/360 basis, in each case, divided by 360 and (B) the Premium Distribution Amount for any prior Distribution Date, plus interest thereon at the Late Payment Rate.

Prepayment Interest Excess: As to any Principal Prepayment with respect to any AHM Mortgage Loan received or, in the case of partial Principal Prepayments, applied by the applicable Servicer or the Master Servicer from the first day through the fifteenth day of any calendar month (other than the calendar month in which the Cut-off Date occurs), all amounts paid by the related Mortgagor in respect of interest on such Principal Prepayment. All Prepayment Interest Excess shall be retained by the related Servicer as additional servicing compensation.

Prepayment Interest Shortfall : As to any Distribution Date, Mortgage Loan and Principal Prepayment received or, in the case of partial Principal Prepayments, applied, during the applicable Prepayment Period, the amount, if any, by which one month’s interest at the related Net Mortgage Rate on such Principal Prepayment exceeds the amount of interest at the Net Mortgage Rate paid in connection with such Principal Prepayment.

Prepayment Period : With respect to any prepayment of an AHM Mortgage Loan and any Distribution Date, the period from and including the 16th day of the month preceding the month in which such Distribution Date occurs and to and including the 15th day of the month in which such Distribution Date occurs, and with respect to any other Mortgage Loan and any Distribution Date, the calendar month preceding the month in which such Distribution Date occurs.

Primary Insurance Policy : Each policy of primary mortgage guaranty insurance or any replacement policy therefor with respect to any Mortgage Loan.

Principal Balance : As to any Mortgage Loan and any Distribution Date, the unpaid principal balance of such Mortgage Loan as of the Due Date in the month preceding the month in which such Distribution Date occurs, as specified in the amortization schedule at the time relating thereto (before any adjustment to such amortization schedule by reason of any moratorium or similar waiver or grace period) after giving effect to any previous partial Principal Prepayments and Liquidation Proceeds allocable to principal received during the Prepayment Period for the prior Distribution Date (other than with respect to any Liquidated Loan), and to the payment of principal due on such Due Date and irrespective of any delinquency in payment by the related Mortgagor. The Principal Balance of any Mortgage Loan that has been prepaid in full or has become a Liquidated Loan during the related Prepayment Period shall be zero.

Principal Distribution Amount : With respect to any Distribution Date, the sum of (i) the Basic Principal Distribution Amount for such Distribution Date and (ii) the Overcollateralization Maintenance Amount for such Distribution Date.

Principal Funds : With respect to any Distribution Date and Loan Group, the excess, if any, of (i) the Principal Remittance Amount for such Loan Group for such Distribution Date over (ii) the Deferred Interest for such Loan Group for the related Due Date.

Principal Prepayment : Any payment of principal by a Mortgagor on a Mortgage Loan that is received in advance of its scheduled Due Date and is not accompanied by an amount representing scheduled interest due on any date or dates in any month or months subsequent to the month of prepayment, excluding any prepayment penalty or premium thereon. Partial Principal Prepayments will be applied by the applicable Servicers in accordance with the terms of the related Servicing Agreements and in accordance with the terms of the related Mortgage Note, and to the extent the Mortgage Note does not provide otherwise, shall be applied in the Prepayment Period preceding the receipt thereof.

Principal Prepayment in Full : Any Principal Prepayment made by a Mortgagor of the entire principal balance of a Mortgage Loan.

Principal Remittance Amount : With respect to any Distribution Date, the sum of (i) all scheduled payments of principal collected on the Mortgage Loans by the related Servicer that were due during the related Due Period and the principal portion of any Advances made with respect to such Distribution Date, (ii) the principal portion of all partial and full principal prepayments of the Mortgage Loans applied by the related Servicer during such 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 Mortgage Loans, (iv) that portion of the Purchase Price, representing principal of any repurchased Mortgage Loan, deposited to the collection account during such Prepayment Period, (v) the principal portion of any related Substitution Adjustment Amount deposited in the Collection Account during such Prepayment Period with respect to the Mortgage Loans and (vi) on the Distribution Date on which the Trust is to be terminated in accordance with Section 10.01 of this Agreement, that portion of the Termination Price representing principal with respect to the Mortgage Loans.

Private Certificate : As specified in the Preliminary Statement.

Proprietary Lease : The lease on a Cooperative Unit evidencing the possessory interest of the owner of the Cooperative Shares in such Cooperative Unit.

Prospectus Supplement : The Prospectus Supplement dated November 14, 2006 relating to the Offered Certificates.

Protected Account : An account established and maintained for the benefit of Certificateholders by each Servicer with respect to the related Mortgage Loans and with respect to REO Property pursuant to the respective Servicing Agreements. Each Protected Account is required to be an Eligible Account.

Purchase Price : With respect to any Mortgage Loan that is purchased by the transferor pursuant to Section 2.02 or 2.03 hereof, a price equal to the outstanding Principal Balance of such Mortgage Loan as of the date of purchase, plus all accrued and unpaid interest thereon, computed at the Mortgage Rate through the end of the calendar month in which the purchase is effected, plus any costs and damages incurred by the Trust in connection with any violation by such Mortgage Loan of any predatory or abusive lending law.

Qualified Insurer : A mortgage guaranty insurance company duly qualified as such under the laws of the state of its principal place of business and each state having jurisdiction over such insurer in connection with the insurance policy issued by such insurer, duly authorized and licensed in such states to transact a mortgage guaranty insurance business in such states and to write the insurance provided by the insurance policy issued by it, approved as a Fannie Mae approved mortgage insurer and having a claims paying ability rating of at least “AA” or equivalent rating by a nationally recognized statistical rating organization. Any replacement insurer with respect to a Mortgage Loan must have at least as high a claims paying ability rating as the insurer it replaces had on the Closing Date.

