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**UNITED      STATES**

**SECURITIES      AND EXCHANGE COMMISSION**

**Washington,      D.C. 20549**

**FORM      10-K**

**[X]      ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT      OF      1934**

**[        ] TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES AND      EXCHANGE ACT OF 1934**

|   | Delaware                                                                                    |   | 74-2440850                                                         |   |
|--------|---------------------------------------------------------------------------------------------|--------|--------------------------------------------------------------------|--------|
|   | (State                or other jurisdiction ofincorporation                or organization) |   | (I.R.S.                Employer Identification                No.) |   |

|   | o                Yes |   | x No |
|--------|----------------------|--------|-----------|

|   | o                Yes |   | x                No |
|--------|----------------------|--------|---------------------|

|   | x                Yes |   | o                No |
|--------|----------------------|--------|---------------------|

| Large                accelerated filer o | Accelerated                filer o |  Non-accelerated                filer x |
|------------------------------------------|------------------------------------|----------------------------------------------|

**DOCUMENTS        INCORPORATED BY REFERENCE**

**PART        I**

**Item        1. Business. **

**Item        1A. Risk Factors.**

**Item        1B. Unresolved Staff Comments.**

**Item        2. Properties.**

**Item        3. Legal Proceedings. **

**Item        4. Submission of Matters to a Vote of Security Holders.**

**PART        II**

**Item        5. Market for Registrant’s Common Equity, Related Stockholder Matters and Issuer        Purchases of Equity Securities.**

**Item        6. Selected Financial Data.**

**Item        7. Management’s Discussion and Analysis of Financial Condition and Results of        Operation.**

**Item        7A. Quantitative and Qualitative Disclosures About Market        Risk.**

**Item        8. Financial Statements and Supplementary Data.**

**Item        9. Changes in and Disagreements With Accountants on Accounting and Financial        Disclosure.**

**Item        9A. Controls and Procedures.**

**Item        9A(T). Controls and Procedures.**

**Item        9B. Other Information.**

**PART        III**

**Item        10. Directors, Executive Officers and Corporate        Governance.**

**Item        11. Executive Compensation.**

**Item        12. Security Ownership of Certain Beneficial Owners and Management and Related        Stockholder Matters.**

**Item        13. Certain Relationships and Related Transactions, and Director        Independences.**

**Item        14. Principal Accounting Fees and Services.**

**PART        IV**

**ADDITIONAL        DISCLOSURE ITEMS PURSUANT TO        GENERAL INSTRUCTION J**

**Item        1112(b) of Regulation AB. Significant Obligors Financial        Information.**

**Item        1114(b)(2) and 1115(b) of Regulation AB. Significant Enhancement Provider        Financial Information.**

**Item        1117 of Regulation AB. Legal Proceedings**

**Item        1119 of Regulation AB. Affiliations and Certain Relationships and Related        Transactions**

**Item        1122 of Regulation AB. Compliance with Applicable Servicing        Criteria.**

**Item        1123 of Regulation AB. Servicer Compliance Statement**

**              **

**Item        15. Exhibits, Financial Statement Schedules.**

| (b)                  See above |
|--------------------------------|

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**SIGNATURES**

|                                  | Lehman                XS Trust                2006-20                      |
|---------------------------------------|----------------------------------------------------------------------------|
|                                  | Aurora                  Loan Services LLC, as Master Servicer              |
|                                  |                                                                       |
|  March                  29, 2007 | /s/                E. Todd Whittemore                                      |
|                                  | By: E.                  Todd Whittemore                               |
|                                  | Title: Executive                  Vice President                      |
|                                  | Aurora                Loan Services                LLC, as Master Servicer |

