8-K 1 csf05004_10505.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): May 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 May 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 May 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: 6/1/2005 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 May 25, 2005 distribution. EX-99.1

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) May 23, 2005
CREDIT SUISSE FIRST BOSTON MORTGAGE SECURITIES CORP.
(Exact name of registrant as specified in its charter)
Delaware (State or other jurisdiction of incorporation)	333-120966 (Commission File Number)		13-3320910 (IRS Employer ID Number)
11 Madison Avenue New York, New York		10010
(Address of principal executive offices)		(Zip Code)
Registrant’s Telephone Number, including area code:		(212) 325-2000
No Change (Former name or former address, if changed since last report)

~~Check~~Certificateholder ~~the~~Distribution ~~appropriate~~Summary ~~box~~(continued) ~~below~~Current ifEnding ~~the~~Cumulative ~~Form~~Realized ~~8-K~~Certificate ~~filing~~Total isRealized ~~intended~~Class toLoss ~~simultaneously~~Balance ~~satisfy~~Distribution Losses 1A1 0.00 196,029,065.30 3,388,531.61 0.00 AP 0.00 2,099,469.35 3,033.45 0.00 2A1 0.00 49,616,772.81 518,643.86 0.00 2A2 0.00 0.00 6,250.00 0.00 2A3 0.00 17,632,371.00 80,815.03 0.00 2A4 0.00 23,805,000.00 109,106.25 0.00 2A5 0.00 99,233,545.62 1,049,787.71 0.00 2A6 0.00 0.00 393,750.00 0.00 2A7 0.00 74,367,322.01 838,927.99 0.00 2A8 0.00 0.00 6,250.00 0.00 2A9 0.00 4,312,500.00 19,765.63 0.00 3A1 0.00 10,202,928.56 75,968.11 0.00 3A2 0.00 6,536,100.60 317,166.90 0.00 3A3 0.00 4,492,000.00 20,588.33 0.00 3A4 0.00 4,921,000.00 99,833.33 0.00 3A5 0.00 4,921,000.00 104,000.00 0.00 3A6 0.00 2,952,000.00 61,750.00 0.00 3A7 0.00 5,116,000.00 23,448.33 0.00 3A8 0.00 3,411,000.00 15,633.75 0.00 3A9 0.00 259,665.24 167,282.68 0.00 3A10 0.00 17,028,137.76 666,793.64 0.00 3A11 0.00 1,596,388.01 68,368.87 0.00 3A12 0.00 4,595,662.79 209,180.74 0.00 3A13 0.00 5,500,055.00 25,208.59 0.00 3A14 0.00 85,417,353.44 580,002.81 0.00 3A15 0.00 11,430,000.00 52,387.50 0.00 3A16 0.00 26,806,679.18 311,473.28 0.00 3A17 0.00 5,500,000.00 25,208.33 0.00 3A18 0.00 5,682,763.16 0.01 0.00 3A19 0.00 2,192,606.47 17,476.86 0.00 3A20 0.00 25,155,872.55 213,874.95 0.00 3A21 0.00 14,582,930.96 70,972.17 0.00 3A22 0.00 4,500,533.33 0.00 0.00 3A23 0.00 1,676,384.37 0.00 0.00 3A24 0.00 5,302,884.89 56,521.15 0.00 3A25 0.00 10,000,000.00 45,833.33 0.00 CB1 0.00 7,770,001.17 51,013.41 0.00 CB2 0.00 2,913,750.19 19,130.03 0.00 CB3 0.00 1,456,875.09 9,565.02 0.00 CB4 0.00 1,214,061.75 7,970.84 0.00 CB5 0.00 971,249.40 6,376.67 0.00 CB6 0.00 728,440.34 4,782.53 0.00 ES 0.00 0.01 0.00 0.00 DB1 0.00 5,244,339.27 27,810.50 0.00 DB2 0.00 2,551,299.40 13,529.43 0.00 DB3 0.00 1,417,388.67 7,516.35 0.00 DB4 0.00 708,694.33 3,758.18 0.00 DB5 0.00 850,432.80 4,509.81 0.00 DB6 0.00 566,954.87 3,006.53 0.00 DB7 0.00 708,697.37 3,758.19 0.00 PP 0.00 100.00 0.42 0.00 AR 0.00 0.00 50.21 0.00 ARL 0.00 0.00 50.21 0.00 1X 0.00 0.00 38,877.08 0.00 2X 0.00 0.00 56,310.37 0.00 3X 0.00 0.00 26,590.92 0.00 Totals 0.00 763,978,277.06 9,928,441.89 0.00 All distributions required by the ~~filing~~Pooling ~~obligation~~and ofServicing Agreement have been calculated by the ~~registrant~~Certificate ~~under~~Administrator ~~any~~on behalf of the ~~following provisions:~~Trustee.

