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

PROSPECTUS SUPPLEMENT (To Prospectus dated January 25, 2005) $2,485,384,000 (Approximate) STRUCTURED ASSET INVESTMENT LOAN TRUST Pass-Through Certificates, Series 2005-5 Aurora Loan Services LLC Master Servicer Lehman Brothers Holdings Inc. Sponsor and Seller CIFG Assurance North America, Inc. Class A8 and Class A9 Certificate Insurer Structured Asset Securities Corporation Depositor Consider carefully the risk factors beginning on page S-18 of this prospectus supplement. For a list of capitalized terms used in this prospectus supplement and the prospectus, see the glossary of defined terms beginning on page S-107 in this prospectus supplement and the index of principal terms on page 126 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: s Eight classes of senior certificates s One class of subordinate senior certificates s Ten 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 June 27, 2005. Credit enhancement for the offered certificates includes excess interest, overcollateralization, subordination, loss allocation and limited crosscollateralization features and primary mortgage insurance, and, in the case of the Class A8 and Class A9 Certificates only, two certificate guaranty insurance policies issued by CIFG Assurance North America, Inc., which will guarantee certain payments of interest and principal to the holders of the Class A8 and Class A9 Certificates, to the extent described in this prospectus supplement. Amounts payable under an interest rate swap agreement provided by ABN AMRO Bank N.V. will be applied to pay certain interest shortfalls, maintain overcollateralization and cover certain losses. The assets of the trust fund will primarily consist of four pools of conventional, first and second lien, adjustable and fixed rate, fully amortizing and balloon, residential mortgage loans. The mortgage loans were originated in accordance with underwriting guidelines that are not as strict as Fannie Mae and Freddie Mac guidelines. As a result, the mortgage loans may experience higher rates of delinquency, foreclosure and bankruptcy than if they had been underwritten in accordance with higher standards. 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 99.91% of their initial total class principal amount before deducting expenses. On or about May 27, 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 May 26, 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. S-ii

Tables of Contents Prospectus Supplement Page The Offered Certificates ;;;;;;;; S-1 Summary of Terms ;;;;;;;;;; S-3 Risk Factors ;;;;;;;;;;;;; S-18 Glossary ;;;;;;;;;;;;;;; S-33 Description of the Certificates ;;;;;; S-33 General ;;;;;;;;;;;;;; S-33 Book-Entry Registration ;;;;;;; S-34 Distributions of Interest ;;;;;;;; S-35 Determination of LIBOR ;;;;;;; S-39 Distributions of Principal ;;;;;;; S-39 Credit Enhancement ;;;;;;;;; S-46 Supplemental Interest Trust ;;;;;; S-50 Optional Purchase of the Loans S-53 Fees and Expenses of the Trust Fund ;;; Description of the Pools ;;;; S-54 S-55 General ;;;;;;;;;;;;;; S-55 Adjustable Rate Loans ;;;; S-58 The Index ;;;;;;;;;;;;; S-58 Primary Insurance ;;;;;; S-58 Pool 1 Loans ;;;;;;;; S-64 Pool 2 Loans ;;;;;;;; S-64 Pool 3 Loans ;;;;;;;; S-64 Pool 4 Loans ;;;;;;;; S-65 Additional Information ;;;;;;;;; S-65 Underwriting Guidelines ;;;;;;;; S-65 BNC Underwriting Guidelines ;;;;; S-66 Option One Underwriting Guidelines ;; General Underwriting Guidelines ;;;; S-67 S-72 The Master Servicer ;;;;;;;;;; S-75 The Servicers ;;;;;;;;;;;;; S-76 General ;;;;;;;;;;;;;; S-76 Option One Corporation ;;; S-77 Servicing of the Loans ;;;;; S-79 General ;;;;;;;;;;;;;; S-79 Servicing Accounts ;;;;;;;;; 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 Primary Insurance ;;;;;; S-81 Collection of Taxes, Assessments and Similar Items ;;;;;;;;;;; S-81 Insurance Coverage ;;;;;;;;; S-82 Evidence as to Compliance ;;;;;; S-82 Master Servicer Default; Servicer Default S-82 Amendment of the Servicing Agreements;;;;;;;;;;;; S-82 Page Custody of the Files ;;; S-83 The Credit Risk Manager;;;;;; S-83 Optional Purchase of Defaulted Loans ;;;;;;;; S-83 Special Servicer for Distressed Loans ;;;;;;;; S-83 Pledge of Servicing Rights ;;;;; S-84 The Trust Agreement ;;;;;;;; S-84 General ;;;;;;;;;;;;; S-84 