Qualified Mortgage Insurer : Any mortgage insurer that is Fannie Mae and Freddie Mac approved.

Rating Agency : Each of the rating agencies specified in the Preliminary Statement. If any such organization or a successor is no longer in existence, “Rating Agency” shall be such nationally recognized statistical rating organization, or other comparable Person, as is designated by the Depositor, notice of which designation shall be given to the Trustee and the Trust Administrator. References herein to a given rating category of a Rating Agency shall mean such rating category without giving effect to any modifiers.

Realized Loss : With respect to each Mortgage Loan that is a Liquidated Mortgage Loan, an amount (not less than zero or more than the Principal Balance of the Mortgage Loan) as of the date of such liquidation, equal to (i) the unpaid Principal Balance of the Liquidated Mortgage Loan as of the date of such liquidation, plus (ii) interest at the Net Mortgage Rate from the Due Date as to which interest was last paid or advanced (and not reimbursed) to Certificateholders up to the Due Date in the month in which Liquidation Proceeds are required to be distributed on the Principal Balance of such Liquidated Mortgage Loan from time to time, minus (iii) the Liquidation Proceeds, if any, received during the month in which such liquidation occurred, to the extent applied as recoveries of interest at the Net Mortgage Rate and to principal of the Liquidated Mortgage Loan. With respect to each Mortgage Loan which has become the subject of a Deficient Valuation, if the principal amount due under the related Mortgage Note has been reduced, 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.

Recognition Agreement : An Agreement among a Cooperative Corporation, a lender and a Mortgagor with respect to a Cooperative Mortgage Loan whereby such parties (i) acknowledge that such lender may make, or intends to make, such Cooperative Mortgage Loan and (ii) make certain agreements with respect to such Cooperative Mortgage Loan.

Record Date : With respect to any Distribution Date and any Class of Delay Certificates or Physical Certificates, the close of business on the last Business Day of the month preceding the month in which such Distribution Date occurs. With respect to any Distribution Date and any Class of No Delay Certificates held in Book-Entry Form, the last Business Day immediately preceding such Distribution Date.

Refinancing Mortgage Loan : Any Mortgage Loan originated in connection with the refinancing of an existing mortgage loan.

Regular Certificates : Each Class of Certificates, other than the Residual Certificates.

Regulation AB : Subpart 229.1100 – Asset Backed Securities (Regulation AB), 17 C.F.R. §§229.1100-229.1123, as such may be amended from time to time, and subject to such clarification and interpretation as have been provided by the Commission in the adopting release (Asset-Backed Securities, Securities Act Release No. 33-8518, 70 Fed Reg. 1,506-1,631 (Jan. 7, 2005)) or by the staff of the Commission, or as may be provided by the Commission or its staff from time to time.

Relevant Servicing Criteria : The Servicing Criteria applicable to each party, as set forth on Exhibit X attached hereto. Multiple parties can have responsibility for the same Relevant Servicing Criteria. With respect to a Servicing Function Participant engaged by any of the Master Servicer, the Trust Administrator or each Servicer, the term Relevant Servicing Criteria may refer to a portion of the Relevant Servicing Criteria applicable to such parties.

Relief Act : The Servicemembers Civil Relief Act, as amended, or any comparable state or local statute (including the comparable provisions under the California Military and Veterans Code, as amended).

Relief Act Reduction : With respect to any Distribution Date and any Mortgage Loan as to which there has been a reduction in the amount of interest collectible thereon for the most recently ended calendar month as a result of the application of the Relief Act, the amount, if any, by which (i) interest collectible on such Mortgage Loan for the most recently ended calendar month is less than (ii) interest accrued thereon for such month pursuant to the Mortgage Note.

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

REMIC Change of Law : Any proposed, temporary or final regulation, revenue ruling, revenue procedure or other official announcement or interpretation relating to REMICs and the REMIC Provisions issued after the Closing Date.

REMIC Maximum Rate : For each Class of Certificates (other than the Class X-1, Class X-2, Class C, Class P and Class R Certificates) and the REMIC regular interest represented thereby, the Net Rate Cap of such Class of Certificates determined without regard to any Available Funds Rate Cap.

REMIC Provisions : Provisions of the federal income tax law relating to real estate mortgage investment conduits, which appear at sections 860A through 860G of Subchapter M of Chapter 1 of the Code, and related provisions, and regulations promulgated thereunder, as foregoing may be in effect from time to time as well as provisions of applicable state laws.

REO Property : A Mortgaged Property acquired by the Trust Fund through foreclosure, deed-in-lieu of foreclosure, repossession or otherwise in connection with a defaulted Mortgage Loan.

Reportable Event : As defined in Section 9.12.

Reporting Servicer : As defined in Section 9.12(b)(i).

Required Insurance Policy : With respect to any Mortgage Loan, any insurance policy that is required to be maintained from time to time under the applicable Servicing Agreement.

Residual Certificates : As specified in the Preliminary Statement.

Residual Interests : As specified in the Preliminary Statement.

Responsible Officer : When used with respect to the Trustee or the Trust Administrator, any Director, any Managing Director, any Associate, any Vice President, any Assistant Vice President, the Secretary, any Assistant Secretary, any Trust Officer or any other officer of the Trustee or Trust Administrator, as applicable, customarily performing functions similar to those performed by any of the above designated officers having direct responsibility for the administration of this Agreement and also to whom, with respect to a particular matter, such matter is referred because of such officer’s knowledge of and familiarity with the particular subject.

