8-K 1 mab04wm1_sep.txt SEPTEMBER 8K 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): September 27, 2004 MASTR ASSET BACKED SECURITIES TRUST Mortgage Pass-Through Certificates, Series 2004-WM1 Trust (Exact name of registrant as specified in its charter) New York (governing law of 333-106982-20 54-2150435 Pooling and Servicing Agreement) (Commission 54-2150436 (State or other File Number) 54-2150437 jurisdiction 54-2150438 of Incorporation) 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 September 27, 2004 a distribution was made to holders of MASTR ASSET BACKED SECURITIES TRUST, Mortgage Pass-Through Certificates, Series 2004-WM1 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-WM1 Trust, relating to the September 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-WM1 Trust (Registrant) By: Wells Fargo Bank, N.A. as Master Servicer By: /s/ Beth Belfield as Assistant Vice President By: Beth Belfield as Assistant Vice President Date: 10/5/2004 INDEX TO EXHIBITS Exhibit Number Description EX-99.1 Monthly report distributed to holders of Mortgage Pass-Through Certificates, Series 2004-WM1 Trust, relating to the September 27, 2004 distribution. EX-99.1

MASTR Asset Backed Securitizations Mortgage Pass-Through Certificates Record Date: 78/31/042004 Distribution Date: 89/2527/042004 MABS Series: 2004-~~WMC1~~WM1 Contact: Customer Service - CTSLink Wells Fargo Bank, N.A. Securities Administration Services 7485 New Horizon Way Frederick, MD 21703 Telephone: (301) 815-6600 Fax: (301) 815-6660 Certificateholder Distribution Summary Certificate Certificate Beginning Class Pass-Through Certificate Interest Principal Class CUSIP Description Rate Balance Distribution Distribution A1 57643LCQ7 SEN 1.~~67000~~83500% ~~216~~204,~~630~~074,~~934~~829.4860 ~~301~~343,~~478~~270.0587 12,~~556~~771,~~104~~627.8847 A2 57643LCR5 SEN 1.~~83000~~99500% 28,170,000.00 4251,~~959~~515.2589 0.00 A3 57643LCS3 SEN 1.~~68000~~84500% ~~129~~123,~~653~~487,~~577~~584.03 ~~181~~208,~~515~~848.0138 67,~~165~~004,~~993~~460.0053 A4 57643LCT1 SEN 1.~~55000~~71500% 5446,~~988~~715,~~433~~823.5819 7173,~~026~~441.7317 8,~~272~~898,~~610~~253.3977 A5 57643LCU8 SEN 1.~~67000~~83500% 79,850,000.00 ~~111~~134,~~124~~314.5835 0.00 A6 57643LCV6 SEN 12.~~85000~~01500% 17,315,000.00 2631,~~693~~982.9625 0.00 M1 57643LCW4 MEZ 12.~~97000~~13500% 52,644,000.00 86103,~~423~~028.9070 0.00 M2 57643LCX2 MEZ 2.~~60000~~76500% 42,653,000.00 92108,~~414~~107.8358 0.00 M3 57643LCY0 MEZ 2.~~80000~~96500% 13,065,000.00 3035,~~485~~509.0058 0.00 M4 57643LCZ7 MEZ 3.~~25000~~41500% 11,912,000.00 3237,~~261~~289.6752 0.00 M5 57643LDA1 MEZ 3.~~40000~~56500% 9,222,000.00 2630,~~129~~136.0073 0.00 M6 57643LDB9 MEZ 4.~~70000~~86500% 11,528,000.00 4551,~~151~~410.3308 0.00 M7 57643LDC7 MEZ 6.00000% 8,454,000.00 42,270.00 0.00 CE MAB4WM1CE OC 0.00000% 8,069,453.80 2,~~923~~532,~~413~~831.9793 0.00 R MAB4WM1R1 RES 0.00000% 0.00 0.00 0.00 R-X MAB4WM1RX RES 0.00000% 0.00 0.00 0.00 P MAB04WM1P Pre_Pay 0.00000% 100.00 ~~552~~612,~~403~~084.8443 0.00 Totals ~~684~~657,~~155~~160,~~498~~790.8962 4,~~565~~396,~~751~~041.1246 2628,~~994~~674,~~708~~341.2777