The Issuing Entity ;;;;;;;; S-84 The Trustee ;;;;;;;;;;; S-85 The Securities Administrator ;;;; S-85 Assignment of Loans ;;; S-85 Representations and Warranties ;;; S-86 Certain Matters Under the Trust Agreement;;;;;;;;;;; S-87 Voting Rights ;;;;;;;;;; S-91 Yield, Prepayment and Life ;;;;;;;;;;;;; S-91 General ;;;;;;;;;;;;; S-91 Overcollateralization;;;;;;;; S-95 Life ;;;;;; S-95 The Certificate Insurance Policies ;;; S-97 The Policies ;;;;;;;;;;; S-97 The Certificate Insurer ;;;;;;; S-99 Material Federal Income Tax Considerations ;;;;;;;;; S-101 General ;;;;;;;;;;;;; S-101 Tax Treatment of the Offered Certificates ;;;;;;;;;; S-101 Legal Investment Considerations;;;; S-103 ERISA Considerations ;;;;;;;; S-103 ERISA Considerations With Respect to the Swap Agreement ;;;;;; S-104 Use of Proceeds ;;;;;;;;;; S-105 Underwriting ;;;;;;;;;;;; S-105 Experts ;;;;;;;;;;;;;; S-106 Legal Matters ;;;;;;;;;;; S-106 Ratings ;;;;;;;;;;;;;; S-106 Glossary of Defined Terms ;;;;;; S-107 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 Swap Agreement Scheduled Notional Amounts and Rates of Payment;;;;;;;;;;;;; S-D-1 S-iii

Prospectus Page Description of the Securities ;;;;;;; 2 General;;;;;;;;;;;;;;; 2 Distributions on the Securities ;;;;; 2 Optional Termination ;;;;;;;;; 4 Optional Purchase of Securities ;;;;; 5 Other Purchases ;;;;;;;;;;; 5 Exchangeable Securities ;;;;;;;; 5 Yield, Prepayment and Maturity Considerations ;;;;;;;;;;; 12 Payment Delays ;;;;;;;;;;; 12 Principal Prepayments;;;;;;;;; 12 Timing of Reduction of PrincipalAmount ; 12 Interest or Principal ;;;;; Securities ;;;;;;;;;;;;;; 12 Final Scheduled Distribution Date ;;;; 12 Prepayments and Life ; 13 Other Factors Affecting Life ;;;;;;;;;;;;;;; 14 The Trust Funds ;;;;;;;;;;;; 15 General;;;;;;;;;;;;;;; 15 Ginnie Mae Certificates ;;;;;;;; 17 Fannie Mae Certificates ;;;;;;;; 18 Freddie Mac Certificates ;;;;;;;; 20 Private -Backed Securities ;;; 22 The Loans ;;;;;;;;; 24 The Manufactured Home Loans ;;;;; 30 Pre Funding Arrangements ;;;;;;; 33 Collection Account and Distribution Account ;;;;;;;;;;;;; 33 Other Funds or Accounts ;;;;;;; 34 Loan Underwriting Procedures and Standards 34 Underwriting Standards ;;;;;;;; 34 Loss Experience ;;;;;;;;;;; 36 Representations and Warranties ;;;;; 37 Substitution of Primary Assets ;;;;; 38 Servicing of Loans ;;;;;;;;;;; 38 General;;;;;;;;;;;;;;; 38 Collection Procedures; Escrow Accounts ; 39 Deposits to and Withdrawals from the Collection Account ;;;;;;;;; 40 Servicing Accounts ;;;;;;;;;; 41 Buy-Down Loans, GPM Loans and Other Subsidized Loans;;;;;;;;;; 41 Advances and Other Payments and Limitations Thereon ;;;;;;;; 43 Maintenance of Insurance Policies and Other Servicing Procedures ;;;;;;;; 43 Page Presentation of Claims; Realization Upon Defaulted Loans ;;;;;;;;;; 46 Enforcement of Due-On-Sale Clauses ;;; 47 Certain Rights Related to Foreclosure ;;; 47 Servicing Compensation and Payment of Expenses ;;;;;;;;;;;;; 47 Evidence as to Compliance;;;;;;;; 48 Certain Matters Regarding the Master Servicer 49 Certain Risks ;;;;;;;;;;;;; 50 Credit Support ;;;;;;;;;;;;; 50 General;;;;;;;;;;;;;;; 50 Subordinate Securities; Subordination Reserve Fund ;;;;;;;;;;; 51 Cross-Support Features ;;;;;;;; 52 Insurance ;;;;;;;;;;;;;; 52 Letter of Credit ;;;;;;;;;;; 52 Financial Guaranty Insurance Policy ;;; 53 Reserve Funds ;;;;;;;;;;;; 53 Description of and Other Insurance 53 Insurance on the Loans ;;;; 54 Hazard Insurance on the Loans ;;;;; 59 Bankruptcy Bond;;;;;;;;;;; 61 Repurchase Bond;;;;;;;;;;; 61 The Agreements ;;;;;;;;;;;; 61 Issuance of Securities ;;;;;;;;; 62 Assignment of Primary Assets ;;;;; 62 Repurchase and Substitution of Non- Conforming Loans ;;;;;;;;; 64 Reports to Securityholders ;;;;;;; 65 Investment of Funds ;;;;;;;;; 66 Event of Default; Rights Upon Event of Default ;;;;;;;;;;;;;; 67 The Trustee ;;;;;;;;;;;;; 69 Duties of the Trustee ;;;;;;;;; 69 Resignation of Trustee ;;;;;;;; 70 Distribution Account ;;;;;;;;; 70 Expense Reserve Fund ;;;;;;;; 71 Amendment of Agreement ;;;;;;; 71 Voting Rights ;;;;;;;;;;;; 71 REMIC Administrator ;;;;;;;;; 71 Administration Agreement ;;;;;;; 71 Periodic Reports ;;;;;;;;;;; 72 Termination ;;;;;;;;;;;;; 72 Legal Aspects of Loans ;;;;;;;;; 73 s ;;;;;;;;;;;;; 73 Junior s; Rights of Senior s ;;;;;;;;;;;; 73 S-iv

Prospectus (continued) Page Cooperative Loans ;;;;;;;;;; 75 Foreclosure on s ;;;;;;; 77 Realizing Upon Cooperative Loan Security 78 Rights of Redemption ;;;;;;;;; 79 Anti-Deficiency Legislation and Other Limitations on Lenders ;;;;;;; 79 Servicemembers Civil Relief Act ;;;; 81 Environmental Considerations ;;;;; 82 Due-on-Sale Clauses in Loans ; 83 Enforceability of Prepayment and Late Payment Fees ;;;;;;;;;;; 84 Equitable Limitations on Remedies ;;; 84 Applicability of Usury Laws ;;;;;; 85 Multifamily and Mixed Use Loans;;;; 85 Leases and Rents ;;;;;;;;;;; 86 Default Interest and Limitations on ;;; Payment ;;;;;;;;;;;;;; 86 Secondary Financing; Due-on-Encumbrance Provisions;;;;;;;;;;;;; 86 Certain Laws and Regulations ;;;;; 87 Americans with Disabilities Act;;;;; 87 Personal Property;;;;;;;;;;; 87 Adjustable Interest Rate Loans ;;;;; 87 Manufactured Home Loans;;;;;;; 88 Material Federal Income Tax ;;;;; Considerations ;;;;;;;;;;;; 91 Types of Securities ;;;;;;;;;;; 91 Page Taxation of Securities Treated as Debt Instruments ;;;;;;;;;;;; 94 Exchangeable Securities ;;;;;;;; 100 REMIC Residual Certificates ;;;;;; 102 Grantor Trust Certificates ;;;;;;; 108 Partner Certificates ;;;;;;;;;; 111 Special Tax Attributes;;;;;;;;; 113 Backup Withholding ;;;;;;;;; 115 Reportable Transactions ;;;;;;;; 115 State and Local Tax Considerations ;;;; 116 ERISA Considerations;;;;;;;;;; 116 General;;;;;;;;;;;;;;; 116 The Underwriter Exemption ;;;;;; 117 Additional Considerations for Securities which are Notes ;;;;;;;;;; 121 Additional Fiduciary Considerations ;;;; 121 Legal Investment Considerations ;;;;; 121 Legal Matters ;;;;;;;;;;;;; 122 The Depositor ;;;;;;;;;;;;; 122 Use of Proceeds ;;;;;;;;;;;; 123 Plan of Distribution;;;;;;;;;;; 123 Additional Information ;;;;;;;;; 124 Incorporation of Certain Documents by Reference ;;;;;;;;;;;;;; 125 Reports to Securityholders ;;;;;;;; 125 Index of Principal Terms ;;;;;;;; 126 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 P, Class X and Class R Certificates. Only the classes of certificates listed in the tables below are offered by this prospectus supplement. Related Class Initial Summary Interest Summary Interest (7) Principal Interest Rate Formula (until Initial Rate Formula (after Initial Initial Certificate Ratings (7) Class Pool(s) Amount (1) Rate (2) Optional Termination Date) (3) Optional Termination Date) (5) Principal Type Interest Type Moody s S&P Fitch A1 ;;; 1 $477,487,000 3.390% LIBOR plus 0.300% (4) LIBOR plus 0.600% (4) Senior Variable Rate Aaa AAA AAA A2 ;;; 2 $259,118,000 3.180% LIBOR plus 0.090% (4) LIBOR plus 0.180% (4) Senior, Sequential Pay Variable Rate Aaa AAA AAA A3 ;;; 2 $305,837,000 3.320% LIBOR plus 0.230% (4) LIBOR plus 0.460% (4) Senior, Sequential Pay Variable Rate Aaa AAA AAA A4 ;;; 3 $379,046,000 3.370% LIBOR plus 0.280% (4) LIBOR plus 0.560% (4) Senior (6) Variable Rate Aaa AAA AAA A5 ;;; 3 $ 94,762,000 3.410% LIBOR plus 0.320% (4) LIBOR plus 0.640% (4) Senior (6) Variable Rate Aaa AAA AAA A6 ;;; 4 $270,215,000 3.180% LIBOR plus 0.090% (4) LIBOR plus 0.180% (4) Senior, Sequential Pay Variable Rate Aaa AAA AAA A7 ;;; 4 $210,927,000 3.300% LIBOR plus 0.210% (4) LIBOR plus 0.420% (4) Senior, Sequential Pay Variable Rate Aaa AAA AAA A8 ;;; 4 $ 95,826,000 3.340% LIBOR plus 0.250% (4) LIBOR plus 0.500% (4) Senior, Sequential Pay Variable Rate Aaa AAA AAA A9 ;;; 1, 2, 3 & 4 $ 48,708,000 3.360% LIBOR plus 0.270% (4) LIBOR plus 0.405% (4) Subordinate Senior Variable Rate Aaa AAA N/R M1 ;;; 1, 2, 3 & 4 $ 37,468,000 3.510% LIBOR plus 0.420% (4) LIBOR plus 0.630% (4) Subordinated Variable Rate Aa1 AA+ AA+ M2 ;;; 1, 2, 3 & 4 $ 68,692,000 3.550% LIBOR plus 0.460% (4) LIBOR plus 0.690% (4) Subordinated Variable Rate Aa2 AA AA M3 ;;; 1, 2, 3 & 4 $ 44,962,000 3.570% LIBOR plus 0.480% (4) LIBOR plus 0.720% (4) Subordinated Variable Rate Aa3 AA- AA- M4 ;;; 1, 2, 3 & 4 $ 37,468,000 3.710% LIBOR plus 0.620% (4) LIBOR plus 0.930% (4) Subordinated Variable Rate A1 A+ A+ M5 ;;; 1, 2, 3 & 4 $ 29,974,000 3.740% LIBOR plus 0.650% (4) LIBOR plus 0.975% (4) Subordinated Variable Rate A2 A A M6 ;;; 1, 2, 3 & 4 $ 29,974,000 3.810% LIBOR plus 0.720% (4) LIBOR plus 1.080% (4) Subordinated Variable Rate A3 A- A- M7 ;;; 1, 2, 3 & 4 $ 27,477,000 4.190% LIBOR plus 1.100% (4) LIBOR plus 1.650% (4) Subordinated Variable Rate Baa1 