-----BEGIN PRIVACY-ENHANCED MESSAGE----- Proc-Type: 2001,MIC-CLEAR Originator-Name: webmaster@www.sec.gov Originator-Key-Asymmetric: MFgwCgYEVQgBAQICAf8DSgAwRwJAW2sNKK9AVtBzYZmr6aGjlWyK3XmZv3dTINen TWSM7vrzLADbmYQaionwg5sDW3P6oaM5D3tdezXMm7z1T+B+twIDAQAB MIC-Info: RSA-MD5,RSA, JZ2uuOSmXPhe/wopE7SI1e8iTz+kWFrvEkIodQ7ePmVz47PPa2wuSRc96srDlYbC 6P16ZjXq42mlH5HCHnnlxw== 0001285923-04-001546.txt : 20041229 0001285923-04-001546.hdr.sgml : 20041229 20041229161408 ACCESSION NUMBER: 0001285923-04-001546 CONFORMED SUBMISSION TYPE: 8-K PUBLIC DOCUMENT COUNT: 2 CONFORMED PERIOD OF REPORT: 20041227 ITEM INFORMATION: Other Events ITEM INFORMATION: Financial Statements and Exhibits FILED AS OF DATE: 20041229 DATE AS OF CHANGE: 20041229 FILER: COMPANY DATA: COMPANY CONFORMED NAME: WaMu Mortgage Pass-Through Certificates, Series 2004-AR12 CENTRAL INDEX KEY: 0001306918 STANDARD INDUSTRIAL CLASSIFICATION: ASSET-BACKED SECURITIES [6189] STATE OF INCORPORATION: DE FISCAL YEAR END: 1231 FILING VALUES: FORM TYPE: 8-K SEC ACT: 1934 Act SEC FILE NUMBER: 333-103345-51 FILM NUMBER: 041231320 BUSINESS ADDRESS: STREET 1: 75 N FAIRWAY DR CITY: VERNON HILLS STATE: IL ZIP: 60061 BUSINESS PHONE: 8475496500 MAIL ADDRESS: STREET 1: 75 N FAIRWAY DR CITY: VERNON HILLS STATE: IL ZIP: 60061 8-K 1 signwamu2004_ar12.htm LETTER

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):  December 27, 2004
 

WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.

WAMU MORTGAGE PASS-THROUGH CERTIFICATES
SERIES 2004-AR12
(Exact name of Registrant as specified in its charter)

Delaware 333-103345-51 94-2528990
(State or other jurisdiction
of incorporation)		 (Commission File Number)(I.R.S. Employer
Identification No.)

1201 THIRD AVENUE, WMT 1706
SEATTLE, WASHINGTON 98101
 (Address of principal executive offices and Zip Code)

Registrant's telephone number, including area code: (206) 377-8555

 

SECTION 8.  OTHER EVENTS

ITEM 8.01 Other Events

     This Current Report on Form 8-K relates to the distribution report furnished to certificate holders in connection with the December 2004 distribution.

SECTION 9.    FINANCIAL STATEMENTS AND EXHIBITS

ITEM 9.01 Financial Statements and Exhibits

(a) Not applicable

(b) Not applicable

(c)  Exhibits

Exhibit No.

Description

99.1

WaMu Mortgage Pass-Through Certificates, Series 2004-AR12
Monthly Distribution Report for December 2004

 

 

2

SIGNATURES

     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.

    WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.

Date:       December 29, 2004
 
By:
 
/s/ Tammy Spriggs
Tammy Spriggs
First Vice President
(Authorized Officer)

 

 

 

 

3

 

 

EXHIBIT INDEX

 

Exhibit No.

Description

99.1

WaMu Mortgage Pass-Through Certificates, Series 2004-AR12
Monthly Distribution Report for December 2004

 EX-99 2 wamu2004_ar12.htm EXHIBIT


WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.
Series: WAMU.04AR12
Distribution Date: 12/27/2004
 
