{"cik":"0001285109","entityType":"operating","sic":"6189","sicDescription":"Asset-Backed Securities","ownerOrg":null,"insiderTransactionForOwnerExists":0,"insiderTransactionForIssuerExists":0,"name":"MASTR ASSET BACKED SECURITIES TRUST 2004-OPT1","tickers":[],"exchanges":[],"ein":"000000000","lei":null,"description":"","website":"","investorWebsite":"","category":"","fiscalYearEnd":"1231","stateOfIncorporation":"DE","stateOfIncorporationDescription":"DE","addresses":{"mailing":{"street1":null,"street2":null,"city":null,"stateOrCountry":null,"zipCode":null,"stateOrCountryDescription":null,"isForeignLocation":null,"foreignStateTerritory":null,"country":null,"countryCode":null},"business":{"street1":"1285 AVE OF THE AMERICAS","street2":null,"city":"NEW YORK","stateOrCountry":"NY","zipCode":"10019","stateOrCountryDescription":"NY","isForeignLocation":null,"foreignStateTerritory":null,"country":null,"countryCode":null}},"phone":null,"flags":"","formerNames":[],"filings":{"recent":{"accessionNumber":["0001056404-05-001639","0001056404-05-000969","0001056404-05-000154","0001056404-04-004172","0001056404-04-003740","0001056404-04-003677","0001056404-04-003409","0001056404-04-002876","0001056404-04-002509","0001056404-04-002235","0001056404-04-002230","0001056404-04-002076","0001056404-04-001830","0001056404-04-001631","0000882377-04-000861","9999999997-04-017915","0000882377-04-000751","0000882377-04-000637"],"filingDate":["2005-03-31","2005-01-28","2005-01-04","2004-12-03","2004-11-03","2004-11-02","2004-10-05","2004-09-03","2004-08-04","2004-07-14","2004-07-13","2004-07-02","2004-06-04","2004-05-07","2004-04-26","2004-04-12","2004-04-09","2004-03-29"],"reportDate":["2004-12-31","","2004-12-27","2004-11-26","2004-07-25","2004-10-25","2004-09-27","2004-08-25","2004-07-25","2004-07-12","2004-07-12","2004-06-25","2004-05-25","2004-04-25","2004-03-22","","2004-03-22",""],"acceptanceDateTime":["2005-03-31T16:21:58.000Z","2005-01-28T18:49:20.000Z","2005-01-04T16:51:36.000Z","2004-12-03T16:05:19.000Z","2004-11-03T14:43:01.000Z","2004-11-02T15:58:04.000Z","2004-10-05T20:24:13.000Z","2004-09-03T15:34:42.000Z","2004-08-04T12:50:13.000Z","2004-07-14T19:22:18.000Z","2004-07-13T16:30:04.000Z","2004-07-02T13:04:23.000Z","2004-06-04T15:22:52.000Z","2004-05-07T17:56:57.000Z","2004-04-23T22:12:43.000Z","2004-04-13T20:19:21.000Z","2004-04-09T14:57:27.000Z","2004-03-29T12:55:40.000Z"],"act":["34","34","34","34","34","34","","","","","","","","","","","",""],"form":["10-K","15-15D","8-K","8-K","8-K/A","8-K","8-K","8-K","8-K","8-K/A","8-K/A","8-K","8-K","8-K","8-K/A","SE","8-K","424B5"],"fileNumber":["333-106982-19","333-106982-19","333-106982-19","333-106982-19","333-106982-19","333-106982-19","333-106982-19","333-106982-19","333-106982-19","333-106982-19","333-106982-19","333-106982-19","333-106982-19","333-106982-19","333-106982-19","333-106982-19","333-106982-19","333-106982-19"],"filmNumber":["05717353","05557296","05504900","041182324","041114955","041112024","041066324","041015658","04950025","04913741","04911581","04897085","04848924","04788277","04752241","04025817","04726401","04694528"],"items":["","","8.01,9.01","8.01,9.01","8.01,9.01","8.01,9.01","8.01,9.01","8.01,9.01","5,7","5,7","5,7","5,7","5,7","5,7","2,7","","2,7",""],"core_type":["10-K","15-15D","8-K","8-K","8-K/A","8-K","8-K","8-K","8-K","8-K/A","8-K/A","8-K","8-K","8-K","8-K/A","SE","8-K","424B5"],"size":[17426,4037,55562,55501,55234,55547,55315,55332,54714,55064,54799,54468,54900,54646,953471,1503,952693,1227487],"isXBRL":[0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0],"isInlineXBRL":[0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0],"isXBRLNumeric":[null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null],"primaryDocument":["mab04op1_2004.txt","mab04op1_2004.txt","mab04op1_dec.txt","mab04op1_nov.txt","mab04op1_jun.txt","mab04op1_oct.txt","mab04op1_sep.txt","mabs04opt1.txt","mab04op1_jul.txt","mab04op1_apr2.txt","mab04op1_apr.txt","mab04op1_june.txt","mab04op1_may.txt","mab04op1.txt","d228338.txt","9999999997-04-017915.paper","d216554.txt","d214864.txt"],"primaryDocDescription":["","","DECEMBER 8-K","NOVEMBER 8K","JUNE 8-K/A","OCTOBER 8-K","SEPTEMBER 8K","AUGUST 8K","JULY 8K","APRIL 8-K/A # 2","APRIL 8KA","JUNE 8-K","MAY 8K","APRIL 8K","MORTGAGE ASSET SECURITIZATION TRANSACTIONS INC","AUTO-GENERATED PAPER DOCUMENT","MORTGAGE ASSET SECURITIZATION TRANSACTIONS INC","MORTGAGE ASSET SECURITIZATION TRANSACTIONS, INC."]},"files":[]}}