Certificateholder Distribution Summary (continued) Current Ending Cumulative Realized Certificate Total Realized Class Loss Balance Distribution Losses A1 0.00 ~~204~~191,~~074~~303,~~829~~202.6013 1213,~~857~~114,~~582~~898.9334 0.00 A2 0.00 28,170,000.00 4251,~~959~~515.2589 0.00 A3 0.00 ~~123~~116,~~487~~483,~~584~~123.0350 67,~~347~~213,~~508~~308.0191 0.00 A4 0.00 4637,~~715~~817,~~823~~569.1942 8,~~343~~971,~~637~~694.1294 0.00 A5 0.00 79,850,000.00 ~~111~~134,~~124~~314.5835 0.00 A6 0.00 17,315,000.00 2631,~~693~~982.9625 0.00 M1 0.00 52,644,000.00 86103,~~423~~028.9070 0.00 M2 0.00 42,653,000.00 92108,~~414~~107.8358 0.00 M3 0.00 13,065,000.00 3035,~~485~~509.0058 0.00 M4 0.00 11,912,000.00 3237,~~261~~289.6752 0.00 M5 0.00 9,222,000.00 2630,~~129~~136.0073 0.00 M6 0.00 11,528,000.00 4551,~~151~~410.3308 0.00 M7 0.00 8,454,000.00 42,270.00 0.00 CE 0.00 8,069,453.80 2,~~923~~532,~~413~~831.9793 0.00 R 0.00 0.00 0.00 0.00 R-X 0.00 0.00 0.00 0.00 P 0.00 100.00 ~~552~~612,~~403~~084.8443 0.00 Totals 0.00 ~~657~~628,~~160~~486,~~790~~448.6285 3133,~~560~~070,~~459~~383.3923 0.00 All distributions required by the Pooling and Servicing Agreement have been calculated by the Certificate Administrator on behalf of the Trustee.

Principal Distribution Statement Original Beginning Scheduled Unscheduled Face Certificate Principal Principal Realized Class Amount Balance Distribution Distribution Accretion Loss (1) A1 253,534,000.00 ~~216~~204,~~630~~074,~~934~~829.4860 0.00 12,~~556~~771,~~104~~627.8847 0.00 0.00 A2 28,170,000.00 28,170,000.00 0.00 0.00 0.00 0.00 A3 151,682,000.00 ~~129~~123,~~653~~487,~~577~~584.03 0.00 67,~~165~~004,~~993~~460.0053 0.00 0.00 A4 80,421,000.00 5446,~~988~~715,~~433~~823.5819 0.00 8,~~272~~898,~~610~~253.3977 0.00 0.00 A5 79,850,000.00 79,850,000.00 0.00 0.00 0.00 0.00 A6 17,315,000.00 17,315,000.00 0.00 0.00 0.00 0.00 M1 52,644,000.00 52,644,000.00 0.00 0.00 0.00 0.00 M2 42,653,000.00 42,653,000.00 0.00 0.00 0.00 0.00 M3 13,065,000.00 13,065,000.00 0.00 0.00 0.00 0.00 M4 11,912,000.00 11,912,000.00 0.00 0.00 0.00 0.00 M5 9,222,000.00 9,222,000.00 0.00 0.00 0.00 0.00 M6 11,528,000.00 11,528,000.00 0.00 0.00 0.00 0.00 M7 8,454,000.00 8,454,000.00 0.00 0.00 0.00 0.00 CE 8,069,309.07 8,069,453.80 0.00 0.00 0.00 0.00 R 0.00 0.00 0.00 0.00 0.00 0.00 R-X 0.00 0.00 0.00 0.00 0.00 0.00 P 100.00 100.00 0.00 0.00 0.00 0.00 Totals 768,519,409.07 ~~684~~657,~~155~~160,~~498~~790.8962 0.00 2628,~~994~~674,~~708~~341.2777 0.00 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.