Class Cusip Orig Prin Bal Begin Prin Bal Int Rate Accrued Int Rate Paid Int Dist Prin Dist Int Shortfall PPIS Uncomp Int Shortfall Prin Loss Deferred Interest Int Reimbursed Unsched Int Prin Reimbursed Subsequent Recoveries Total Dist Ending Class Bal
A1 92922FZE1 $200,000,000.00 $198,445,538.32 2.5875000000% 2.5875000000% $427,898.19 $1,306,297.21 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $1,734,195.41 $197,139,241.11
A2A 92922FZF8 $850,000,000.00 $843,393,537.86 2.5775000000% 2.5775000000% $1,811,539.04 $5,551,763.16 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $7,363,302.19 $837,841,774.70
A2B 92922FZV3 $150,000,000.00 $148,834,153.74 2.6475000000% 2.6475000000% $328,365.35 $979,722.91 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $1,308,088.26 $147,854,430.83
A3 92922FZG6 $276,500,000.00 $273,412,494.19 2.4475000000% 2.4475000000% $557,647.57 $2,594,596.11 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $3,152,243.68 $270,817,898.08
A4A 92922FZH4 $50,000,000.00 $49,441,680.69 2.4375000000% 2.4375000000% $100,428.41 $469,185.55 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $569,613.97 $48,972,495.14
A4B 92922FZJ0 $9,000,000.00 $8,899,502.52 2.5075000000% 2.5075000000% $18,596.25 $84,453.40 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $103,049.65 $8,815,049.12
A5 92922FZK7 $146,509,000.00 $146,509,000.00 2.6775000000% 2.6775000000% $326,898.21 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $326,898.21 $146,509,000.00
X 92922FZL5 $0.00 $0.00 0.0000000000% 0.0000000000% $1,686,036.84 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $1,686,036.84 $0.00
X_NOTIONAL XXXXXXXXX $1,784,625,919.00 $1,771,547,600.43 1.1420772449% 1.1420772449% $1,686,036.84 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $1,686,036.84 $1,760,558,220.59
X_PRINCIPAL XXXXXXXXX $0.00 $0.00 0.0000000000% 0.0000000000% $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00
B1 92922FZN1 $41,046,000.00 $41,043,949.33 2.8375000000% 2.8375000000% $97,051.84 $1,344.57 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $98,396.41 $41,042,604.76
B2 92922FZP6 $20,523,000.00 $20,521,974.67 3.2375000000% 3.2375000000% $55,366.58 $672.29 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $56,038.86 $20,521,302.38
B3 92922FZQ4 $12,492,000.00 $12,491,375.90 3.2875000000% 3.2875000000% $34,221.17 $409.21 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $34,630.37 $12,490,966.69
B4 92922FZS0 $9,815,000.00 $9,814,509.64 3.2875000000% 3.2875000000% $26,887.67 $321.52 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $27,209.18 $9,814,188.12
B5 92922FZT8 $12,492,000.00 $12,491,375.90 3.2875000000% 3.2875000000% $34,221.17 $409.21 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $34,630.37 $12,490,966.69
B6 92922FZU5 $6,248,819.86 $6,248,507.67 3.2875000000% 3.2875000000% $17,118.31 $204.69 $0.00 $0.00 $0.00 $0.01 $0.00 $0.00 $0.00 $0.00 $0.00 $17,323.00 $6,248,302.97
Y XXXXXXXXX $0.00 $0.00 0.0000000000% 0.0000000000% $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00
R 92922FZR2 $100.00 $0.00 0.0000000000% 0.0000000000% $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00
R_SYN XXXXXXXXX $0.00 $0.00 0.0000000000% 0.0000000000% $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00
YIELD_PAYMENTS XXXXXXXXX $0.00 $0.00 0.0000000000% 0.0000000000% $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00
Total   $1,784,625,919.86 $1,771,547,600.43     $5,522,276.58 $10,989,379.83 $0.00 $0.00 $0.00 $0.01 $0.00 $0.00 $0.00 $0.00 $0.00 $16,511,656.41 $1,760,558,220.59



WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.
Series: WAMU.04AR12
Distribution Date: 12/27/2004
 