RFC : Residential Funding Company, LLC, formerly known as Residential Funding Corporation, and its successors and assigns, in its capacity as Servicer of the RFC Serviced Loans.

RFC Serviced Mortgage Loans : The Mortgage Loans for which RFC is listed as “Servicer” on the Mortgage Loan Schedule.

RFC Servicing Agreement : Solely with respect to the RFC Serviced Mortgage Loans, the Standard Terms and Provisions of Sale and Servicing Agreement, dated as of May 30, 2006, as amended by Amendment Number One, dated as of August 23, 2006, and as modified by the Reference Agreement, dated as of May 30, 2006, each by and between the Transferor, as initial owner, and RFC, as company, as the same may be amended from time to time (as modified pursuant to the related Assignment Agreement).

Rolling Sixty-Day Delinquency Rate: With respect to any Distribution Date on or after the Stepdown Date, the average of the Sixty-Day Delinquency Rates for the two immediately preceding Distribution Dates.

Sarbanes-Oxley Act : The Sarbanes-Oxley Act of 2002 and the rules and regulations of the Commission promulgated thereunder (including any interpretations thereof by the Commission’s staff).

Sarbanes-Oxley Certification : A written certification signed by an officer of the Master Servicer that complies with (i) the Sarbanes-Oxley Act, and (ii) Exchange Act Rules 13a-14(d) and 15d-14(d), as in effect from time to time; provided that if, after the Closing Date (a) the Sarbanes-Oxley Act is amended, (b) the Rules referred to in clause (ii) are modified or superseded by any subsequent statement, rule or regulation of the Commission or any statement of a division thereof, or (c) any future releases, rules and regulations are published by the Commission from time to time pursuant to the Sarbanes-Oxley Act, which in any such case affects the form or substance of the required certification and results in the required certification being, in the reasonable judgment of the Master Servicer, materially more onerous than the form of certification required as of the Closing Date, the Sarbanes-Oxley Certification shall be as agreed to by the Master Servicer and the Depositor following a negotiation in good faith to determine how to comply with any such new requirements.

S&P : Standard and Poor’s Ratings Services, a division of The McGraw-Hill Companies, Inc., or any successor thereto. If S&P is designated as a Rating Agency in the Preliminary Statement, for purposes of Section 11.05(b), the address for notices to S&P shall be Standard and Poor’s Ratings Services, a division of The McGraw-Hill Companies, Inc., 55 Water Street, New York, New York 10041, Attention: Residential Mortgage Monitoring Group, or such other address as S&P may hereafter furnish to each other party to this Agreement.

Scheduled Payment : The scheduled monthly payment on a Mortgage Loan due on any Due Date allocable to principal and/or interest on such Mortgage Loan which, unless otherwise specified herein, shall give effect to any related Debt Service Reduction and any Deficient Valuation that affects the amount of the monthly payment due on such Mortgage Loan.

Securities Act : The Securities Act of 1933, as amended.

Security Agreement : With respect to a Cooperative Mortgage Loan, the agreement or mortgage creating a security interest in favor of the originator of the Cooperative Mortgage Loan in the related Cooperative Shares.

Senior Certificates : As specified in the Preliminary Statement.

Senior Enhancement Percentage : With respect to any Distribution Date on or after the Stepdown Date, a fraction (expressed as a percentage):

(a)

the numerator of which is the sum of:

(i)

the aggregate Class Principal Balance of the Mezzanine Certificates immediately prior to that Distribution Date and

(ii)

the Overcollateralization Amount, in each case prior to the distribution of the Principal Distribution Amount on such Distribution Date, and,

(b)

the denominator of which is the aggregate Stated Principal Balance of the Mortgage Loans after giving effect to distributions to be made on that Distribution Date.

Senior Principal Distribution Amount : For any Distribution Date, the excess of:

(a)

the aggregate Class Principal Balance of the Senior Certificates (other than the Interest Only Certificates) immediately prior to such Distribution Date, over

(b)

the lesser of (A) the product of (i) (x) 75.1251065375% on any Distribution Date on or after the Stepdown Date and prior to the Distribution Date in November 2012 or (y) 80.1000852300% on any Distribution Date on or after the Stepdown Date and on or after the Distribution Date in November 2012 and (ii) the aggregate Stated Principal Balance of the Loans as of the Due Date in the month of that Distribution Date (after giving effect to principal prepayments received in the related Prepayment Period) and (B) the aggregate Stated Principal Balance of the Loans as of the Due Date in the month of that Distribution Date (after giving effect to principal prepayments received in the related Prepayment Period) minus the OC Floor.

Servicers : AHM, Cenlar, Countrywide, GMACM, IndyMac and RFC.

Servicer Remittance Date : With respect to any Distribution Date, the 18th day of the month in which such Distribution Date occurs, or if such 18th day is not a Business Day, the first Business Day immediately preceding such 18th day.

Servicing Advances : All customary, reasonable and necessary “out of pocket” costs and expenses incurred in the performance by the Master Servicer of its master servicing obligations or the applicable Servicer, as the case may be, of its servicing obligations.

Servicing Agreements :

(a)

the AHM Servicing Agreement;

(b)

the Cenlar Servicing Agreement;

(c)

the Countrywide Servicing Agreement;

(d)

the GMACM Servicing Agreement;

(e)

the IndyMac Servicing Agreement

(f)

the RFC Servicing Agreement; and

(g)

the Assignment Agreements.

Servicing Criteria : The “servicing criteria” set forth in Item 1122(d) of Regulation AB, as such may be amended from time to time.