Principal Distribution Statement (continued) Total Ending Ending Total Principal Certificate Certificate Principal Class Reduction Balance Percentage Distribution A1 12,~~556~~771,~~104~~627.8847 ~~204~~191,~~074~~303,~~829~~202.6013 0.~~80492096~~75454654 12,~~556~~771,~~104~~627.8847 A2 0.00 28,170,000.00 1.00000000 0.00 A3 67,~~165~~004,~~993~~460.0053 ~~123~~116,~~487~~483,~~584~~123.0350 0.~~81412154~~76794296 67,~~165~~004,~~993~~460.0053 A4 8,~~272~~898,~~610~~253.3977 4637,~~715~~817,~~823~~569.1942 0.~~58089085~~47024495 8,~~272~~898,~~610~~253.3977 A5 0.00 79,850,000.00 1.00000000 0.00 A6 0.00 17,315,000.00 1.00000000 0.00 M1 0.00 52,644,000.00 1.00000000 0.00 M2 0.00 42,653,000.00 1.00000000 0.00 M3 0.00 13,065,000.00 1.00000000 0.00 M4 0.00 11,912,000.00 1.00000000 0.00 M5 0.00 9,222,000.00 1.00000000 0.00 M6 0.00 11,528,000.00 1.00000000 0.00 M7 0.00 8,454,000.00 1.00000000 0.00 CE 0.00 8,069,453.80 1.00001794 0.00 R 0.00 0.00 0.00000000 0.00 R-X 0.00 0.00 0.00000000 0.00 P 0.00 100.00 1.00000000 0.00 Totals 2628,~~994~~674,~~708~~341.2777 ~~657~~628,~~160~~486,~~790~~448.6285 0.~~85509980~~81778865 2628,~~994~~674,~~708~~341.2777

Principal Distribution Factors Statement Original Beginning Scheduled Unscheduled Face Certificate Principal Principal Class (2) Amount Balance Distribution Distribution Accretion A1 253,534,000.00 ~~854~~804.~~44529917~~92095577 0.00000000 4950.~~52434340~~37441712 0.00000000 A2 28,170,000.00 1000.00000000 0.00000000 0.00000000 0.00000000 A3 151,682,000.00 ~~854~~814.~~77233310~~12154395 0.00000000 4046.~~65078915~~17858764 0.00000000 A4 80,421,000.00 ~~683~~580.~~75714776~~89085177 0.00000000 ~~102~~110.~~86629599~~64589809 0.00000000 A5 79,850,000.00 1000.00000000 0.00000000 0.00000000 0.00000000 A6 17,315,000.00 1000.00000000 0.00000000 0.00000000 0.00000000 M1 52,644,000.00 1000.00000000 0.00000000 0.00000000 0.00000000 M2 42,653,000.00 1000.00000000 0.00000000 0.00000000 0.00000000 M3 13,065,000.00 1000.00000000 0.00000000 0.00000000 0.00000000 M4 11,912,000.00 1000.00000000 0.00000000 0.00000000 0.00000000 M5 9,222,000.00 1000.00000000 0.00000000 0.00000000 0.00000000 M6 11,528,000.00 1000.00000000 0.00000000 0.00000000 0.00000000 M7 8,454,000.00 1000.00000000 0.00000000 0.00000000 0.00000000 CE 8,069,309.07 1000.01793586 0.00000000 0.00000000 0.00000000 R 0.00 0.00000000 0.00000000 0.00000000 0.00000000 R-X 0.00 0.00000000 0.00000000 0.00000000 0.00000000 P 100.00 1000.00000000 0.00000000 0.00000000 0.00000000 (2) All Classes are per $1000 denomination.

Principal Distribution Factors Statement (continued) Total Ending Ending Total Realized Principal Certificate Certificate Principal Class Loss (3) Reduction Balance Percentage Distribution A1 0.00000000 4950.~~52434340~~37441712 ~~804~~754.~~92095577~~54653865 0.~~80492096~~75454654 4950.~~52434340~~37441712 A2 0.00000000 0.00000000 1,000.00000000 1.00000000 0.00000000 A3 0.00000000 4046.~~65078915~~17858764 ~~814~~767.~~12154395~~94295632 0.~~81412154~~76794296 4046.~~65078915~~17858764 A4 0.00000000 ~~102~~110.~~86629599~~64589809 ~~580~~470.~~89085177~~24495368 0.~~58089085~~47024495 ~~102~~110.~~86629599~~64589809 A5 0.00000000 0.00000000 1,000.00000000 1.00000000 0.00000000 A6 0.00000000 0.00000000 1,000.00000000 1.00000000 0.00000000 M1 0.00000000 0.00000000 1,000.00000000 1.00000000 0.00000000 M2 0.00000000 0.00000000 1,000.00000000 1.00000000 0.00000000 M3 0.00000000 0.00000000 1,000.00000000 1.00000000 0.00000000 M4 0.00000000 0.00000000 1,000.00000000 1.00000000 0.00000000 M5 0.00000000 0.00000000 1,000.00000000 1.00000000 0.00000000 M6 0.00000000 0.00000000 1,000.00000000 1.00000000 0.00000000 M7 0.00000000 0.00000000 1,000.00000000 1.00000000 0.00000000 CE 0.00000000 0.00000000 1,000.01793586 1.00001794 0.00000000 R 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000 R-X 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000 P 0.00000000 0.00000000 1,000.00000000 1.00000000 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.

