8-K 1 csf05004_10508.txt 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): August 25, 2005 CREDIT SUISSE FIRST BOSTON MORTGAGE SECURITIES CORPORATION Mortgage-Backed P/T Certificates, Series 2005-4 Trust (Exact name of registrant as specified in its charter) New York (governing law of 333-120966-14 Pooling and Servicing Agreement) (Commission 54-2173124 (State or other File Number) 54-2173125 jurisdiction 54-2173126 of Incorporation) 54-2173127 IRS EIN 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 August 25, 2005 a distribution was made to holders of CREDIT SUISSE FIRST BOSTON MORTGAGE SECURITIES CORPORATION, Mortgage-Backed P/T Certificates, Series 2005-4 Trust. ITEM 9.01 Financial Statements and Exhibits (c) Exhibits Exhibit Number Description EX-99.1 Monthly report distributed to holders of Mortgage-Backed P/T Certificates, Series 2005-4 Trust, relating to the August 25, 2005 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. CREDIT SUISSE FIRST BOSTON MORTGAGE SECURITIES CORPORATION Mortgage-Backed P/T Certificates, Series 2005-4 Trust (Registrant) By: Wells Fargo Bank, N.A. as Trust Administrator By: /s/ Beth Belfield as Officer By: Beth Belfield as Officer Date: 8/29/2005 INDEX TO EXHIBITS Exhibit Number Description EX-99.1 Monthly report distributed to holders of Mortgage-Backed P/T Certificates, Series 2005-4 Trust , relating to the August 25, 2005 distribution. EX-99.1

Delinquency Status By Groups

REO Detail - All Mortgage Loans in REO during Current Period

Foreclosure Detail - All Mortgage Loans in Foreclosure during Current Period

Group

Prepayment - Voluntary Prepayments

Realized Loss Report - Collateral Summary

CSFB Mortgage-Backed Pass-Through Certificates Series 2005-4 8-K