Class Orig Face Beg Bal Prin Loss Prin Reimbursed Subsequent Recoveries Deferred Interest Total Prin End Cert Pct End Cert Bal
A1 $200,000,000.00 $198,445,538.32 $0.00 $0.00 $0.00 $0.00 $1,306,297.21 0.9856962056 $197,139,241.11
A2A $850,000,000.00 $843,393,537.86 $0.00 $0.00 $0.00 $0.00 $5,551,763.16 0.9856962055 $837,841,774.70
A2B $150,000,000.00 $148,834,153.74 $0.00 $0.00 $0.00 $0.00 $979,722.91 0.9856962055 $147,854,430.83
A3 $276,500,000.00 $273,412,494.19 $0.00 $0.00 $0.00 $0.00 $2,594,596.11 0.9794499026 $270,817,898.08
A4A $50,000,000.00 $49,441,680.69 $0.00 $0.00 $0.00 $0.00 $469,185.55 0.9794499028 $48,972,495.14
A4B $9,000,000.00 $8,899,502.52 $0.00 $0.00 $0.00 $0.00 $84,453.40 0.9794499022 $8,815,049.12
A5 $146,509,000.00 $146,509,000.00 $0.00 $0.00 $0.00 $0.00 $0.00 1.0000000000 $146,509,000.00
X $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 0.0000000000 $0.00
X_NOTIONAL $1,784,625,919.00 $1,771,547,600.43 $0.00 $0.00 $0.00 $0.00 $0.00 0.9865138693 $1,760,558,220.59
X_PRINCIPAL $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 0.0000000000 $0.00
B1 $41,046,000.00 $41,043,949.33 $0.00 $0.00 $0.00 $0.00 $1,344.57 0.9999172821 $41,042,604.76
B2 $20,523,000.00 $20,521,974.67 $0.00 $0.00 $0.00 $0.00 $672.29 0.9999172821 $20,521,302.38
B3 $12,492,000.00 $12,491,375.90 $0.00 $0.00 $0.00 $0.00 $409.21 0.9999172823 $12,490,966.69
B4 $9,815,000.00 $9,814,509.64 $0.00 $0.00 $0.00 $0.00 $321.52 0.9999172817 $9,814,188.12
B5 $12,492,000.00 $12,491,375.90 $0.00 $0.00 $0.00 $0.00 $409.21 0.9999172823 $12,490,966.69
B6 $6,248,819.86 $6,248,507.67 $0.01 $0.00 $0.00 $0.00 $204.69 0.9999172820 $6,248,302.97
Y $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 0.0000000000 $0.00
R $100.00 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 0.0000000000 $0.00
R_SYN $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 0.0000000000 $0.00
YIELD_PAYMENTS $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 0.0000000000 $0.00
Total $1,784,625,919.86 $1,771,547,600.43 $0.01 $0.00 $0.00 $0.00 $10,989,379.83 0.9865138688 $1,760,558,220.59



WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.
Series: WAMU.04AR12
Distribution Date: 12/27/2004
PER $1000 DENOMINATION
Class Orig Face Beg Bal Prin Loss Prin Reimbursed Subsequent Recoveries Deferred Interest Total Prin End Cert Pct End Cert Bal
A1 $200,000,000.00 992.22769160 0.00000000 0.00000000 0.00000000 0.00000000 6.53148605 0.9856962056 985.69620555
A2A $850,000,000.00 992.22769160 0.00000000 0.00000000 0.00000000 0.00000000 6.53148607 0.9856962055 985.69620553
A2B $150,000,000.00 992.22769160 0.00000000 0.00000000 0.00000000 0.00000000 6.53148607 0.9856962055 985.69620553
A3 $276,500,000.00 988.83361371 0.00000000 0.00000000 0.00000000 0.00000000 9.38371107 0.9794499026 979.44990264
A4A $50,000,000.00 988.83361380 0.00000000 0.00000000 0.00000000 0.00000000 9.38371100 0.9794499028 979.44990280
A4B $9,000,000.00 988.83361333 0.00000000 0.00000000 0.00000000 0.00000000 9.38371111 0.9794499022 979.44990222
A5 $146,509,000.00 1,000.00000000 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000 1.0000000000 1,000.00000000
X $0.00 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000 0.0000000000 0.00000000
X_NOTIONAL $1,784,625,919.00 992.67167509 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000 0.9865138693 986.51386929
X_PRINCIPAL $0.00 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000 0.0000000000 0.00000000
B1 $41,046,000.00 999.95003971 0.00000000 0.00000000 0.00000000 0.00000000 0.03275764 0.9999172821 999.91728207
B2 $20,523,000.00 999.95003996 0.00000000 0.00000000 0.00000000 0.00000000 0.03275788 0.9999172821 999.91728207
B3 $12,492,000.00 999.95004003 0.00000000 0.00000000 0.00000000 0.00000000 0.03275776 0.9999172823 999.91728226
B4 $9,815,000.00 999.95003974 0.00000000 0.00000000 0.00000000 0.00000000 0.03275802 0.9999172817 999.91728171
B5 $12,492,000.00 999.95004003 0.00000000 0.00000000 0.00000000 0.00000000 0.03275776 0.9999172823 999.91728226
B6 $6,248,819.86 999.95004017 0.00000160 0.00000000 0.00000000 0.00000000 0.03275659 0.9999172820 999.91728198
Y $0.00 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000 0.0000000000 0.00000000
R $100.00 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000 0.0000000000 0.00000000
R_SYN $0.00 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000 0.0000000000 0.00000000
YIELD_PAYMENTS $0.00 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000 0.0000000000 0.00000000



WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.
Series: WAMU.04AR12
Distribution Date: 12/27/2004
 
Class Orig Face Int Rate Accrued Int Rate Paid Beg Cert Prin/Not Bal Current Int Accrued Int Shortfall PPIS Uncompensated Int Shortfall Unscheduled Int Int Reimbursed Total Int Dist
A1 $200,000,000.00 2.5875000000% 2.5875000000% $198,445,538.32 $427,898.19 $0.00 $0.00 $0.00 $0.00 $0.00 $427,898.19
A2A $850,000,000.00 2.5775000000% 2.5775000000% $843,393,537.86 $1,811,539.04 $0.00 $0.00 $0.00 $0.00 $0.00 $1,811,539.04
A2B $150,000,000.00 2.6475000000% 2.6475000000% $148,834,153.74 $328,365.35 $0.00 $0.00 $0.00 $0.00 $0.00 $328,365.35
A3 $276,500,000.00 2.4475000000% 2.4475000000% $273,412,494.19 $557,647.57 $0.00 $0.00 $0.00 $0.00 $0.00 $557,647.57
A4A $50,000,000.00 2.4375000000% 2.4375000000% $49,441,680.69 $100,428.41 $0.00 $0.00 $0.00 $0.00 $0.00 $100,428.41
A4B $9,000,000.00 2.5075000000% 2.5075000000% $8,899,502.52 $18,596.25 $0.00 $0.00 $0.00 $0.00 $0.00 $18,596.25
A5 $146,509,000.00 2.6775000000% 2.6775000000% $146,509,000.00 $326,898.21 $0.00 $0.00 $0.00 $0.00 $0.00 $326,898.21
X $0.00 0.0000000000% 0.0000000000% $0.00 $1,686,036.84 $0.00 $0.00 $0.00 $0.00 $0.00 $1,686,036.84
X_NOTIONAL $1,784,625,919.00 1.1420772449% 1.1420772449% $1,771,547,600.43 $1,686,036.84 $0.00 $0.00 $0.00 $0.00 $0.00 $1,686,036.84
X_PRINCIPAL $0.00 0.0000000000% 0.0000000000% $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00
B1 $41,046,000.00 2.8375000000% 2.8375000000% $41,043,949.33 $97,051.84 $0.00 $0.00 $0.00 $0.00 $0.00 $97,051.84
B2 $20,523,000.00 3.2375000000% 3.2375000000% $20,521,974.67 $55,366.58 $0.00 $0.00 $0.00 $0.00 $0.00 $55,366.58
B3 $12,492,000.00 3.2875000000% 3.2875000000% $12,491,375.90 $34,221.17 $0.00 $0.00 $0.00 $0.00 $0.00 $34,221.17
B4 $9,815,000.00 3.2875000000% 3.2875000000% $9,814,509.64 $26,887.67 $0.00 $0.00 $0.00 $0.00 $0.00 $26,887.67
B5 $12,492,000.00 3.2875000000% 3.2875000000% $12,491,375.90 $34,221.17 $0.00 $0.00 $0.00 $0.00 $0.00 $34,221.17
B6 $6,248,819.86 3.2875000000% 3.2875000000% $6,248,507.67 $17,118.31 $0.00 $0.00 $0.00 $0.00 $0.00 $17,118.31
Y $0.00 0.0000000000% 0.0000000000% $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00
R $100.00 0.0000000000% 0.0000000000% $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00
R_SYN $0.00 0.0000000000% 0.0000000000% $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00
YIELD_PAYMENTS $0.00 0.0000000000% 0.0000000000% $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00
Total $1,784,625,919.86     $1,771,547,600.43 $5,522,276.58 $0.00 $0.00 $0.00 $0.00 $0.00 $5,522,276.58



WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.
Series: WAMU.04AR12
Distribution Date: 12/27/2004
PER $1000 DENOMINATION
Class Orig Face Int Rate Accrued Int Rate Paid Beg Cert Prin/Not Bal Curent Int Accrued Int Shortfall PPIS Uncompensated Int Shortfall Unscheduled Int Int Reimbursed Total Int Dist
A1 $200,000,000.00 2.5875000000% 2.5875000000% 992.22769160 2.13949095 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000 2.13949095
A2A $850,000,000.00 2.5775000000% 2.5775000000% 992.22769160 2.13122240 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000 2.13122240
A2B $150,000,000.00 2.6475000000% 2.6475000000% 992.22769160 2.18910233 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000 2.18910233
A3 $276,500,000.00 2.4475000000% 2.4475000000% 988.83361371 2.01680857 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000 2.01680857
A4A $50,000,000.00 2.4375000000% 2.4375000000% 988.83361380 2.00856820 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000 2.00856820
A4B $9,000,000.00 2.5075000000% 2.5075000000% 988.83361333 2.06625000 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000 2.06625000
A5 $146,509,000.00 2.6775000000% 2.6775000000% 1,000.00000000 2.23125003 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000 2.23125003
X $0.00 0.0000000000% 0.0000000000% 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000
X_NOTIONAL $1,784,625,919.00 1.1420772449% 1.1420772449% 992.67167509 0.94475645 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000 0.94475645
X_PRINCIPAL $0.00 0.0000000000% 0.0000000000% 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000
B1 $41,046,000.00 2.8375000000% 2.8375000000% 999.95003971 2.36446523 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000 2.36446523
B2 $20,523,000.00 3.2375000000% 3.2375000000% 999.95003996 2.69778200 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000 2.69778200
B3 $12,492,000.00 3.2875000000% 3.2875000000% 999.95004003 2.73944685 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000 2.73944685
B4 $9,815,000.00 3.2875000000% 3.2875000000% 999.95003974 2.73944677 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000 2.73944677
B5 $12,492,000.00 3.2875000000% 3.2875000000% 999.95004003 2.73944685 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000 2.73944685
B6 $6,248,819.86 3.2875000000% 3.2875000000% 999.95004017 2.73944687 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000 2.73944687
Y $0.00 0.0000000000% 0.0000000000% 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000
R $100.00 0.0000000000% 0.0000000000% 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000
R_SYN $0.00 0.0000000000% 0.0000000000% 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000
YIELD_PAYMENTS $0.00 0.0000000000% 0.0000000000% 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000



WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.
MASTER SERVICING
MORTGAGE PASS-THROUGH CERTIFICATES
12/2004 DISTRIBUTION REPORT
SERIES: WAMU 04AR12
WEIGHTED AVERAGE PC RATE: 3.74065%
WEIGHTED AVERAGE MATURITY: 361.07614
WEIGHTED AVERAGE LOAN AGE: 4.80488
POOL NUMBER: 2589
ISSUE DATE: 10/26/2004
CERTIFICATE BALANCE AT ISSUE: $1,784,625,919.86
  TOTAL NUMBER
OF MORTAGES 		CERTIFICATE ACCOUNT
ACTIVITY (@ PCRATE) 		CERTIFICATE BALANCE
OUTSTANDING
BALANCES FROM LAST FISCAL MONTH-END: 3455   $1,771,547,600.43
PRINCIPAL POOL COLLECTION(S):      
Scheduled Principal Collection Due Current Month   ($231,385.45)  
Unscheduled Principal Collection/Reversals   $2,526,451.07  
Liquidations-in-full 16 $8,694,314.22  
Subsequent Recoveries   $0.00  
Net principal Distributed   $10,989,379.84 -$10,989,379.84
 
CAPITAL LOSS (PRINCIPAL WRITTEN OFF):     $0.00
 
BALANCE CURRENT FISCAL MONTH-END: 3439   $1,760,558,220.59
 
SCHEDULED INTEREST AT MORTGAGE RATE:   $6,149,699.80  
 
UNSCHEDULED INTEREST AT MORTGAGE RATE:      
Unscheduled Interest Collection/Reversals   $0.00  
Interest Uncollected on Liquidation   $0.00  
Interest Uncollected on Non-Earning Assets   $0.00  
Interest Uncollected on Prepayment   $0.00  
Uncompensated Uncollected Interest   $0.00  
Net Unscheduled Interest Distributed   $0.00  
 
