STRUCTURED ASSET INVESTMENT LOAN TRUST Mortgage Pass-Through Certificates, Series

PROSPECTUS SUPPLEMENT (To Prospectus dated September 26, 2005) $1,835,336,000 (Approximate) STRUCTURED ASSET INVESTMENT LOAN TRUST Pass-Through Certificates, Series 2005-11 Aurora Loan Services LLC Master Servicer Lehman Brothers Holdings Inc. Sponsor and Seller Structured Asset Securities Corporation Depositor Consider carefully the risk factors beginning on page S-18 of this prospectus supplement and on page 2 of the prospectus. For a list of capitalized terms used in this prospectus supplement and the prospectus, see the glossary of defined terms beginning on page S-105 in this prospectus supplement and the index of principal terms on page 158 in the prospectus. The certificates will represent interests in the trust fund only and will not represent interests in or obligations of any other entity. This prospectus supplement may be used to offer and sell the certificates offered hereby only if accompanied by the prospectus. The trust will issue certificates including the following classes offered hereby: Š Seven classes of senior certificates Š Eight classes of subordinate certificates The classes of certificates offered by this prospectus supplement are listed, together with their initial class principal amounts and interest rates, in the table under The Offered Certificates on page S-1 of this prospectus supplement. This prospectus supplement and the accompanying prospectus relate only to the offering of the certificates listed in the table on page S-1 and not to the other classes of certificates that will be issued by the trust fund as described in this prospectus supplement. Principal and interest will be payable monthly, as described in this prospectus supplement. The first expected distribution date will be January 25, 2006. Credit enhancement for the offered certificates includes excess interest, overcollateralization, subordination, loss allocation and limited crosscollateralization features and primary mortgage insurance. Amounts payable under an interest rate swap agreement and an interest rate cap agreement, both provided by HSBC Bank USA, National Association, will be applied to pay certain interest shortfalls, maintain overcollateralization and repay certain losses. The assets of the trust fund will primarily consist of three pools of conventional, first and second lien, adjustable and fixed rate, fully amortizing and balloon, residential mortgage loans, which were originated in accordance with underwriting guidelines that are not as strict as Fannie Mae and Freddie Mac guidelines. Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved the certificates or determined that this prospectus supplement or the accompanying prospectus is accurate or complete. Any representation to the contrary is a criminal offense. The certificates offered by this prospectus supplement will be purchased by Lehman Brothers Inc., as underwriter, from Structured Asset Securities Corporation, and are being offered from time to time for sale to the public in negotiated transactions or otherwise at varying prices to be determined at the time of sale. The underwriter has the right to reject any order. Proceeds to Structured Asset Securities Corporation from the sale of these certificates will be approximately 99.96% of their initial total class principal amount before deducting expenses. On or about December 28, 2005, delivery of the certificates offered by this prospectus supplement will be made through the book-entry facilities of The Depository Trust Company, Clearstream Banking Luxembourg and the Euroclear System. Underwriter: LEHMAN BROTHERS The date of this prospectus supplement is December 21, 2005

Important notice about information presented in this prospectus supplement and the accompanying prospectus: We provide information to you about the certificates offered by this prospectus supplement in two separate documents that progressively provide more detail: (1) the accompanying prospectus, which provides general information, some of which may not apply to your certificates and (2) this prospectus supplement, which describes the specific terms of your certificates. If information varies between this prospectus supplement and the accompanying prospectus, you should rely on the information in this prospectus supplement. You should rely only on the information contained or incorporated by reference in this prospectus supplement and the accompanying prospectus. We have not authorized anyone to provide you with different information. We are not offering the certificates in any state where the offer is not permitted. We do not claim that the information in this prospectus supplement and prospectus is accurate as of any date other than the dates stated on their respective covers. Dealers will deliver a prospectus supplement and prospectus when acting as underwriters of the certificates and with respect to their unsold allotments or subscriptions. In addition, all dealers selling the certificates will be required to deliver a prospectus supplement and prospectus for ninety days following the date of this prospectus supplement. We include cross-references in this prospectus supplement and the accompanying prospectus to captions in these materials where you can find further related discussions. The following tables of contents provide the pages on which these captions are located. For European Investors Only In relation to each Member State of the European Economic Area which has implemented the Prospectus Directive (each, a Relevant Member State ), the underwriter has represented and agreed that with effect from and including the date on which the Prospectus Directive is implemented in that Relevant Member State (the Relevant Implementation Date ) it has not made and will not make an offer of certificates to the public in that Relevant Member State prior to the publication of a prospectus in relation to the certificates which has been approved by the competent authority in that Relevant Member State or, where appropriate, approved in another Relevant Member State and notified to the competent authority in that Relevant Member State, all in accordance with the Prospectus Directive, except that it may, with effect from and including the Relevant Implementation Date, make an offer of certificates to the public in that Relevant Member State at any time: (a) to legal entities which are authorized or regulated to operate in the financial markets or, if not so authorized or regulated, whose corporate purpose is solely to invest in securities; (b) to any legal entity which has two or more of (1) an average of at least 250 employees during the last financial year; (2) a total balance sheet of more than 43,000,000 and (3) an annual net turnover of more than 50,000,000, as shown in its last annual or consolidated accounts; or (c) in any other circumstances which do not require the publication by the issuer of a prospectus pursuant to Article 3 of the Prospectus Directive. For the purposes of this provision, the expression an offer of certificates to the public in relation to any certificates in any Relevant Member State means the communication in any form and by any means of sufficient information on the terms of the offer and the certificates to be offered so as to enable an investor to decide to purchase or subscribe the certificates, as the same may be varied in that Member State by any measure implementing the Prospectus Directive in that Member State and the expression Prospectus Directive means Directive 2003/71/EC and includes any relevant implementing measure in each Relevant Member State. S-ii

Table of Contents Prospectus Supplement Page The Offered Certificates... S-1 SummaryofTerms... S-3 Risk Factors... S-18 Glossary... S-30 Description of the Certificates... S-30 General... S-30 Book-Entry Registration... S-31 Distributions of Interest... S-32 Determination of LIBOR... S-34 Distributions of Principal... S-35 Credit Enhancement... S-39 Supplemental Interest Trust... S-43 The Final Maturity Reserve Trust... S-47 Optional Purchase of the Loans.. S-48 Fees and Expenses of the Trust Fund... S-49 Description of the Pools... S-51 General... S-51 Adjustable Rate Loans... S-53 TheIndex... S-53 PrimaryInsurance... S-53 Pool 1 Loans... S-59 Pool 2 Loans... S-59 Pool 3 Loans... S-59 Additional Information... S-60 Underwriting Guidelines... S-60 BNC Underwriting Guidelines... S-60 General Underwriting Guidelines... S-62 The Master Servicer... S-64 The Servicers... S-66 General... S-66 Option One Corporation... S-66 JPMorgan Chase Bank, National Association... S-68 Wells Fargo Bank, N.A.... S-71 HomEq Servicing Corporation... S-71 Administration of the Trust Fund... S-73 Servicing and Administrative Responsibilities... S-73 Trust Accounts... S-76 Example of Distributions... S-77 Loan Servicing... S-79 General... S-79 Servicing Accounts and the Collection Account... S-80 Servicing Compensation and Payment of Expenses... S-80 Waiver or Modification of Loan Terms... S-80 Prepayment Interest Shortfalls... S-81 Advances... S-81 PrimaryInsurance... S-81 Collection of Taxes, Assessments and Similar Items... S-81 Insurance Coverage... S-81 Page EvidenceastoCompliance... S-82 Master Servicer Default; Servicer Default... S-82 Amendment of the Servicing Agreements... S-82 Custody of the Files... S-83 TheCreditRiskManager... S-83 Optional Purchase of Defaulted Loans... S-83 Special Servicer for Distressed Loans... S-83 PledgeofServicingRights... S-84 The Trust Agreement... S-84 General... S-84 The Issuing Entity... S-84 The Trustee... S-85 The Securities Administrator... S-85 AssignmentofLoans... S-85 Representations and Warranties... S-86 Certain Matters Under the Trust Agreement... S-87 Reports to Certificateholders... S-91 VotingRights... S-93 Yield, Prepayment and Life... S-93 General... S-93 Overcollateralization... S-97 Life... S-97 Material Federal Income Tax Considerations... S-98 General... S-98 Tax Treatment of the Offered Certificates... S-99 Legal Investment Considerations... S-101 ERISA Considerations... S-101 Use of Proceeds... S-102 Underwriting... S-102 LegalMatters... S-103 Ratings... S-103 Glossary of Defined Terms... S-105 Annex A: Global Clearance, Settlement and Tax Documentation Procedures... S-A-1 Annex B: Certain Characteristics of the Loans... S-B-1 Annex C-1: Assumed Loan Characteristics... S-C-1-1 Annex C-2: Principal Amount Decrement Tables... S-C-2-1 Annex D-1: Swap Agreement Scheduled Notional Amounts and Rates of Payment... S-D-1-1 Annex D-2: Interest Rate Cap Agreement Scheduled Notional Amounts and Strike Rate... S-D-2-1 S-iii

Prospectus Page Risk Factors... 2 Description of the Securities... 29 General... 29 Distributions on the Securities... 29 Optional Termination... 32 Optional Purchase of Securities... 32 Other Purchases... 32 Exchangeable Securities... 32 Book-Entry Registration... 34 Yield, Prepayment and Maturity Considerations... 39 Payment Delays... 39 PrincipalPrepayments... 39 Timing of Reduction of Principal Amount... 39 Interest or Principal Securities... 40 Final Scheduled Distribution Date... 40 Prepayments and Life... 40 Other Factors Affecting Life... 41 The Trust Funds... 43 General... 43 Ginnie Mae Certificates... 44 Fannie Mae Certificates... 46 Freddie Mac Certificates... 48 Private -Backed Securities... 50 TheLoans... 52 The Manufactured Home Loans... 58 Multifamily and Mixed Use Loans... 59 Pre-Funding Arrangements... 61 Collection Account and Distribution Account... 62 Other Funds or Accounts... 63 Loan Underwriting Procedures and Standards... 63 Underwriting Standards... 63 Loss Experience... 65 Representations and Warranties... 65 Substitution of Primary Assets... 67 Servicing of Loans... 67 General... 67 Collection Procedures; Escrow Accounts... 68 Deposits to and Withdrawals from the Collection Account... 68 Servicing Accounts... 70 Buy-Down Loans, GPM Loans and Other Subsidized Loans... 70 Page Advances and Other Payments, and Limitations Thereon... 72 Maintenance of Insurance Policies and Other ServicingProcedures... 72 Presentation of Claims; Realization Upon Defaulted Loans... 75 Enforcement of Due-On-Sale Clauses... 76 Certain Rights Related to Foreclosure... 76 Servicing Compensation and Payment of Expenses... 77 EvidenceastoCompliance... 78 Certain Matters Regarding the Master Servicer... 78 Certain Risks... 79 Credit Support... 79 General... 79 Subordinate Securities; Subordination Reserve Fund... 80 Cross-Support Features... 81 Insurance... 81 LetterofCredit... 82 Financial Guaranty Insurance Policy... 82 Reserve Funds... 82 Description of and Other Insurance... 83 InsuranceontheLoans... 83 Hazard Insurance on the Loans... 89 BankruptcyBond... 91 RepurchaseBond... 91 The Agreements... 91 Issuance of Securities... 91 Assignment of Primary Assets... 92 Repurchase and Substitution of Non-ConformingLoans... 94 Reports to Securityholders... 95 Investment of Funds... 96 Event of Default; Rights Upon Event of Default... 97 The Trustee... 99 Duties of the Trustee... 100 Resignation of Trustee... 100 Distribution Account... 100 Expense Reserve Fund... 101 Amendment of Agreement... 101 VotingRights... 102 REMIC Administrator... 102 Administration Agreement... 102 S-iv