Interest Distribution Statement Beginning Payment of Original Current Certificate/ Current Unpaid Current Face Certificate Notional Accrued Interest Interest Class Amount Rate Balance Interest Shortfall Shortfall A1 253,534,000.00 1.~~67000~~83500% ~~216~~204,~~630~~074,~~934~~829.4860 ~~301~~343,~~478~~270.0587 0.00 0.00 A2 28,170,000.00 1.~~83000~~99500% 28,170,000.00 4251,~~959~~515.2589 0.00 0.00 A3 151,682,000.00 1.~~68000~~84500% ~~129~~123,~~653~~487,~~577~~584.03 ~~181~~208,~~515~~848.0138 0.00 0.00 A4 80,421,000.00 1.~~55000~~71500% 5446,~~988~~715,~~433~~823.5819 7173,~~026~~441.7317 0.00 0.00 A5 79,850,000.00 1.~~67000~~83500% 79,850,000.00 ~~111~~134,~~124~~314.5835 0.00 0.00 A6 17,315,000.00 12.~~85000~~01500% 17,315,000.00 2631,~~693~~982.9625 0.00 0.00 M1 52,644,000.00 12.~~97000~~13500% 52,644,000.00 86103,~~423~~028.9070 0.00 0.00 M2 42,653,000.00 2.~~60000~~76500% 42,653,000.00 92108,~~414~~107.8358 0.00 0.00 M3 13,065,000.00 2.~~80000~~96500% 13,065,000.00 3035,~~485~~509.0058 0.00 0.00 M4 11,912,000.00 3.~~25000~~41500% 11,912,000.00 3237,~~261~~289.6752 0.00 0.00 M5 9,222,000.00 3.~~40000~~56500% 9,222,000.00 2630,~~129~~136.0073 0.00 0.00 M6 11,528,000.00 4.~~70000~~86500% 11,528,000.00 4551,~~151~~410.3308 0.00 0.00 M7 8,454,000.00 6.00000% 8,454,000.00 42,270.00 0.00 0.00 CE 8,069,309.07 0.00000% 8,069,453.80 0.00 0.00 0.00 R 0.00 0.00000% 0.00 0.00 0.00 0.00 R-X 0.00 0.00000% 0.00 0.00 0.00 0.00 P 100.00 0.00000% 100.00 0.00 0.00 0.00 Totals 768,519,409.07 1,~~089~~251,~~933~~125.3110 0.00 0.00

Interest Distribution Statement (continued) Remaining Ending Non-Supported Total Unpaid Certificate/ Interest Realized Interest Interest Notional Class Shortfall Losses (4) Distribution Shortfall Balance A1 0.00 0.00 ~~301~~343,~~478~~270.0587 0.00 ~~204~~191,~~074~~303,~~829~~202.6013 A2 0.00 0.00 4251,~~959~~515.2589 0.00 28,170,000.00 A3 0.00 0.00 ~~181~~208,~~515~~848.0138 0.00 ~~123~~116,~~487~~483,~~584~~123.0350 A4 0.00 0.00 7173,~~026~~441.7317 0.00 4637,~~715~~817,~~823~~569.1942 A5 0.00 0.00 ~~111~~134,~~124~~314.5835 0.00 79,850,000.00 A6 0.00 0.00 2631,~~693~~982.9625 0.00 17,315,000.00 M1 0.00 0.00 86103,~~423~~028.9070 0.00 52,644,000.00 M2 0.00 0.00 92108,~~414~~107.8358 0.00 42,653,000.00 M3 0.00 0.00 3035,~~485~~509.0058 0.00 13,065,000.00 M4 0.00 0.00 3237,~~261~~289.6752 0.00 11,912,000.00 M5 0.00 0.00 2630,~~129~~136.0073 0.00 9,222,000.00 M6 0.00 0.00 4551,~~151~~410.3308 0.00 11,528,000.00 M7 0.00 0.00 42,270.00 0.00 8,454,000.00 CE 0.00 0.00 2,~~923~~532,~~413~~831.9793 0.00 8,069,453.80 R 0.00 0.00 0.00 0.00 0.00 R-X 0.00 0.00 0.00 0.00 0.00 P 0.00 0.00 ~~552~~612,~~403~~084.8443 0.00 100.00 Totals 0.00 0.00 4,~~565~~396,~~751~~041.1246 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.

