UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

PURSUANT TO SECTION 13 OR 15(d) OF THE

SECURITIES EXCHANGE ACT OF 1934

Date of Report (Date of earliest event reported)

July 30, 2004

STRUCTURED ASSET SECURITIES CORPORATION (as Depositor under the Trust Agreement dated as of July 1, 2004, providing for the issuance of Structured Asset Securities Corporation Mortgage Pass-Through Certificates, Series 2004-16XS)

Structured Asset Securities Corporation

(Exact Name of Registrant as Specified in its Charter)

Delaware

333-115858

74-2440850

(State or Other Jurisdiction

Of Incorporation)

(Commission

File Number)

(I.R.S. Employer

Identification No.)

745 Seventh Avenue, 7^th Floor

New York, NY

(Address of Principal Executive Offices)

10019

(Zip Code)

Registrant’s telephone number, including area code: (212) 526-7000

No Change

(Former Name or Former Address, if Changed Since Last Report)

Item 5. Other Events

The Registrant registered issuances of Structured Asset Securities Corporation Mortgage Pass-Through Certificates Series 2004-16XS, on a delayed or continuous basis pursuant to Rule 415 under the Securities Act of 1933, as amended (the “Act”), by a Registration Statement on Form S-3 (Registration File No. 333-115858) (the “Registration Statement”). Pursuant to the Registration Statement, the Registrant issued approximately $248,701,000 in aggregate principal amount of Class A1, Class A2, Class A3A, Class A3B, Class A4A, Class A4B, Class M1, Class M2 and Class M3 Structured Asset Securities Corporation Mortgage Pass-Through Certificates, Series 2004-16XS on July 30, 2004. This Current Report on Form 8-K is being filed to satisfy an undertaking, contained in the definitive Prospectus dated June 25, 2004, as supplemented by the Prospectus Supplement dated July 26, 2004 (the “Prospectus Supplement”), to file a copy of the Trust Agreement (as defined below) and other operative agreements executed in connection with the issuance of the Certificates, a form of which was filed as an exhibit to the Registration Statement.

The Offered Certificates and the Other Certificates were issued pursuant to a Trust Agreement (the “Trust Agreement”), attached hereto as Exhibit 4.1, dated as of July 1, 2004, among Structured Asset Securities Corporation, as depositor, Wilmington Trust Company, as trustee, Citibank, N.A., as securities administrator and Aurora Loan Services Inc., as master servicer. The “Offered Certificates” consist of the following classes: Class A1, Class A2, Class A3A, Class A3B, Class A4A, Class A4B, Class M1, Class M2 and Class M3. The Certificates and the “Other Certificates” (consisting of the Class P, Class X and Class R Certificates), evidence all of the beneficial ownership interest in a trust fund (the “Trust Fund”) the assets of which consist primarily of a pool of certain conventional, first lien, fixed rate, fully amortizing and balloon, residential mortgage loans (the “Mortgage Loans”) with an aggregate outstanding principal balance of approximately $249,074,707 as of July 1, 2004, together with certain other assets. Capitalized terms used herein and not otherwise defined shall have the meanings assigned to them in the Trust Agreement.

Item 7. Financial Statements; Pro Forma Financial Information and Exhibits

(a)

Not applicable.

(b)

Not applicable.

(c)

Exhibits:

4.1

Trust Agreement dated as of July 1, 2004, among Structured Asset Securities Corporation, as Depositor, Wilmington Trust Company, as Trustee, Citibank, N.A., as securities administrator and Aurora Loan Services Inc., as Master Servicer.

99.1

Mortgage Loan Sale and Assignment Agreement dated as of July 1, 2004, between Lehman Brothers Holdings Inc., as Seller, and Structured Asset Securities Corporation, as Purchaser.

99.2

Servicing Agreement dated as of July 1, 2004, among Aurora Loan Services Inc., as Master Servicer and Servicer, and Lehman Brothers Holdings Inc., as Seller.

99.3

MBIA Insurance Corporation Certificate Guaranty Insurance Policy No. 44201 in the amounts of $35,441,000 and $11,719,000 for each of the Class A3B and Class A4B Certificates, respectively.

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the Registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

STRUCTURED ASSET SECURITIES

CORPORATION

By: /s/ Daniel E. Israeli

Name: Daniel E. Israeli

Title: Vice President

Dated: July 30, 2004

EXHIBIT INDEX

Exhibit No.

Structured Asset Securities Corp Mortgage Pass-Through Certificates, Series 2004-16XS 8-K