BBB+ BBB+ M8 ;;; 1, 2, 3 & 4 $ 18,734,000 4.340% LIBOR plus 1.250% (4) LIBOR plus 1.875% (4) Subordinated Variable Rate Baa2 BBB BBB M9 ;;; 1, 2, 3 & 4 $ 24,979,000 4.890% LIBOR plus 1.800% (4) LIBOR plus 2.700% (4) Subordinated Variable Rate Baa3 BBB- BBB- B ;;;; 1, 2, 3 & 4 $ 23,730,000 5.590% LIBOR plus 2.500% (4) LIBOR plus 3.750% (4) Subordinated Variable Rate Ba2 BBB- N/R (1) These balances are approximate, as described in this prospectus supplement. (2) Reflects the interest rate as of the closing date. (3) Reflects the summary 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 summary 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 A4 and Class A5 Certificates will receive payments of principal concurrently, on a pro rata basis, unless cumulative realized losses or delinquencies on the mortgage loans exceed specified levels, in which case these classes will be treated as senior, sequential pay classes, as described under Description of the Certificates Distributions of Principal. (7) The designation N/R means that the specified rating agency will not publicly rate this class of certificates. S-1

The offered certificates will also have the following characteristics: Class Certificate Insurance Policy Record Date (1) Delay / Accrual Interest Accrual Period (2) Convention Final Scheduled Distribution Date Minimum Denominations Incremental Denominations CUSIP Number A1 ;;;;;; No DD 0 day Actual/360 6/25/2035 $25,000 $1 86358E SW 7 A2 ;;;;;; No DD 0 day Actual/360 6/25/2035 $25,000 $1 86358E SX 5 A3 ;;;;;; No DD 0 day Actual/360 6/25/2035 $25,000 $1 86358E SY 3 A4 ;;;;;; No DD 0 day Actual/360 6/25/2035 $25,000 $1 86358E SZ 0 A5 ;;;;;; No DD 0 day Actual/360 6/25/2035 $25,000 $1 86358E TA 4 A6 ;;;;;; No DD 0 day Actual/360 6/25/2035 $25,000 $1 86358E TB 2 A7 ;;;;;; No DD 0 day Actual/360 6/25/2035 $25,000 $1 86358E TC 0 A8 ;;;;;; Yes DD 0 day Actual/360 6/25/2035 $25,000 $1 86358E TD 8 A9 ;;;;;; Yes DD 0 day Actual/360 6/25/2035 $25,000 $1 86358E TE 6 M1;;;;;; No DD 0 day Actual/360 6/25/2035 $100,000 $1 86358E TF 3 M2;;;;;; No DD 0 day Actual/360 6/25/2035 $100,000 $1 86358E TG 1 M3;;;;;; No DD 0 day Actual/360 6/25/2035 $100,000 $1 86358E TH 9 M4;;;;;; No DD 0 day Actual/360 6/25/2035 $100,000 $1 86358E TJ 5 M5;;;;;; No DD 0 day Actual/360 6/25/2035 $100,000 $1 86358E TK 2 M6;;;;;; No DD 0 day Actual/360 6/25/2035 $100,000 $1 86358E TL 0 M7;;;;;; No DD 0 day Actual/360 6/25/2035 $100,000 $1 86358E TM 8 M8;;;;;; No DD 0 day Actual/360 6/25/2035 $100,000 $1 86358E TN 6 M9;;;;;; No DD 0 day Actual/360 6/25/2035 $100,000 $1 86358E TP 1 B ;;;;;; No DD 0 day Actual/360 6/25/2035 $100,000 $1 86358E TQ 9 (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 May 25, 2005, in the case of the first interest accrual period) and ending on the calendar day immediately before the related distribution date. S-2

Parties Summary of Terms s 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. s 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. s 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. s 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 May 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. 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 2005-5, a common law trust formed under the laws of the state of New York. Trustee U.S. Bank National Association. 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, one of the servicers and Lehman Brothers Inc., will oversee the servicing of the mortgage loans by the servicers. Primary Servicers On the closing date, Option One Corporation, Aurora Loan Services LLC and various other servicers will service approximately 79.49%, 13.22% and 7.29%, respectively, of the mortgage loans. It is anticipated that servicing of approximately 68.40% of the mortgage loans initially serviced by Option One Corporation will be transferred to one or more other servicers as described under The Loans Servicing of the Loans below. Securities Administrator Wells Fargo Bank, N.A., will be responsible for preparing monthly distribution statements and S-3