Interest 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 A1 253,534,000.00 1.~~67000~~83500% ~~854~~804.~~44529917~~92095577 1.~~18910304~~35394413 0.00000000 0.00000000 A2 28,170,000.00 1.~~83000~~99500% 1000.00000000 1.~~52500000~~82875009 0.00000000 0.00000000 A3 151,682,000.00 1.~~68000~~84500% ~~854~~814.~~77233310~~12154395 1.~~19668128~~37688308 0.00000000 0.00000000 A4 80,421,000.00 1.~~55000~~71500% ~~683~~580.~~75714776~~89085177 0.~~88318636~~91320886 0.00000000 0.00000000 A5 79,850,000.00 1.~~67000~~83500% 1000.00000000 1.~~39166662~~68208328 0.00000000 0.00000000 A6 17,315,000.00 12.~~85000~~01500% 1000.00000000 1.~~54166676~~84708345 0.00000000 0.00000000 M1 52,644,000.00 12.~~97000~~13500% 1000.00000000 1.~~64166667~~95708343 0.00000000 0.00000000 M2 42,653,000.00 2.~~60000~~76500% 1000.00000000 2.~~16666659~~53458326 0.00000000 0.00000000 M3 13,065,000.00 2.~~80000~~96500% 1000.00000000 2.~~33333333~~71791657 0.00000000 0.00000000 M4 11,912,000.00 3.~~25000~~41500% 1000.00000000 23.~~70833361~~13041639 0.00000000 0.00000000 M5 9,222,000.00 3.~~40000~~56500% 1000.00000000 23.~~83333333~~26791694 0.00000000 0.00000000 M6 11,528,000.00 4.~~70000~~86500% 1000.00000000 34.~~91666638~~45958362 0.00000000 0.00000000 M7 8,454,000.00 6.00000% 1000.00000000 5.00000000 0.00000000 0.00000000 CE 8,069,309.07 0.00000% 1000.01793586 0.00000000 0.00000000 0.00000000 R 0.00 0.00000% 0.00000000 0.00000000 0.00000000 0.00000000 R-X 0.00 0.00000% 0.00000000 0.00000000 0.00000000 0.00000000 P 100.00 0.00000% 1000.00000000 0.00000000 0.00000000 0.00000000 (5) All Classes are per $1000 denomination.

Interest Distribution Factors Statement (continued) Remaining Ending Non-Supported Total Unpaid Certificate/ Interest Realized Interest Interest Notional Class Shortfall Losses (6) Distribution Shortfall Balance A1 0.00000000 0.00000000 1.~~18910304~~35394413 0.00000000 ~~804~~754.~~92095577~~54653865 A2 0.00000000 0.00000000 1.~~52500000~~82875009 0.00000000 1000.00000000 A3 0.00000000 0.00000000 1.~~19668128~~37688308 0.00000000 ~~814~~767.~~12154395~~94295632 A4 0.00000000 0.00000000 0.~~88318636~~91320886 0.00000000 ~~580~~470.~~89085177~~24495368 A5 0.00000000 0.00000000 1.~~39166662~~68208328 0.00000000 1000.00000000 A6 0.00000000 0.00000000 1.~~54166676~~84708345 0.00000000 1000.00000000 M1 0.00000000 0.00000000 1.~~64166667~~95708343 0.00000000 1000.00000000 M2 0.00000000 0.00000000 2.~~16666659~~53458326 0.00000000 1000.00000000 M3 0.00000000 0.00000000 2.~~33333333~~71791657 0.00000000 1000.00000000 M4 0.00000000 0.00000000 23.~~70833361~~13041639 0.00000000 1000.00000000 M5 0.00000000 0.00000000 23.~~83333333~~26791694 0.00000000 1000.00000000 M6 0.00000000 0.00000000 34.~~91666638~~45958362 0.00000000 1000.00000000 M7 0.00000000 0.00000000 5.00000000 0.00000000 1000.00000000 CE 0.00000000 0.00000000 ~~362~~313.~~28801557~~88460995 0.00000000 1000.01793586 R 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000 R-X 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000 P 0.00000000 0.00000000 ~~5524038~~6120844.~~40000000~~30000000 0.00000000 1000.00000000 (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.

CERTIFICATEHOLDER ACCOUNT STATEMENT CERTIFICATE ACCOUNT Beginning Balance 0.00 Deposits Payments of Interest and Principal 3132,~~295~~734,~~970~~853.9993 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 ~~552~~612,~~403~~084.8443 Total Deposits 3133,~~848~~346,~~374~~938.8336 Withdrawals Reimbursement for Servicer Advances 0.00 Payment of Service Fee ~~287~~276,~~915~~555.4413 Payment of Interest and Principal 3133,~~560~~070,~~459~~383.3923 Total Withdrawals (Pool Distribution Amount) 3133,~~848~~346,~~374~~938.8336 Ending Balance 0.00

SERVICING FEES Gross Servicing Fee ~~285~~273,~~064~~816.8096 Administrator fee 2,~~850~~738.6417 Supported Prepayment/Curtailment Interest Shortfall 0.00 Net Servicing Fee ~~287~~276,~~915~~555.4413

LOAN STATUS STRATIFICATION/CREDIT ENHANCEMENT STATEMENT DELINQUENCY STATUS DELINQUENT BANKRUPTCY FORECLOSURE REO Total 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 014 0 0 014 01,203,198.0075 0.00 0.00 01,203,198.0075 30 Days 5648 01 01 0 5650 910,~~610~~254,~~759~~850.7255 066,770.0085 0114,009.0085 0.00 910,~~610~~435,~~759~~631.7225 60 Days 2817 0 0 0 2817 63,~~735~~026,~~498~~983.9960 0.00 0.00 0.00 63,~~735~~026,~~498~~983.9960 90 Days 157 06 032 03 1548 2527,~~091,666~~144.5393 01,108,167.0041 05,830,728.0008 0506,477.0059 27,~~091~~972,~~666~~518.5301 120 Days 110 0 0 0 110 ~~2,175,751~~0.6500 0.00 0.00 0.00 ~~2,175,751~~0.6500 150 Days 50 0 0 0 50 ~~501,908~~0.4700 0.00 0.00 0.00 ~~501,908~~0.4700 180+ Days 0 0 0 0 0 0.00 0.00 0.00 0.00 0.00 Totals ~~115~~72 021 033 03 ~~115~~129 2113,~~115~~808,~~585~~979.3608 02,378,137.0001 05,944,737.0093 0506,477.0059 2122,~~115~~638,~~585~~331.3661 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.~~000000~~348866% 0.000000% 0.000000% 0.~~000000~~348866% 0.~~000000~~191290% 0.000000% 0.000000% 0.~~000000~~191290% 30 Days 1.~~340996~~196113% 0.~~000000~~024919% 0.~~000000~~024919% 0.000000% 1.~~340996~~245951% 1.~~461338~~630366% 0.~~000000~~010616% 0.~~000000~~018126% 0.000000% 1.~~461338~~659108% 60 Days 0.~~670498~~423623% 0.000000% 0.000000% 0.000000% 0.~~670498~~423623% 10.~~024148~~481245% 0.000000% 0.000000% 0.000000% 10.~~024148~~481245% 90 Days 0.~~359195~~174433% 0.~~000000~~149514% 0.~~000000~~797408% 0.~~000000~~074757% 01.~~359195~~196113% 0.~~318043~~083808% 0.~~000000~~176182% 0.~~000000~~926998% 0.~~000000~~080522% 01.~~318043~~267510% 120 Days 0.~~263410~~000000% 0.000000% 0.000000% 0.000000% 0.~~263410~~000000% 0.~~330828~~000000% 0.000000% 0.000000% 0.000000% 0.~~330828~~000000% 150 Days 0.~~119732~~000000% 0.000000% 0.000000% 0.000000% 0.~~119732~~000000% 0.~~076316~~000000% 0.000000% 0.000000% 0.000000% 0.~~076316~~000000% 180+ Days 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% 0.000000% Totals 21.~~753831~~794169% 0.~~000000~~523299% 0.~~000000~~822327% 0.~~000000~~074757% 23.~~753831~~214553% 32.~~210674~~195419% 0.~~000000~~378088% 0.~~000000~~945123% 0.~~000000~~080522% 3.~~210674~~599153%