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**EXHIBIT      INDEX **

| **Exhibit                    Number** | **Description**                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |
|---------------------------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| 4                                     | Trust                        Agreement dated as of December 1, 2006, among Structured                        Asset Securities                        Corporation, as Depositor, Aurora Loan Services LLC, as Master                        Servicer,                        and LaSalle Bank National Association, as Trustee (incorporated                        herein by                        reference from Exhibit 4.1 of the Current Report on Form                        8-K of the                        registrant, as filed with the Commission on January 12,                        2007). |
| 10                                    | Incorporated                  by reference as Exhibit (4).                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |
| 31                                    | Sarbanes-Oxley                    Certification                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |
| 33                                    | Report                  on assessment of                  compliance with servicing criteria for asset-backed                  securities                                                                                                                                                                                                                                                                                                                                                                                                                                                                   |
| (a)                                   |     Aurora                    Loan Services LLC, as Master Servicer                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     |
| (b)                                   |     LaSalle                    Bank National Association, as Trustee, paying agent and                    Custodian                                                                                                                                                                                                                                                                                                                                                                                                                                                                |
| (c)                                   |     Deutsche                    Bank                    National Trust Company, as Custodian and as sub-contractor for                    IndyMac                    Bank FSB                                                                                                                                                                                                                                                                                                                                                                                                           |
| (d)                                   |     US                    Bank                    National Association, as Custodian                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |
| (e)                                   |     Wells                    Fargo Bank, National Association, as Custodian                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |
| (f)                                   |     First                  American Real Estate Solutions of Texas, L.P., as sub-contractor                  for Aurora Loan Services LLC                                                                                                                                                                                                                                                                                                                                                                                                                                     |
| (g)                                   |     Newport                  Management Corporation, as  sub-contractor for Aurora Loan Services                  LLC                                                                                                                                                                                                                                                                                                                                                                                                                                                              |
| (h)                                   |     IndyMac                  Bank, FSB, as servicer                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     |
| (i)                              |     Newport                  Management Corporation, as sub-contractor for IndyMac Bank                  FSB                                                                                                                                                                                                                                                                                                                                                                                                                                                                            |
| (j)                                   |     Aurora                  Loan                  Services LLC, as servicer                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |
| 34                                    | Attestation                  report on                  assessment of compliance with servicing criteria for asset-backed                  securities                                                                                                                                                                                                                                                                                                                                                                                                                                                       |
| (a)                                   |     Aurora                    Loan Services LLC, as Master Servicer                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     |
| (b)                                   |     LaSalle                    Bank National Association, as Trustee, paying agent and                    Custodian                                                                                                                                                                                                                                                                                                                                                                                                                                                                |
| (c)                                   |     Deutsche                    Bank                    National Trust Company, as Custodian and as sub-contractor for                    IndyMac                    Bank FSB                                                                                                                                                                                                                                                                                                                                                                                                           |
| (d)                                   |     US                    Bank                    National Association, as Custodian                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |
| (e)                                   |     Wells                    Fargo, Bank National Association, as Custodian                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |
| (f)                                   |     First                  American Real Estate Solutions of Texas, L.P., as                   sub-contractor for Aurora Loan Services LLC                                                                                                                                                                                                                                                                                                                                                                                                                                    |
| (g)                                   |     Newport                  Management Corporation, as  sub-contractor for Aurora Loan Services                  LLC                                                                                                                                                                                                                                                                                                                                                                                                                                                              |
| (h)                                   |     IndyMac                  Bank, FSB, as servicer                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     |
| (i)                                   |     Newport                  Management Corporation, as sub-contractor for IndyMac Bank                  FSB                                                                                                                                                                                                                                                                                                                                                                                                                                                                            |
| (j)                                   |     Aurora                  Loan Services LLC, as servicer                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |
| 35                                    | Servicer                  compliance                  statement                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |
| (a)                                   |     Aurora                    Loan Services LLC, as Master Servicer                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     |
| (b)                                   |     IndyMac                  Bank,                  FSB, as servicer                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |
| (c)                                   |     Aurora                  Loan                  Services LLC, as servicer                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |