8-K 1 mab03op1.txt JULY 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): July 25, 2003 MASTR ASSET BACKED SECURITIES TRUST Mortgage Pass-Through Certificates, Series 2003-OP1 Trust (Exact name of registrant as specified in its charter) New York (governing law of 333-75724-15 54-2102389 Pooling and Servicing Agreement) (Commission 54-2102390 (State or other File Number) IRS EIN jurisdiction of Incorporation) c/o Wells Fargo Bank Minnesota, 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) ITEM 5. Other Events On July 25, 2003 a distribution was made to holders of MASTR ASSET BACKED SECURITIES TRUST, Mortgage Pass-Through Certificates, Series 2003-OP1 Trust. ITEM 7. Financial Statements and Exhibits (c) Exhibits furnished in accordance with Item 601(a) of Regulation S-K Exhibit Number Description EX-99.1 Monthly report distributed to holders of Mortgage Pass-Through Certificates, Series 2003-OP1 Trust, relating to the July 25, 2003 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 2003-OP1 Trust By: Wells Fargo Bank Minnesota, N.A., as Trustee By: /s/ Beth Belfield, Assistant Vice President By: Beth Belfield, Assistant Vice President Date: 8/6/03 INDEX TO EXHIBITS Exhibit Number Description EX-99.1 Monthly report distributed to holders of Mortgage Pass-Through Certificates, Series 2003-OP1 Trust, relating to the July 25, 2003 distribution. EX-99.1

MASTR Asset Backed Securitizations Mortgage Pass-Through Certificates Record Date: 56/3130/03 Distribution Date: 67/25/03 MABS Series: 2003-OP1 Contact: Customer Service - CTSLink Wells Fargo Bank Minnesota, 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 A-1 57643LAQ9 SEN 2.~~32000~~03500% ~~901~~883,~~440~~035,~~901~~570.5230 1,~~684~~497,~~692~~481.8815 1822,~~405~~916,~~331~~705.2248 A-2 57643LAJ5 SEN 1.~~74000~~45500% ~~336~~328,~~032~~809,~~357~~297.1183 ~~471~~398,~~005~~681.3527 75,~~223~~816,~~059~~569.2833 M-1 57643LAK2 MEZ 21.~~17000~~88500% 58,600,000.00 ~~102~~92,~~436~~050.0683 0.00 M-2 57643LAL0 MEZ 32.~~17000~~88500% 51,275,000.00 ~~130~~123,~~936~~273.4164 0.00 M-3 57643LAM8 MEZ 43.~~07000~~78500% 21,975,000.00 7269,~~047~~312.4881 0.00 M-4 57643LAN6 MEZ 54.~~22000~~93500% 18,313,000.00 7775,~~006~~312.1621 0.00 MV-5 57643LAP1 MEZ 4.~~82000~~53500% 4,650,000.00 1817,~~054~~573.9212 0.00 MF-5 57643LAR7 MEZ 6.00000% 10,000,000.00 50,000.00 0.00 CE MAB03OP1C OC 0.00000% 10,980,010.85 5,~~405~~516,~~276~~885.4629 0.00 R-I MAB03OPR1 RES 0.00000% 0.00 0.00 0.00 R-II MAB03OPR2 RES 0.00000% 0.00 0.00 0.00 P MAB03OPTP Pre_Pay 0.00000% 100.00 ~~664~~632,~~383~~560.6401 0.00 Totals 1,~~413~~387,~~266~~637,~~369~~978.4898 8,~~675~~473,~~839~~130.3633 2528,~~628~~733,~~390~~274.5081