Prospectus (Continued) Page PeriodicReports... 102 Termination... 102 Legal Aspects of Loans... 103 s... 103 Junior s; Rights of Senior s... 104 Cooperative Loans... 105 Foreclosure on s... 107 Realizing Upon Cooperative Loan Security... 108 RightsofRedemption... 109 Anti-Deficiency Legislation and Other Limitations on Lenders... 110 Servicemembers Civil Relief Act... 112 Environmental Considerations... 113 Due-on-SaleClausesinLoans... 114 Enforceability of Prepayment Charges, Late Payment Fees and Debt-Acceleration Clauses... 115 Equitable Limitations on Remedies... 115 Applicability of Usury Laws... 115 Multifamily and Mixed Use Loans... 116 Leases and Rents... 117 Default Interest and Limitations on Payment... 117 Secondary Financing; Due-on-Encumbrance Provisions... 117 Certain Laws and Regulations... 118 Americans with Disabilities Act... 118 Personal Property... 118 Page Adjustable Interest Rate Loans... 118 Manufactured Home Loans... 119 Material Federal Income Tax Considerations.. 122 Types of Securities... 123 Taxation of Securities Treated as Debt Instruments... 125 Exchangeable Securities... 131 REMIC Residual Certificates... 134 Grantor Trust Certificates... 140 Partner Certificates... 143 Special Tax Attributes... 145 Backup Withholding... 147 Reportable Transactions... 147 State and Local Tax Considerations... 148 ERISA Considerations... 148 General... 148 The Underwriter Exemption... 149 Additional Considerations for Securities whicharenotes... 153 Additional Fiduciary Considerations... 153 Legal Investment Considerations... 154 LegalMatters... 155 TheDepositor... 155 Use of Proceeds... 155 Plan of Distribution... 155 AdditionalInformation... 156 Incorporation of Certain Documents by Reference... 157 Reports to Securityholders... 157 IndexofPrincipalTerms... 158 S-v

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The Offered Certificates The certificates consist of the classes of certificates listed in the tables below, together with the Class B1, Class B2, Class P, Class X, Class LT-R and Class R Certificates. Only the classes of certificates listed in the tables below are offered by this prospectus supplement. Class Related Pools(s) Class Initial Amount (1) Rate (2) Principal Interest Interest Rate Formula (until Initial Optional Termination Date) (3)(4) Interest Rate Formula (after Initial Optional Principal Termination Date) (4)(5) Type Interest Type Initial Certificate Ratings Moody s S&P Fitch A1... 1 $ 47,815,000 4.59875% LIBOR plus 0.220% LIBOR plus 0.440% Senior Variable Rate Aaa AAA AAA A2... 2 $480,647,000 4.58875% LIBOR plus 0.210% LIBOR plus 0.420% Senior (6) Variable Rate Aaa AAA AAA A3... 2 $ 53,405,000 4.67875% LIBOR plus 0.300% LIBOR plus 0.600% Senior (6) Variable Rate Aaa AAA AAA A4... 3 $576,638,000 4.46875% LIBOR plus 0.090% LIBOR plus 0.180% Senior, Sequential Pay Variable Rate Aaa AAA AAA A5... 3 $100,000,000 4.66875% LIBOR plus 0.290% LIBOR plus 0.580% Senior, Sequential Pay (7) Variable Rate Aaa AAA AAA A6... 3 $166,582,000 4.59875% LIBOR plus 0.220% LIBOR plus 0.440% Senior, Sequential Pay (7) Variable Rate Aaa AAA AAA A7... 3 $114,349,000 4.73875% LIBOR plus 0.360% LIBOR plus 0.720% Senior, Sequential Pay Variable Rate Aaa AAA AAA M1... 1,2&3 $132,032,000 4.78875% LIBOR plus 0.410% LIBOR plus 0.615% Subordinated Variable Rate Aa2 AA AA M2... 1,2&3 $ 33,710,000 4.92875% LIBOR plus 0.550% LIBOR plus 0.825% Subordinated Variable Rate Aa3 AA- AA- M3... 1,2&3 $ 29,965,000 5.01875% LIBOR plus 0.640% LIBOR plus 0.960% Subordinated Variable Rate A1 A+ A+ M4... 1,2&3 $ 29,028,000 5.05875% LIBOR plus 0.680% LIBOR plus 1.020% Subordinated Variable Rate A2 A A M5... 1,2&3 $ 22,473,000 5.10875% LIBOR plus 0.730% LIBOR plus 1.095% Subordinated Variable Rate A3 A- A- M6... 1,2&3 $ 20,600,000 6.07875% LIBOR plus 1.700% LIBOR plus 2.550% Subordinated Variable Rate Baa1 BBB+ BBB+ M7... 1,2&3 $ 16,855,000 6.57875% LIBOR plus 2.200% LIBOR plus 3.300% Subordinated Variable Rate Baa2 BBB BBB M8... 1,2&3 $ 11,237,000 6.87875% LIBOR plus 2.500% LIBOR plus 3.750% Subordinated Variable Rate Baa3 BBB- BBB- (1) These balances are approximate, as described in this prospectus supplement. (2) Reflects the interest rate as of the closing date. (3) Reflects the interest rate formula up to and including the earliest possible distribution date on which the master servicer has the option to purchase the mortgage loans as described in this prospectus supplement under Description of the Certificates Optional Purchase of the Loans. (4) Subject to the applicable net funds cap, as described in this prospectus supplement under Summary of Terms The Certificates Payments on the Certificates Interest Payments. (5) Reflects the interest rate formula after the option to purchase the mortgage loans is not exercised by the master servicer at the earliest possible distribution date as described in this prospectus supplement under Description of the Certificates Optional Purchase of the Loans. (6) The Class A2 and Class A3 Certificates will receive payments of principal concurrently, in proportion to their class principal amounts, unless cumulative realized losses or delinquencies on the mortgage loans exceed certain levels, in which case these classes will be treated as senior, sequential pay classes, as described under Description of the Certificates Distributions of Principal Principal Distribution Priorities. (7) The Class A5 and Class A6 Certificates will receive payments of principal concurrently, in proportion to their class principal amounts, as described under Description of the Certificates Distributions of Principal Principal Distribution Priorities. S-1

The offered certificates will also have the following characteristics: Class Record Delay/Accrual Interest Accrual Date (1) Period (2) Convention Final Scheduled Expected Final Minimum Incremental Distribution Date (3) Distribution Date (4) Denominations (5) Denominations CUSIP Number A1... DD 0day Actual/360 1/25/2036 6/25/2012 $ 25,000 $1 86358E ZM 1 A2... DD 0day Actual/360 1/25/2036 6/25/2012 $ 25,000 $1 86358E ZN 9 A3... DD 0day Actual/360 1/25/2036 6/25/2012 $ 25,000 $1 86358E ZP 4 A4... DD 0day Actual/360 1/25/2036 11/25/2007 $ 25,000 $1 86358E ZQ 2 A5... DD 0day Actual/360 1/25/2036 3/25/2011 $ 25,000 $1 86358E ZR 0 A6... DD 0day Actual/360 1/25/2036 3/25/2011 $ 25,000 $1 86358E ZS 8 A7... DD 0day Actual/360 1/25/2036 6/25/2012 $ 25,000 $1 86358E ZT 6 M1... DD 0day Actual/360 1/25/2036 4/25/2012 $100,000 $1 86358E ZU 3 M2... DD 0day Actual/360 1/25/2036 6/25/2012 $100,000 $1 86358E ZV 1 M3... DD 0day Actual/360 1/25/2036 6/25/2012 $100,000 $1 86358E ZW 9 M4... DD 0day Actual/360 1/25/2036 6/25/2012 $100,000 $1 86358E ZX 7 M5... DD 0day Actual/360 1/25/2036 6/25/2012 $100,000 $1 86358E ZY 5 M6... DD 0day Actual/360 1/25/2036 6/25/2012 $100,000 $1 86358E ZZ 2 M7... DD 0day Actual/360 1/25/2036 6/25/2012 $100,000 $1 86358E A2 2 M8... DD 0day Actual/360 1/25/2036 6/25/2012 $100,000 $1 86358E A3 0 (1) DD = For any distribution date, the close of business on the business day immediately before that distribution date. (2) 0 day = For any distribution date, the interest accrual period will be the period beginning on the immediately preceding distribution date (or December 25, 2005, in the case of the first interest accrual period) and ending on the calendar day immediately before the related distribution date. (3) The final scheduled distribution date for the offered certificates is based upon the second distribution date after the date of the last scheduled payment of the latest maturing thirty-year mortgage loan. (4) The expected final distribution date, based upon (a) a constant prepayment rate of 30% per annum and the modeling assumptions used in this prospectus supplement, each as described under Yield, Prepayment and Life Life and (b) the assumption that the option to purchase the mortgage loans is exercised by the master servicer on the earliest possible distribution date as described in this prospectus supplement under Description of the Certificates Optional Purchase of the Loans. The actual final distribution date for each class of offered certificates may be earlier or later, and could be substantially later, than the applicable expected final distribution date listed above. (5) With respect to initial European investors only, the underwriter will only sell offered certificates in minimum total investment amounts of $100,000. S-2

Summary of Terms This summary highlights selected information from this document and does not contain all of the information that you need to consider in making your investment decision. To understand all of the terms of the offering of the certificates, it is necessary that you read carefully this entire document and the accompanying prospectus. While this summary contains an overview of certain calculations, cash flow priorities and other information to aid your understanding, you should read carefully the full description of these calculations, cash flow priorities and other information in this prospectus supplement and the accompanying prospectus before making any investment decision. Some of the information that follows consists of forward-looking statements relating to future economic performance or projections and other financial items. Forward-looking statements are subject to a variety of risks and uncertainties, such as general economic and business conditions and regulatory initiatives and compliance, many of which are beyond the control of the parties participating in this transaction. Accordingly, what actually happens may be very different from the projections included in this prospectus supplement. Whenever we refer to a percentage of some or all of the mortgage loans in the trust fund, that percentage has been calculated on the basis of the total scheduled principal balance of those mortgage loans as of December 1, 2005, unless we specify otherwise. We explain in this prospectus supplement under Glossary of Defined Terms how the scheduled principal balance of a mortgage loan is determined. Whenever we refer in this Summary of Terms or in the Risk Factors section of this prospectus supplement to the total principal balance of any mortgage loans, we mean the total of their scheduled principal balances unless we specify otherwise. Parties Sponsor and Seller Lehman Brothers Holdings Inc. will sell the mortgage loans to the depositor. Depositor Structured Asset Securities Corporation, a Delaware special purpose corporation, will sell the mortgage loans to the issuing entity. The depositor s address is 745 Seventh Avenue, New York, New York 10019, and its telephone number is (212) 526-7000. Issuing Entity Structured Asset Investment Loan Trust 2005-11, a common law trust formed under the laws of the State of New York. Trustee U.S. Bank National Association. Securities Administrator Wells Fargo Bank, N.A., will be responsible for preparing monthly distribution statements and certain tax information for investors and certain tax filings for the trust fund. Master Servicer Aurora Loan Services LLC, an affiliate of the seller, the depositor and Lehman Brothers Inc., will oversee the servicing of the mortgage loans by the servicers. Primary Servicers On the closing date, Option One Corporation, JPMorgan Chase Bank, National Association, Wells Fargo Bank, N.A., HomEq Servicing Corporation and Aurora Loan Services LLC will service approximately 76.54%, 8.44%, 7.51%, 5.99% and 1.52%, respectively, of the mortgage loans included in the trust fund. It is anticipated that on or about January 1, 2006, the servicing of approximately 21.96% and 0.28% of the mortgage loans initially serviced by Option One S-3