OTHER INFORMATION Current Period Class A Insufficient Funds 0.00 Principal Balance of Contaminated Properties 0.00 Periodic Advance ~~151~~163,~~616~~758.4452 Class A-6 157,547,309.07 20.50010803% 157,547,453.80 2325.~~97395828~~06775669% 2.~~634819~~755032% 0.000000% Class M-1 104,903,309.07 13.65005331% 104,903,453.80 1516.~~96313342~~69144243% 8.~~010825~~376314% 0.000000% Class M-2 62,250,309.07 8.10003083% 62,250,453.80 9.~~47263663~~90482037% 6.~~490497~~786622% 0.000000% Class M-3 49,185,309.07 6.40000870% 49,185,453.80 7.~~48453872~~82601660% 12.~~988098~~078804% 0.000000% Class M-4 37,273,309.07 4.85001532% 37,273,453.80 5.~~67189253~~93066945% 1.~~812646~~895347% 0.000000% Class CE 0.00 0.00000000% 0.00 0.00000000% 1.~~227927~~283950% 0.000000% Class R-I 0.00 0.00000000% 0.00 0.00000000% 0.000000% 0.000000% Please Refer to the Prospectus Supplement for a Full Description of Loss Exposure

COLLATERAL STATEMENT Collateral Description Mixed Fixed & Arm Weighted Average Gross Coupon 7.~~430051~~425740% Weighted Average Net Coupon 6.~~925051~~925740% Weighted Average Pass-Through Rate 6.~~930051~~920740% Weighted Average Maturity(Stepdown Calculation ) ~~332~~331 Beginning Scheduled Collateral Loan Count 4,~~327~~176 Number Of Loans Paid In Full ~~151~~163 Ending Scheduled Collateral Loan Count 4,~~176~~013 Beginning Scheduled Collateral Balance ~~684~~657,~~155~~160,~~498~~790.8962 Ending Scheduled Collateral Balance ~~657~~628,~~160~~486,~~790~~448.6285 Ending Actual Collateral Balance at 31-~~Jul~~Aug-2004 ~~657~~628,~~668~~990,~~364~~605.7176 Monthly P &I Constant 4,~~776~~589,~~093~~212.7014 Special Servicing Fee 0.00 Prepayment Penalties ~~552~~612,~~403~~084.8443 Realized Loss Amount 0.00 Cumulative Realized Loss 0.00 Ending Scheduled Balance for Premium Loans ~~657~~628,~~160~~486,~~790~~448.6285 Scheduled Principal ~~540~~522,~~002~~624.0145 Unscheduled Principal 2628,~~454~~151,~~706~~717.2632

Other Income 65-6,~~171~~075.0154

Miscellaneous Reporting Net Monthly Excess Cashflow 2,~~923~~532,~~413~~832.9501 Extra Prinicpal Distribution Amount 0.00 OC Amount 8,069,453.80 OC Deficiency Amount 0.00 OC Release Amount 0.00 OC Target Amount 8,069,453.8079 Stepdown 0.00 Trigger Event 0.00 Credit Enhancement Percentage 23.973958%

Group Level Collateral Statement Group Group 1 Group 2 Group 3 Collateral Description Fixed 15/30 & ARM Fixed 15/30 & ARM Fixed 15/30 & ARM Weighted Average Coupon Rate 8.~~249887~~233583 7.~~209697~~209235 8.~~219793~~220443 Weighted Average Net Rate 7.~~749887~~733583 6.~~709697~~709235 7.~~719794~~720443 Weighted Average Maturity ~~289~~288 ~~351~~350 ~~291~~290 Beginning Loan Count ~~1,014~~981 1,~~369~~322 ~~524~~512 Loans Paid In Full 3336 4750 1216 Ending Loan Count ~~981~~945 1,~~322~~272 ~~512~~496 Beginning Scheduled Balance 8380,~~596~~693,~~274~~597.8196 ~~233~~224,~~693~~039,~~403~~975.9087 4443,~~638~~672,~~487~~139.0380 Ending scheduled Balance 8077,~~693~~921,~~597~~110.9677 ~~224~~214,~~039~~040,~~975~~835.8759 4342,~~672~~543,~~139~~981.8069 Record Date 0708/31/2004 0708/31/2004 0708/31/2004 Principal And Interest Constant ~~647~~625,~~587~~176.6985 1,~~588~~524,~~855~~202.7740 ~~344~~337,~~971~~944.5759 Scheduled Principal 7271,~~871~~512.1933 ~~184~~178,~~806~~238.9640 3938,~~205~~774.6430 Unscheduled Principal 2,~~829~~700,~~805~~974.6686 9,~~468~~820,~~621~~901.0788 ~~927~~1,~~141~~089,383.5981 Scheduled Interest ~~574~~553,~~716~~664.5052 1,~~404~~345,~~048~~964.8100 ~~305~~299,~~765~~170.9329 Servicing Fees 3433,~~831~~622.7733 9793,~~372~~349.2498 18,~~599~~196.3672 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 ~~348~~336.3221 ~~973~~933.7451 ~~185~~181.9896 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 ~~539~~519,~~884~~705.7698 1,~~306~~251,~~676~~680.5751 ~~287~~280,~~166~~791.5961 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 7.~~744888~~728583 6.~~704696~~704235 7.~~714793~~715443