[Principal ]Distribution ~~Written~~Statement ~~communications~~Original ~~pursuant~~Beginning toScheduled ~~Rule~~Unscheduled ~~425~~Face ~~under~~Certificate ~~the~~Principal ~~Securities~~Principal ~~Act~~Realized Class Amount Balance Distribution Distribution Accretion Loss (1) 1A1 198,590,138.00 198,590,138.00 747,132.49 1,813,940.21 0.00 0.00 AP 2,102,502.80 2,102,502.80 2,984.29 49.15 0.00 0.00 2A1 50,000,000.00 50,000,000.00 41,671.31 341,555.88 0.00 0.00 2A2 0.00 0.00 0.00 0.00 0.00 0.00 2A3 17,632,371.00 ~~CFR~~17,632,371.00 ~~230~~0.00 0.00 0.00 0.00 2A4 23,805,000.00 23,805,000.00 0.00 0.00 0.00 0.00 2A5 100,000,000.00 100,000,000.00 83,342.62 683,111.76 0.00 0.00 2A6 0.00 0.00 0.00 0.00 0.00 0.00 2A7 75,000,000.00 75,000,000.00 68,796.06 563,881.93 0.00 0.00 2A8 0.00 0.00 0.00 0.00 0.00 0.00 2A9 4,312,500.00 4,312,500.00 0.00 0.00 0.00 0.00 3A1 10,232,000.00 10,232,000.00 3,836.63 25,234.81 0.00 0.00 3A2 6,822,000.00 6,822,000.00 37,730.84 248,168.56 0.00 0.00 3A3 4,492,000.00 4,492,000.00 0.00 0.00 0.00 0.00 3A4 5,000,000.00 5,000,000.00 10,425).82 [68,574.18 ]0.00 ~~Soliciting~~0.00 ~~material~~3A5 ~~pursuant~~5,000,000.00 to5,000,000.00 ~~Rule~~10,425.82 ~~14a-12~~68,574.18 ~~under~~0.00 ~~the~~0.00 ~~Exchange~~3A6 ~~Act~~3,000,000.00 (3,000,000.00 6,334.68 41,665.32 0.00 0.00 3A7 5,116,000.00 5,116,000.00 0.00 0.00 0.00 0.00 3A8 3,411,000.00 3,411,000.00 0.00 0.00 0.00 0.00 3A9 425,000.00 425,000.00 21,819.63 143,515.13 0.00 0.00 3A10 17,639,807.00 ~~CFR~~17,639,807.00 ~~240~~80,723.~~14a-12)~~48 [530,945.76 ]0.00 ~~Pre-commencement~~0.00 ~~communications~~3A11 ~~pursuant~~1,653,732.00 to1,653,732.00 ~~Rule~~7,567.83 ~~14d-2(d)~~49,776.17 ~~under~~0.00 ~~the~~0.00 ~~Exchange~~3A12 ~~Act~~4,760,744.00 (4,760,744.00 21,786.17 ~~CFR~~143,295.04 ~~240~~0.~~14d-2~~00 0.00 3A13 5,500,055.00 5,500,055.00 0.00 0.00 0.00 0.00 3A14 85,605,000.00 85,605,000.00 24,764.17 162,882.39 0.00 0.00 3A15 11,430,000.00 11,430,000.00 0.00 0.00 0.00 0.00 3A16 26,994,428.00 26,994,428.00 24,777.67 162,971.15 0.00 0.00 3A17 5,500,000.00 5,500,000.00 0.00 0.00 0.00 0.00 3A18 5,656,836.00 5,656,836.00 0.00 0.00 (b25,927.16)) [0.00 ]3A19 ~~Pre-commencement~~2,200,000.00 ~~communications~~2,200,000.00 ~~pursuant~~975.74 to6,417.78 ~~Rule~~0.00 ~~13e-~~0.00 3A20 25,254,000.00 25,254,000.00 12,950.12 85,177.33 0.00 0.00 3A21 14,609,466.00 14,609,466.00 3,501.89 23,033.14 0.00 0.00 3A22 4,480,000.00 4,480,000.00 0.00 0.00 (c20,533.33) ~~under~~0.00 ~~the~~3A23 ~~Exchange~~1,668,736.00 ~~Act~~1,668,736.00 0.00 0.00 (177,648.37) ~~CFR~~0.00 ~~240~~3A24 5,312,534.~~13e-4~~00 5,312,534.00 1,273.42 8,375.69 0.00 0.00 3A25 10,000,000.00 10,000,000.00 0.00 0.00 0.00 0.00 CB1 7,786,694.00 7,786,694.00 16,692.83 0.00 0.00 0.00 CB2 2,920,010.00 2,920,010.00 6,259.81 0.00 0.00 0.00 CB3 1,460,005.00 1,460,005.00 3,129.91 0.00 0.00 0.00 CB4 1,216,670.00 1,216,670.00 2,608.25 0.00 0.00 0.00 CB5 973,336.00 973,336.00 2,086.60 0.00 0.00 0.00 CB6 730,005.30 730,005.30 1,564.96 0.00 0.00 0.00 ES 0.01 0.01 0.00 0.00 0.00 0.00 DB1 5,248,096.00 5,248,096.00 3,756.73 0.00 0.00 0.00 DB2 2,553,127.00 2,553,127.00 1,827.60 0.00 0.00 0.00 DB3 1,418,404.00 1,418,404.00 1,015.33 0.00 0.00 0.00 DB4 709,202.00 709,202.00 507.67 0.00 0.00 0.00 DB5 851,042.00 851,042.00 609.20 0.00 0.00 0.00 DB6 567,361.00 567,361.00 406.13 0.00 0.00 0.00 DB7 709,205.04 709,205.04 507.67 0.00 0.00 0.00 PP 100.00 100.00 0.00 0.00 0.00 0.00 AR 50.00 50.00 14.59 35.41 0.00 0.00 ARL 50.00 50.00 14.59 35.41 0.00 0.00 1X 0.00 0.00 0.00 0.00 0.00 0.00 2X 0.00 0.00 0.00 0.00 0.00 0.00 3X 0.00 0.00 0.00 0.00 0.00 0.00 Totals 770,349,207.15 770,349,207.15 1,253,822.55 5,171,216.38 (c54,108.86) 0.00 (1) Amount Does Not Include Excess Special Hazard, Bankruptcy, or Fraud Losses Unless Otherwise Disclosed. Please Refer to the Prospectus Supplement for a Full Description.

~~Item~~Principal 8Distribution Statement (continued) Total Ending Ending Total Principal Certificate Certificate Principal Class Reduction Balance Percentage Distribution 1A1 2,561,072.70 196,029,065.30 0.98710373 2,561,072.70 AP 3,033.45 2,099,469.35 0.99855722 3,033.45 2A1 383,227.19 49,616,772.81 0.99233546 383,227.19 2A2 0.00 0.00 0.00000000 0.00 2A3 0.00 17,632,371.00 1.00000000 0.00 2A4 0.00 23,805,000.00 1.00000000 0.00 2A5 766,454.38 99,233,545.62 0.99233546 766,454.38 2A6 0.00 0.00 0.00000000 0.00 2A7 632,677.99 74,367,322.01 0.99156429 632,677.99 2A8 0.00 0.00 0.00000000 0.00 2A9 0.00 4,312,500.00 1.00000000 0.00 3A1 29,071.44 10,202,928.56 0.99715877 29,071.44 3A2 285,899.40 6,536,100.60 0.95809156 285,899.40 3A3 0.00 4,492,000.00 1.00000000 0.00 3A4 79,000.00 4,921,000.00 0.98420000 79,000.00 3A5 79,000.00 4,921,000.00 0.98420000 79,000.00 3A6 48,000.00 2,952,000.00 0.98400000 48,000.00 3A7 0.00 5,116,000.00 1.00000000 0.00 3A8 0.00 3,411,000.00 1.00000000 0.00 3A9 165,334.76 259,665.24 0.61097704 165,334.76 3A10 611,669.24 17,028,137.76 0.96532449 611,669.24 3A11 57,343.99 1,596,388.01 0.96532450 57,343.99 3A12 165,081.21 4,595,662.79 0.96532449 165,081.21 3A13 0.00 5,500,055.00 1.00000000 0.00 3A14 187,646.56 85,417,353.44 0.99780800 187,646.56 3A15 0.00 11,430,000.00 1.00000000 0.00 3A16 187,748.82 26,806,679.18 0.99304490 187,748.82 3A17 0.00 5,500,000.00 1.00000000 0.00 3A18 (25,927.16) 5,682,763.16 1.00458333 (25,927.16) 3A19 7,393.53 2,192,606.47 0.99663930 7,393.53 3A20 98,127.45 25,155,872.55 0.99611438 98,127.45 3A21 26,535.04 14,582,930.96 0.99818371 26,535.04 3A22 (20,533.33) 4,500,533.33 1.00458333 (20,533.33) 3A23 (7,648.37) 1,676,384.37 1.00458333 (7,648.37) 3A24 9,649.11 5,302,884.89 0.99818371 9,649.11 3A25 0.00 10,000,000.00 1.00000000 0.00 CB1 16,692.83 7,770,001.17 0.99785624 16,692.83 CB2 6,259.81 2,913,750.19 0.99785624 6,259.81 CB3 3,129.91 1,456,875.09 0.99785623 3,129.91 CB4 2,608.25 1,214,061.75 0.99785624 2,608.25 CB5 2,086.60 971,249.40 0.99785624 2,086.60 CB6 1,564.96 728,440.34 0.99785623 1,564.96 ES 0.00 0.01 1.00000000 0.00 DB1 3,756.73 5,244,339.27 0.99928417 3,756.73 DB2 1,827.60 2,551,299.40 0.99928417 1,827.60 DB3 1,015.33 1,417,388.67 0.99928417 1,015.33 DB4 507.67 708,694.33 0.99928417 507.67 DB5 609.20 850,432.80 0.99928417 609.20 DB6 406.13 566,954.87 0.99928418 406.13 DB7 507.67 708,697.37 0.99928417 507.67 PP 0.00 100.00 1.00000000 0.00 AR 50.00 0.00 0.00000000 50.00 ARL 50.00 0.00 0.00000000 50.00 1X 0.00 0.00 0.00000000 0.00 2X 0.00 0.00 0.00000000 0.00 3X 0.00 0.00 0.00000000 0.00 Totals 6,370,930.09 763,978,277.06 0.99172982 6,370,930.09