Corporation will be transferred to Wells Fargo Bank, N.A. and JPMorgan Chase Bank, National Association, respectively, and on or about February 1, 2006, the servicing of approximately 45.46% of the mortgage loans initially serviced by Option One Corporation will be transferred to JPMorgan Chase Bank, National Association and approximately 31.95% of the mortgage loans initially serviced by Option One Corporation will be transferred to HomEq Servicing Corporation. Credit Risk Manager Clayton Fixed Income Services Inc. (formerly known as The Murrayhill Company) will monitor and advise the servicers with respect to default management of the mortgage loans and also prepare certain loan-level reports for the trust fund which will be available for review by certificateholders. Originators BNC, Inc., an affiliate of the seller, the depositor, the master servicer and Lehman Brothers Inc. originated approximately 76.31% of the mortgage loans to be included in the trust fund. The remainder of the mortgage loans were originated by various other banks, savings and loans and other mortgage lending institutions, none of which originated more than approximately 9.45% of the mortgage loans. Swap Counterparty HSBC Bank USA, National Association. Cap Counterparty HSBC Bank USA, National Association. LPMI Insurers On the closing date, Guaranty Insurance Corporation, PMI Insurance Co. and Republic Insurance Company will provide primary mortgage insurance for certain of the first lien mortgage loans with original loan-to-value ratios in excess of 80%. The Certificates The certificates offered by this prospectus supplement will be issued with the initial approximate characteristics set forth under The Offered Certificates in the table on page S-1. The offered certificates will be issued in bookentry form. The minimum denominations and the incremental denominations of each class of offered certificates are set forth in the table on page S-2. The certificates represent ownership interests in a trust fund, the assets of which will consist primarily of conventional, adjustable and fixed rate, fully amortizing and balloon, first and second lien, residential mortgage loans having a total principal balance as of the cut-off date, which is December 1, 2005, of approximately $1,872,790,458. In addition, the supplemental interest trust will hold an interest rate swap agreement and an interest rate cap agreement for the benefit of the certificateholders and the final maturity reserve trust will hold the final maturity reserve account for the benefit of the certificateholders. The mortgage loans to be included in the trust fund will be divided into three mortgage pools: pool 1, pool 2 and pool 3. Pool 1 will consist of those mortgage loans in the trust fund with original principal balances that do not exceed the applicable Freddie Mac maximum original loan amount limitations for one- to four-family residential mortgaged properties. Pool 2 will consist of those mortgage loans in the trust fund with original principal balances that do not exceed the applicable Fannie Mae maximum original loan amount limitations for one- to four-family residential mortgaged properties. Pool 3 will consist of mortgage loans with original principal balances that may be less than, equal to, or in excess of, Fannie Mae or Freddie Mac original loan amount limitations. Payments of principal and interest on the Class A1 Certificates will be based primarily on collections from pool 1 mortgage loans. Payments of principal and interest on the Class A2 and A3 Certificates will be based primarily on collections from pool 2 mortgage loans. Payments of principal and interest on the Class A4, A5, A6 and A7 Certificates will be based primarily on collections from pool 3 mortgage loans. Payments of principal and interest on the Class M1, M2, M3, M4, M5, M6, M7, M8, B1 and B2 Certificates will be based on collections from all of the mortgage pools as described herein. S-4

The rights of holders of the Class M1, M2, M3, M4, M5, M6, M7, M8, B1 and B2 Certificates to receive payments of principal and interest will be subordinate to the rights of the holders of certificates having a senior priority of payment, as described in this Summary of Terms under Enhancement of Likelihood of Payment on the Certificates Subordination of Payments below. We refer to the Class M1, M2, M3, M4, M5, M6, M7, M8, B1 and B2 Certificates collectively as subordinate certificates. We refer to the Class A1, A2, A3, A4, A5, A6 and A7 Certificates collectively as senior certificates. The Class P Certificates will be entitled to receive all the cash flow from the mortgage pools solely arising from prepayment premiums paid by the borrowers on certain voluntary, full and partial prepayments of the mortgage loans. Accordingly, these amounts will not be available for payments to the servicers or to holders of other classes of certificates. The Class X Certificates will be entitled to receive any monthly excess cashflow remaining after required distributions are made to the offered certificates and the Class B1 and B2 Certificates. The Class B1, Class B2, Class X, Class P, Class LT-R and Class R Certificates are not offered by this prospectus supplement. The offered certificates will have an approximate total initial principal amount of $1,835,336,000. Any difference between the total principal amount of the offered certificates on the date they are issued and the approximate total principal amount of the offered certificates as reflected in this prospectus supplement will not exceed 5%. Payments on the Certificates Principal and interest on the certificates will be paid on the 25th day of each month, beginning in January 2006. However, if the 25th day is not a business day, payments will be made on the next business day after the 25th day of the month. Interest Payments Interest will accrue on each class of offered certificates at the applicable annual rates described below: Class A1 Certificates: the lesser of (1) the applicable annual rate as described in the table on page S-1 and (2) with respect to any distribution date on which any of the Class A2, A3, A4, A5, A6 or A7 Certificates are outstanding, the pool 1 net funds cap; and after the distribution date on which the class principal amounts of the Class A2, A3, A4, A5, A6 