Credit Risk Manager 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., Option One Corporation and various other banks, savings and loans and other mortgage lending institutions originated the mortgage loans to be included in the trust fund. Swap Counterparty ABN AMRO Bank N.V. Certificate Insurer CIFG Assurance North America, Inc. will provide certificate guaranty insurance policies for the Class A8 and Class A9 Certificates, which will guarantee certain payments of interest and principal to holders of the Class A8 and Class A9 Certificates, to the extent described in this prospectus supplement. 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-tovalue 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, first and second lien, adjustable and fixed rate, fully amortizing and balloon, residential mortgage loans having a total principal balance as of the cut-off date, which is May 1, 2005, of approximately $2,497,873,627. In addition, the supplemental interest trust will hold an interest rate swap agreement for the benefit of the certificateholders. The mortgage loans to be included in the trust fund will be divided into four mortgage pools: pool 1, pool 2, pool 3 and pool 4. Pool 1 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 2 and pool 3 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 4 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 the pool 1 mortgage loans. Payments of principal and interest on the Class A2 and A3 Certificates will be based primarily on collections from the pool 2 mortgage loans. Payments of principal and interest on the Class A4 and A5 Certificates will be based primarily on collections from the pool 3 mortgage loans. Payments of principal and interest on the Class A6, A7 and A8 Certificates will be based primarily on collections from the pool 4 mortgage loans. Payments of principal and interest on the Class A9, M1, M2, M3, M4, M5, M6, M7, M8, M9 and B Certificates will be based on collections from all four mortgage pools as described herein. The rights of holders of the Class A9, M1, M2, M3, M4, M5, M6, M7, M8, M9 and B 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 S-4

Class M1, M2, M3, M4, M5, M6, M7, M8, M9 and B Certificates collectively as subordinate certificates. We refer to the Class A9 Certificates as subordinate senior certificates. We refer to the Class A1, A2, A3, A4, A5, A6, A7 and A8 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. The Class X, Class P and Class R Certificates are not offered by this prospectus supplement. The offered certificates will have an approximate total initial principal amount of $2,485,384,000. 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 June 2005. 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: s 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, A7 or A8 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, A7 and A8 Certificates have each been reduced to zero, the subordinate net funds cap. s 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, A7 or A8 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, A7 and A8 Certificates have each been reduced to zero, the subordinate net funds cap. s 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, A7 or A8 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, A7 and A8 Certificates have each been reduced to zero, the subordinate net funds cap. s 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, A3, A6, A7 or A8 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, A3, A6, A7 and A8 Certificates have each been reduced to zero, the subordinate net funds cap. s 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, A3, A6, A7 or A8 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, A3, A6, A7 and A8 Certificates have each been S-5

reduced to zero, the subordinate net funds cap. s 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, A3, A4 or A5 Certificates are outstanding, the pool 4 net funds cap, and after the distribution date on which the class principal amounts of the Class A1, A2, A3, A4 and A5 Certificates have each been reduced to zero, the subordinate net funds cap. s 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, A3, A4 or A5 Certificates are outstanding, the pool 4 net funds cap, and after the distribution date on which the class principal amounts of the Class A1, A2, A3, A4 and A5 Certificates have each been reduced to zero, the subordinate net funds cap. s Class A8 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, A3, A4 or A5 Certificates are outstanding, the pool 4 net funds cap, and after the distribution date on which the class principal amounts of the Class A1, A2, A3, A4 and A5 Certificates have each been reduced to zero, the subordinate net funds cap. Interest will accrue on each class of the Class A9, M1, M2, M3, M4, M5, M6, M7, M8, M9 and B 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 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 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 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 swap payments owed to the swap counterparty allocable to pool 3. The pool 4 net funds cap is a limitation generally based on the weighted average mortgage rates of the pool 4 mortgage loans during the applicable collection period, net of certain fees and expenses of the trust fund, any swap payments owed to the swap counterparty allocable to pool 4 and the monthly premium due to the certificate insurer for the certificate guaranty insurance policy benefiting the Class A8 Certificates for that distribution date. The subordinate net funds cap is generally the weighted average of the pool 1 net funds cap, the pool 2 net funds cap, the pool 3 net funds cap and the pool 4 net funds cap, net of the monthly premium due to the certificate insurer for the certificate guaranty insurance policy benefiting the Class A9 Certificates for that distribution date. See Description of the Certificates Distributions of Interest 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. S-6

The Interest Rate Swap Agreement The trustee, on behalf of the supplemental interest trust, will enter into an interest rate swap agreement with ABN AMRO Bank N.V., as swap counterparty. Under the interest rate swap agreement, on each distribution date, beginning on the distribution date in July 2005 and ending on the distribution date in May 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 3.38% to 4.75% 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. To the extent that a fixed payment exceeds the floating payment on 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. Any net amounts received under the interest rate swap agreement will be paid by the supplemental interest trust and applied to pay interest shortfalls, maintain overcollateralization and cover 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 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 the different certificate classes, (2) funds received on the mortgage loans that are available to make principal payments on the certificates and (3) the application of excess interest from each mortgage pool 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: s whether a distribution date occurs before or on or after the stepdown date, which is the later of (1) the distribution date in June 2008 and (2) the first distribution date on which the ratio of (a) the total principal balance of the subordinate senior certificates and 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; s a cumulative loss trigger event occurs when cumulative losses on the mortgage loans are higher than certain levels specified in this prospectus supplement; s a delinquency event occurs 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 s in the case of pool 3, a sequential trigger event occurs if (a) before the distribution date in June 2008, a cumulative loss trigger event occurs or (b) on or after the distribution date in June 2008, a cumulative loss trigger event or a delinquency event occurs. See Description of the Certificates Distributions of Principal in this prospectus supplement for the 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 source of cash available to make interest and principal payments on the certificates will be the assets of the trust fund and the S-7

supplemental interest 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, other than the Class A8 and Class A9 Certificates, which will have the benefit of certificate guaranty insurance policies issued by CIFG Assurance North America, Inc. 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 and an interest rate swap agreement, and, for the benefit of the Class A8 and Class A9 Certificates only, certificate guaranty insurance policies. The certificates, other than the Class A8 and Class A9 Certificates, will not be insured by any financial guaranty insurance policy. The Class B Certificates are more likely to experience losses than the Class M9, M8, M7, M6, M5, M4, M3, M2, M1 and A9 Certificates and the senior certificates. The Class M9 Certificates are more likely to experience losses than the Class M8, M7, M6, M5, M4, M3, M2, M1 and A9 Certificates and the senior certificates. The Class M8 Certificates are more likely to experience losses than the Class M7, M6, M5, M4, M3, M2, M1 and A9 Certificates and the senior certificates. The Class M7 Certificates are more likely to experience losses than the Class M6, M5, M4, M3, M2, M1 and A9 Certificates and the senior certificates. The Class M6 Certificates are more likely to experience losses than the Class M5, M4, M3, M2, M1 and A9 Certificates and the senior certificates. The Class M5 Certificates are more likely to experience losses than the Class M4, M3, M2, M1 and A9 Certificates and the senior certificates. The Class M4 Certificates are more likely to experience losses than the Class M3, M2, M1 and A9 Certificates and the senior certificates. The Class M3 Certificates are more likely to experience losses than the Class M2, M1 and A9 Certificates and the senior certificates. The Class M2 Certificates are more likely to experience losses than the Class M1 and A9 Certificates and the senior certificates. The Class M1 Certificates are more likely to experience losses than the Class A9 Certificates and the senior certificates. The Class A9 Certificates are more likely to experience losses than the senior certificates. See Risk Factors Potential Inadequacy of Credit Enhancement, 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 and the interest rate swap agreement. Subordination of Payments Certificates with an A in their class designation (other than the Class A9 Certificates) will have a payment priority as a group over all other certificates. The Class A9 Certificates will have a payment priority over the Class M1, M2, M3, M4, M5, M6, M7, M8, M9 and B Certificates; the Class M1 Certificates will have a payment priority over the Class M2, M3, M4, M5, M6, M7, M8, M9 and B Certificates; the Class M2 Certificates will have a payment priority over the Class M3, M4, M5, M6, M7, M8, M9 and B Certificates; the Class M3 Certificates will have a payment priority over the Class M4, M5, M6, M7, M8, M9 and B Certificates; the Class M4 Certificates will have a payment priority over the Class M5, M6, M7, M8, M9 and B Certificates; the Class M5 Certificates will have a payment priority over the Class M6, M7, M8, M9 and B Certificates; the Class M6 Certificates will have a payment priority over the Class M7, M8, M9 and B Certificates; the Class M7 Certificates will have a payment priority over the Class M8, M9 and B Certificates; the Class M8 Certificates will have a payment priority over the Class M9 and B Certificates; and the Class M9 Certificates will have a payment priority over the Class B Certificates. Each class of offered certificates will have a payment priority over the Class X and Class R Certificates. S-8

See Risk Factors Potential Inadequacy of Credit Enhancement and Description of the Certificates Credit Enhancement Subordination in this prospectus supplement. 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 or subordinate senior 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 B Certificates until it is reduced to zero, then in reduction of the principal amount of the Class M9 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, then in reduction of the principal amount of the Class M1 Certificates until it is reduced to zero and finally in reduction of the principal amount of the Class A9 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. If a loss has been allocated to reduce the principal amount of a subordinate senior certificate, that certificate will have the benefit of the Class A9 certificate guaranty insurance policy and will be entitled to reimbursement of any losses allocated to it on the final scheduled distribution date (to the extent not previously reimbursed). If the applicable subordination is insufficient to absorb losses, then holders of senior certificates (other than the Class A8 Certificates, which have the benefit of the Class A8 certificate guaranty insurance policy) will incur losses and may never receive all of their principal payments. See Risk Factors Potential Inadequacy of Credit Enhancement 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, certain fees and expenses of the trust fund, any swap payments owed to the swap counterparty and the premiums payable under the Class A8 and Class A9 certificate guaranty insurance policies. 