~~Other~~Principal ~~Events~~Distribution Factors Statement Original Beginning Scheduled Unscheduled Face Certificate Principal Principal Class (2) Amount Balance Distribution Distribution Accretion 1A1 198,590,138.00 1000.00000000 3.76218325 9.13409008 0.00000000 AP 2,102,502.80 1000.00000000 1.41939882 0.02337690 0.00000000 2A1 50,000,000.00 1000.00000000 0.83342620 6.83111760 0.00000000 2A2 0.00 0.00000000 0.00000000 0.00000000 0.00000000 2A3 17,632,371.00 1000.00000000 0.00000000 0.00000000 0.00000000 2A4 23,805,000.00 1000.00000000 0.00000000 0.00000000 0.00000000 2A5 100,000,000.00 1000.00000000 0.83342620 6.83111760 0.00000000 2A6 0.00 0.00000000 0.00000000 0.00000000 0.00000000 2A7 75,000,000.00 1000.00000000 0.91728080 7.51842573 0.00000000 2A8 0.00 0.00000000 0.00000000 0.00000000 0.00000000 2A9 4,312,500.00 1000.00000000 0.00000000 0.00000000 0.00000000 3A1 10,232,000.00 1000.00000000 0.37496384 2.46626368 0.00000000 3A2 6,822,000.00 1000.00000000 5.53075931 36.37768396 0.00000000 3A3 4,492,000.00 1000.00000000 0.00000000 0.00000000 0.00000000 3A4 5,000,000.00 1000.00000000 2.08516400 13.71483600 0.00000000 3A5 5,000,000.00 1000.00000000 2.08516400 13.71483600 0.00000000 3A6 3,000,000.00 1000.00000000 2.11156000 13.88844000 0.00000000 3A7 5,116,000.00 1000.00000000 0.00000000 0.00000000 0.00000000 3A8 3,411,000.00 1000.00000000 0.00000000 0.00000000 0.00000000 3A9 425,000.00 1000.00000000 51.34030588 337.68265882 0.00000000 3A10 17,639,807.00 1000.00000000 4.57621107 30.09929530 0.00000000 3A11 1,653,732.00 1000.00000000 4.57621307 30.09929662 0.00000000 3A12 4,760,744.00 1000.00000000 4.57621120 30.09929540 0.00000000 3A13 5,500,055.00 1000.00000000 0.00000000 0.00000000 0.00000000 3A14 85,605,000.00 1000.00000000 0.28928415 1.90272052 0.00000000 3A15 11,430,000.00 1000.00000000 0.00000000 0.00000000 0.00000000 3A16 26,994,428.00 1000.00000000 0.91788090 6.03721442 0.00000000 3A17 5,500,000.00 1000.00000000 0.00000000 0.00000000 0.00000000 3A18 5,656,836.00 1000.00000000 0.00000000 0.00000000 (4.58333245) 3A19 2,200,000.00 1000.00000000 0.44351818 2.91717273 0.00000000 3A20 25,254,000.00 1000.00000000 0.51279480 3.37282530 0.00000000 3A21 14,609,466.00 1000.00000000 0.23970007 1.57659014 0.00000000 3A22 4,480,000.00 1000.00000000 0.00000000 0.00000000 (4.58333259) 3A23 1,668,736.00 1000.00000000 0.00000000 0.00000000 (4.58333134) 3A24 5,312,534.00 1000.00000000 0.23970105 1.57659038 0.00000000 3A25 10,000,000.00 1000.00000000 0.00000000 0.00000000 0.00000000 CB1 7,786,694.00 1000.00000000 2.14376345 0.00000000 0.00000000 CB2 2,920,010.00 1000.00000000 2.14376321 0.00000000 0.00000000 CB3 1,460,005.00 1000.00000000 2.14376663 0.00000000 0.00000000 CB4 1,216,670.00 1000.00000000 2.14376125 0.00000000 0.00000000 CB5 973,336.00 1000.00000000 2.14376125 0.00000000 0.00000000 CB6 730,005.30 1000.00000000 2.14376526 0.00000000 0.00000000 ES 0.01 0.00000000 0.00000000 0.00000000 0.00000000 DB1 5,248,096.00 1000.00000000 0.71582723 0.00000000 0.00000000 DB2 2,553,127.00 1000.00000000 0.71582808 0.00000000 0.00000000 DB3 1,418,404.00 1000.00000000 0.71582567 0.00000000 0.00000000 DB4 709,202.00 1000.00000000 0.71583272 0.00000000 0.00000000 DB5 851,042.00 1000.00000000 0.71582836 0.00000000 0.00000000 DB6 567,361.00 1000.00000000 0.71582291 0.00000000 0.00000000 DB7 709,205.04 1000.00000000 0.71582966 0.00000000 0.00000000 PP 100.00 1000.00000000 0.00000000 0.00000000 0.00000000 AR 50.00 1000.00000000 291.80000000 708.20000000 0.00000000 ARL 50.00 1000.00000000 291.80000000 708.20000000 0.00000000 1X 0.00 0.00000000 0.00000000 0.00000000 0.00000000 2X 0.00 0.00000000 0.00000000 0.00000000 0.00000000 3X 0.00 0.00000000 0.00000000 0.00000000 0.00000000

~~Credit~~Principal ~~Suisse~~Distribution ~~First~~Factors ~~Boston~~Statement ~~Mortgage~~(continued) ~~Securities~~Total ~~Corp.~~Ending ~~(the~~Ending ~~“Company”~~Total Realized Principal Certificate Certificate Principal Class Loss (3) ~~entered~~Reduction ~~into~~Balance aPercentage ~~Pooling~~Distribution ~~and~~1A1 ~~Servicing~~0.00000000 ~~Agreement~~12.89627333 ~~dated~~987.10372667 as0.98710373 of12.89627333 ~~April~~AP 0.00000000 1,.44278048 ~~2005~~998.55721952 ~~(the~~0.99855722 ~~“Agreement”)~~1.44278048 ~~among~~2A1 ~~the~~0.00000000 ~~Credit~~7.66454380 ~~Suisse~~992.33545620 ~~First~~0.99233546 ~~Boston~~7.66454380 ~~Mortgage~~2A2 ~~Securities~~0.00000000 ~~Corp~~0.00000000 as0.00000000 ~~depositor,~~0.00000000 U0.S00000000 2A3 0.00000000 ~~Bank~~0.00000000 1,000.00000000 ~~National~~1.00000000 ~~Association,~~0.00000000 as2A4 ~~trustee~~0.00000000 ~~(the~~0.00000000 ~~“Trustee”)~~1,000.00000000 ~~Wells~~1.00000000 ~~Fargo~~0.00000000 ~~Bank,~~2A5 N0.A00000000 7.,66454380 as992.33545620 a0.99233546 ~~servicer~~7.66454380 ~~(in~~2A6 ~~such~~0.00000000 ~~capacity,~~0.00000000 a0.00000000 ~~“Servicer”),~~0.00000000 ~~master~~0.00000000 ~~servicer~~2A7 ~~(in~~0.00000000 ~~such~~8.43570653 ~~capacity,~~991.56429347 ~~the~~0.99156429 ~~“Master~~8.43570653 ~~Servicer”)~~2A8 ~~and~~0.00000000 as0.00000000 ~~trust~~0.00000000 ~~administrator~~0.00000000 ~~(in~~0.00000000 ~~such~~2A9 ~~capacity~~0.00000000 0.00000000 1,000.00000000 ~~the~~1.00000000 ~~“Trust~~0.00000000 ~~Administrator”),~~3A1 ~~DLJ~~0.00000000 ~~Mortgage~~2.84122752 ~~Capital,~~997.15877248 ~~Inc~~0.99715877 2.84122752 3A2 0.00000000 41.90844327 958.09155673 0.95809156 41.90844327 3A3 0.00000000 0.00000000 1,000.00000000 as1.00000000 ~~seller~~0.00000000 ~~(the~~3A4 ~~“Seller”)~~0.00000000 15.80000000 984.20000000 0.98420000 15.80000000 3A5 0.00000000 15.80000000 984.20000000 0.98420000 15.80000000 3A6 0.00000000 16.00000000 984.00000000 0.98400000 16.00000000 3A7 0.00000000 0.00000000 1,000.00000000 ~~Washington~~1.00000000 ~~Mutual~~0.00000000 ~~Mortgage~~3A8 ~~Securities~~0.00000000 ~~Corp~~0.00000000 1,000.00000000 as1.00000000 a0.00000000 ~~servicer~~3A9 (a0.00000000 ~~“Servicer”)~~389.02296471 610.97703529 0.61097704 389.02296471 3A10 0.00000000 34.67550637 965.32449363 0.96532449 34.67550637 3A11 0.00000000 34.67550365 965.32449635 0.96532450 34.67550365 3A12 0.00000000 34.67550660 965.32449340 0.96532449 34.67550660 3A13 0.00000000 0.00000000 1,000.00000000 ~~Bank~~1.00000000 of0.00000000 ~~America~~3A14 0.00000000 2.19200467 997.80799533 0.99780800 2.19200467 3A15 0.00000000 0.00000000 1,000.00000000 ~~National~~1.00000000 ~~Association~~0.00000000 3A16 0.00000000 6.95509533 993.04490467 0.99304490 6.95509533 3A17 0.00000000 0.00000000 1,000.00000000 as1.00000000 a0.00000000 ~~servicer~~3A18 0.00000000 (a4.58333245) ~~“Servicer”~~1,004.58333245 1.00458333 (4.58333245) ~~and Select~~3A19 ~~Portfolio~~0.00000000 ~~Servicing,~~3.36069545 ~~Inc~~996.~~, as~~63930455 a0.99663930 ~~servicer~~3.36069545 ~~(in~~3A20 ~~such~~0.00000000 ~~capacity~~3.88562010 996.11437990 0.99611438 3.88562010 3A21 0.00000000 1.81629089 998.18370911 0.99818371 1.81629089 3A22 0.00000000 (4.58333259) 1,004.58333259 a1.00458333 ~~“Servicer”~~(4.58333259) ~~and~~3A23 as0.00000000 ~~special~~(4.58333134) ~~servicer~~1,004.58333134 1.00458333 (in4.58333134) ~~such~~3A24 ~~capacity~~0.00000000 1.81629143 998.18370857 0.99818371 1.81629143 3A25 0.00000000 0.00000000 1,000.00000000 ~~the~~1.00000000 ~~“Special~~0.00000000 ~~Servicer”)~~CB1 ~~providing~~0.00000000 ~~for~~2.14376345 ~~the~~997.85623655 ~~issuance~~0.99785624 of2.14376345 ~~the~~CB2 ~~CSFB~~0.00000000 ~~Mortgage-Backed~~2.14376321 ~~Pass-Through~~997.85623679 ~~Certificates,~~0.99785624 ~~Series~~2.14376321 ~~2005-4~~CB3 0. ~~The~~00000000 ~~Certificates~~2.14376663 ~~were~~997.85623337 ~~issued~~0.99785623 on2.14376663 ~~April~~CB4 280.00000000 2.14376125 997.85623875 0.99785624 2.14376125 CB5 0.00000000 2.14376125 997.85623875 0.99785624 2.14376125 CB6 0.00000000 2.14376526 997.85623474 0.99785623 2.14376526 ES 0.00000000 0.00000000 0.00000000 1.00000000 0.00000000 DB1 0.00000000 0.71582723 999.28417277 0.99928417 0.71582723 DB2 0.00000000 0.71582808 999.28417192 0.99928417 0.71582808 DB3 0.00000000 0.71582567 999.28417433 0.99928417 0.71582567 DB4 0.00000000 0.71583272 999.28416728 0.99928417 0.71583272 DB5 0.00000000 0.71582836 999.28417164 0.99928417 0.71582836 DB6 0.00000000 0.71582291 999.28417709 0.99928418 0.71582291 DB7 0.00000000 0.71582966 999.28417034 0.99928417 0.71582966 PP 0.00000000 0.00000000 1,000.00000000 ~~2005~~1.00000000 ~~The~~0.00000000 ~~Pooling~~AR ~~and~~0.00000000 ~~Servicing~~1,000.00000000 ~~Agreement~~0.00000000 is0.00000000 ~~annexed~~1,000.00000000 ~~hereto~~ARL as0.00000000 ~~Exhibit~~1,000.00000000 990.00000000 0.00000000 1,000.00000000 1X 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000 2X 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000 3X 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000 (3) Amount Does Not Include Excess Special Hazard, Bankruptcy, or Fraud Losses Unless Otherwise Disclosed. Please Refer to the Prospectus Supplement for a Full Description.

~~Item~~Interest 9Distribution Statement Beginning Payment of Original Current Certificate/ Current Unpaid Current Face Certificate Notional Accrued Interest Interest Class Amount Rate Balance Interest Shortfall Shortfall 1A1 198,590,138.00 5.00000% 198,590,138.00 827,458.91 0.00 0.00 AP 2,102,502.80 0.00000% 2,102,502.80 0.00 0.00 0.00 2A1 50,000,000.00 3.25000% 50,000,000.00 135,416.67 0.00 0.00 2A2 0.00 0.10000% 75,000,000.00 6,250.00 0.00 0.00 2A3 17,632,371.00 5.50000% 17,632,371.00 80,815.03 0.00 0.00 2A4 23,805,000.00 5.50000% 23,805,000.00 109,106.25 0.00 0.00 2A5 100,000,000.00 3.40000% 100,000,000.00 283,333.33 0.00 0.00 2A6 0.00 2.10000% 225,000,000.00 393,750.00 0.00 0.00 2A7 75,000,000.00 3.30000% 75,000,000.00 206,250.00 0.00 0.00 2A8 0.00 0.15000% 50,000,000.00 6,250.00 0.00 0.00 2A9 4,312,500.00 5.50000% 4,312,500.00 19,765.63 0.00 0.00 3A1 10,232,000.00 5.50000% 10,232,000.00 46,896.67 0.00 0.00 3A2 6,822,000.00 5.50000% 6,822,000.00 31,267.50 0.00 0.00 3A3 4,492,000.00 5.50000% 4,492,000.00 20,588.33 0.00 0.00 3A4 5,000,000.00 5.00000% 5,000,000.00 20,833.33 0.00 0.00 3A5 5,000,000.00 6.00000% 5,000,000.00 25,000.00 0.00 0.00 3A6 3,000,000.00 5.50000% 3,000,000.00 13,750.00 0.00 0.00 3A7 5,116,000.00 5.50000% 5,116,000.00 23,448.33 0.00 0.00 3A8 3,411,000.00 5.50000% 3,411,000.00 15,633.75 0.00 0.00 3A9 425,000.00 5.50000% 425,000.00 1,947.92 0.00 0.00 3A10 17,639,807.00 3.75000% 17,639,807.00 55,124.40 0.00 0.00 3A11 1,653,732.00 8.00000% 1,653,732.00 11,024.88 0.00 0.00 3A12 4,760,744.00 11.11579% 4,760,744.00 44,099.53 0.00 0.00 3A13 5,500,055.00 5.50000% 5,500,055.00 25,208.59 0.00 0.00 3A14 85,605,000.00 5.50000% 85,605,000.00 392,356.25 0.00 0.00 3A15 11,430,000.00 5.50000% 11,430,000.00 52,387.50 0.00 0.00 3A16 26,994,428.00 5.50000% 26,994,428.00 123,724.46 0.00 0.00 3A17 5,500,000.00 5.50000% 5,500,000.00 25,208.33 0.00 0.00 3A18 5,656,836.00 5.50000% 5,656,836.00 25,927.17 0.00 0.00 3A19 2,200,000.00 5.50000% 2,200,000.00 10,083.33 0.00 0.00 3A20 25,254,000.00 5.50000% 25,254,000.00 115,747.50 0.00 0.00 3A21 14,609,466.00 3.65000% 14,609,466.00 44,437.13 0.00 0.00 3A22 4,480,000.00 5.50000% 4,480,000.00 20,533.33 0.00 0.00 3A23 1,668,736.00 5.50000% 1,668,736.00 7,648.37 0.00 0.00 3A24 5,312,534.00 10.58750% 5,312,534.00 46,872.04 0.00 0.00 3A25 10,000,000.00 5.50000% 10,000,000.00 45,833.33 0.00 0.00 CB1 7,786,694.00 5.28911% 7,786,694.00 34,320.58 0.00 0.00 CB2 2,920,010.00 5.28911% 2,920,010.00 12,870.22 0.00 0.00 CB3 1,460,005.00 5.28911% 1,460,005.00 6,435.11 0.00 0.00 CB4 1,216,670.00 5.28911% 1,216,670.00 5,362.59 0.00 0.00 CB5 973,336.00 5.28911% 973,336.00 4,290.07 0.00 0.00 CB6 730,005.30 5.28911% 730,005.30 3,217.57 0.00 0.00 ES 0.01 0. ~~Financial~~00000% ~~Statements~~0.01 ~~and~~0.00 ~~Exhibits~~0.00 0.00 DB1 5,248,096.00 5.50000% 5,248,096.00 24,053.77 0.00 0.00 DB2 2,553,127.00 5.50000% 2,553,127.00 11,701.83 0.00 0.00 DB3 1,418,404.00 5.50000% 1,418,404.00 6,501.02 0.00 0.00 DB4 709,202.00 5.50000% 709,202.00 3,250.51 0.00 0.00 DB5 851,042.00 5.50000% 851,042.00 3,900.61 0.00 0.00 DB6 567,361.00 5.50000% 567,361.00 2,600.40 0.00 0.00 DB7 709,205.04 5.50000% 709,205.04 3,250.52 0.00 0.00 PP 100.00 5.00000% 100.00 0.42 0.00 0.00 AR 50.00 5.00000% 50.00 0.21 0.00 0.00 ARL 50.00 5.00000% 50.00 0.21 0.00 0.00 1X 0.00 5.00000% 9,330,497.91 38,877.07 0.00 0.00 2X 0.00 5.50000% 12,285,897.05 56,310.36 0.00 0.00 3X 0.00 5.50000% 5,801,655.15 26,590.92 0.00 0.00 Totals 770,349,207.15 3,557,511.78 0.00 0.00

Interest Distribution Statement (acontinued) Remaining Ending Non-Supported Total Unpaid Certificate/ Interest Realized Interest Interest Notional Class Shortfall Losses (4) Distribution Shortfall Balance 1A1 0.00 0.00 827,458.91 0.00 196,029,065.30 AP 0.00 0.00 0.00 0.00 2,099,469.35 2A1 0.00 0.00 135,416.67 0.00 49,616,772.81 2A2 0.00 0.00 6,250.00 0.00 74,367,322.01 2A3 0.00 0.00 80,815.03 0.00 17,632,371.00 2A4 0.00 0.00 109,106.25 0.00 23,805,000.00 2A5 0.00 0.00 283,333.33 0.00 99,233,545.62 2A6 0.00 0.00 393,750.00 0.00 223,217,640.44 2A7 0.00 0.00 206,250.00 0.00 74,367,322.01 2A8 0.00 0.00 6,250.00 0.00 49,616,772.81 2A9 0.00 0.00 19,765.63 0.00 4,312,500.00 3A1 0.00 0.00 46,896.67 0.00 10,202,928.56 3A2 0.00 0.00 31,267.50 0.00 6,536,100.60 3A3 0.00 0.00 20,588.33 0.00 4,492,000.00 3A4 0.00 0.00 20,833.33 0.00 4,921,000.00 3A5 0.00 0.00 25,000.00 0.00 4,921,000.00 3A6 0.00 0.00 13,750.00 0.00 2,952,000.00 3A7 0.00 0.00 23,448.33 0.00 5,116,000.00 3A8 0.00 0.00 15,633.75 0.00 3,411,000.00 3A9 0.00 0.00 1,947.92 0.00 259,665.24 3A10 0.00 0.00 55,124.40 0.00 17,028,137.76 3A11 0.00 0.00 11,024.88 0.00 1,596,388.01 3A12 0.00 0.00 44,099.53 0.00 4,595,662.79 3A13 0.00 0.00 25,208.59 0.00 5,500,055.00 3A14 0.00 0.00 392,356.25 0.00 85,417,353.44 3A15 0.00 0.00 52,387.50 0.00 11,430,000.00 3A16 0.00 0.00 123,724.46 0.00 26,806,679.18 3A17 0.00 0.00 25,208.33 0.00 5,500,000.00 3A18 0.00 0.00 25,927.17 0.00 5,682,763.16 3A19 0.00 0.00 10,083.33 0.00 2,192,606.47 3A20 0.00 0.00 115,747.50 0.00 25,155,872.55 3A21 0.00 0.00 44,437.13 0.00 14,582,930.96 3A22 0.00 0.00 20,533.33 0.00 4,500,533.33 3A23 0.00 0.00 7,648.37 0.00 1,676,384.37 3A24 0.00 0.00 46,872.04 0.00 5,302,884.89 3A25 0.00 0.00 45,833.33 0.00 10,000,000.00 CB1 0.00 0.00 34,320.58 0.00 7,770,001.17 CB2 0.00 0.00 12,870.22 0.00 2,913,750.19 CB3 0.00 0.00 6,435.11 0.00 1,456,875.09 CB4 0.00 0.00 5,362.59 0.00 1,214,061.75 CB5 0.00 0.00 4,290.07 0.00 971,249.40 CB6 0.00 0.00 3,217.57 0.00 728,440.34 ES 0.00 0.00 0.00 0.00 0.01 DB1 0.00 0.00 24,053.77 0.00 5,244,339.27 DB2 0.00 0.00 11,701.83 0.00 2,551,299.40 DB3 0.00 0.00 6,501.02 0.00 1,417,388.67 DB4 0.00 0.00 3,250.51 0.00 708,694.33 DB5 0.00 0.00 3,900.61 0.00 850,432.80 DB6 0.00 0.00 2,600.40 0.00 566,954.87 DB7 0.00 0.00 3,250.52 0.00 708,697.37 PP 0.00 0.00 0.42 0.00 100.00 AR 0.00 0.00 0.21 0.00 0.00 ARL 0.00 0.00 0.21 0.00 0.00 1X 0.00 0.00 38,877.08 0.00 9,200,700.40 2X 0.00 0.00 56,310.37 0.00 12,220,906.09 3X 0.00 0.00 26,590.92 0.00 5,758,290.93 Totals 0.00 0.00 3,557,511.80 0.00 (4) Amount Does Not Include Excess Special Hazard, Bankruptcy, or Fraud Losses Unless Otherwise Disclosed. Please Refer to the Prospectus Supplement for a Full Description.