Certificateholder Distribution Summary (continued) Current Ending Cumulative Realized Certificate Total Realized Class Loss Balance Distribution Losses A-1 0.00 ~~883~~860,~~035~~118,~~570~~864.3082 2024,~~090~~414,~~024~~186.1063 0.00 A-2 0.00 ~~328~~322,~~809~~992,~~297~~728.8350 76,~~694~~215,~~064~~250.6360 0.00 M-1 0.00 58,600,000.00 ~~102~~92,~~436~~050.0683 0.00 M-2 0.00 51,275,000.00 ~~130~~123,~~936~~273.4164 0.00 M-3 0.00 21,975,000.00 7269,~~047~~312.4881 0.00 M-4 0.00 18,313,000.00 7775,~~006~~312.1621 0.00 MV-5 0.00 4,650,000.00 1817,~~054~~573.9212 0.00 MF-5 0.00 10,000,000.00 50,000.00 0.00 CE 0.00 10,980,010.85 5,~~405~~516,~~276~~885.4629 0.00 R-I 0.00 0.00 0.00 0.00 R-II 0.00 0.00 0.00 0.00 P 0.00 100.00 ~~664~~632,~~383~~560.6401 0.00 Totals 0.00 1,~~387~~358,~~637~~904,~~978~~704.9817 3437,~~304~~206,~~229~~405.8614 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) A-1 939,100,000.00 ~~901~~883,~~440~~035,~~901~~570.5230 0.00 1822,~~405~~916,~~331~~705.2248 0.00 0.00 A-2 349,107,000.00 ~~336~~328,~~032~~809,~~357~~297.1183 0.00 75,~~223~~816,~~059~~569.2833 0.00 0.00 M-1 58,600,000.00 58,600,000.00 0.00 0.00 0.00 0.00 M-2 51,275,000.00 51,275,000.00 0.00 0.00 0.00 0.00 M-3 21,975,000.00 21,975,000.00 0.00 0.00 0.00 0.00 M-4 18,313,000.00 18,313,000.00 0.00 0.00 0.00 0.00 MV-5 4,650,000.00 4,650,000.00 0.00 0.00 0.00 0.00 MF-5 10,000,000.00 10,000,000.00 0.00 0.00 0.00 0.00 CE 10,981,347.20 10,980,010.85 0.00 0.00 0.00 0.00 R-I 0.00 0.00 0.00 0.00 0.00 0.00 R-II 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 1,464,001,447.20 1,~~413~~387,~~266~~637,~~369~~978.4898 0.00 2528,~~628~~733,~~390~~274.5081 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 A-1 1822,~~405~~916,~~331~~705.2248 ~~883~~860,~~035~~118,~~570~~864.3082 0.~~94029983~~91589699 1822,~~405~~916,~~331~~705.2248 A-2 75,~~223~~816,~~059~~569.2833 ~~328~~322,~~809~~992,~~297~~728.8350 0.~~94185822~~92519694 75,~~223~~816,~~059~~569.2833 M-1 0.00 58,600,000.00 1.00000000 0.00 M-2 0.00 51,275,000.00 1.00000000 0.00 M-3 0.00 21,975,000.00 1.00000000 0.00 M-4 0.00 18,313,000.00 1.00000000 0.00 MV-5 0.00 4,650,000.00 1.00000000 0.00 MF-5 0.00 10,000,000.00 1.00000000 0.00 CE 0.00 10,980,010.85 0.99987831 0.00 R-I 0.00 0.00 0.00000000 0.00 R-II 0.00 0.00 0.00000000 0.00 P 0.00 100.00 1.00000000 0.00 Totals 2528,~~628~~733,~~390~~274.5081 1,~~387~~358,~~637~~904,~~978~~704.9817 0.~~94783921~~92821268 2528,~~628~~733,~~390~~274.5081

Principal Distribution Factors Statement Original Beginning Scheduled Unscheduled Face Certificate Principal Principal Class (2) Amount Balance Distribution Distribution Accretion A-1 939,100,000.00 ~~959~~940.~~89873445~~29982994 0.00000000 1924.~~59890450~~40283833 0.00000000 A-2 349,107,000.00 ~~962~~941.~~54832218~~85822063 0.00000000 2016.~~69010154~~66127958 0.00000000 M-1 58,600,000.00 1000.00000000 0.00000000 0.00000000 0.00000000 M-2 51,275,000.00 1000.00000000 0.00000000 0.00000000 0.00000000 M-3 21,975,000.00 1000.00000000 0.00000000 0.00000000 0.00000000 M-4 18,313,000.00 1000.00000000 0.00000000 0.00000000 0.00000000 MV-5 4,650,000.00 1000.00000000 0.00000000 0.00000000 0.00000000 MF-5 10,000,000.00 1000.00000000 0.00000000 0.00000000 0.00000000 CE 10,981,347.20 999.87830728 0.00000000 0.00000000 0.00000000 R-I 0.00 0.00000000 0.00000000 0.00000000 0.00000000 R-II 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 A-1 0.00000000 1924.~~59890450~~40283833 ~~940~~915.~~29982994~~89699161 0.~~94029983~~91589699 1924.~~59890450~~40283833 A-2 0.00000000 2016.~~69010154~~66127958 ~~941~~925.~~85822063~~19694105 0.~~94185822~~92519694 2016.~~69010154~~66127958 M-1 0.00000000 0.00000000 1,000.00000000 1.00000000 0.00000000 M-2 0.00000000 0.00000000 1,000.00000000 1.00000000 0.00000000 M-3 0.00000000 0.00000000 1,000.00000000 1.00000000 0.00000000 M-4 0.00000000 0.00000000 1,000.00000000 1.00000000 0.00000000 MV-5 0.00000000 0.00000000 1,000.00000000 1.00000000 0.00000000 MF-5 0.00000000 0.00000000 1,000.00000000 1.00000000 0.00000000 CE 0.00000000 0.00000000 999.87830728 0.99987831 0.00000000 R-I 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000 R-II 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, Bankrupcy, 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 A-1 939,100,000.00 2.~~32000~~03500% ~~901~~883,~~440~~035,~~901~~570.5230 1,~~684~~497,~~692~~481.8815 0.00 0.00 A-2 349,107,000.00 1.~~74000~~45500% ~~336~~328,~~032~~809,~~357~~297.1183 ~~471~~398,~~005~~681.3527 0.00 0.00 M-1 58,600,000.00 21.~~17000~~88500% 58,600,000.00 ~~102~~92,~~436~~050.0683 0.00 0.00 M-2 51,275,000.00 32.~~17000~~88500% 51,275,000.00 ~~130~~123,~~936~~273.4165 0.00 0.00 M-3 21,975,000.00 43.~~07000~~78500% 21,975,000.00 7269,~~047~~312.4881 0.00 0.00 M-4 18,313,000.00 54.~~22000~~93500% 18,313,000.00 7775,~~006~~312.1721 0.00 0.00 MV-5 4,650,000.00 4.~~82000~~53500% 4,650,000.00 1817,~~054~~573.9213 0.00 0.00 MF-5 10,000,000.00 6.00000% 10,000,000.00 50,000.00 0.00 0.00 CE 10,981,347.20 0.00000% 10,980,010.85 0.00 0.00 0.00 R-I 0.00 0.00000% 0.00 0.00 0.00 0.00 R-II 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 1,464,001,447.20 2,~~606~~323,~~179~~685.2705 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 A-1 0.00 0.00 1,~~684~~497,~~692~~481.8815 0.00 ~~883~~860,~~035~~118,~~570~~864.3082 A-2 0.00 0.00 ~~471~~398,~~005~~681.3527 0.00 ~~328~~322,~~809~~992,~~297~~728.8350 M-1 0.00 0.00 ~~102~~92,~~436~~050.0683 0.00 58,600,000.00 M-2 0.00 0.00 ~~130~~123,~~936~~273.4164 0.00 51,275,000.00 M-3 0.00 0.00 7269,~~047~~312.4881 0.00 21,975,000.00 M-4 0.00 0.00 7775,~~006~~312.1621 0.00 18,313,000.00 MV-5 0.00 0.00 1817,~~054~~573.9212 0.00 4,650,000.00 MF-5 0.00 0.00 50,000.00 0.00 10,000,000.00 CE 0.00 0.00 5,~~405~~516,~~276~~885.4629 0.00 10,980,010.85 R-I 0.00 0.00 0.00 0.00 0.00 R-II 0.00 0.00 0.00 0.00 0.00 P 0.00 0.00 ~~664~~632,~~383~~560.6401 0.00 100.00 Totals 0.00 0.00 8,~~675~~473,~~839~~130.3633 0.00 (4) Amount Does Not Include Excess Special Hazard, Bankrupcy, 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 A-1 939,100,000.00 2.