and A7 Certificates have each been reduced to zero, the subordinate net funds cap. Class A2 Certificates: the lesser of (1) the applicable annual rate as described in the table on page S-1 and (2) with respect to any distribution date on which any of the Class A1, A4, A5, A6 or A7 Certificates are outstanding, the pool 2 net funds cap; and after the distribution date on which the class principal amounts of the Class A1, A4, A5, A6 and A7 Certificates have each been reduced to zero, the subordinate net funds cap. Class A3 Certificates: the lesser of (1) the applicable annual rate as described in the table on page S-1 and (2) with respect to any distribution date on which any of the Class A1, A4, A5, A6 or A7 Certificates are outstanding, the pool 2 net funds cap; and after the distribution date on which the class principal amounts of the Class A1, A4, A5, A6 and A7 Certificates have each been reduced to zero, the subordinate net funds cap. Class A4 Certificates: the lesser of (1) the applicable annual rate as described in the table on page S-1 and (2) with respect to any distribution date on which any of the Class A1, A2 or A3 Certificates are outstanding, the pool 3 net funds cap; and after the distribution date on which the class principal amounts of the Class A1, A2 and A3 Certificates have each been reduced to zero, the subordinate net funds cap. Class A5 Certificates: the lesser of (1) the applicable annual rate as described in the table on page S-1 and (2) with respect to any distribution date on which any of the Class A1, A2 or A3 Certificates are outstanding, the pool 3 net funds S-5

cap; and after the distribution date on which the class principal amounts of the Class A1, A2 and A3 Certificates have each been reduced to zero, the subordinate net funds cap. Class A6 Certificates: the lesser of (1) the applicable annual rate as described in the table on page S-1 and (2) with respect to any distribution date on which any of the Class A1, A2 or A3 Certificates are outstanding, the pool 3 net funds cap; and after the distribution date on which the class principal amounts of the Class A1, A2 and A3 Certificates have each been reduced to zero, the subordinate net funds cap. Class A7 Certificates: the lesser of (1) the applicable annual rate as described in the table on page S-1 and (2) with respect to any distribution date on which any of the Class A1, A2 or A3 Certificates are outstanding, the pool 3 net funds cap; and after the distribution date on which the class principal amounts of the Class A1, A2 and A3 Certificates have each been reduced to zero, the subordinate net funds cap. Interest will accrue on each class of the Class M1, M2, M3, M4, M5, M6, M7 and M8 Certificates at an annual rate equal to the lesser of (1) the applicable annual rate as described in the table on page S-1 and (2) the subordinate net funds cap. If the option to purchase the mortgage loans is not exercised by the master servicer on the initial optional termination date as described under The Loans Optional Purchase of the Loans below, then with respect to the next distribution date and each distribution date thereafter, the annual rate in clause (1) of each interest rate formula set forth above will be increased for each class of offered certificates to the applicable annual rate as described in the table on page S-1, subject in each case to the applicable net funds cap. See The Loans Optional Purchase of the Loans below. The pool 1 net funds cap is a limitation generally based on the weighted average mortgage rates of the pool 1 mortgage loans during the applicable collection period, net of certain fees and expenses of the trust fund and any net swap payments owed to the swap counterparty allocable to pool 1. The pool 2 net funds cap is a limitation generally based on the weighted average mortgage rates of the pool 2 mortgage loans during the applicable collection period, net of certain fees and expenses of the trust fund and any net swap payments owed to the swap counterparty allocable to pool 2. The pool 3 net funds cap is a limitation generally based on the weighted average mortgage rates of the pool 3 mortgage loans during the applicable collection period, net of certain fees and expenses of the trust fund and any net swap payments owed to the swap counterparty allocable to pool 3. The subordinate net funds cap is generally the weighted average of the pool 1 net funds cap, the pool 2 net funds cap and the pool 3 net funds cap. See Description of the Certificates Distributions of Interest Interest Distribution Priorities in this prospectus supplement for the priority of payment of interest and Glossary of Defined Terms in this prospectus supplement for a description of the defined terms relevant to the payment of interest. The Interest Rate Swap Agreement The trustee, on behalf of the supplemental interest trust, will enter into an interest rate swap agreement with HSBC Bank USA, National Association, as swap counterparty. Under the interest rate swap agreement, one business day prior to each distribution date, beginning in February 2006 and ending in December 2010, the supplemental interest trust will be obligated to make fixed payments at the applicable rate of payment owed by the trust fund, which will range from 4.59% to 5.05% annually, as described in this prospectus supplement, and the swap counterparty will be obligated to make floating payments at LIBOR (as determined under the interest rate swap agreement), in each case calculated on a scheduled notional amount and adjusted to a monthly basis. To the extent that a fixed payment exceeds the floating payment relating to any distribution date, amounts otherwise available to certificateholders will be applied to make a net swap payment to the swap counterparty, and to the extent that a floating payment exceeds the fixed payment on any distribution date, the swap counterparty will owe a net swap payment to the supplemental interest trust. S-6