~~Not~~Interest ~~applicable~~Distribution Factors Statement Beginning Payment of Original Current Certificate/ Current Unpaid Current Face Certificate Notional Accrued Interest Interest Class (5) Amount Rate Balance Interest Shortfall Shortfall 1A1 198,590,138.00 5.00000% 1000.00000000 4.16666668 0.00000000 0.00000000 AP 2,102,502.80 0.00000% 1000.00000000 0.00000000 0.00000000 0.00000000 2A1 50,000,000.00 3.25000% 1000.00000000 2.70833340 0.00000000 0.00000000 2A2 0.00 0.10000% 1000.00000000 0.08333333 0.00000000 0.00000000 2A3 17,632,371.00 5.50000% 1000.00000000 4.58333312 0.00000000 0.00000000 2A4 23,805,000.00 5.50000% 1000.00000000 4.58333333 0.00000000 0.00000000 2A5 100,000,000.00 3.40000% 1000.00000000 2.83333330 0.00000000 0.00000000 2A6 0.00 2.10000% 1000.00000000 1.75000000 0.00000000 0.00000000 2A7 75,000,000.00 3.30000% 1000.00000000 2.75000000 0.00000000 0.00000000 2A8 0.00 0.15000% 1000.00000000 0.12500000 0.00000000 0.00000000 2A9 4,312,500.00 5.50000% 1000.00000000 4.58333449 0.00000000 0.00000000 3A1 10,232,000.00 5.50000% 1000.00000000 4.58333366 0.00000000 0.00000000 3A2 6,822,000.00 5.50000% 1000.00000000 4.58333333 0.00000000 0.00000000 3A3 4,492,000.00 5.50000% 1000.00000000 4.58333259 0.00000000 0.00000000 3A4 5,000,000.00 5.00000% 1000.00000000 4.16666600 0.00000000 0.00000000 3A5 5,000,000.00 6.00000% 1000.00000000 5.00000000 0.00000000 0.00000000 3A6 3,000,000.00 5.50000% 1000.00000000 4.58333333 0.00000000 0.00000000 3A7 5,116,000.00 5.50000% 1000.00000000 4.58333268 0.00000000 0.00000000 3A8 3,411,000.00 5.50000% 1000.00000000 4.58333333 0.00000000 0.00000000 3A9 425,000.00 5.50000% 1000.00000000 4.58334118 0.00000000 0.00000000 3A10 17,639,807.00 3.75000% 1000.00000000 3.12500018 0.00000000 0.00000000 3A11 1,653,732.00 8.00000% 1000.00000000 6.66666667 0.00000000 0.00000000 3A12 4,760,744.00 11.11579% 1000.00000000 9.26315929 0.00000000 0.00000000 3A13 5,500,055.00 5.50000% 1000.00000000 4.58333417 0.00000000 0.00000000 3A14 85,605,000.00 5.50000% 1000.00000000 4.58333333 0.00000000 0.00000000 3A15 11,430,000.00 5.50000% 1000.00000000 4.58333333 0.00000000 0.00000000 3A16 26,994,428.00 5.50000% 1000.00000000 4.58333327 0.00000000 0.00000000 3A17 5,500,000.00 5.50000% 1000.00000000 4.58333273 0.00000000 0.00000000 3A18 5,656,836.00 5.50000% 1000.00000000 4.58333422 0.00000000 0.00000000 3A19 2,200,000.00 5.50000% 1000.00000000 4.58333182 0.00000000 0.00000000 3A20 25,254,000.00 5.50000% 1000.00000000 4.58333333 0.00000000 0.00000000 3A21 14,609,466.00 3.65000% 1000.00000000 3.04166696 0.00000000 0.00000000 3A22 4,480,000.00 5.50000% 1000.00000000 4.58333259 0.00000000 0.00000000 3A23 1,668,736.00 5.50000% 1000.00000000 4.58333134 0.00000000 0.00000000 3A24 5,312,534.00 10.58750% 1000.00000000 8.82291577 0.00000000 0.00000000 3A25 10,000,000.00 5.50000% 1000.00000000 4.58333300 0.00000000 0.00000000 CB1 7,786,694.00 5.28911% 1000.00000000 4.40759326 0.00000000 0.00000000 CB2 2,920,010.00 5.28911% 1000.00000000 4.40759449 0.00000000 0.00000000 CB3 1,460,005.00 5.28911% 1000.00000000 4.40759449 0.00000000 0.00000000 CB4 1,216,670.00 5.28911% 1000.00000000 4.40759614 0.00000000 0.00000000 CB5 973,336.00 5.28911% 1000.00000000 4.40759409 0.00000000 0.00000000 CB6 730,005.30 5.28911% 1000.00000000 4.40759814 0.00000000 0.00000000 ES 0.01 0.00000% 0.00000000 0.00000000 0.00000000 0.00000000 DB1 5,248,096.00 5.50000% 1000.00000000 4.58333270 0.00000000 0.00000000 DB2 2,553,127.00 5.50000% 1000.00000000 4.58333252 0.00000000 0.00000000 DB3 1,418,404.00 5.50000% 1000.00000000 4.58333451 0.00000000 0.00000000 DB4 709,202.00 5.50000% 1000.00000000 4.58333451 0.00000000 0.00000000 DB5 851,042.00 5.50000% 1000.00000000 4.58333431 0.00000000 0.00000000 DB6 567,361.00 5.50000% 1000.00000000 4.58332525 0.00000000 0.00000000 DB7 709,205.04 5.50000% 1000.00000000 4.58332896 0.00000000 0.00000000 PP 100.00 5.00000% 1000.00000000 4.20000000 0.00000000 0.00000000 AR 50.00 5.00000% 1000.00000000 4.20000000 0.00000000 0.00000000 ARL 50.00 5.00000% 1000.00000000 4.20000000 0.00000000 0.00000000 1X 0.00 5.00000% 1000.00009753 4.16666658 0.00000000 0.00000000 2X 0.00 5.50000% 1000.73545223 4.58670404 0.00000000 0.00000000 3X 0.00 5.50000% 1000.00002585 4.58333355 0.00000000 0.00000000 (5) Per $1 denomination.

Interest Distribution Factors Statement (bcontinued) Remaining Ending Non-Supported Total Unpaid Certificate/ Interest Realized Interest Interest Notional Class Shortfall Losses (6) Distribution Shortfall Balance 1A1 0.00000000 0.00000000 4.16666668 0.00000000 987.10372667 AP 0.00000000 0.00000000 0.00000000 0.00000000 998.55721952 2A1 0.00000000 0.00000000 2.70833340 0.00000000 992.33545620 2A2 0.00000000 0.00000000 0.08333333 0.00000000 991.56429347 2A3 0.00000000 0.00000000 4.58333312 0.00000000 1000.00000000 2A4 0.00000000 0.00000000 4.58333333 0.00000000 1000.00000000 2A5 0.00000000 0.00000000 2.83333330 0.00000000 992.33545620 2A6 0.00000000 0.00000000 1.75000000 0.00000000 992.07840196 2A7 0.00000000 0.00000000 2.75000000 0.00000000 991.56429347 2A8 0.00000000 0.00000000 0.12500000 0.00000000 992.33545620 2A9 0.00000000 0.00000000 4.58333449 0.00000000 1000.00000000 3A1 0.00000000 0.00000000 4.58333366 0.00000000 997.15877248 3A2 0.00000000 0.00000000 4.58333333 0.00000000 958.09155673 3A3 0.00000000 0.00000000 4.58333259 0.00000000 1000.00000000 3A4 0.00000000 0.00000000 4.16666600 0.00000000 984.20000000 3A5 0.00000000 0.00000000 5.00000000 0.00000000 984.20000000 3A6 0.00000000 0.00000000 4.58333333 0.00000000 984.00000000 3A7 0.00000000 0.00000000 4.58333268 0.00000000 1000.00000000 3A8 0.00000000 0.00000000 4.58333333 0.00000000 1000.00000000 3A9 0.00000000 0.00000000 4.58334118 0.00000000 610.97703529 3A10 0.00000000 0.00000000 3.12500018 0.00000000 965.32449363 3A11 0.00000000 0.00000000 6.66666667 0.00000000 965.32449635 3A12 0.00000000 0.00000000 9.26315929 0.00000000 965.32449340 3A13 0.00000000 0.00000000 4.58333417 0.00000000 1000.00000000 3A14 0.00000000 0.00000000 4.58333333 0.00000000 997.80799533 3A15 0.00000000 0.00000000 4.58333333 0.00000000 1000.00000000 3A16 0.00000000 0.00000000 4.58333327 0.00000000 993.04490467 3A17 0.00000000 0.00000000 4.58333273 0.00000000 1000.00000000 3A18 0.00000000 0.00000000 4.58333422 0.00000000 1004.58333245 3A19 0.00000000 0.00000000 4.58333182 0.00000000 996.63930455 3A20 0.00000000 0.00000000 4.58333333 0.00000000 996.11437990 3A21 0.00000000 0.00000000 3.04166696 0.00000000 998.18370911 3A22 0.00000000 0.00000000 4.58333259 0.00000000 1004.58333259 3A23 0.00000000 0.00000000 4.58333134 0.00000000 1004.58333134 3A24 0.00000000 0.00000000 8.82291577 0.00000000 998.18370857 3A25 0.00000000 0.00000000 4.58333300 0.00000000 1000.00000000 CB1 0.00000000 0.00000000 4.40759326 0.00000000 997.85623655 CB2 0.00000000 0.00000000 4.40759449 0.00000000 997.85623679 CB3 0.00000000 0.00000000 4.40759449 0.00000000 997.85623337 CB4 0.00000000 0.00000000 4.40759614 0.00000000 997.85623875 CB5 0.00000000 0.00000000 4.40759409 0.00000000 997.85623875 CB6 0.00000000 0.00000000 4.40759814 0.00000000 997.85623474 ES 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000 DB1 0.00000000 0.00000000 4.58333270 0.00000000 999.28417277 DB2 0.00000000 0.00000000 4.58333252 0.00000000 999.28417192 DB3 0.00000000 0.00000000 4.58333451 0.00000000 999.28417433 DB4 0.00000000 0.00000000 4.58333451 0.00000000 999.28416728 DB5 0.00000000 0.00000000 4.58333431 0.00000000 999.28417164 DB6 0.00000000 0.00000000 4.58332525 0.00000000 999.28417709 DB7 0.00000000 0.00000000 4.58332896 0.00000000 999.28417034 PP 0.00000000 0.00000000 4.20000000 0.00000000 1000.00000000 AR 0.00000000 0.00000000 4.20000000 0.00000000 0.00000000 ARL 0.00000000 0.00000000 4.20000000 0.00000000 0.00000000 1X 0.00000000 0.00000000 4.16666765 0.00000000 986.08899397 2X 0.00000000 0.00000000 4.58670485 0.00000000 995.44167861 3X 0.00000000 0.00000000 4.58333355 0.00000000 992.52556900 (6) Amount Does Not Include Excess Special Hazard, Bankruptcy,or Fraud Losses Unless Otherwise Disclosed. Please Refer to the Prospectus Supplement for a Full Description.

~~Not~~CERTIFICATEHOLDER ~~applicable~~ACCOUNT STATEMENT CERTIFICATE ACCOUNT Beginning Balance 0.00 Deposits Payments of Interest and Principal 10,075,568.35 Liquidations, Insurance Proceeds, Reserve Funds 0.00 Proceeds from Repurchased Loans 0.00 Other Amounts (Servicer Advances) 0.00 Realized Loss (Gains, Subsequent Expenses & Recoveries) 0.00 Prepayment Penalties 0.00 Total Deposits 10,075,568.35 Withdrawals Reimbursement for Servicer Advances 0.00 Payment of Service Fee 147,126.46 Payment of Interest and Principal 9,928,441.89 Total Withdrawals (Pool Distribution Amount) 10,075,568.35 Ending Balance 0.00

~~(c)~~PREPAYMENT/CURTAILMENT INTEREST SHORTFALL Total Prepayment/Curtailment Interest Shortfall 0.00 Servicing Fee Support 0.00 Non-Supported Prepayment/Curtailment Interest Shortfall 0.00

~~Exhibits:~~SERVICING FEES Gross Servicing Fee 146,841.44 External Master Servicing Fee 71.89 Miscellaneous Fee 213.13 Supported Prepayment/Curtailment Interest Shortfall 0.00 Net Servicing Fee 147,126.46

OTHER ACCOUNTS Beginning Current Current Ending Account Type Balance Withdrawals Deposits Balance 3-A-4 Rounding 999.99 256.121 0.00 743.78 3-A-5 Rounding 999.99 256.21 0.00 743.78 3-A-6 Rounding 999.99 753.73 0.00 246.26

~~The~~Delinquency ~~Pooling~~Status ~~and~~By ~~Servicing~~Groups ~~Agreement~~DELINQUENT ~~dated~~BANKRUPTCY asFORECLOSURE REO Total G1 30Y Conf AltA No of ~~April~~Loans No of Loans No of Loans No of Loans No of Loans Principal Balance Principal Balance Principal Balance Principal Balance Principal Balance 0-29 Days 0 0 0 0 0.00 0.00 0.00 0.00 30 Days 0 0 0 0 0 0.00 0.00 0.00 0.00 0.00 60 Days 0 0 0 0 0 0.00 0.00 0.00 0.00 0.00 90 Days 0 0 0 0 0 0.00 0.00 0.00 0.00 0.00 120 Days 0 0 0 0 0 0.00 0.00 0.00 0.00 0.00 150 Days 0 0 0 0 0 0.00 0.00 0.00 0.00 0.00 180 Days 0 0 0 0 0 0.00 0.00 0.00 0.00 0.00 Totals 0 0 0 0 0 0.00 0.00 0.00 0.00 0.00 0-29 Days 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 30 Days 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 60 Days 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 90 Days 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 120 Days 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 150 Days 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 180 Days 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% Totals 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% DELINQUENT BANKRUPTCY FORECLOSURE REO Total G2 30Y Conf AltA No of Loans No of Loans No of Loans No of Loans No of Loans Principal Balance Principal Balance Principal Balance Principal Balance Principal Balance 0-29 Days 0 0 0 0 0.00 0.00 0.00 0.00 30 Days 0 0 0 0 0 0.00 0.00 0.00 0.00 0.00 60 Days 1 0 0 0 1 296,000.00 ~~2005~~0.00 0.00 0.00 296,000.00 by90 ~~and~~Days ~~among~~0 ~~the~~0 ~~Company,~~0 ~~the~~0 ~~Seller,~~0 ~~the~~0.00 ~~Servicers,~~0.00 ~~the~~0.00 ~~Special~~0.00 ~~Servicer~~0.00 120 Days 0 0 0 0 0 0.00 0.00 0.00 0.00 0.00 150 Days 0 0 0 0 0 0.00 0.00 0.00 0.00 0.00 180 Days 0 0 0 0 0 0.00 0.00 0.00 0.00 0.00 Totals 1 0 0 0 1 296,000.00 ~~the~~0.00 ~~Master~~0.00 ~~Servicer~~0.00 296,000.00 ~~the~~0-29 ~~Trustee~~Days ~~and~~0.000000% ~~the~~0.000000% ~~Trust~~0.000000% ~~Administrator~~0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 30 Days 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 60 Days 0.085251% 0.000000% 0.000000% 0.000000% 0.085251% 0.123940% 0.000000% 0.000000% 0.000000% 0.123940% 90 Days 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 120 Days 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 150 Days 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 180 Days 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% Totals 0.085251% 0.000000% 0.000000% 0.000000% 0.085251% 0.123940% 0.000000% 0.000000% 0.000000% 0.123940% DELINQUENT BANKRUPTCY FORECLOSURE REO Total G3 30Y Conf AltA No of Loans No of Loans No of Loans No of Loans No of Loans Principal Balance Principal Balance Principal Balance Principal Balance Principal Balance 0-29 Days 0 0 0 0 0.00 0.00 0.00 0.00 30 Days 0 0 0 0 0 0.00 0.00 0.00 0.00 0.00 60 Days 0 0 0 0 0 0.00 0.00 0.00 0.00 0.00 90 Days 0 0 0 0 0 0.00 0.00 0.00 0.00 0.00 120 Days 0 0 0 0 0 0.00 0.00 0.00 0.00 0.00 150 Days 0 0 0 0 0 0.00 0.00 0.00 0.00 0.00 180 Days 0 0 0 0 0 0.00 0.00 0.00 0.00 0.00 Totals 0 0 0 0 0 0.00 0.00 0.00 0.00 0.00 0-29 Days 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 30 Days 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 60 Days 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 90 Days 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 120 Days 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 150 Days 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 180 Days 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% Totals 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 0.000000%

~~SIGNATURES~~Group Level Collateral Statement Group G1 30Y Conf AltA G2 30Y Conf AltA G3 30Y Conf AltA Collateral Description Mixed Fixed Mixed Fixed Mixed Fixed Weighted Average Coupon Rate 5.442203 5.926477 5.845483 Weighted Average Net Rate 5.219892 5.676164 5.595483 Weighted Average Maturity 175 356 356 Beginning Loan Count 369 1,180 564 Loans Paid In Full 4 7 3 Ending Loan Count 365 1,173 561 Beginning Scheduled Balance 205,261,513.38 240,603,111.95 281,406,840.94 Ending scheduled Balance 202,675,250.02 238,811,324.40 279,415,227.95 Record Date 04/29/2005 04/29/2005 04/29/2005 Principal And Interest Constant 1,703,208.69 1,391,556.58 1,641,990.41 Scheduled Principal 772,313.01 203,282.59 271,191.36 Unscheduled Principal 1,813,950.35 1,588,504.96 1,720,421.63 Scheduled Interest 930,895.68 1,188,273.99 1,370,799.05 Servicing Fees 38,026.61 50,188.42 58,626.41 Master Servicing Fees 0.00 0.00 0.00 Trustee Fee 0.00 0.00 0.00 FRY Amount 0.00 0.00 0.00 Special Hazard Fee 0.00 0.00 0.00 Other Fee 19.28 249.19 16.55 Pool Insurance Fee 0.00 0.00 0.00 Spread Fee 1 0.00 0.00 0.00 Spread Fee 2 0.00 0.00 0.00 Spread Fee 3 0.00 0.00 0.00 Net Interest 892,849.79 1,137,836.38 1,312,156.09 Realized Loss Amount 0.00 0.00 0.00 Cumulative Realized Loss 0.00 0.00 0.00 Percentage of Cumulative Losses 0.0000 0.0000 0.0000 Prepayment Penalties 0.00 0.00 0.00 Special Servicing Fee 0.00 0.00 0.00 Pass-Through Rate 5.219779 5.674921 5.595412

~~Pursuant~~Group toLevel ~~the~~Collateral ~~requirements~~Statement ofGroup ~~the~~Total ~~Securities~~Collateral ~~Exchange~~Description ~~Act~~Mixed ofFixed ~~1934~~Weighted Average Coupon Rate 5.758458 Weighted Average Net Rate 5.529718 Weighted Average Maturity 1 Beginning Loan Count 2,113 ~~the~~Loans ~~registrant~~Paid ~~duly~~In ~~caused~~Full ~~this~~14 ~~report~~Ending toLoan beCount ~~signed~~2,099 onBeginning ~~its~~Scheduled ~~behalf~~Balance by727,271,466.27 ~~the~~Ending ~~undersigned~~scheduled ~~hereunto~~Balance ~~duly~~720,901,802.37 ~~authorized~~Record Date 04/29/2005 Principal And Interest Constant 4,736,755.68 Scheduled Principal 1,246,786.96 Unscheduled Principal 5,122,876.94 Scheduled Interest 3,489,968.72 Servicing Fees 146,841.44 Master Servicing Fees 0.00 Trustee Fee 0.00 FRY Amount 0.00 Special Hazard Fee 0.00 Other Fee 285.02 Pool Insurance Fee 0.00 Spread Fee 1 0.00 Spread Fee 2 0.00 Spread Fee 3 0.00 Net Interest 3,342,842.26 Realized Loss Amount 0.00 Cumulative Realized Loss 0.00 Percentage of Cumulative Losses 0.0000 Prepayment Penalties 0.00 Special Servicing Fee 0.00 Pass-Through Rate 5.515699

~~CREDIT~~Miscellaneous ~~SUISSE~~Reporting ~~FIRST~~Group ~~BOSTON~~G1 ~~MORTGAGE~~30Y ~~SECURITIES~~Conf ~~CORP~~AltA Insurance Proceeds 0.00 Net Liquidation Proceeds 0.00 Repurchase Principal 0.00 Subsequent Losses 0.00 Subsequent Loss Recoveries 0.00 Substitution Amount 0.00 Substitution Adjustment Amount 0.00 Group G2 30Y Conf AltA Insurance Proceeds 0.00 Net Liquidation Proceeds 0.00 Repurchase Principal 0.00 Subsequent Losses 0.00 Subsequent Loss Recoveries 0.00 Substitution Amount 0.00 Substitution Adjustment Amount 0.00 Group G3 30Y Conf AltA Insurance Proceeds 0.00 Net Liquidation Proceeds 0.00 Repurchase Principal 0.00 Subsequent Losses 0.00 Subsequent Loss Recoveries 0.00 Substitution Amount 0.00 Substitution Adjustment Amount 0.00

Group

By: /s/ Kevin Steele

Name: Kevin Steele

Title: Director

Dated: May 23, 2005

Exhibit Index

Exhibit

Page

99.1

Pooling and Servicing Agreement dated as of April 1, 2005,

by and among the Company, the Seller, the Servicers, the

Special Servicer, the Master Servicer, the Trust Administrator

and the Trustee.

Filing Compare · CSFB Mortgage-Backed Pass-Through Certificates Series 2005-4