~~32000~~03500% ~~959~~940.~~89873445~~29982994 1.~~79394407~~59459179 0.00000000 0.00000000 A-2 349,107,000.00 1.~~74000~~45500% ~~962~~941.~~54832218~~85822063 1.~~34917189~~14200308 0.00000000 0.00000000 M-1 58,600,000.00 21.~~17000~~88500% 1000.00000000 1.~~74805563~~57083328 0.00000000 0.00000000 M-2 51,275,000.00 32.~~17000~~88500% 1000.00000000 2.~~55361112~~40416675 0.00000000 0.00000000 M-3 21,975,000.00 43.~~07000~~78500% 1000.00000000 3.~~27861115~~15416655 0.00000000 0.00000000 M-4 18,313,000.00 54.~~22000~~93500% 1000.00000000 4.~~20500027~~11249986 0.00000000 0.00000000 MV-5 4,650,000.00 4.~~82000~~53500% 1000.00000000 3.~~88277849~~77916774 0.00000000 0.00000000 MF-5 10,000,000.00 6.00000% 1000.00000000 5.00000000 0.00000000 0.00000000 CE 10,981,347.20 0.00000% 999.87830728 0.00000000 0.00000000 0.00000000 R-I 0.00 0.00000% 0.00000000 0.00000000 0.00000000 0.00000000 R-II 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 A-1 0.00000000 0.00000000 1.~~79394407~~59459179 0.00000000 ~~940~~915.~~29982994~~89699161 A-2 0.00000000 0.00000000 1.~~34917189~~14200308 0.00000000 ~~941~~925.~~85822063~~19694105 M-1 0.00000000 0.00000000 1.~~74805563~~57083328 0.00000000 1000.00000000 M-2 0.00000000 0.00000000 2.~~55361112~~40416655 0.00000000 1000.00000000 M-3 0.00000000 0.00000000 3.~~27861115~~15416655 0.00000000 1000.00000000 M-4 0.00000000 0.00000000 4.~~20499973~~11249986 0.00000000 1000.00000000 MV-5 0.00000000 0.00000000 3.~~88277849~~77916559 0.00000000 1000.00000000 MF-5 0.00000000 0.00000000 5.00000000 0.00000000 1000.00000000 CE 0.00000000 0.00000000 ~~492~~502.~~22343685~~38692845 0.00000000 999.87830728 R-I 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000 R-II 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000 P 0.00000000 0.00000000 ~~6643836~~6325600.~~40000000~~10000000 0.00000000 1000.00000000 (6) Amount Does Not Include Excess Special Hazard, Bankrupcy,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 3538,~~153~~075,~~498~~943.3642 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(12,037.0017) Prepayment Penalties ~~664~~632,~~383~~560.6401 Total Deposits 3538,~~817~~696,~~882~~466.0026 Withdrawals Reimbursement for Servicer Advances 0.00 Payment of Service Fee 1,~~513~~490,~~652~~061.1412 Payment of Interest and Principal 3437,~~304~~206,~~229~~405.8614 Total Withdrawals (Pool Distribution Amount) 3538,~~817~~696,~~882~~466.0026 Ending Balance 0.00

SERVICING FEES Gross Servicing Fee ~~588~~578,~~860~~182.9625 Radian ~~921~~908,~~258~~407.0096 Trustee Fee - Wells Fargo 3,~~533~~470.1891 Supported Prepayment/Curtailment Interest Shortfall 0.00 Net Servicing Fee 1,~~513~~490,~~652~~061.1412

