8-K 1 mab04op1_dec.txt DECEMBER 8-K 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): December 27, 2004 MASTR ASSET BACKED SECURITIES TRUST Mortgage Pass-Through Certificates, Series 2004-OPT1 Trust (Exact name of registrant as specified in its charter) New York (governing law of 333-106982-19 54-2150433 Pooling and Servicing Agreement) (Commission 54-2150434 (State or other File Number) IRS EIN jurisdiction of Incorporation) c/o Wells Fargo Bank, N.A. 9062 Old Annapolis Road Columbia, MD 21045 (Address of principal executive offices) (Zip Code) Registrant's telephone number, including area code: (410) 884-2000 (Former name or former address, if changed since last report) Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions (see General Instruction A.2. below): [ ] Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425) [ ] Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12) [ ] Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act(17 CFR 240.14d-2(b)) [ ] Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act(17 CFR 240.13e-4(c)) ITEM 8.01 Other Events On December 27, 2004 a distribution was made to holders of MASTR ASSET BACKED SECURITIES TRUST, Mortgage Pass-Through Certificates, Series 2004-OPT1 Trust. ITEM 9.01 Financial Statements and Exhibits (c) Exhibits Exhibit Number Description EX-99.1 Monthly report distributed to holders of Mortgage Pass-Through Certificates, Series 2004-OPT1 Trust, relating to the December 27, 2004 distribution. 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. MASTR ASSET BACKED SECURITIES TRUST Mortgage Pass-Through Certificates, Series 2004-OPT1 Trust (Registrant) By: Wells Fargo Bank, N.A. as Trustee By: /s/ Beth Belfield as Assistant Vice President By: Beth Belfield as Assistant Vice President Date: 12/31/2004 INDEX TO EXHIBITS Exhibit Number Description EX-99.1 Monthly report distributed to holders of Mortgage Pass-Through Certificates, Series 2004-OPT1 Trust, relating to the December 27, 2004 distribution. EX-99.1

MASTR ASSET BACKED SECURITIES TRUST 2004-OPT1 8-K