Any net amounts received under the interest rate swap agreement will be deposited into the interest rate swap account and applied to pay interest shortfalls, maintain overcollateralization and repay losses, as described in this prospectus supplement. See Description of the Certificates Supplemental Interest Trust Interest Rate Swap Agreement and Application of Deposits and Payments Received by the Supplemental Interest Trust Interest Rate Swap Agreement in this prospectus supplement. The Interest Rate Cap Agreement The trustee, on behalf of the supplemental interest trust, will enter into an interest rate cap agreement with HSBC Bank USA, National Association, as cap counterparty. Under the interest rate cap agreement, on the business day prior to each distribution date, beginning on the distribution date in January 2007 and ending on the distribution date in December 2010, the cap counterparty will be obligated to make payments to the supplemental interest trust if one-month LIBOR (as determined under the interest rate cap agreement) moves above 5.50%, in each case calculated on a scheduled notional amount and adjusted to a monthly basis. Any amounts received under the interest rate cap agreement will be deposited into the interest rate cap account and applied to pay interest shortfalls, maintain overcollateralization and repay losses, as described in this prospectus supplement. See Description of the Certificates Supplemental Interest Trust The Interest Rate Cap Agreement and Application of Deposits and Payments Received by the Supplemental Interest Trust Interest Rate Cap Agreement in this prospectus supplement. Principal Payments The amount of principal payable to the offered certificates will be determined by (1) formulas that allocate portions of principal payments received on the mortgage loans among the mortgage pools and among the different certificate classes, (2) funds received on the mortgage loans that are available to make principal payments on the certificates, (3) the application of excess interest from the mortgage pools to pay principal on the certificates and (4) any amounts released from the final maturity reserve account on the earlier of the final scheduled distribution date and the termination of the trust fund to pay principal on the certificates. Funds received on the mortgage loans may consist of (1) expected monthly scheduled payments or (2) unexpected payments resulting from prepayments or defaults by borrowers, liquidation of defaulted mortgage loans or repurchases of mortgage loans under the circumstances described in this prospectus supplement. The manner of allocating payments of principal on the mortgage loans will differ, as described in this prospectus supplement, depending upon the occurrence of several different events or triggers: whether a distribution date occurs before or on or after the stepdown date, which is the earlier of (A) the first distribution date following the distribution date on which the class principal amounts of all the senior certificates have been paid to zero or (B) the later of (1) the distribution date in January 2009 and (2) the first distribution date on which the ratio of (a) the total principal balance of the subordinate certificates plus any overcollateralization amount to (b) the total principal balance of the mortgage loans in the trust fund equals or exceeds the percentage specified in this prospectus supplement; whether a cumulative loss trigger event occurs, which is when cumulative losses on the mortgage loans are higher than certain levels specified in this prospectus supplement; whether a delinquency event occurs, which is when the rate of delinquencies of the mortgage loans over any three-month period is higher than certain levels set forth in this prospectus supplement; and whether, in the case of pool 2, a sequential trigger event occurs, which will occur if (a) before the distribution date in January 2008, a cumulative loss trigger event occurs or (b) on or after the distribution date in January 2008, a cumulative loss trigger event or a delinquency event occurs. See Description of the Certificates Distributions of Principal Principal Distribution Priorities in this prospectus supplement for the S-7

priority of payment of principal and Glossary of Defined Terms in this prospectus supplement for a description of the defined terms relevant to the payment of principal. Limited Recourse The only sources of cash available to make interest and principal payments on the certificates will be the assets of the trust fund, the supplemental interest trust and the final maturity reserve trust. The trust fund will have no source of cash other than collections and recoveries of the mortgage loans through insurance or otherwise. No other entity will be required or expected to make any payments on the certificates. Enhancement of Likelihood of Payment on the Certificates In order to enhance the likelihood that holders of more senior classes of certificates will receive regular distributions of interest and principal, the payment structure of this securitization includes excess interest, overcollateralization, subordination, loss allocation and limited cross-collateralization features, primary mortgage insurance, an interest rate swap agreement and an interest rate cap agreement. The Class B2 Certificates are more likely to experience losses than the Class B1, M8, M7, M6, M5, M4, M3, M2 and M1 Certificates and the senior certificates. The Class B1 Certificates are more likely to experience losses than the Class M8, M7, M6, M5, M4, M3, M2 and M1 Certificates and the senior certificates. The Class M8 Certificates are more likely to experience losses than the Class M7, M6, M5, M4, M3, M2 and M1 Certificates and the senior certificates. The Class M7 Certificates are more likely to experience losses than the Class M6, M5, M4, M3, M2 and M1 Certificates and the senior certificates. The Class M6 Certificates are more likely to experience losses than the Class M5, M4, M3, M2 and M1 Certificates and the senior certificates. The Class M5 Certificates are more likely to experience losses than the Class M4, M3, M2 and M1 Certificates and the senior certificates. The Class M4 Certificates are more likely to experience losses than the Class M3, M2 and M1 Certificates and the senior certificates. The Class M3 Certificates are more likely to experience losses than the Class M2 and M1 Certificates and the senior certificates. The Class M2 Certificates are more likely to experience losses than the Class M1 Certificates and the senior certificates. The Class M1 Certificates are more likely to experience losses than the senior certificates. See Risk Factors Risks Related to Potential Inadequacy of Credit Enhancement and Other Support, Description of the Certificates Credit Enhancement and Supplemental Interest Trust in this prospectus supplement for a more detailed description of excess interest, overcollateralization, subordination, loss allocation, primary mortgage insurance, limited cross-collateralization, the interest rate cap agreement and the interest rate swap agreement. Subordination of Payments Certificates with an A in their class designation will have a payment priority as a group over all other certificates. The Class M1 Certificates will have a payment priority over the Class M2, M3, M4, M5, M6, M7, M8, B1 and B2 Certificates; the Class M2 Certificates will have a payment priority over the Class M3, M4, M5, M6, M7, M8, B1 and B2 Certificates; the Class M3 Certificates will have a payment priority over the Class M4, M5, M6, M7, M8, B1 and B2 Certificates; the Class M4 Certificates will have a payment priority over the Class M5, M6, M7, M8, B1 and B2 Certificates; the Class M5 Certificates will have a payment priority over the Class M6, M7, M8, B1 and B2 Certificates; the Class M6 Certificates will have a payment priority over the Class M7, M8, B1 and B2 Certificates; the Class M7 Certificates will have a payment priority over the Class M8, B1 and B2 Certificates; the Class M8 Certificates will have a payment priority over the Class B1 and B2 Certificates; and the Class B1 Certificates will have a payment priority over the Class B2 Certificates. Each class of offered certificates and the Class B1 and Class B2 Certificates will have a payment priority over the Class X, Class LT-R and Class R Certificates. See Risk Factors Risks Related to Potential Inadequacy of Credit Enhancement and Other Support and Description of the Certificates Credit Enhancement Subordination in this prospectus supplement. S-8

Allocation of Losses As described in this prospectus supplement, amounts representing losses on the mortgage loans (to the extent that those losses exceed excess interest and any overcollateralization, as described in this prospectus supplement) will be applied to reduce the principal amount of the subordinate class of certificates still outstanding that has the lowest payment priority, until the principal amount of that class of certificates has been reduced to zero. For example, losses in excess of overcollateralization and excess interest will first be allocated in reduction of the principal amount of the Class B2 Certificates, until it is reduced to zero, then in reduction of the principal amount of the Class B1 Certificates until it is reduced to zero, then in reduction of the principal amount of the Class M8 Certificates until it is reduced to zero, then in reduction of the principal amount of the Class M7 Certificates until it is reduced to zero, then in reduction of the principal amount of the Class M6 Certificates until it is reduced to zero, then in reduction of the principal amount of the Class M5 Certificates until it is reduced to zero, then in reduction of the principal amount of the Class M4 Certificates until it is reduced to zero, then in reduction of the principal amount of the Class M3 Certificates until it is reduced to zero, then in reduction of the principal amount of the Class M2 Certificates until it is reduced to zero and finally in reduction of the principal amount of the Class M1 Certificates until it is reduced to zero. If a loss has been allocated to reduce the principal amount of a subordinate certificate, it is unlikely that investors will receive any payment in respect of that reduction. See Risk Factors Risks Related to Potential Inadequacy of Credit Enhancement and Other Support and Description of the Certificates Credit Enhancement Application of Realized Losses in this prospectus supplement. Excess Interest The mortgage loans bear interest each month that in the aggregate is expected to exceed the amount needed to pay monthly interest on the offered certificates and the Class B1 and Class B2 Certificates, certain fees and expenses of the trust fund, any net swap payments owed to the swap counterparty and on and after the distribution date in January 2016, amounts deposited in the final maturity reserve account. This excess interest received from the mortgage loans each month will be available to absorb realized losses on the mortgage loans and to maintain the required level of overcollateralization. See Risk Factors Risks Related to Potential Inadequacy of Credit Enhancement and Other Support and Description of the Certificates Credit Enhancement Excess Interest in this prospectus supplement. Overcollateralization On the closing date, the total principal balance of the mortgage loans in the trust fund is expected to exceed the total principal amount of the offered certificates and the Class B1 and Class B2 Certificates by approximately $9,364,458, which represents approximately 0.50% of the total principal balance of the mortgage loans in the trust fund as of December 1, 2005. This condition is referred to in this prospectus supplement as overcollateralization. Thereafter, to the extent described in this prospectus supplement, a portion of excess interest may be applied to pay principal on the certificates to the extent needed to maintain the required level of overcollateralization. We cannot, however, assure you that sufficient interest will be generated by the mortgage loans to maintain any level of overcollateralization. See Risk Factors Risks Related to Potential Inadequacy of Credit Enhancement and Other Support and Description of the Certificates Credit Enhancement Overcollateralization in this prospectus supplement. Limited Cross-Collateralization Under certain limited circumstances, principal payments on the mortgage loans in a mortgage pool may be distributed as principal to holders of the senior certificates corresponding to the other mortgage pools. If the senior certificates relating to the other mortgage pools have been retired, then principal payments on the mortgage loans relating to the S-9