Servicing Fee : As to each Mortgage Loan and any Distribution Date, an amount payable out of each full payment of interest received on such Mortgage Loan and equal to one twelfth of the Servicing Fee Rate multiplied by the Principal Balance of such Mortgage Loan as of the Due Date in the month immediately preceding the month in which such Distribution Date occurs (after giving effect to any Scheduled Payments due on such Mortgage Loan on such Due Date).

Servicing Fee Rate : With respect to each Mortgage Loan, the per annum rate set forth on the Mortgage Loan Schedule.

Servicing Function Participant : Any Sub-Servicer or Subcontractor of a Servicer, the Master Servicer, the Custodian or the Trust Administrator, respectively.

Sixty-Day Delinquency Rate: With respect to any Distribution Date on or after the Stepdown Date, a fraction, expressed as a percentage, the numerator of which is the aggregate Stated Principal Balance for such Distribution Date of all Loans that were 60 or more days Delinquent as of the close of business on the last day of the calendar month preceding such Distribution Date (including Loans in foreclosure, bankruptcy and REO Properties) and the denominator of which is the aggregate Stated Principal Balance for such Distribution Date of the Loans as of the related Due Date (after giving effect to principal prepayments in the Prepayment Period related to that prior Due Date).

Standard & Poor’s Glossary : The Standard & Poor’s LEVELS® Glossary.

Startup Day : The Closing Date.

Stated Principal Balance : For any Mortgage Loan and date of determination, the unpaid principal balance of the Mortgage Loan as of the most recent Due Date, as specified in its amortization schedule at that time (before any adjustment to the amortization schedule for any moratorium or similar waiver or grace period), after giving effect to (i) the payment of principal due on that Due Date, irrespective of any delinquency in payment by the related mortgagor, (ii) prepayments of principal and the principal portion of liquidation proceeds received with respect to that Loan through the last day of the related Prepayment Period and (iii) any Deferred Interest added to the principal balance of that Mortgage Loan pursuant to the terms of the related mortgage note on or prior to that Due Date. The Stated Principal Balance of a Liquidated Loan is zero.

Stepdown Date : The earlier to occur of:

(a)

the Distribution Date following the Distribution Date on which the aggregate Class Principal Balance of the Senior Certificates (other than the Interest Only Certificates) is reduced to zero, and

(b)

the later to occur of (x) the Distribution Date in November 2009 and (y) the first Distribution Date on which a fraction, the numerator of which is the excess of the aggregate Stated Principal Balance of the Loans as of the Due Date in the month preceding the month in which that Distribution Date occurs (after giving effect to principal prepayments received in the Prepayment Period related to that Due Date) over the aggregate Class Principal Balance of the Senior Certificates (other than the Interest Only Certificates) immediately prior to that Distribution Date, and the denominator of which is the aggregate Stated Principal Balance of the Loans as of the Due Date in the month of the current Distribution Date (after giving effect to principal prepayments received in the Prepayment Period related to that Due Date) is greater than or equal to (a) 24.8748934625% on any Distribution Date prior to the Distribution Date in November 2012 and (b) 19.8999147700% on any Distribution Date on or after the Distribution Date in November 2012.

Stepdown Target Subordination Percentage : With respect to each Class of Mezzanine Certificates, the respective percentages indicated in the following table:

	Stepdown Target Subordination Percentage (1)	Stepdown Target Subordination Percentage (2)
Class M-1	19.1248175573%	15.2998540459%
Class M-2	13.8749102173%	11.0999281738%
Class M-3	12.1249411039%	9.6999528832%
Class M-4	8.2500006263%	6.6000005011%
Class M-5	5.9999871208%	4.7999896966%
Class M-6	4.4999781171%	3.5999824936%
Class M-7	3.1248870817%	2.4999096654%
Class M-8	1.2500000000%	1.0000000000%

__________________

(1) For any Distribution Date occurring on or after the Stepdown Date and prior to the Distribution Date occurring in November 2012.

(2) For any Distribution Date occurring on or after the Stepdown Date and on or after the Distribution Date in November 2012.

Stock Power : With respect to a Cooperative Mortgage Loan, an assignment of the stock certificate or an assignment of the Cooperative Shares issued by the Cooperative Corporation.

Subcontractor : Any vendor, subcontractor or other Person that is not responsible for the overall servicing of Mortgage Loans but performs one or more discrete functions identified in Item 1122(d) of Regulation AB with respect to Mortgage Loans under the direction or authority of any Servicer (or a Sub-Servicer of any Servicer), the Master Servicer, the Custodian or the Trust Administrator.

Subordinated Portion: For any Distribution Date and Loan Group, the excess, if any, of (x) the aggregate Stated Principal Balance of the Mortgage Loans in the related Loan Group as of the Due Date in the prior month (after giving effect to Principal Prepayments in the Prepayment Period related to that prior Due Date) over (y) the aggregate Class Principal Balance of the related Senior Certificates (other than the Interest Only Certificates) immediately prior to such Distribution Date.

Subservicer : Any Person that services Mortgage Loans on behalf of a Servicer, and is responsible for the performance (whether directly or through subservicers or Subcontractors) of servicing functions required to be performed under this Agreement, any related Servicing Agreement or any sub-servicing agreement that are identified in Item 1122(d) of Regulation AB.

Subsequent Recoveries : Unanticipated amounts received on a liquidated Mortgage Loan the absence of which resulted in a Realized Loss in a prior month.

Subsidiary REMIC : As specified in the Preliminary Statement.