OTHER ACCOUNTS Beginning Current Current Ending Account Type Balance Withdrawals Deposits Balance Reserve Fund 1,000.0001 0.00 0.0100 1,000.0100 Reserve Fund 0.00 0.00 0.00 0.00

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 1617 1 0 1718 12,~~620~~035,~~829~~614.7365 115,~~865~~790.7695 0.00 12,~~736~~151,~~695~~405.4960 30 Days ~~105~~141 1 32 0 ~~109~~144 1422,~~453~~188,~~547~~698.6777 5099,~~310~~644.6584 ~~362~~264,~~952~~107.9997 0.00 1422,~~866~~552,~~811~~451.3158 60 Days 22 35 4737 0 7264 3,~~001~~700,~~477~~324.7995 ~~306~~450,~~502~~764.7456 64,~~769~~085,~~516~~074.8984 0.00 108,~~077~~236,~~497~~164.4235 90 Days 36 811 71110 01 82128 ~~482~~773,~~479~~626.6371 ~~985~~1,~~884~~290,011.2371 1116,~~426~~807,~~088~~060.1088 055,883.0099 1218,~~894~~926,~~451~~583.9629 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 ~~130~~169 2834 ~~122~~150 01 ~~280~~354 1726,~~937~~662,~~505~~650.0943 23,~~963~~876,~~527~~035.3576 1821,~~674~~272,~~423~~034.7464 055,883.0099 3951,~~575~~866,~~456~~604.1882 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.~~169924~~184023% 0.~~010620~~010825% 0.000000% 0.~~180544~~194847% 0.~~116768~~149754% 0.~~008347~~008518% 0.000000% 0.~~125115~~158272% 30 Days 1.~~115123~~526304% 0.~~010620~~010825% 0.~~031861~~021650% 0.000000% 1.~~157604~~558779% 1.~~041260~~632354% 0.~~003624~~007331% 0.~~026148~~019430% 0.000000% 1.~~071033~~659114% 60 Days 0.~~233645~~238147% 0.~~031861~~054124% 0.~~499150~~400520% 0.000000% 0.~~764656~~692791% 0.~~216232~~272221% 0.~~022081~~033161% 0.~~487689~~300526% 0.000000% 0.~~726002~~605909% 90 Days 0.~~031861~~064949% 0.~~084962~~119073% 01.~~754036~~190734% 0.~~000000~~010825% 01.~~870858~~385581% 0.~~034759~~056913% 0.~~071025~~094902% 01.~~823157~~236444% 0.~~000000~~004111% 01.~~928940~~392370% 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 1.~~380629~~829400% 0.~~297366~~368045% 1.~~295667~~623728% 0.~~000000~~010825% 23.~~973662~~831998% 1.~~292251~~961489% 0.~~213498~~285148% 1.~~345340~~564918% 0.~~000000~~004111% 23.~~851089~~815666%

OTHER INFORMATION Current Period Class A Insufficient Funds 0.00 Principal Balance of Contaminated Properties 0.00 Periodic Advance ~~626~~660,~~714~~478.38 Class A-1 524,901,347.20 35.85388172% 504,602,308.68 36.36411775% 63.635875% 0.000000% Class A-2 175,794,347.20 12.00779873% 175,793,010.85 12.66850674% 23.695611% 0.000000% Class M-1 117,194,347.20 8.00507045% 117,193,010.85 8.44550327% 4.223003% 0.000000% Class M-2 65,919,347.20 4.50268320% 65,918,010.85 4.75037523% 3.695128% 0.000000% Class M-3 43,944,347.20 3.00166009% 43,943,010.85 3.16674893% 1.583626% 0.000000% Class M-4 25,631,347.20 1.75077335% 25,630,010.85 1.84702431% 1.319725% 0.000000% Class CE 0.00 0.00000000% 0.00 0.00000000% 0.791273% 0.000000% Class R-I 0.00 0.00000000% 0.00 0.00000000% 0.000000% 0.000000% Class R-II 0.00 0.00000000% 0.00 0.00000000% 0.000000% 0.000000% Please Refer to the Prospectus Supplement for a Full Description of Loss Exposure32

Class A-1 524,901,347.20 35.85388172% 498,785,739.35 36.70498290% 63.295010% 0.000000% Class A-2 175,794,347.20 12.00779873% 175,793,010.85 12.93637518% 23.768608% 0.000000% Class M-1 117,194,347.20 8.00507045% 117,193,010.85 8.62407868% 4.312297% 0.000000% Class M-2 65,919,347.20 4.50268320% 65,918,010.85 4.85081924% 3.773259% 0.000000% Class M-3 43,944,347.20 3.00166009% 43,943,010.85 3.23370805% 1.617111% 0.000000% Class M-4 25,631,347.20 1.75077335% 25,630,010.85 1.88607860% 1.347629% 0.000000% Class CE 0.00 0.00000000% 0.00 0.00000000% 0.808004% 0.000000% Class R-I 0.00 0.00000000% 0.00 0.00000000% 0.000000% 0.000000% Class R-II 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 8.~~087739~~079341% Weighted Average Net Coupon 7.~~587739~~579341% Weighted Average Pass-Through Rate 6.~~802502~~790767% Weighted Average Maturity(Stepdown Calculation ) ~~350~~349 Beginning Scheduled Collateral Loan Count 9,~~567~~416 Number Of Loans Paid In Full ~~151~~178 Ending Scheduled Collateral Loan Count 9,~~416~~238 Beginning Scheduled Collateral Balance 1,~~413~~387,~~266~~637,~~369~~978.4999 Ending Scheduled Collateral Balance 1,~~387~~358,~~637~~904,~~978~~704.9918 Ending Actual Collateral Balance at 3130-~~May~~Jun-2003 1,~~388~~359,~~081~~306,~~939~~719.2006 Monthly P &I Constant 10,~~601~~407,~~405~~187.2395 Special Servicing Fee 0.00 Prepayment Penalties ~~664~~632,~~383~~560.6401 Realized Loss Amount 012,037.0017 Cumulative Realized Loss 012,037.0017 Ending Scheduled Balance for Premium Loans 1,~~387~~358,~~637~~904,~~978~~704.9918 Scheduled Principal 1,~~076~~064,~~297~~521.3215 Unscheduled Principal 2427,~~552~~668,~~093~~753.1866

Miscellaneous Reporting Net Monthly Excess Cashflow 5,~~405~~528,~~276~~922.4644 Extra Prinicpal Distribution Amount 012,037.0017 OC Amount 10,980,010.85 OC Deficiency Amount 012,037.0017 OC Release Amount 0.00 OC Target Amount 10,980,010.85 Stepdown NO Trigger Event NO Credit Enhancement Percentage 12.~~668507~~936375%

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 7.~~684790~~673923 8.~~271919~~264298 7.~~632167~~619496 Weighted Average Net Rate 7.~~184790~~173923 7.~~771919~~764298 7.~~132167~~119495 ~~Pass-Through Rate 6.273448 7.028069 6.225589~~ Weighted Average Maturity ~~350~~349 ~~350~~349 ~~341~~340 Beginning Loan Count ~~820~~800 6,~~646~~545 1,~~454~~439 Loans Paid In Full 2010 ~~101~~139 1519 Ending Loan Count ~~800~~790 6,~~545~~406 1,~~439~~420 Beginning Scheduled Balance ~~103~~101,~~839~~463,~~321~~543.8261 ~~926~~910,~~511~~481,~~187~~634.6463 ~~204~~202,~~296~~039,~~625~~979.8150 Ending scheduled Balance ~~101~~100,~~463~~046,~~543~~023.6160 ~~910~~888,~~481~~992,~~634~~049.6361 ~~202~~199,~~039~~336,~~979~~906.5021 Record Date 0506/3130/2003 0506/3130/2003 0506/3130/2003 Principal And Interest Constant ~~772~~756,~~696~~063.3209 76,~~014~~889,~~875~~297.0449 1,~~510~~492,~~040~~348.4774 Scheduled Principal 107,~~710~~210.1823 ~~628~~618,~~187~~888.2608 ~~210~~209,~~685~~479.4376 Unscheduled Principal 21,~~268~~310,~~068~~309.0378 1520,~~401~~870,~~365~~696.7594 2,~~045~~493,~~960~~593.8853 Scheduled Interest ~~664~~648,~~986~~852.1486 6,~~386~~270,~~687~~409.7841 1,~~299~~282,~~355~~868.0498 Servicing Fees 4342,~~266~~276.4147 ~~386~~379,~~046~~366.3086 8584,~~123~~183.5947 Master Servicing Fees 0.00 0.00 0.00 Trustee Fee ~~259~~253.6181 2,~~316~~277.2762 ~~510~~505.7541 FRY Amount 0.00 0.00 0.00 Special Hazard Fee 0.00 0.00 0.00 Other Fee 7877,~~601~~317.3601 ~~572~~564,~~004~~430.3658 ~~153~~152,~~831~~535.7162 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 ~~542~~606,~~858~~576.7639 5,~~426~~891,~~320~~042.8555 1,~~059~~198,~~888~~685.9951 Realized Loss Amount 0.00 0.00 0.00 Cumulative Realized Loss 0.00 0.00 0.00 Percentage of Cumulative Losses 0.00 0.00 0.00 Prepayment Penalties 0.00 0.00 0.00 Special Servicing Fee 0.00 0.00 0.00 Pass-Through Rate 6.256500 7.017386 6.210520

Group Level Collateral Statement Group Group 4 Total Collateral Description Fixed 15/30 & ARM Mixed Fixed & Arm Weighted Average Coupon Rate 7.~~887699~~881488 8.~~087739~~079341 Weighted Average Net Rate 7.~~387699~~381487 7.~~587739~~579341 ~~Pass-Through Rate 6.599875 6.802502~~ Weighted Average Maturity ~~341~~340 ~~350~~349 Beginning Loan Count ~~647~~632 9,~~567~~416 Loans Paid In Full 1510 ~~151~~178 Ending Loan Count ~~632~~622 9,~~416~~238 Beginning Scheduled Balance ~~178~~173,~~619~~652,~~234~~821.2225 1,~~413~~387,~~266~~637,~~369~~978.4999 Ending scheduled Balance ~~173~~170,~~652~~529,~~821~~724.2576 1,~~387~~358,~~637~~904,~~978~~704.9918 Record Date 0506/3130/2003 0506/3130/2003 Principal And Interest Constant 1,~~303~~269,~~793~~478.4063 10,~~601~~407,~~405~~187.2395 Scheduled Principal ~~129~~128,~~714~~943.4508 1,~~076~~064,~~297~~521.3215 Unscheduled Principal 42,~~836~~994,~~698~~153.5241 2427,~~552~~668,~~093~~753.1866 Scheduled Interest 1,~~174~~140,~~078~~535.9555 9,~~525~~342,~~107~~666.9180 Servicing Fees 7472,~~424~~355.6645 ~~588~~578,~~860~~182.9625 Master Servicing Fees 0.00 0.00 Trustee Fee ~~446~~434.5507 3,~~533~~470.1891 FRY Amount 0.00 0.00 Special Hazard Fee 0.00 0.00 Other Fee ~~116~~114,~~820~~124.5775 ~~921~~908,~~258~~407.0096 Pool Insurance Fee 0.00 0.00 Spread Fee 1 0.00 0.00 Spread Fee 2 0.00 0.00 Spread Fee 3 0.00 0.00 Net Interest ~~982~~1,~~387~~068,180.1710 8,~~011~~764,~~455~~484.7755 Realized Loss Amount 012,037.0017 012,037.0017 Cumulative Realized Loss 012,037.0017 012,037.0017 Percentage of Cumulative Losses 0.00 0.00 Prepayment Penalties 0.00 0.00 Special Servicing Fee 0.00 0.00 Pass-Through Rate 6.589847 6.790767

Filing Compare · MORTGAGE ASSET SECURITIZATION TRANSACTIONS INC SER 2003-OPT1