OTHER:      
Loan Conversion Fees   $0.00  
Expense Reimbursements   $0.00  
Gain on Liquidations   $0.00  
Hazard Insurance Premium Refunds   $0.00  
Recoveries Carried Forward   $0.00  
Net Other Distributions   $0.00  



WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.
MASTER SERVICING
MORTGAGE PASS-THROUGH CERTIFICATES
12/2004 DISTRIBUTION REPORT
  TOTAL NUMBER
OF MORTAGES 		CERTIFICATE ACCOUNT
ACTIVITY (@ PCRATE) 		CERTIFICATE BALANCE
OUTSTANDING
SCHEDULED SERVICING FEE EXPENSES:   $627,423.23  
 
UNSCHEDULED SERVICING FEES:      
Unscheduled Service Fee Collections/Reversals   $0.00  
Servicing Fees Uncollected on Liquidation   $0.00  
Servicing Fees Uncollected/Non-Earning Assets   $0.00  
Net Unscheduled Service Fees Distributed   $0.00  
 
MISCELLANEOUS EXPENSES:   $0.00  
 
NET FUNDS DISTRIBUTED:   $16,511,656.41  



WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.
MASTER SERVICING
MORTGAGE PASS-THROUGH CERTIFICATES
12/2004 DISTRIBUTION REPORT
SERIES: WAMU 04AR12
WEIGHTED AVERAGE PC RATE: 3.74065%
WEIGHTED AVERAGE MATURITY: 361.07614
WEIGHTED AVERAGE LOAN AGE: 4.80488
POOL NUMBER: ALL
ISSUE DATE: 10/26/2004
CERTIFICATE BALANCE AT ISSUE: $1,784,625,919.86
  TOTAL NUMBER
OF MORTAGES 		CERTIFICATE ACCOUNT
ACTIVITY (@ PCRATE) 		CERTIFICATE BALANCE
OUTSTANDING
BALANCES FROM LAST FISCAL MONTH-END: 3455   $1,771,547,600.43
PRINCIPAL POOL COLLECTION(S):      
Scheduled Principal Collection Due Current Month   ($231,385.45)  
Unscheduled Principal Collection/Reversals   $2,526,451.07  
Liquidations-in-full 16 $8,694,314.22  
Subsequent Recoveries   $0.00  
Net principal Distributed   $10,989,379.84 -$10,989,379.84
 
CAPITAL LOSS (PRINCIPAL WRITTEN OFF):     $0.00
 
BALANCE CURRENT FISCAL MONTH-END: 3439   $1,760,558,220.59
 
SCHEDULED INTEREST AT MORTGAGE RATE:   $6,149,699.80  
 
UNSCHEDULED INTEREST AT MORTGAGE RATE:      
Unscheduled Interest Collection/Reversals   $0.00  
Interest Uncollected on Liquidation   $0.00  
Interest Uncollected on Non-Earning Assets   $0.00  
Interest Uncollected on Prepayment   $0.00  
Uncompensated Uncollected Interest   $0.00  
Net Unscheduled Interest Distributed   $0.00  
 
OTHER:      
Loan Conversion Fees   $0.00  
Expense Reimbursements   $0.00  
Gain on Liquidations   $0.00  
Hazard Insurance Premium Refunds   $0.00  
Recoveries Carried Forward   $0.00  
Net Other Distributions   $0.00  



WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.
MASTER SERVICING
MORTGAGE PASS-THROUGH CERTIFICATES
12/2004 DISTRIBUTION REPORT
  TOTAL NUMBER
OF MORTAGES 		CERTIFICATE ACCOUNT
ACTIVITY (@ PCRATE) 		CERTIFICATE BALANCE
OUTSTANDING
SCHEDULED SERVICING FEE EXPENSES:   $627,423.23  
 
UNSCHEDULED SERVICING FEES:      
Unscheduled Service Fee Collections/Reversals   $0.00  
Servicing Fees Uncollected on Liquidation   $0.00  
Servicing Fees Uncollected/Non-Earning Assets   $0.00  
Net Unscheduled Service Fees Distributed   $0.00  
 
MISCELLANEOUS EXPENSES:   $0.00  
 
NET FUNDS DISTRIBUTED:   $16,511,656.41  



WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.
Series: WAMU.04AR12
Distribution Date: 12/27/2004
 
Distribution by Group
Pool ID Principal Interest Total  
Pool - 2589 $10,989,379.84 $5,522,276.57 $16,511,656.41  
Aggregate $10,989,379.84 $5,522,276.57 $16,511,656.41  
 
Number of Loans and Aggregate Principal Balance By Group
Pool ID Beg Bal Beg Count Paid Off / Liq Count Rem Count Sched Prin End Bal Sched Prin Prin PrePay / Liq Unsched Prin / Rev Total Prin
Pool - 2589 $1,771,547,600.43 3455 16 3439 $1,760,558,220.59 ($231,385.45) $8,694,314.22 $2,526,451.07 $10,989,379.84
Aggregate $1,771,547,600.43 3455 16 3439 $1,760,558,220.59 ($231,385.45) $8,694,314.22 $2,526,451.07 $10,989,379.84
 
Delinquency Information by Group
Pool ID 1 Month Count Sched End Balance 2 Months Count Sched End Balance 3 Months Count Sched End Balance 4 Months Count Sched End Balance  
Pool - 2589 24 $13,178,464.55 1 $673,299.71 0 $0.00 0 $0.00  
Aggregate 24 $13,178,464.55 1 $673,299.71 0 $0.00 0 $0.00  
 
Foreclosure and REO Information by Group
Pool ID Foreclosure Count Sched End Balance REO Count Sched End Balance
Pool - 2589 0 $0.00 0 $0.00
Aggregate 0 $0.00 0 $0.00
 
Aggregate Loss Amounts by Group
Pool ID Count Loss Amount  
Pool - 2589 0 $0.00  
Aggregate 0 $0.00  



WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.
Series: WAMU.04AR12
Distribution Date: 12/27/2004
 
INSURANCE RESERVES - Group 1
Insurance Type Original Balance Claims In Progress Claims Paid Coverage Adjustments Coverage Remaining
MPI $0.00 $0.00 $0.00 $0.00 $0.00
Special Hazard $0.00 $0.00 $0.00 $0.00 $0.00
Bankruptcy Bond
Single-Units $0.00 $0.00 $0.00 $0.00 $0.00
Multi-Units $0.00 $0.00 $0.00 $0.00 $0.00
Mortgage Repurchase $0.00 $0.00 $0.00 $0.00 $0.00
 
INSURANCE RESERVES - Aggregate
Insurance Type Original Balance Claims In Progress Claims Paid Coverage Adjustments Coverage Remaining
MPI $0.00 $0.00 $0.00 $0.00 $0.00
Special Hazard $0.00 $0.00 $0.00 $0.00 $0.00
Bankruptcy Bond
Single-Units $0.00 $0.00 $0.00 $0.00 $0.00
Multi-Units $0.00 $0.00 $0.00 $0.00 $0.00
Mortgage Repurchase $0.00 $0.00 $0.00 $0.00 $0.00



WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.
Series: WAMU.04AR12
Distribution Date: 12/27/2004
 
The Subordinate Certificates provide, to the limited extent described in the Prospectus Supplement, credit support, as well as special hazard, bankruptcy, and fraud coverage to certain Certificates. The "Prospectus Supplement" is that certain Prospectus Supplement, dated October 22,2004 to that certain Prospectus Supplement, dated February 10,2004, to which certain certificates were offered. The special hazard, bankruptcy, and Fraud coverage (collectively, "Credit Enhancements") provided by the Subordinate certificates provide coverage to the Loans, subject to the conditions and limitations to payment specified thereunder.
 
The Class Principal Balances of each Class of the Class B1,B2,B3,B4,B5,B6 Certificatesimmediately after the principal and interest distribution on 200412 are as follows:
Class Class Principal Balance
B1 $41,042,604.76
B2 $20,521,302.38
B3 $12,490,966.69
B4 $9,814,188.12
B5 $12,490,966.69
B6 $6,248,302.97
Total $102,608,331.62
Capitalized items used but not defined herein have the meanings ascribed to them in the Prospectus Supplement.
The amount of the special hazard coverage, bankruptcy coverage, and fraud coverage, as of the above referenced distribution date, is $0.00, $0.00, $0.00 respectively, and such coverages are referred to in the table above under the column "Insurance Type" as "special hazard," "bankruptcy bond," and "mortgage repurchase," respectively. However, no policy of insurance exists for any such coverage, notwithstanding the reference to "insurance."


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