Subsidiary REMIC Regular Interest : As specified in the Preliminary Statement.

Substitution Adjustment Amount : With respect to any Mortgage Loan that is purchased by the originator is an amount equal to the excess of the Principal Balance of the related Deleted Mortgage Loan over the Principal Balance of such Eligible Substitute Mortgage Loan, pursuant to Section 2.03.

Supplemental Interest Trust : A trust created pursuant to Section 4.06 of this Agreement, separate from the Trust, the corpus of which shall be held by the Supplemental Interest Trust Trustee, in trust, for the benefit of the holders of the Senior Certificates and the Mezzanine Certificates.

Supplemental Interest Trust Trustee : Wells Fargo, not in its individual capacity, but solely in its capacity as trustee of the Supplemental Interest Trust for the benefit of the Holders of the Certificates under this Agreement, and any successor thereto.

Tax Matters Person : In the case of each REMIC created by this Agreement, the person designated as “tax matters person” in the manner provided under Treasury Regulations Section 1.860F-4(d) and Treasury Regulations Section 301.6231(a)(7)-1 for such REMIC.

Termination Price : As defined in Section 10.01(d).

Transfer : Any direct or indirect transfer or sale of any Ownership Interest in a Residual Certificate.

Transferor : UBS Real Estate Securities Inc., a Delaware corporation, seller of the Mortgage Loans to the Depositor pursuant to the Mortgage Loan Purchase Agreement.

Trigger Event : A Trigger Event is in effect with respect to any Distribution Date on or after the Stepdown Date if either a Delinquency Trigger Event is in effect with respect to that Distribution Date or a Cumulative Loss Trigger Event is in effect with respect to that Distribution Date.

Trust : As defined in Section 2.01(c).

Trust Administrator : Wells Fargo in its capacity as Trust Administrator hereunder, and its successors and assigns, or any successor trust administrator appointed hereunder.

Trust Administrator Compensation : All investment earnings on amounts on deposit in the Distribution Account.

Trust Collateral : As defined in Section 10.01(a).

Trust Fund : The corpus of the trust created hereunder consisting of: (a) the Mortgage Loan Purchase Agreement and the Servicing Agreements solely as each such Servicing Agreement relates to the Mortgage Loans being serviced by the related Servicer (other than those rights under the Servicing Agreements that do not relate to servicing of the Mortgage Loans (including, without limitation, the representations and warranties made by the applicable Servicer (with respect to the Mortgage Loans sold to the Transferor) and the document delivery requirements of such Servicer and the remedies (including indemnification) available for breaches thereto), which rights were retained by the Transferor pursuant to the Assignment Agreements); (b) the Mortgage Loans and all interest and principal received on or with respect thereto after the Cut-off Date to the extent not applied in computing the Cut-off Date Principal Balance thereof; (c) the Collection Account, the Policy Payments Account, the Distribution Account and all amounts deposited therein pursuant to the applicable provisions of this Agreement (other than, in the case of the Collection Account, any prepayment penalties (exclusive of the Class P Prepayment Charges) deposited therein which shall be retained by the Transferor); (d) property that secured a Mortgage Loan and has been acquired by foreclosure, deed-in-lieu of foreclosure or otherwise; and (e) all proceeds of the conversion, voluntary or involuntary, of any of the foregoing.

Trustee : U.S. Bank, and, if a successor trustee is appointed hereunder, such successor.

UBSRES : UBS Real Estate Securities Inc., and its successors and assigns.

Underwriter’s Exemption : Prohibited Transaction Exemption 2002-41, 67 Fed. Reg. 54487 (2002), as amended (or any successor thereto), or any substantially similar administrative exemption granted by the U.S. Department of Labor.

Unpaid Realized Loss Amount : For any Class of Certificates, (x) the portion of the aggregate Applied Realized Loss Amount previously allocated to that Class remaining unpaid from prior Distribution Dates minus (y) any increase in the Class Principal Balance of that Class due to the allocation of Subsequent Recoveries to the Class Principal Balance of that Class.

U.S. Bank : U.S. Bank National Association, a national banking association organized under the laws of the United States, and its successors and assigns.

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 Senior Certificates, the Mezzanine Certificates and the Class C Certificates in proportion to the then outstanding Certificate Principal Balances of their respective Certificates, 1% of all Voting Rights will be allocated among 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.

Wells Fargo : Wells Fargo Bank, N.A. and its successors and assigns.

Section 1.02. Certain Calculations.

Unless otherwise specified herein, for purposes of determining amounts with respect to the Certificates and the rights and obligations of the parties hereto, all calculations of interest for the Delay Certificates (other than as provided in the Mortgage Loan documents) provided for herein shall be made on the basis of a 360-day year consisting of twelve 30 day months and all calculations of interest for the No Delay Certificates (other than as provide din the Mortgage Loan documents) provided for herein shall be made on the basis of the actual number of days in a year assumed to consist of 360 days.

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;
REPRESENTATIONS AND WARRANTIES

Section 2.01. Conveyance of Mortgage Loans.

(a)

The Depositor, concurrently with the execution and delivery hereof, hereby sells, transfers, assigns, sets over and otherwise conveys to the Trustee for the benefit of the Certificateholders and the Certificate Insurer, without recourse, all the right, title and interest of the Depositor in and to the Trust Fund together with all rights assigned by the Transferor to the Depositor, pursuant to the Mortgage Loan Purchase Agreement, solely with respect to the Mortgage Loans, and, solely with respect to the Mortgage Loans, all of the Transferor’s right, title and interest in and to the Servicing Agreements solely as each such Servicing Agreement relates to the Mortgage Loans being serviced by the related Servicer (other than those rights under the Servicing Agreements that do not relate to servicing of the Mortgage Loans (including, without limitation, the representations and warranties made by each Servicer (in its capacity as loan seller to the Transferor) and the document delivery requirements of such Servicer and the remedies (including indemnification) available for breaches thereto), which rights were retained by the Transferor pursuant to the Assignment Agreements. In connection with the foregoing assignments, the Transferor has caused each Servicer to enter into the related Assignment Agreement.

(b)

(i) In connection with the transfer and assignment set forth in clause (a) above, the Depositor has delivered or caused to be delivered to the Custodian, on behalf of the Trustee, for the benefit of the Certificateholders and the Certificate Insurer the following documents or instruments with respect to each Mortgage Loan that is not a Cooperative Mortgage Loan so assigned:

(A)

the original Mortgage Note endorsed by manual or facsimile signature in blank in the following form: “Pay to the order of ___________ without recourse,” with all intervening endorsements showing a complete chain of endorsement from the originator to the Person endorsing the Mortgage Note (each such endorsement being sufficient to transfer all right, title and interest of the party so endorsing, as noteholder or assignee thereof, in and to that Mortgage Note); or, with respect to any Lost Mortgage Note, a lost note affidavit from the related originator or the Transferor stating that the original Mortgage Note was lost or destroyed, together with a copy of such Mortgage Note;

(B)

except as provided below, the original recorded Mortgage or a copy of such Mortgage certified by the related originator as being a true and complete copy of the Mortgage;

(C)

a duly executed assignment of the Mortgage (which may be included in a blanket assignment or assignments), endorsed in blank (except with respect to MERS designated Mortgage Loans) together with, except as provided below, all interim recorded assignments of such mortgage (each such assignment, when duly and validly completed, to be in recordable form and sufficient to effect the assignment of and transfer to the assignee thereof, under the Mortgage to which the assignment relates); provided that, if the related Mortgage has not been returned from the applicable public recording office, such assignment of the Mortgage may exclude the information to be provided by the recording office;

(D)

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

(E)

except as provided below, the original or duplicate original lender’s title policy and all riders thereto.

(ii)

In connection with the transfer and assignment set forth in clause (a) above, the Depositor has delivered or caused to be delivered to the Custodian, on behalf of the Trustee, for the benefit of the Certificateholders and the Certificate Insurer the following documents or instruments with respect to each Cooperative Mortgage Loan so assigned:

(A)

the Cooperative Shares, together with the Stock Power in blank;

(B)

the executed Security Agreement;

(C)

the executed Proprietary Lease and the Assignment of Proprietary Lease to the originator of the Cooperative Mortgage Loan;

(D)

the executed Recognition Agreement, if any;

(E)

copies of the original Financing Statement, and any continuation statements, filed by the originator of such Cooperative Mortgage Loan as secured party, each with evidence of recording thereof, evidencing the interest of the originator under the Security Agreement and the Assignment of Proprietary Lease;

(F)

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

(G)

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

(H)

for any Cooperative Mortgage Loan that has been modified or amended, the original instrument or instruments effecting such modification or amendment.

Notwithstanding the foregoing, if any Mortgage has been recorded in the name of Mortgage Electronic Registration System, Inc. (“MERS”) or its designee, no assignment of Mortgage in favor of the Trustee will be required to be prepared or delivered and instead, the Master Servicer shall enforce the obligations of the applicable Servicer under its related Servicing Agreement to cause the Trustee to be shown as the owner of the related Mortgage Loan on the records of MERS for the purpose of the system of recording transfers of beneficial ownership of mortgages maintained by MERS.

If in connection with any Mortgage Loan the Depositor cannot deliver (a) the original recorded Mortgage, (b) all interim recorded assignments or (c) the lender’s title policy (together with all riders thereto) satisfying the requirements of clause (b)(i)(B), (C) or (E) above, respectively, concurrently with the execution and delivery hereof because such document or documents have not been returned from the applicable public recording office in the case of clause (b)(i)(B) or (C) above, or because the title policy has not been delivered to either the Custodian or the Depositor by the applicable title insurer in the case of clause (b)(i)(E) above, the Depositor shall promptly deliver to the Custodian, in the case of clause (b)(i)(B) or (C) above, such original Mortgage or such interim assignment, as the case may be, with evidence of recording indicated thereon upon receipt thereof from the public recording office, or a copy thereof, certified, if appropriate, by the relevant recording office, but in no event shall any such delivery of the original Mortgage and each such interim assignment or a copy thereof, certified, if appropriate, by the relevant recording office, be made later than one year following the Closing Date, or, in the case of clause (b)(i)(E) above, no later than 120 days following the Closing Date; provided , however , in the event the Depositor is unable to deliver by such date each Mortgage and each such interim assignment by reason of the fact that any such documents have not been returned by the appropriate recording office, or, in the case of each such interim assignment, because the related Mortgage has not been returned by the appropriate recording office, the Depositor shall deliver such documents to the Custodian as promptly as possible upon receipt thereof and, in any event, within 720 days following the Closing Date. The Depositor shall forward or cause to be forwarded to the Custodian (a) from time to time additional original documents evidencing an assumption or modification of a Mortgage Loan and (b) any other documents required to be delivered by the Depositor to the Custodian. In the event that the original Mortgage is not delivered and in connection with the payment in full of the related Mortgage Loan and the public recording office requires the presentation of a “lost instruments affidavit and indemnity” or any equivalent document, because only a copy of the Mortgage can be delivered with the instrument of satisfaction or reconveyance, the Custodian shall execute and deliver or cause to be executed and delivered such a document to the public recording office. In the case where a public recording office retains the original recorded Mortgage or in the case where a Mortgage is lost after recordation in a public recording office, the Transferor shall deliver to the Custodian a copy of such Mortgage certified by such public recording office to be a true and complete copy of the original recorded Mortgage.

