POOLING AND SERVICING AGREEMENT

THIS POOLING AND SERVICING AGREEMENT, dated as of April 1, 2006, among HSI ASSET SECURITIZATION CORPORATION, as depositor (the “ Depositor ”), NATIONAL CITY HOME LOAN SERVICES, INC., as servicer (the “ Servicer ”), FIRST FRANKLIN FINANCIAL CORPORATION, as mortgage loan seller (the “ Mortgage Loan Seller ”), WELLS FARGO BANK, N.A., a national banking association, as master servicer (in such capacity, the “ Master Servicer ”) as securities administrator (in such capacity, the “ Securities Administrator ”) and as custodian (in such capacity, “the Custodian ”), and DEUTSCHE BANK NATIONAL TRUST COMPANY, a national banking association, as trustee (the “ Trustee ”).

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

The Securities Administrator on behalf of the Trust Fund (exclusive of (i) the Swap Agreement, (ii) the Cap Agreement (iii) the right to receive and the obligation to pay Basis Risk Carryover Amounts, (iv) the Supplemental Interest Trust and the Supplemental Interest Trust Account and (v) the obligation to pay Class I Shortfalls (collectively, the “ Excluded Trust Assets ”) shall elect that two segregated asset pools within the Trust Fund 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, “ REMIC 1 ,” REMIC 2, ” “REMIC 3” and “ REMIC 4 ,”; REMIC 4 also being referred to herein as the “ Upper Tier 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 election.

Each Certificate, other than the Class R Certificates, represents ownership of a regular interest in the Upper Tier REMIC for purposes of the REMIC Provisions. In addition, each Certificate, other than the Class R, Class X and Class P Certificates, represents (i) the right to receive payments with respect to any Basis Risk Carryover Amounts and (ii) the obligation to pay Class I Shortfalls. The Class R Certificate represents ownership of the sole Class of residual interest in each of REMIC 1, REMIC 2, REMIC 3 and the Upper Tier REMIC for purposes of the REMIC Provisions.

The Upper Tier REMIC shall hold as its assets the uncertificated Lower Tier Interests in REMIC 3, other than the Class LT3-R interest, and each such Lower Tier Interest is hereby designated as a regular interest in REMIC 3 for purposes of the REMIC Provisions. REMIC 3 shall hold as its assets the uncertificated Lower Tier Interests in REMIC 2, and each such Lower Tier Interest is hereby designated as a regular interest in REMIC 2. REMIC 2 shall hold as its assets the uncertificated Lower Tier Interests in REMIC 1, and each such Lower Tier Interest is hereby designated as a regular interest in REMIC 1. REMIC 1 shall hold as its assets the property of the Trust Fund other than the Lower Tier Interests in REMIC 1, REMIC 2 and REMIC 3 and the Excluded Trust Assets.

(i)   first, to each interest in REMIC 3 having a Corresponding Class in REMIC 4 (other than a REMIC 3 interest having an “A-IO” in its class designation) until the outstanding principal amount of each such interest equals one-half of the outstanding principal amount of the Corresponding Class of Certificates for such interest immediately after such Distribution Date;

(ii)   finally, to the Class LT3-Q Interest, any remaining amounts.

The Upper Tier REMIC shall issue the following Classes of Upper Tier REMIC Regular Interests and each such interest, other than the Class R Interest, is hereby designated as a regular interest in the Upper Tier REMIC.

The minimum denomination for each Class of Certificates, other than the Class P, Class R and the Class X Certificates, will be $25,000 of Certificate Balance (notional balance in the case of Class A-IO Certificates) ($100,000 with respect to initial investors resident in a Member State of the European Economic Area subject to Prospectus Directive 2003/71/EC) with integral multiples of $1 in excess thereof, except that one Certificate in each Class may be issued in a different amount. The minimum denomination for each of the Class P and Class X Certificates will be a 10.00% Percentage Interest in such Class, and the minimum denomination for the Class R Certificates shall be 100% Percentage Interest in such Class.

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

ERISA-Restricted

ERISA-Restricted

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 8.12(a)(ii).

Accepted Servicing Practices : With respect to any Mortgage Loan and the Servicer, the servicing and administration of such Mortgage Loan (i) in the same manner in which, and with the same care, skill, prudence and diligence with which the Servicer generally services and administers similar mortgage loans with similar mortgagors (A) for other third parties, giving due consideration to customary and usual standards of practice of prudent institutional residential mortgage lenders servicing their own mortgage loans or (B) held in the Servicer’s own portfolio, whichever standard is higher, and (ii) in accordance with applicable local, state and federal laws, rules and regulations.