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 Potential Inadequacy of Credit Enhancement 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 by approximately $12,489,627, which represents approximately 0.50% of the total principal balance of the mortgage loans in the trust fund as of May 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 Potential Inadequacy of Credit Enhancement and Description of the S-9

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 one mortgage pool have been retired, then principal payments on the mortgage loans relating to the retired senior certificates will be distributed to the remaining senior certificates of the other mortgage pools, if any, before being distributed to the subordinate classes of certificates. See Risk Factors Potential Inadequacy of Credit Enhancement and Description of the Certificates Distributions of Principal in this prospectus supplement. Primary Insurance Approximately 0.27% of the first lien mortgage loans with original loan-to-value ratios in excess of 80% are covered by existing borrower-paid primary mortgage insurance policies. In addition, on the closing date, loan-level primary mortgage insurance policies will be obtained on behalf of the trust fund from Guaranty Insurance Corporation, PMI Insurance Co. and Republic Insurance Company in order to provide initial primary mortgage insurance coverage for approximately 81.59% of those first lien mortgage loans with original loan-to-value ratios in excess of 80%. However, these primary mortgage insurance policies will provide only limited protection against losses on defaulted mortgage loans. See Risk Factors Potential Inadequacy of Credit Enhancement Primary Insurance and Description of the Pools Primary Insurance in this prospectus supplement. The Interest Rate Swap Agreement Any net swap payment received under the interest rate swap agreement will be applied to pay interest shortfalls, maintain overcollateralization and cover losses, as described in this prospectus supplement. See Risk Factors Potential Inadequacy of Credit Enhancement The Interest Rate Swap Agreement, Description of the Certificates Supplemental Interest Trust Interest Rate Swap Agreement and Application of Deposits and Payments Received by the Supplemental Interest Trust in this prospectus supplement. The Class A8 and Class A9 Certificate Guaranty Insurance Policies The CIFG Assurance North America, Inc. certificate guaranty insurance policies will guarantee certain interest and principal payments to holders of the Class A8 and Class A9 Certificates under the circumstances described in this prospectus supplement. No other classes of certificates will benefit from the certificate guaranty insurance policies. For information about CIFG Assurance North America, Inc. and for a more detailed discussion of the CIFG Assurance North America, Inc. certificate guaranty insurance policies, see The Certificate Insurance Policies in this prospectus supplement. Fees and Expenses Before payments are made on the certificates, the servicers will be paid a monthly fee calculated either as 0.50% annually, or in the case of some of the mortgage loans serviced by Option One, calculated starting at 0.30% annually and gradually increasing to up to 0.65% annually, on the principal balance of the mortgage loans serviced by that servicer (subject to reduction as described in this prospectus supplement). In addition, the providers of the loan-level primary mortgage insurance policies will be paid a monthly fee calculated as an annual percentage on the principal balance of each mortgage loan insured by that primary mortgage insurance provider. These fees will be 0.950% annually for Guaranty Insurance Corporation, 1.510% annually for Republic Insurance Company and between 0.263% and 2.224% annually (with a weighted average as of the cut-off date of approximately 0.970% annually) for PMI Insurance Co. S-10