If an assignment of Mortgage is to be recorded, the Depositor shall cause the Mortgage to be assigned to “U.S. Bank National Association, in trust for the MASTR Adjustable Rate Mortgages Trust 2006-OA2 for the benefit of the Holders of the Mortgage Pass-Through Certificates, Series 2006-OA2” and, subject to Section 2.02, the Master Servicer shall enforce the obligations of the related Servicer pursuant to the related Servicing Agreement to (i) cause such assignment to be in proper form for recording in the appropriate public office for real property records and (ii) cause to be delivered for recording in the appropriate public office for real property records the assignments of the Mortgages to the Trustee, except that, with respect to any assignments of Mortgage as to which the related Servicer has not received the information required to prepare such assignment in recordable form, the related Servicer’s obligation to do so and to deliver the same for such recording shall be as soon as practicable after receipt of such information and in any event within ninety (90) days after receipt thereof and except that the related Servicer need not cause to be recorded any assignment which relates to a Mortgage Loan (a) in any state where, in an Opinion of Counsel addressed to the Trustee, such recording is not required to protect the Trustee’s interests in the Mortgage Loan against the claim of any subsequent transferee or any successor to or creditor of the Depositor or the Transferor, (b) in any state where recordation is not required by either Rating Agency to obtain the initial ratings on the Certificates set forth in the Prospectus Supplement or (c) with respect to any Mortgage which has been recorded in the name of MERS, or its designee. As of the date hereof, recordation is not required in any state by either Rating Agency to obtain the initial rating on the Certificates (upon which statement the Master Servicer, the Trustee and the Custodian may conclusively rely).

In the case of Mortgage Loans that have been prepaid in full as of the Closing Date, the Depositor, in lieu of delivering the above documents to the Custodian on behalf of the Trustee, will deposit in the Collection Account the portion of such payment that is required to be deposited in the Collection Account pursuant to Section 3.07 hereof.

(c)

The Depositor does hereby establish, pursuant to the further provisions of this Agreement and the laws of the State of New York, an express trust (the “Trust”) to be known, for convenience, as “MASTR Adjustable Rate Mortgages Trust 2006-OA2” and U.S. Bank National Association is hereby appointed as Trustee in accordance with the provisions of this Agreement.

(d)

The Depositor and the Trustee on behalf of the Trust agree and understand that it is not intended that any Loan be included in the Trust Fund that is (i) a “High Cost Home Loan” as defined in the New Jersey Home Ownership Act effective November 27, 2003, (ii) a “High Cost Home Loan” as defined in the New Mexico Home Loan Protection Act effective January 1, 2004, (iii) a “High Cost Home Mortgage Loan” as defined in the Massachusetts Predatory Home Loan Practices Act effective November 7, 2004, (iv) a “high risk home loan” under the Illinois High Risk Home Loan Act, effective as of January 1, 2004, or (v) a “high cost home loan” under the Indiana High Cost Home Loan Law, effective January 1, 2005. The Trustee shall be entitled to indemnification from the Depositor and the Trust Fund for any loss, liability or expense arising out of, or in connection with, the provisions of the preceding sentence, including, without limitation, all costs, liabilities and expenses (including reasonable legal fees and expenses) of investigating and defending itself against any claim, action or proceeding, pending or threatened, relating to such provisions.

(e)

Each of the Collection Account and Distribution Account shall at all times be an Eligible Account, provided that the Collection Account may be deemed to be a sub-account of the Distribution Account. If at any time either the Collection Account or the Distribution Account ceases to be an Eligible Account, the Master Servicer or the Trust Administrator, as applicable, shall immediately establish and maintain a new Collection Account or Distribution Account, as applicable, that is an Eligible Account, and shall immediately transfer all funds on deposit in the former Collection Account or Distribution Account, as applicable, to the new Collection Account or Distribution Account, as applicable.

(f)

The Depositor hereby directs the Trust Administrator to execute, deliver and perform its obligations under the Cap Contract. The Transferor, the Depositor, the Master Servicer, the Trustee and the Holders of the Senior Certificates (other than Group 3 Certificates) and the Mezzanine Certificates by their acceptance of such Certificates acknowledge and agree that the Trust Administrator shall execute, deliver and perform its obligations under the Cap Contract and shall do so solely in its capacity as Trust Administrator, and not in its individual capacity. Every provision of this Agreement relating to the conduct or affecting the liability of or affording protection to the Trust Administrator shall apply to the Trust Administrator’s execution of the Cap Contract, and the performance of its duties and satisfaction of its obligations thereunder.

Section 2.02. Acceptance by Trustee of the Mortgage Loans.

The Custodian, on behalf of the Trustee, acknowledges receipt of the documents identified in the Initial Certification issued by it in the form annexed hereto as Exhibit G and declares that it holds and will hold such related documents and the other documents delivered to it constituting the Mortgage Files, and the Custodian and Trustee together declare that it holds or will hold such other assets as are included in the Trust Fund, in trust for the exclusive use and benefit of all present and future Certificateholders and the Certificate Insurer. The Custodian acknowledges that it will maintain possession of the Mortgage Notes held by it in the State of Minnesota, unless otherwise permitted by the Rating Agencies, the Trustee and the Certificate Insurer.