Account : Any of the Collection Account, the Distribution Account and any Escrow Account, and with respect to the Supplemental Interest Trust, the Excess Reserve Fund Account and the Supplemental Interest Trust Account. Each Account shall be an Eligible Account.

Additional Disclosure Notification : The form of notice set forth on Exhibit Y.

Additional Form 10-D Disclosure : As defined in Section 8.12(a)(i).

Additional Form 10-K Disclosure : As defined in Section 8.12(a)(ii).

Additional Termination Event : As defined in the Cap Agreement or the Swap Agreement, as applicable.

Adjustable Rate Mortgage Loan : A Mortgage Loan which provides for the adjustment of the Mortgage Rate payable in respect thereto.

Adjustment Date : As to any Adjustable Rate Mortgage Loan, the first Due Date on which the related Mortgage Rate adjusts as set forth in the related Mortgage Note and each Due Date thereafter on which the Mortgage Rate adjusts as set forth in the related Mortgage Note.

Advance : Any P&I Advance or Servicing Advance.

Affected Party : As defined in the Swap Agreement.

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

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

Amounts Held for Future Distribution : As to the Certificates on any Distribution Date, the aggregate amount held in the Collection Account at the close of business on the related Determination Date on account of (i) Principal Prepayments, Insurance Proceeds, Condemnation Proceeds, Liquidation Proceeds and Subsequent Recoveries on the Mortgage Loans received after the end of the related Prepayment Period and (ii) all Scheduled Payments on the Mortgage Loans due after the end of the related Due Period.

Applied Realized Loss Amount : With respect to any Distribution Date, the amount, if any, by which the aggregate Class Certificate Balance of the LIBOR Certificates and the Principal-Only Certificates after distributions of principal on such Certificates on such Distribution Date exceeds the aggregate Stated Principal Balance of the Mortgage Loans for such Distribution Date.

Appraised Value : The value set forth in an appraisal made in connection with the origination of the related Mortgage Loan as the value of the Mortgaged Property.

Assignment of Mortgage : An assignment of the Mortgage, notice of transfer or equivalent instrument in recordable form (other than the assignee’s name and recording information not yet returned from the recording office), reflecting the sale of the Mortgage to the Trustee.

Available Funds : With respect to any Distribution Date and the Mortgage Loans to the extent received by the Master Servicer (x) the sum of (i) all scheduled installments of interest (net of the related Expense Fees) and principal due on the Due Date on such Mortgage Loans in the related Due Period and received by the Servicer on or prior to the related Determination Date, together with any P&I Advances in respect thereof; (ii) all Condemnation Proceeds, Insurance Proceeds, Liquidation Proceeds and Subsequent Recoveries received by the Servicer during the related Prepayment Period (in each case, net of unreimbursed expenses incurred in connection with a liquidation or foreclosure and unreimbursed Advances, if any); (iii) all partial or full prepayments on the Mortgage Loans received by the Servicer during the related Prepayment Period together with all Compensating Interest paid by the Servicer in connection therewith (excluding any Prepayment Charges); (iv) all Substitution Adjustment Amounts with respect to the substitutions of Mortgage Loans that occur on or prior to the related Determination Date; (v) all amounts received with respect to such Distribution Date as the Repurchase Price in respect of a Mortgage Loan repurchased by the Mortgage Loan Seller or the Sponsor on or prior to the related Determination Date; and (vi) the proceeds with respect to the termination of the Trust Fund pursuant to clause (a) of Section 11.01; reduced by (y) amounts in reimbursement for Advances previously made with respect to the Mortgage Loans and other amounts as to which the Servicer, the Depositor, the Master Servicer, the Securities Administrator or the Trustee are entitled to be paid or reimbursed pursuant to this Agreement.

Back-up Certification : As defined in Section 3.24.

Basic Principal Payment Amount : With respect to any Distribution Date, the excess of (i) the Principal Remittance Amount for such Distribution Date over (ii) the Excess Overcollateralization Amount, if any, for such Distribution Date.