Group Level Collateral Statement Group Group 4 Group 5 Group 6 Collateral Description Fixed 15/30 & ARM Fixed 15/30 & ARM Fixed 15/30 & ARM Weighted Average Coupon Rate 7.~~166642~~163610 8.~~648741~~630866 6.~~843266~~835450 Weighted Average Net Rate 6.~~666641~~663610 8.~~148739~~130866 6.~~343266~~335450 Weighted Average Maturity ~~351~~350 ~~250~~249 ~~351~~350 Beginning Loan Count ~~710~~684 ~~371~~352 ~~339~~325 Loans Paid In Full 2629 1916 1416 Ending Loan Count ~~684~~655 ~~352~~336 ~~325~~309 Beginning Scheduled Balance ~~124~~118,~~039~~839,~~481~~835.3457 5351,~~544~~168,~~857~~247.1357 ~~144~~138,~~642~~746,~~994~~993.6885 Ending scheduled Balance ~~118~~112,~~839~~963,~~835~~533.5715 5149,~~168~~699,~~247~~454.5732 ~~138~~131,~~746~~317,~~993~~533.8533 Record Date 0708/31/2004 0708/31/2004 0708/31/2004 Principal And Interest Constant ~~840~~805,~~248~~190.8207 ~~422~~403,~~734~~573.7858 ~~931~~893,~~695~~124.0765 Scheduled Principal 9995,~~460~~754.0786 3635,~~821~~551.7869 ~~106~~102,~~836~~792.3787 Unscheduled Principal 5,~~100~~780,~~185~~547.7056 21,~~339~~433,~~787~~241.7856 57,~~789~~326,~~164~~667.4665 Scheduled Interest ~~740~~709,~~788~~435.7521 ~~385~~368,~~913~~021.0089 ~~824~~790,~~858~~331.7078 Servicing Fees 5149,~~683~~516.1460 2221,~~310~~320.3609 6057,~~267~~811.9324 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 ~~516~~495.8417 ~~223~~213.1021 ~~602~~578.6611 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 ~~689~~659,~~105~~423.5744 ~~363~~346,~~602~~488.5659 ~~764~~731,~~590~~942.8243 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 6.~~661641~~658610 8.~~143741~~125866 6.~~338266~~330450

Group Level Collateral Statement Group Total Collateral Description Mixed Fixed & Arm Weighted Average Coupon Rate 7.~~430051~~425740 Weighted Average Net Rate 6.~~925051~~925740 Weighted Average Maturity ~~332~~331.00 Record Date 0708/31/2004 Principal And Interest Constant 4,~~776~~589,~~093~~212.7014 Beginning Loan Count 4,~~327~~176 Loans Paid In Full ~~151~~163 Ending Loan Count 4,~~176~~013 Beginning Scheduled Balance ~~684~~657,~~155~~160,~~498~~790.8962 Ending Scheduled Balance ~~657~~628,~~160~~486,~~790~~448.6285 Scheduled Principal ~~540~~522,~~002~~624.0145 Unscheduled Principal 2628,~~454~~151,~~706~~717.2632 Scheduled Interest 4,~~236~~066,~~091~~587.69 Servicing Fee ~~285~~273,~~064~~816.8096 Master Servicing Fee 0.00 Trustee Fee 0.00 Fry Amount 0.00 Special Hazard Fee 0.00 Other Fee 2,~~850~~738.6417 Pool Insurance Fee 0.00 Spread 1 0.00 Spread 2 0.00 Spread 3 0.00 Net Interest 3,~~951~~790,~~026~~032.8756 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 6.~~930051~~920740

Filing Compare · MORTGAGE ASSET SEC TRANS INC MASTR AS BK SEC TR 2004 WMC1