The Custodian agrees to execute and deliver on the Closing Date to the Depositor and the Trustee an Initial Certification in the form annexed hereto as Exhibit G. Based on its review and examination, and only as to the documents identified in such Initial Certification, the Custodian acknowledges, subject to any applicable exceptions noted on Exhibit G, that such documents appear regular on their face and relate to such Mortgage Loan. The Custodian shall be under no duty or obligation to (i) inspect, review or examine said documents, instruments, certificates or other papers to determine that the same are genuine, enforceable or appropriate for the represented purpose or that they have actually been recorded in the real estate records or that they are other than what they purport to be on their face or (ii) determine whether the Mortgage File should include any of the documents specified in Section 2.01(b)(i)(D) with respect to each Mortgage Loan that is not a Cooperative Mortgage Loan and Section 2.01(b)(ii)(H) with respect to each Cooperative Mortgage Loan, unless the Mortgage Loan Schedule indicates that such documents are applicable.

Not later than 90 days after the Closing Date, the Custodian shall deliver to the Depositor, the Certificate Insurer, the Trustee and the Transferor a Final Certification in the form annexed hereto as Exhibit H, with any applicable exceptions noted thereon. The Custodian shall make available, upon request of any Certificateholder or the Certificate Insurer, a copy of any exceptions noted on the Initial Certification or the Final Certification. The Custodian shall make available, upon request of the Trustee, the identity of the originator for any Mortgage Loan with a material exception.

If, in the course of such review, the Custodian finds any document constituting a part of a related Mortgage File which does not meet the requirements of Section 2.01, the Custodian shall list such as an exception in the Final Certification; provided , however , that the Custodian shall not make any determination as to whether (i) any endorsement is sufficient to transfer all right, title and interest of the party so endorsing, as noteholder or assignee thereof, in and to that Mortgage Note, (ii) any assignment is in recordable form or is sufficient to effect the assignment of and transfer to the assignee thereof under the mortgage to which the assignment relates or (iii) the Mortgage File should include any of the documents specified in Section 2.01(b)(i)(D) with respect to each Mortgage Loan that is not a Cooperative Mortgage Loan and Section 2.01(b)(ii)(H) with respect to each Cooperative Mortgage Loan, unless the Mortgage Loan Schedule indicates that such documents are applicable.

Upon receiving each Final Certification from the Custodian, the Trustee shall notify the Transferor and the Certificate Insurer of any document defects listed as exceptions in each such Final Certification. The Transferor shall promptly correct or cure such document defects, and if the Transferor fails to correct or cure the defect within ninety (90) days of the earlier of its discovery or its receipt of written notice of any document constituting a part of a Mortgage File that does not meet the requirements of Section 2.01, and such defect materially and adversely affects the interests of the Certificateholders or the Certificate Insurer in the related Mortgage Loan, the Transferor shall repurchase the affected Mortgage Loan from the Trustee at the Purchase Price. In each case, such Deleted Mortgage Loan will be removed from the Trust. Any such purchase of a Deleted Mortgage Loan shall not be effected prior to the delivery to the Custodian of a Request for Release substantially in the form of Exhibit M. The Purchase Price for any such Deleted Mortgage Loan shall be paid by the Transferor to the Master Servicer for deposit in the Collection Account on or prior to the Distribution Account Deposit Date for the Distribution Date in the month following the month of repurchase and, upon receipt of such deposit, the Master Servicer shall instruct the Custodian to release, and the Custodian shall release, the related Mortgage File to the Transferor and the Trustee shall execute and deliver at the Transferor’s written request such instruments of transfer or assignment prepared by the Transferor, in each case without recourse, representation or warranty, as shall be necessary to vest in the Transferor, or a designee, the Trustee’s interest in any Deleted Mortgage Loan released pursuant hereto. The Transferor shall promptly reimburse the Master Servicer and the Trustee for any expenses reasonably incurred by the Master Servicer or the Trustee in respect of enforcing such repurchase by the Transferor.

The Custodian shall retain possession and custody of each related Mortgage File in accordance with and subject to the terms and conditions set forth herein. Pursuant to the terms of the related Servicing Agreement, the Master Servicer shall cause each of the related Servicers to promptly deliver to the Custodian who shall thereupon promptly deposit within each Mortgage File, upon the execution or receipt thereof, the originals of such other documents or instruments constituting the Mortgage File as come into the possession of the related Servicers from time to time.

It is understood and agreed that the obligations of the Transferor hereunder to purchase any Mortgage Loan which does not meet the requirements of Section 2.01 above or substitute for the related Mortgage Loan an Eligible Substitute Mortgage Loan shall constitute the sole remedies respecting such defect available to the Trustee, the Master Servicer, the Depositor and any Certificateholder.

Section 2.03. Remedies for Breaches of Representations and Warranties.

The Transferor hereby makes the representations and warranties set forth in Schedule II hereto, and by this reference incorporated herein, to the Depositor, the Certificate Insurer and the Trustee, as of the Closing Date, or if so specified therein, as of the Cut-off Date. With respect to any representation and warranties set forth on Schedule II hereto which are made to the best of the Transferor’s knowledge if it is discovered by any of the Depositor, the Certificate Insurer, the Master Servicer, the Transferor, any Servicer, the Trustee or the Trust Administrator that the substance of such representation and warranty is inaccurate and such inaccuracy materially and adversely affects the value of the related Mortgage Loan or the interests of the Certificateholders or the Certificate Insurer therein, notwithstanding the Transferor’s lack of knowledge with respect to the substance of such representation or warranty, such inaccuracy shall be deemed a breach of the applicable representation or warra