Basis Risk Carryover Amount : With respect to each Class of LIBOR Certificates, as of any Distribution Date, the sum of (A) if on such Distribution Date the Interest Rate for any Class of LIBOR Certificates is based upon the Group I Available Funds Cap, the Group II Available Funds Cap or the Class M Available Funds Cap, as applicable, the excess of (i) the amount of interest such Class of Certificates would otherwise be entitled to receive on such Distribution Date had such rate been calculated (x) as the sum of LIBOR and the applicable Interest Margin on such Class of Certificates for such Distribution Date, over (ii) the amount of interest payable on such Class of Certificates at, with respect to the Class I-A Certificates, the Group I Available Funds Cap, at, with respect to the Class II-A-1, Class II-A-2, Class II-A-3 and Class II-A-4 Certificates, the Group II Available Funds Cap, and at, with respect to any Class M Certificate, the Class M Available Funds Cap, as applicable, for such Distribution Date and (B) the portion of any such excess described in clause (A) for such Class of Certificates from all previous Distribution Dates not previously paid, together with interest thereon at a rate equal the applicable Interest Rate for each such Class of Certificates for such Distribution Date. With respect to the Interest-Only Certificates, as of any Distribution Date, the sum of (A) if on such Distribution Date the Interest Rate of the Interest-Only Certificates is based on the Class A-IO Available Funds Cap, the excess of (i) the amount of interest that the Interest-Only Certificates would otherwise have been entitled to receive on such Distribution Date had the Interest Rate equaled 1.50% per annum over (ii) the amount of interest payable on the Interest-Only Certificates if subject to the Class A-IO Available Funds Cap for such Distribution Date and (B) the portion of such excess described in clause (A) for the Interest-Only Certificates from all previous Distribution Dates not previously paid, together with interest thereon at a rate equal to 1.50% per annum.

Basis Risk Payment : For any Distribution Date, an amount equal to the lesser of (i) the aggregate of the Basis Risk Carryover Amounts of the LIBOR Certificates and the Interest-Only Certificates for such Distribution Date and (ii) the Class X Distributable Amount (prior to any reduction for Basis Risk Payments).

Best’s : Best’s Key Rating Guide, as the same shall be amended from time to time.

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

Business Day : Any day other than (i) Saturday or Sunday, or (ii) a day on which banking and savings and loan institutions, in (a) the States of New York, California, Maryland or Minnesota, (b) the Commonwealth of Pennsylvania or any other State in which the Servicer’s servicing operations are located, or (c) any State in which the Corporate Trust Office is located, are authorized or obligated by law or executive order to be closed.

Cap Account : The sub-account of the Supplemental Interest Trust Account created pursuant to Section 4.06(a).

Cap Agreement : The interest rate cap agreement (Reference No. 2440376) entered into by the Supplemental Interest Trust and the Cap Counterparty, dated May 5, 2006, which agreement provides for the monthly payment specified to the Securities Administrator (for the benefit of Certificateholders) commencing with the Distribution Date in November 2006 and ending on the Distribution Date in August 2012, by the Cap Counterparty, but subject to the conditions set forth therein, together with any schedule, confirmations or other agreements relating thereto, attached as Exhibit P.

Cap Amount : With respect to each Distribution Date, the amount of any Cap Payment deposited into the Cap Account.

Cap Counterparty : The counterparty to the Supplemental Interest Trust under the Cap Agreement, and any successor in interest or its assigns. Initially, the Cap Counterparty shall be ABN AMRO Bank, N.V.

Cap Payment : With respect to each Distribution Date, any payment required to be made by the Cap Counterparty to the Supplemental Interest Trust pursuant to the terms of the Cap Agreement.

Cap Payment Dat e: For as long as the Cap Agreement is in effect or any amounts remain unpaid thereunder, the Business Day immediately preceding each Distribution Date.

Cap Replacement Receipts : As defined in Section 4.08(b)(i).

Cap Replacement Receipts Account : As defined in Section 4.08(b)(i).

Certificate Balance : With respect to any Certificate, other than a Class A-IO, Class X, Class P or Class R Certificate, at any date, the maximum dollar amount of principal to which the Holder thereof is then entitled hereunder, such amount being equal to the Denomination thereof minus all distributions of principal previously made with respect thereto and in the case of any Class M Certificates, reduced by any Applied Realized Loss Amounts allocated to such Class of Certificates pursuant to Section 4.05; provided, however , that immediately following the Distribution Date on which a Subsequent Recovery is distributed, the Class Certificate Balances of any Class or Classes of Certificates that have been previously reduced by Applied Realized Loss Amounts will be increased, in order of seniority, by the amount of any Subsequent Recovery distributed on such Distribution Date (up to the amount of Unpaid Realized Loss Amount for such Class or Classes for such Distribution Date). The Class P Certificates are issued with an initial Class P Principal Amount of $100. The Class X and Class R Certificates have no Certificate Balance. The Class A-IO Certificates are issued with a Class Notional Balance.

Certificate Group : The Group I Certificates or the Group II Certificates, as applicable.

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

Certificate Register : The register maintained pursuant to Section 5.02.

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 Depositor or any Affiliate of the Depositor 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 Depositor) owns 100.00% 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 Securities Administrator is entitled to rely conclusively on a certification of the Depositor or any Affiliate of the Depositor in determining which Certificates are registered in the name of an Affiliate of the Depositor.

Certification Parties : As defined in Section 3.24.

Certifying Person : As defined in Section 3.24.

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

Class I-A Certificates : All Certificates bearing the Class designation of “Class I-A”.

Class II-A-1 Certificates : All Certificates bearing the Class designation of “Class II-A-1”.

Class II-A-2 Certificates : All Certificates bearing the Class designation of “Class II-A-2”.

Class II-A-3 Certificates : All Certificates bearing the Class designation of “Class II-A-3”.

Class II-A-4 Certificates : All Certificates bearing the Class designation of “Class II-A-4”.

Class II-A-5 Certificates : All Certificates bearing the Class designation of “Class II-A-5”.

Class A Certificates : As specified in the Preliminary Statement.

Class A-IO Available Funds Cap : With respect to the Class A-IO Certificates and any Distribution Date, a per annum rate equal to (x) the weighted average of the Expense Adjusted Mortgage Rate of the Mortgage Loans then in effect on the beginning of the related Due Period minus (y) a percentage equal to the product of (i) a fraction, the numerator of which is equal to the Net Derivative Payment or Swap Termination Payment (other than a Swap Termination Payment resulting from a Derivative Counterparty Trigger Event) made to the Swap Counterparty with respect to such Due Period, and the denominator of which is equal to the Pool Balance as of the beginning of the related Due Period and (ii) 12.

Class A-IO Certificates : All Certificates bearing the Class designation of “Class A-IO”.

Class Certificate Balance : With respect to any Class of LIBOR Certificates and the Principal-Only Certificates and as to any date of determination, the aggregate of the Certificate Balances of all Certificates of such Class as of such date. With respect to the Class A-IO, Class X, Class P and Class R Certificates, zero. With respect to any Lower Tier Interest, the initial Class Principal Balance as shown or described in the table set forth in the Preliminary Statement to this Agreement for the issuing REMIC, as reduced by any principal distributed with respect to such Lower Tier Interest and Realized Losses allocated to such Lower Tier Interest.

Class I Shortfalls: As defined in Section 8.11 hereof. For purposes of clarity, the Class I Shortfall for any Distribution Date shall equal the amount payable to the Derivative Counterparty on such Distribution Date in excess of the amount payable with respect to the Class LT4-I interest in the Upper Tier REMIC on such Distribution Date, all as further provided in Section 8.11 hereof.

Class M Available Funds Cap : With respect to the Class M Certificates as of any Distribution Date, a per annum rate equal to the weighted average of the Group I Available Funds Cap and the Group II Available Funds Cap, weighted on the basis of the Group Subordinate Amount for the Group I Mortgage Loans and the Group Subordinate Amount for the Group II Mortgage Loans, respectively.

Class M Certificates : As specified in the Preliminary Statement.

Class M Principal Payment Amount : With respect to any Distribution Date and any Class of Class M Certificates, the lesser of (i) the excess of (a) the Principal Payment Amount over (b) the aggregate amount distributed on that Distribution Date as principal to all Classes of Certificates more senior than that Class of Class M Certificates ( provided , however , for this purpose, the Class M-1, Class M-2 and Class M-3 Certificates will be treated as having the same seniority) and (ii) the excess of (a) the sum of the aggregate Class Certificate Balances of all Class of Certificates more senior than that Class of Class M Certificates (after giving effect to all amounts distributed on that Distribution Date to those Classes of more senior certificates ( provided , however , for this purpose, the Class M-1, Class M-2 and Class M-3 Certificates will be treated as having the same seniority)) and the Class Certificate Balance of that Class of Class M Certificates immediately prior to that Distribution Date over (b) the lesser of:

(x)   the percentage set forth in the table below for the applicable Class of Class M Certificates multiplied by the aggregate Stated Principal Balance of the Mortgage Loans for that Distribution Date: