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): ~~August~~October 25, 2005 (Date of earliest event reported) Indymac MBS Inc (as Depositor under the Pooling and Servicing Agreement, dated as June 1, 2005, providing for the issuance of IndyMac INDX Mortgage Loan Trust 2005-AR12 Mortgage Pass-Through Certificates, Series 2005-AR12) (Exact name of registrant as specified in charter) DELAWARE (State or Other Jurisdiction of Incorporation) 333-119384-26 95-4791925 (Commission File Number) (I.R.S. Employer Identification No.) 155 NORTH LAKE AVENUE PASADENA, CALIFORNIA 91101 (Address of principal executive offices) (Zip Code) Registrant's Telephone Number, Including Area Code: (800) 669-2300 (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(b) under the Exchange Act (17 CFR 240.14a-12(b)) [ ] 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 Attached hereto is a copy of the Monthly Remittance Statements to the Certificateholders which was derived from the monthly information submitted by the Master Servicer of the Trust to the Trustee. Item 9.01 Financial Statements and Exhibits (c) Exhibits: Exhibit No. Description 99.1 Monthly Remittance Statement to the Certificateholders dated as of ~~August~~October 25, 2005. 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. Deutsche Bank National Trust Company, in its capacity as Trustee under the Pooling and Servicing Agreement on behalf of Indymac MBS Inc, Registrant Date: ~~Aug~~Oct 2628, 2005 By: /s/ Katherine M. Wannenmacher Katherine M. Wannenmacher Vice President EXHIBIT INDEX DOCUMENT 99.1 Monthly Remittance Statement to the Certificateholders dated as of ~~August~~October 25, 2005.

IndyMac INDX Mortgage Loan Trust 2005-AR12

Mortgage Pass-Through Certificates

August 25, 2005 Distribution

October 25, 2005 Distribution

Contents

TABLE OF CONTENTS

Page

Contents

Certificate Payment Report

Collection Account Report

Credit Enhancement Report

Collateral Report

Delinquency Report

REO Report

Prepayment Report

Prepayment Detail Report

10.

Realized Loss Report

11.

Realized Loss Detail Report

12.

Triggers, Adj. Rate Cert. and Miscellaneous Report

13.

Other Related Information

Total Number of Pages

CONTACTS

Administrator: Brent Hoyler

Direct Phone Number: (714)247-6322

Address: Deutsche Bank

1761 E. St. Andrew Place, Santa Ana, CA 92705

Web Site: https://www.tss.db.com/invr

Factor Information: (800) 735-7777

Main Phone Number: (714) 247-6000

ISSUANCE INFORMATION

Seller:

IndyMac Bank

Cut-Off Date: June 1, 2005

Certificate Insurer(s):

Closing Date: June 6, 2005

First Payment Date: July 25, 2005

Servicer(s):

IndyMac Bank Servicer

Distribution Date: August 25, 2005

Distribution Date: October 25, 2005

Underwriter(s):

Greenwich Capital Markets Underwriter

Record Date: ~~August~~October 24, 2005

July 29, 2005

September 30, 2005

Page 1 of 24

IndyMac INDX Mortgage Loan Trust 2005-AR12

Mortgage Pass-Through Certificates

Master Remic Series 2005-AR12

Certificate Payment Report for August 25, 2005 Distribution

Certificate Payment Report for October 25, 2005 Distribution

Distribution in Dollars - Current Period

Prior

Current

Class

Original

Principal

Total

Realized

Deferred

Principal

Class

Type

Face Value

Balance

Interest

Principal

Distribution

Losses

Interest

Balance

(1)

(2)

(3)

(4)=(2)+(3)

(5)

(6)

(7)=(1)-(3)-(5)+(6)

1-A-1

STEP

575,877,000.00

~~570~~561,~~233~~495,~~130~~546.6152

1,~~826~~849,~~646~~971.8085

36,~~367~~863,~~110~~522.6678

58,~~193~~713,~~757~~494.4663

~~566~~554,~~866~~632,~~019~~023.9574

2-A-1A

STEP

310,489,000.00

~~306~~298,~~040~~885,~~651~~758.3863

~~975~~979,~~079~~930.5217

24,~~388~~205,~~194~~091.9091

35,~~363~~185,~~274~~022.4208

~~303~~294,~~652~~680,~~456~~666.4872

2-A-1B

STEP

129,370,000.00

~~127~~124,~~516~~535,~~527~~331.3867

~~410~~412,~~674~~315.0673

~~995~~1,~~078~~752,115.0099

12,~~405~~164,~~752~~431.0672

~~126~~122,~~521~~783,~~449~~215.3868

2-A-1C

STEP

77,623,000.00

7674,~~510~~722,~~902~~161.1063

251,~~019~~606.5212

~~597~~1,~~054~~051,283.4914

~~848~~1,~~074~~302,889.0126

7573,~~913~~670,~~847~~878.6149

2-A-2

STEP

63,987,000.00

6361,~~070~~595,~~263~~750.8769

~~206~~207,~~923~~406.0258

~~492~~866,~~170~~604.1867

~~699~~1,~~093~~074,011.2025

6260,~~578~~729,~~093~~146.6903

A-X-1

SUB

~~742~~688,~~237~~192.8270

A-X-2

SUB

~~641~~859,~~928~~575.7372

A-R

SUB

100.00

~~0.01~~-

A-PO

SUB

100.00

B-1

SUB

32,167,000.00

32,121,~~319~~265.0222

~~108~~111,~~980~~523.5025

~~53.80~~-

~~109~~111,~~034~~523.3025

32,121,265.22

B-2

SUB

25,228,000.00

25,192,~~173~~131.2304

9091,~~243~~930.9628

~~42.19~~-

9091,~~286~~930.1528

25,192,131.04

B-3

SUB

17,659,000.00

17,633,~~922~~892.1158

7475,~~557~~002.2082

~~29.53~~-

7475,~~586~~002.7382

17,633,892.58

B-4

SUB

4,414,000.00

4,407,~~731~~724.5921

19,~~283~~812.5172

~~7.38~~-

19,~~290~~812.8972

4,407,724.21

B-5

SUB

6,937,000.00

6,927,~~148~~137.6303

3031,~~305~~137.7848

~~11.60~~-

3031,~~317~~137.3848

6,927,137.03

B-6

SUB

5,676,000.00

5,667,~~939~~929.4091

2425,~~796~~477.8334

~~9.49~~-

2425,~~806~~477.3234

5,667,929.91

B-7

SUB

6,937,000.00

6,927,~~148~~137.6303

3031,~~305~~137.7848

~~11.60~~-

3031,~~317~~137.3848

6,927,137.03

B-8

SUB

5,049,717.91

5,042,~~546~~538.7126

22,~~060~~666.7821

~~8.45~~-

22,~~069~~666.2321

5,042,538.26

Total

1,261,413,917.91

1,~~247~~225,~~291~~154,~~504~~404.6742

5,~~455~~657,~~043~~686.8144

714,~~839~~738,~~782~~618.2848

1320,~~294~~396,~~826~~304.0992

1,~~239~~210,~~451~~415,~~722~~785.3994

Interest Accrual Detail

Current Period Factor Information per $1,000 of Original Face

Orig. Principal

Prior

Current

Period

(with Notional)

Principal

Total

Principal

Class

Starting

Ending

Method

Cusip

Balance

Interest

Principal

Distribution

Balance

(1)

(2)

(3)

(4)=(2)+(3)

(5)

1-A-1

0709/2526/05

0810/24/05

A-Act/360

45660LMF3

575,877,000.00

~~990~~975.~~199523~~026866

3.~~171939~~212443

511.~~846927~~918383

915.~~018866~~130826

~~984~~963.~~352596~~108483

2-A-1A

0709/2526/05

0810/24/05

A-Act/360

45660LMG1

310,489,000.00

~~985~~962.~~673088~~629139

3.~~140464~~156087

713.~~691721~~543449

1016.~~832185~~699536

~~977~~949.~~981366~~085690

2-A-1B

0709/2526/05

0810/24/05

A-Act/360

45660LMH9

129,370,000.00

~~985~~962.~~673088~~629139

3.~~174415~~187105

713.~~691721~~543449

1016.~~866136~~730554

~~977~~949.~~981366~~085690

2-A-1C

0709/2526/05

A-Act/360

45660LQB8

77,623,000.00

~~985~~962.~~673088~~629139

3.~~233829~~241386

713.~~691721~~543449

1016.~~925551~~784835

~~977~~949.~~981366~~085690

2-A-2

0709/2526/05

A-Act/360

45660LMJ5

63,987,000.00

~~985~~962.~~673088~~629139

3.~~233829~~241386

713.~~691721~~543449

1016.~~925551~~784835

~~977~~949.~~981366~~085690

A-X-1

0810/24/05

A-30/360

45660LMK2

A-X-2

0810/24/05

A-30/360

45660LML0

A-R

0810/24/05

F-30/360

45660LQC6

100.00

~~0.094000~~-

A-PO

0810/24/05

A-30/360

45660LMM8

100.00

1,000.000000

B-1

0709/25/05

0810/24/05

A-30/360

45660LMN6

32,167,000.00

998.~~579881~~578208

3.~~387960~~467008

~~0.001673~~-

3.~~389632~~467008

998.578208

B-2

0709/25/05

0810/24/05

A-30/360

45660LMP1

25,228,000.00

998.~~579881~~578208

3.~~577135~~643978

~~0.001672~~-

3.~~578807~~643978

998.578208

B-3

0709/25/05

0810/24/05

A-30/360

45660LMQ9

17,659,000.00

998.~~579881~~578208

4.~~222051~~247286

~~0.001672~~-

4.~~223723~~247286

998.578208

B-4

0709/25/05

0810/24/05

A-30/360

45660LMR7

4,414,000.00

998.~~579880~~578208

4.~~368715~~488609

~~0.001672~~-

4.~~370387~~488609

998.578208

B-5

0709/25/05

0810/24/05

A-30/360

45660LMS5

6,937,000.00

998.~~579880~~578208

4.~~368716~~488609

~~0.001672~~-

4.~~370388~~488609

998.578208

B-6

0709/25/05

0810/24/05

A-30/360

45660LMT3

5,676,000.00

998.~~579880~~578208

4.~~368716~~488608

~~0.001672~~-

4.~~370388~~488608

998.578208

B-7

0709/25/05

0810/24/05

A-30/360

45660LMU0

6,937,000.00

998.~~579880~~578208

4.~~368716~~488609

~~0.001672~~-

4.~~370388~~488609

998.578208

B-8

0709/25/05

0810/24/05

A-30/360

45660LQE2

5,049,717.91

998.~~579881~~578208

4.~~368715~~488608

~~0.001673~~-

4.~~370389~~488608

998.578208

Page 2 of 24

IndyMac INDX Mortgage Loan Trust 2005-AR12

Mortgage Pass-Through Certificates

Master Remic Series 2005-AR12

Certificate Payment Report for August 25, 2005 Distribution

Certificate Payment Report for October 25, 2005 Distribution

Distribution in Dollars - to Date

Current

Original

Unscheduled

Scheduled

Total

Realized

Deferred

Principal

Class

Face Value

Interest

Principal

Distribution

Losses

Interest

Balance

(1)

(2)

(3)

(4)

(5)=(3)+(4)

(6)=(2)+(5)

(7)

(8)

(9)=(1)-(5)-(7)+(8)

1-A-1

575,877,000.00

46,~~499~~349,~~515~~487.9176

915,~~010~~874,~~980~~502.0583

1322,~~510~~223,~~495~~990.9659

~~566~~554,~~866~~632,~~019~~023.9574

2-A-1A

310,489,000.00

23,~~407~~387,~~727~~657.5168

611,~~836~~041,~~543~~635.5243

914,~~244~~429,~~271~~293.0311

~~303~~294,~~652~~680,~~456~~666.4872

2-A-1B

129,370,000.00

1,~~014~~426,~~652~~968.2801

24,~~848~~600,~~550~~666.6261

0.00

24,~~848~~600,~~550~~666.6261

36,~~863~~027,~~202~~634.9062

~~126~~122,~~521~~783,~~449~~215.3868

2-A-1C

77,623,000.00

~~620~~872,~~806~~412.8799

12,~~709~~760,~~152~~435.3953

23,~~329~~632,~~959~~848.2652

7573,~~913~~670,~~847~~878.6149

2-A-2

63,987,000.00

~~511~~719,~~749~~156.9856

12,~~408~~275,~~906~~510.3197

12,~~920~~994,~~656~~667.2953

6260,~~578~~729,~~093~~146.6903

A-X-1

12,~~513~~201,~~801~~994.8252

A-X-2

~~641~~1,~~928~~718,351.7362

A-R

100.00

0.39

100.00

100.39

A-PO

100.00

B-1

32,167,000.00

~~267~~379,~~912~~435.2954

45,734.78

~~313~~425,~~647~~170.0732

32,121,265.22

B-2

25,228,000.00

~~222~~314,~~445~~375.6997

35,868.96

~~258~~350,~~314~~244.6593

25,192,131.04

B-3

17,659,000.00

~~185~~260,~~122~~124.1698

31,855.61

25,107.42

~~210~~285,~~229~~232.5840

17,633,892.58

B-4

4,414,000.00

4868,~~722~~535.4416

32,399.76

6,275.79

5474,~~998~~810.2395

4,407,724.21

B-5

6,937,000.00

76107,~~571~~709.7220

19,655.25

9,862.97

86117,~~434~~572.6917

6,927,137.03

B-6

5,676,000.00

6288,~~652~~129.6296

1,814.71

6,255.38

8,070.09

7096,~~722~~200.7105

5,667,929.91

B-7

6,937,000.00

76107,~~571~~709.7220

4,410.80

5,452.17

9,862.97

86117,~~434~~572.6917

6,927,137.03

B-8

5,049,717.91

5578,~~739~~405.5980

4,101.25

3,078.40

7,179.65

6285,~~919~~585.2445

5,042,538.26

Total

1,261,413,917.91

1218,~~205~~080,~~921~~455.7134

1831,~~790~~611,~~311~~042.5725

35,~~214~~132,~~548~~436.3919

2136,~~962~~700,~~195~~814.5200

3454,~~168~~781,~~117~~269.2334

1,~~239~~210,~~451~~415,~~722~~785.3994

Interest Detail

Pass-

Prior Principal

Non-

Prior

Unscheduled

Paid or

Current

Through

(with Notional)

Accrued

Supported

Unpaid

Interest

Optimal

Deferred

Unpaid

Class

Rate

Balance

Interest

Interest SF

Interest

Adjustments

Interest

(1)

(2)

(3)

(4)

(5)=(1)-(2)+(3)+(4)

(6)

(7)=(5)-(6)

1-A-1

34.~~72000~~09000%

~~570~~561,~~233~~495,~~130~~546.6152

1,~~826~~849,~~646~~971.8085

2-A-1A

34.~~70000~~07000%

~~306~~298,~~040~~885,~~651~~758.3863

~~975~~979,~~079~~930.5217

2-A-1B

34.~~74000~~11000%

~~127~~124,~~516~~535,~~527~~331.3867

~~410~~412,~~674~~315.0673

2-A-1C

34.~~81000~~18000%

7674,~~510~~722,~~902~~161.1063

251,~~019~~606.5212

2-A-2

34.~~81000~~18000%

6361,~~070~~595,~~263~~750.8769

~~206~~207,~~923~~406.0258

A-X-1

0.80000%

1,~~113~~032,~~356~~289,~~724~~052.7957

~~742~~688,~~237~~192.8270

A-X-2

0.~~61759~~78639%

1,~~247~~225,~~291~~154,~~504~~404.6842

~~641~~802,~~928~~873.7393

~~641~~859,~~928~~575.7372

A-R

45.~~91000~~28000%

~~0.01~~-

A-PO

100.00

B-1

34.~~94000~~31000%

32,121,~~319~~265.0222

~~108~~111,~~980~~523.5025

B-2

4.~~16000~~53000%

25,192,~~173~~131.2304

9091,~~243~~930.9628

B-3

45.~~91000~~28000%

17,633,~~922~~892.1158

7475,~~557~~002.2082

B-4

5.~~08056~~58000%

4,407,~~731~~724.5921

19,~~283~~812.5172

B-5

5.~~08056~~58000%

6,927,~~148~~137.6303

3031,~~305~~137.7848

B-6

5.~~08056~~58000%

5,667,~~939~~929.4091

2425,~~796~~477.8334

B-7

5.~~08056~~58000%

6,927,~~148~~137.6303

3031,~~305~~137.7848

B-8

5.~~08056~~58000%

5,042,~~546~~538.7126

22,~~060~~666.7821

Total

3,~~607~~482,~~939~~597,~~734~~861.1441

5,~~455~~600,~~043~~984.8166

5,~~455~~657,~~043~~686.8144

Page 3 of 24

IndyMac INDX Mortgage Loan Trust 2005-AR12

Mortgage Pass-Through Certificates

Collection Account Report for August 25, 2005 Distribution

Collection Account Report for October 25, 2005 Distribution

Collection Account Report

SUMMARY

GROUP 2

GROUP 1

TOTAL

Principal Collections

47,~~472~~875,~~599~~095.6170

36,~~367~~863,~~182~~522.6878

714,~~839~~738,~~782~~618.2948

Principal Withdrawals

0.00

Principal Other Accounts

0.00

TOTAL PRINCIPAL

47,~~472~~875,~~599~~095.6170

36,~~367~~863,~~182~~522.6878

714,~~839~~738,~~782~~618.2948

Interest Collections

2,~~754~~815,~~744~~053.5332

2,~~817~~897,~~507~~025.3024

5,~~572~~712,~~251~~078.8356

Interest Withdrawals

0.00

Interest Other Accounts

0.00

056,701.0076

Interest Fees

(5451,~~956~~609.2298)

(6259,~~251~~483.8089)

(~~117~~111,~~208~~093.0388)

TOTAL INTEREST

2,~~699~~763,~~788~~443.3134

2,~~755~~894,~~255~~243.5011

5,~~455~~657,~~043~~686.8044

TOTAL AVAILABLE FUNDS TO BONDHOLDERS

710,~~172~~638,~~387~~539.9204

69,~~122~~757,~~438~~765.1889

1320,~~294~~396,~~826~~304.0992

Interest Payable to Bondholders

2,~~699~~763,~~788~~443.3134

2,~~755~~894,~~255~~243.5011

5,~~455~~657,~~043~~686.8044

PRINCIPAL - COLLECTIONS

GROUP 2

GROUP 1

TOTAL

Scheduled Principal

~~1,221~~0.8600

~~866~~0.4200

~~2,088~~0.2800

Curtailments

(~~356~~636,~~113~~743.1312)

(~~523~~583,~~877~~774.7989)

(~~879~~1,~~990~~220,518.9201)

Prepayments in Full

48,~~827~~511,~~490~~838.8882

37,~~890~~447,~~194~~297.0567

815,~~717~~959,~~684~~136.9349

Repurchases/Substitutions

0.00

Liquidations

0.00

Insurance Principal

0.00

Other Additional Principal

0.00

LESS: Delinquent Principal

~~(1,221~~0.~~86)~~00

~~(866~~0.~~42)~~00

~~(2,088~~0.~~28)~~00

LESS: Realized Losses

0.00

PLUS: Recoveries

0.00

PLUS: Substitution Shortfall Principal

0.00

PLUS: Principal Loan Adjustments

0.00

PLUS: Principal Advanced

~~1,221~~0.8600

~~866~~0.4200

~~2,088~~0.2800

TOTAL PRINCIPAL

47,~~472~~875,~~599~~095.6170

36,~~367~~863,~~182~~522.6878

714,~~839~~738,~~782~~618.2948

Page 4 of 24

IndyMac INDX Mortgage Loan Trust 2005-AR12

Mortgage Pass-Through Certificates

Collection Account Report for August 25, 2005 Distribution

Collection Account Report for October 25, 2005 Distribution

Collection Account Report

PRINCIPAL - WITHDRAWALS

GROUP 2

GROUP 1

TOTAL

SPACE INTENTIONALLY LEFT BLANK

PRINCIPAL - OTHER ACCOUNTS

GROUP 2

GROUP 1

TOTAL

TOTAL PRINCIPAL OTHER ACCOUNTS

0.00

INTEREST - COLLECTIONS

GROUP 2

GROUP 1

TOTAL

Scheduled Interest

2,~~896~~955,~~098~~547.4618

23,~~950~~030,~~490~~033.9389

5,~~846~~985,~~589~~581.3907

Repurchases/Substitutions

0.00

Liquidations

0.00

Insurance Interest

0.00

Other Additional Interest

0.00

LESS: Prepayment Interest Shortfalls

(24,~~534~~867.3473)

(25,~~107~~689.1339)

(410,~~641~~557.4712)

LESS: Delinquent Interest

(2,~~094~~171,~~254~~781.1169)

(2,~~020~~104,~~509~~146.8018)

(4,~~114~~275,~~763~~927.9187)

LESS: Interest Realized Losses

0.00

PLUS: Compensating Interest

24,~~534~~867.3473

25,~~107~~689.1339

410,~~641~~557.4712

LESS: Civil Relief Act Shorfalls

0.00

PLUS: Substiution Shortfall Interest

0.00

PLUS: Interest Loan Adjustments

0.00

LESS: Excess, Special Hazard, Fraud, & Bankruptcy Interest Losses

0.00

Interest Advanced

12,~~952~~031,~~900~~287.1883

1,~~887~~971,~~526~~137.1753

34,~~840~~002,~~426~~425.3536

Shortfall reserve deposits

0.00

TOTAL INTEREST

2,~~754~~815,~~744~~053.5332

2,~~817~~897,~~507~~025.3024

5,~~572~~712,~~251~~078.8356

Page 5 of 24

IndyMac INDX Mortgage Loan Trust 2005-AR12

Mortgage Pass-Through Certificates

Collection Account Report for August 25, 2005 Distribution

Collection Account Report for October 25, 2005 Distribution

Collection Account Report

INTEREST - WITHDRAWALS

GROUP 2

GROUP 1

TOTAL

SPACE INTENTIONALLY LEFT BLANK

INTEREST - OTHER ACCOUNTS

GROUP 2

GROUP 1

TOTAL

Prepayment Penalties

0.00

056,701.0076

Interest Coverage Amount for First Period

0.00

TOTAL INTEREST OTHER ACCOUNTS

0.00

056,701.0076

INTEREST - FEES

GROUP 2

GROUP 1

TOTAL

Current Servicing Fees

5450,~~070~~743.3004

6158,~~370~~615.7320

~~115~~109,~~441~~358.0324

Trustee Fees

~~885~~866.9294

~~881~~868.0769

1,~~767~~735.0064

TOTAL INTEREST FEES

5451,~~956~~609.2298

6259,~~251~~483.8089

~~117~~111,~~208~~093.0388

Page 6 of 24

IndyMac INDX Mortgage Loan Trust 2005-AR12

Mortgage Pass-Through Certificates

Credit Enhancement Report for August 25, 2005 Distribution

Credit Enhancement Report for October 25, 2005 Distribution

Credit Enhancement Report

ACCOUNTS

GROUP 2

GROUP 1

TOTAL

Carryover Shortfall Reserve Fund Beginning Balance

1,000.00

Required Reserve Fund Deposit

~~1,895~~0.1500

Carryover Shortfall Amount

~~2,895~~0.1500

Carryover Shortfall Reserve Fund Ending Balance

01,000.00

INSURANCE

GROUP 2

GROUP 1

TOTAL

SPACE INTENTIONALLY LEFT BLANK

STRUCTURAL FEATURES

GROUP 2

GROUP 1

TOTAL

SPACE INTENTIONALLY LEFT BLANK

Page 7 of 24

IndyMac INDX Mortgage Loan Trust 2005-AR12

Mortgage Pass-Through Certificates

Collateral Report for August 25, 2005 Distribution

Collateral Report for October 25, 2005 Distribution

Collateral Report

COLLATERAL

GROUP 2

GROUP 1

TOTAL

Loan Count:

Original

1251

2721

3972

Prior

1,~~236~~210

2,~~698~~655

3,~~934~~865

Prefunding

Scheduled Paid Offs

Full Voluntary Prepayments

(914)

(1730)

(2644)

Repurchases

Liquidations

Current

1,~~227~~196

2,~~681~~625

3,~~908~~821

Principal Balance:

Original

633,754,255.80

627,659,662.11

1,261,413,917.91

Prior

~~625~~611,~~357~~958,~~532~~088.4530

~~621~~613,~~933~~196,~~972~~316.2312

1,~~247~~225,~~291~~154,~~504~~404.6842

Prefunding

Scheduled Principal

~~(1,221.86)~~-

~~(866.42)~~-

~~(2,088.28)~~-

Partial and Full Voluntary Prepayments

(47,~~471~~875,~~377~~095.7570)

(36,~~366~~863,~~316~~522.2678)

(714,~~837~~738,~~694~~618.0148)

Repurchases

Liquidations

Current

~~620~~604,~~884~~082,~~932~~992.8460

~~618~~606,~~566~~332,~~789~~793.5534

1,~~239~~210,~~451~~415,~~722~~785.3994

PREFUNDING

GROUP 2

GROUP 1

TOTAL

SPACE INTENTIONALLY LEFT BLANK

Group 1

Group 2

Current Prin Balance by Groups (in millions of dollars)

Total Current Principal Balance (in millions of dollars)

Page 8 of 24

IndyMac INDX Mortgage Loan Trust 2005-AR12

Mortgage Pass-Through Certificates

Collateral Report for August 25, 2005 Distribution

Collateral Report for October 25, 2005 Distribution

Collateral Report

CHARACTERISTICS

GROUP 2

GROUP 1

TOTAL

Weighted Average Coupon Original

4.427351%

4.232134%

4.330214%

Weighted Average Coupon Prior

45.~~427351~~666104%

45.~~232134~~800378%

45.~~330214~~733115%

Weighted Average Coupon Current

5.~~557330~~795587%

5.~~692870~~929652%

5.~~624914~~862687%

Weighted Average Months to Maturity Original

359

Weighted Average Months to Maturity Prior

~~359~~357

Weighted Average Months to Maturity Current

~~358~~356

Weighted Avg Remaining Amortization Term Original

358

Weighted Avg Remaining Amortization Term Prior

~~358~~356

Weighted Avg Remaining Amortization Term Current

~~357~~355

Weighted Average Seasoning Original

1.93

1.78

1.86

Weighted Average Seasoning Prior

13.93

13.78

13.86

Weighted Average Seasoning Current

24.9392

24.78

24.8685

Note: Original information refers to deal issue.

Group 1

Group 2

WAC by Groups

Total WAC

WARAT by Groups

Total WARAT

Note: Dates correspond to distribution dates.

Page 9 of 24

IndyMac INDX Mortgage Loan Trust 2005-AR12

Mortgage Pass-Through Certificates

Collateral Report for August 25, 2005 Distribution

Collateral Report for October 25, 2005 Distribution

Collateral Report

ARM CHARACTERISTICS

GROUP 2

GROUP 1

TOTAL

Weighted Average Margin Original

2.924%

3.059%

Weighted Average Margin Prior

2.~~924~~927%

3.~~059~~061%

Weighted Average Margin Current

2.~~928~~931%

3.~~060~~063%

Weighted Average Max Rate Original

8.864%

8.869%

Weighted Average Max Rate Prior

8.~~864~~862%

8.~~869~~870%

Weighted Average Max Rate Current

8.862%

8.~~870~~871%

Weighted Average Min Rate Original

1.090%

1.082%

Weighted Average Min Rate Prior

1.~~090~~091%

1.~~082~~081%

Weighted Average Min Rate Current

1.091%

1.~~081~~080%

Weighted Average Cap Up Original

Weighted Average Cap Up Prior

Weighted Average Cap Up Current

Weighted Average Cap Down Original

Weighted Average Cap Down Prior

Weighted Average Cap Down Current

Note: Original information refers to deal issue.

SERVICING FEES / ADVANCES

GROUP 2

GROUP 1

TOTAL

Current Servicing Fees

5450,~~070~~743.3004

6158,~~370~~615.7320

~~115~~109,~~441~~358.0324

Delinquent Servicing Fees

~~141~~140,~~353~~493.9386

~~132~~133,~~983~~008.6465

~~274~~273,~~337~~502.5751

TOTAL SERVICING FEES

~~195~~191,~~424~~236.2390

~~194~~191,~~354~~623.3785

~~389~~382,~~778~~860.6075

Total Servicing Fees

~~195~~191,~~424~~236.2390

~~194~~191,~~354~~623.3785

~~389~~382,~~778~~860.6075

Compensating Interest

(24,~~534~~867.3473)

(25,~~107~~689.1339)

(410,~~641~~557.4712)

Delinquent Servicing Fees

(~~141~~140,~~353~~493.9386)

(~~132~~133,~~983~~008.6465)

(~~274~~273,~~337~~502.5751)

COLLECTED SERVICING FEES

5145,~~535~~875.9631

5952,~~263~~925.6081

~~110~~98,~~799~~801.5612

Total Advanced Principal For Current Payment Date

~~1,221~~0.8600

~~866~~0.4200

~~2,088~~0.2800

Total Advanced Interest For Current Payment Date

12,~~952~~031,~~900~~287.1883

1,~~887~~971,~~526~~137.1753

34,~~840~~002,~~426~~425.3536

TOTAL ADVANCES FOR CURRENT PERIOD

12,~~954~~031,~~122~~287.0483

1,~~888~~971,~~392~~137.5953

34,~~842~~002,~~514~~425.6336

ADDITIONAL COLLATERAL INFORMATION

GROUP 2

GROUP 1

TOTAL

Prepayment Interest Shortfall (PPIS)

24,~~534~~867.3473

25,~~107~~689.1339

410,~~641~~557.4712

Compensating Interest

(24,~~534~~867.3473)

(25,~~107~~689.1339)

(410,~~641~~557.4712)

Net Prepayment Interest Shortfall (Net PPIS)

0.00

Weighted Average Net Mortgage Rate

5.~~180630~~418887%

5.~~316170~~552952%

5.~~248214~~485987%

Current Deferred Interest

~~865~~962,~~126~~998.3718

~~919~~1,~~513~~023,520.7103

1,~~784~~986,~~640~~518.0821

Cumulative Deferred Interest

13,~~482~~355,~~161~~516.3526

13,~~523~~514,~~534~~877.2720

36,~~005~~870,~~695~~393.6246

Net Deferred Interest

0.00

Cumulative Net Deferred Interest

0.00

Page 10 of 24

IndyMac INDX Mortgage Loan Trust 2005-AR12

Mortgage Pass-Through Certificates

Delinquency Report for August 25, 2005 Distribution

Delinquency Report for October 25, 2005 Distribution

Delinquency Report - Total

<1 PAYMENT

1 PAYMENT

2 PAYMENTS

3+ PAYMENTS

TOTAL

DELINQUENT

Balance

###########

12,~~367~~016,~~715~~153.0440

~~658,361.35~~-

-530,270.52

1312,~~026~~546,~~076~~423.3992

% Balance

6971.8536%

10.0099%

0.0500%

0.0004%

1.0504%

# Loans

2,~~643~~649

3739

-2

3941

% # Loans

6769.6333%

01.9502%

0.0500%

0.0005%

1.0007%

FORECLOSURE

Balance

% Balance

0.00%

# Loans

% # Loans

0.00%

BANKRUPTCY

Balance

% Balance

0.00%

# Loans

% # Loans

0.00%

REO

Balance

% Balance

0.00%

# Loans

% # Loans

0.00%

TOTAL

Balance

12,~~367~~016,~~715~~153.0440

~~658,361.35~~-

-530,270.52

1312,~~026~~546,~~076~~423.3992

% Balance

0.00%

10.0099%

0.0500%

0.0004%

1.0504%

# Loans

3739

-2

3941

% # Loans

0.00%

01.9502%

0.0500%

0.0005%

1.0007%

Note: <1 Payment = 1-30days, 1 Payment = 31-60days, 2 Payments = 61-90days, 3+ Payments = 91+

6 Months Moving Average

1 or 2 Payments Delinquent

3 or More Payments Delinquent

Total Foreclosure

Total Bankruptcy and REO

Note: Dates correspond to distribution dates.

Page 11 of 24

IndyMac INDX Mortgage Loan Trust 2005-AR12

Mortgage Pass-Through Certificates

Delinquency Report for August 25, 2005 Distribution

Delinquency Report for October 25, 2005 Distribution

Delinquency Report - Group 1 Group

<1 PAYMENT

1 PAYMENT

2 PAYMENTS

3+ PAYMENTS

TOTAL

DELINQUENT

Balance

###########

56,~~633~~400,~~959~~082.3967

~~280,055.75~~-

-530,270.52

56,~~914~~930,~~015~~353.1419

% Balance

6769.9214%

01.9106%

0.0500%

0.0009%

01.9614%

# Loans

1,~~767~~778

2426

-2

2528

% # Loans

6567.9173%

0.9099%

0.0400%

0.0008%

01.9307%

FORECLOSURE

Balance

% Balance

0.00%

# Loans

% # Loans

0.00%

BANKRUPTCY

Balance

% Balance

0.00%

# Loans

% # Loans

0.00%

REO

Balance

% Balance

0.00%

# Loans

% # Loans

0.00%

TOTAL

Balance

56,~~633~~400,~~959~~082.3967

~~280,055.75~~-

-530,270.52

56,~~914~~930,~~015~~353.1419

% Balance

0.00%

01.9106%

0.0500%

0.0009%

01.9614%

# Loans

2426

-2

2528

% # Loans

0.00%

0.9099%

0.0400%

0.0008%

01.9307%

Note: <1 Payment = 1-30days, 1 Payment = 31-60days, 2 Payments = 61-90days, 3+ Payments = 91+

6 Months Moving Average

1 or 2 Payments Delinquent

3 or More Payments Delinquent

Total Foreclosure

Total Bankruptcy and REO

Note: Dates correspond to distribution dates.

Page 12 of 24

IndyMac INDX Mortgage Loan Trust 2005-AR12

Mortgage Pass-Through Certificates

Delinquency Report for August 25, 2005 Distribution

Delinquency Report for October 25, 2005 Distribution

Delinquency Report - Group 2 Group

<1 PAYMENT

1 PAYMENT

2 PAYMENTS

3+ PAYMENTS

TOTAL

DELINQUENT

Balance

###########

65,~~733~~616,~~755~~070.6573

~~378,305.60~~-

75,~~112~~616,~~061~~070.2573

% Balance

7173.7858%

10.0893%

0.0600%

0.00%

10.1593%

# Loans

~~876~~871

1413

% # Loans

7172.3983%

1.0609%

0.0800%

0.00%

1.1409%

FORECLOSURE

Balance

% Balance

0.00%

# Loans

% # Loans

0.00%

BANKRUPTCY

Balance

% Balance

0.00%

# Loans

% # Loans

0.00%

REO

Balance

% Balance

0.00%

# Loans

% # Loans

0.00%

TOTAL

Balance

65,~~733~~616,~~755~~070.6573

~~378,305.60~~-

75,~~112~~616,~~061~~070.2573

% Balance

0.00%

10.0893%

0.0600%

0.00%

10.1593%

# Loans

1413

% # Loans

0.00%

1.0609%

0.0800%

0.00%

1.1409%

Note: <1 Payment = 1-30days, 1 Payment = 31-60days, 2 Payments = 61-90days, 3+ Payments = 91+

6 Months Moving Average

1 or 2 Payments Delinquent

3 or More Payments Delinquent

Total Foreclosure

Total Bankruptcy and REO

Note: Dates correspond to distribution dates.

Page 13 of 24

IndyMac INDX Mortgage Loan Trust 2005-AR12

Mortgage Pass-Through Certificates

REO Report for August 25, 2005 Distribution

REO Report for October 25, 2005 Distribution

REO Report - Mortgage Loans that Become REO During Current Distribution

SUMMARY

LOAN GROUP

Total Loan Count = 0

Loan Group 1 = Group 1; REO Book Value = 000.00

Total Original Principal Balance = 000.00

Loan Group 2 = Group 2; REO Book Value = 000.00

Total Current Balance = 000.00

REO Book Value = 000.00

REO Book Value reported corresponds to total REO loans, including loans that become REO during current distribution.

Loan Number

Original

Stated

Current

State &

Principal

Paid to

Note

LTV at

Original

Origination

Loan Group

Balance

Date

Rate

Origination

Term

Date

SPACE INTENTIONALLY LEFT BLANK

Page 14 of 24

IndyMac INDX Mortgage Loan Trust 2005-AR12

Mortgage Pass-Through Certificates

Prepayment Report for August 25, 2005 Distribution

Prepayment Report for October 25, 2005 Distribution

Prepayment Report - Voluntary Prepayments

VOLUNTARY PREPAYMENTS

GROUP 2

GROUP 1

TOTAL

Current

Number of Paid in Full Loans

914

1730

2644

Number of Repurchased Loans

Total Number of Loans Prepaid in Full

914

1730

2644

Paid in Full Balance

48,~~827~~511,~~490~~838.8882

37,~~890~~447,~~194~~297.0567

815,~~717~~959,~~684~~136.9349

Repurchased Loans Balance

Curtailments Amount

(~~356~~636,~~113~~743.1312)

(~~523~~583,~~877~~774.7989)

(~~879~~1,~~990~~220,518.9201)

Total Prepayment Amount

47,~~471~~875,~~377~~095.7570

36,~~366~~863,~~316~~522.2678

714,~~837~~738,~~694~~618.0148

Cumulative

Number of Paid in Full Loans

2354

3894

61148

Number of Repurchased Loans

Total Number of Loans Prepaid in Full

2455

4096

64151

Paid in Full Balance

1330,~~067~~990,~~698~~434.0457

922,~~010~~460,~~531~~686.1942

2253,~~078~~451,~~229~~120.2399

Repurchased Loans Balance

438,951.46

530,750.00

969,701.46

Curtailments Amount

(12,~~000~~121,~~414~~210.2049)

(~~909~~2,~~066~~125,225.1719)

(14,~~909~~246,~~480~~435.3768)

Total Prepayment Amount

1229,~~506~~308,~~235~~175.3054

820,~~632~~866,~~215~~211.0223

2150,~~138~~174,~~450~~386.3277

Total Prepayments by Groups (in thousands of dollars)

Total Prepayments (in thousands of dollars)

Page 15 of 24

IndyMac INDX Mortgage Loan Trust 2005-AR12

Mortgage Pass-Through Certificates

Prepayment Report for August 25, 2005 Distribution

Prepayment Report for October 25, 2005 Distribution

Prepayment Report - Voluntary Prepayments

VOLUNTARY PREPAYMENT RATES

GROUP 2

GROUP 1

TOTAL

SMM

01.7229%

01.5412%

01.6320%

3 Months Avg SMM

1.15%

0.84%

1.00%

12 Months Avg SMM

Avg SMM Since Cut-off

01.9918%

0.6984%

01.8401%

CPR

814.2539%

612.3163%

713.2952%

3 Months Avg CPR

12.93%

9.66%

11.31%

12 Months Avg CPR

Avg CPR Since Cut-off

1113.2825%

79.9865%

911.6547%

PSA

~~1408~~1461.0963%

~~1132~~1320.3795%

~~1274~~1392.9768%

3 Months Avg PSA Approximation

1646.05%

1276.81%

1466.91%

12 Months Avg PSA Approximation

Avg PSA Since Cut-off Approximation

~~2320~~1932.2348%

~~1746~~1469.7972%

~~2046~~1709.6419%

Group 1

Group 2

CPR by Groups

Total CPR

PSA by Groups

Total PSA

Page 16 of 24

IndyMac INDX Mortgage Loan Trust 2005-AR12

Mortgage Pass-Through Certificates

Prepayment Report for August 25, 2005 Distribution

Prepayment Report for October 25, 2005 Distribution

Prepayment Report - Voluntary Prepayments

Group 1

Group 2

CPR Avg since Cut-Off by Groups

Total CPR Avg since Cut-Off

PSA Avg since Cut-Off by Groups

Total PSA Avg since Cut-Off

PREPAYMENT CALCULATION METHODOLOGY

Single Monthly Mortality (SMM): (Voluntary partial and full prepayments + Repurchases)/(Beg Principal Balance - Sched Principal)

Conditional Prepayment Rate (CPR): 1-((1-SMM)^12)

PSA Standard Prepayment Model: CPR/(0.02*min(30,WAS))

Average SMM over period between nth month and mth month (AvgSMMn,m): [(1-SMMn) * (1-SMMn+1) *…….*(1-SMMm)]^(1/months in period n,m)

Average CPR over period between the nth month and mth month (AvgCPRn,m): 1-((1-AvgSMMn,m)^12)

Average PSA Approximation over period between the nth month and mth month: AvgCPRn,m/(0.002*Avg WASn,m))

Average WASn,m: (min(30,WASn)+min(30,WASn+1)+…….+min(30,WASm)/(number of months in the period n,m)

Weighted Average Seasoning (WAS)

Note: Prepayment rates are calculated since deal issue date and include partial and full voluntary prepayments and repurchases.

Dates correspond to distribution dates.

PLEASE NOTE: Negative Amortization Amounts are included in Voluntary Partial Prepayments

Page 17 of 24

IndyMac INDX Mortgage Loan Trust 2005-AR12

Mortgage Pass-Through Certificates

Prepayment Detail Report for August 25, 2005 Distribution

Prepayment Detail Report for October 25, 2005 Distribution

Prepayment Detail Report - Loans Prepaid in Full During Current Distribution

SUMMARY

LOAN GROUP

Total Loan Count = 26

Loan Group 1 = Group 1

Total Loan Count = 44

Loan Group 1 = Group 1

Total Original Principal Balance = 8,730,897.00

Loan Group 2 = Group 2

Total Original Principal Balance = 16,021,065.00

Loan Group 2 = Group 2

Total Prepayment Amount = 8,717,684.93

Total Prepayment Amount = 15,959,136.49

Loan Number

Original

Current

State &

Type Prepayment

Loan

Principal

Prepayment

Note

LTV at

Origination

Loan Group

Status

Balance

Amount

Date

Rate

Origination

Original Term

Date

120791247 1

97,500.00

96,532.72

Jul-28-05

6.383%

VA - 79.92%

Paid Off - 360

Feb-11-05

120388741 1

275,000.00

275,243.16

Sep-22-05

5.615%

CA - 41.67%

Paid Off - 360

Dec-13-04

120811499 1

179,500.00

179,135.70

Aug-01-05

5.483%

FL - 95.00%

Paid Off - 360

May-10-05

120941632 1

222,300.00

222,776.03

Oct-06-05

5.915%

NJ - 46.80%

Paid Off - 360

Apr-20-05

121057842 1

204,000.00

203,765.73

Aug-12-05

5.483%

CA - 80.00%

Paid Off - 360

Apr-08-05

120977910 1

281,500.00

281,251.48

Sep-16-05

4.865%

CO - 74.08%

Paid Off - 360

Sep-13-04

121072722 1

150,710.00

150,461.73

Aug-09-05

5.033%

NV - 70.00%

Paid Off - 360

Mar-31-05

121022713 1

105,000.00

105,110.63

Sep-22-05

5.915%

FL - 60.00%

Paid Off - 360

Apr-08-05

121163350 1

310,000.00

310,297.74

Jul-25-05

6.083%

FL - 74.70%

Paid Off - 360

Mar-25-05

121103171 1

339,200.00

340,446.19

Oct-13-05

6.615%

CA - 80.00%

Paid Off - 360

Apr-12-05

121191996 1

161,600.00

161,400.75

Aug-01-05

5.383%

GA - 80.00%

Paid Off - 360

Apr-21-05

121105536 1

288,000.00

287,964.91

Sep-29-05

5.965%

CA - 73.85%

Paid Off - 360

Apr-20-05

121199590 1

216,000.00

215,769.90

Jul-29-05

5.583%

IL - 80.00%

Paid Off - 360

Apr-25-05

121116367 1

184,488.00

185,114.62

Oct-03-05

6.415%

FL - 80.00%

Paid Off - 360

Apr-25-05

121204144 1

295,556.00

294,851.68

Jul-25-05

5.583%

CA - 80.00%

Paid Off - 360

Apr-29-05

121126790 1

285,000.00

285,535.66

Oct-12-05

5.315%

WA - 71.25%

Paid Off - 360

Jun-07-04

121241882 1

338,000.00

337,194.53

Aug-01-05

5.033%

MD - 65.00%

Paid Off - 360

May-06-05

121132430 1

143,500.00

143,987.42

Sep-19-05

6.415%

FL - 60.04%

Paid Off - 360

Apr-18-05

121258244 1

223,531.00

223,292.90

Jul-25-05

5.733%

FL - 70.00%

Paid Off - 360

Apr-29-05

121136605 1

200,000.00

200,290.13

Sep-28-05

5.715%

AZ - 80.00%

Paid Off - 360

Apr-13-05

121276718 1

305,000.00

304,662.41

Aug-03-05

5.533%

CA - 65.59%

Paid Off - 360

Apr-22-05

121140063 1

289,500.00

289,758.73

Oct-03-05

6.015%

CA - 75.00%

Paid Off - 360

May-04-05

121278881 1

93,750.00

93,463.96

Aug-09-05

6.283%

FL - 75.00%

Paid Off - 360

Apr-15-05

121144405 1

352,500.00

353,343.28

Sep-29-05

6.015%

CA - 75.00%

Paid Off - 360

Apr-22-05

121286469 1

198,000.00

197,528.15

Aug-01-05

5.683%

FL - 60.00%

Paid Off - 360

May-04-05

121151056 1

237,000.00

237,329.08

Sep-23-05

5.615%

FL - 74.06%

Paid Off - 360

Apr-15-05

121287123 1

180,000.00

179,449.89

Jul-22-05

5.333%

FL - 55.38%

Paid Off - 360

Apr-22-05

121172592 1

127,000.00

126,653.75

Sep-28-05

5.565%

CA - 48.85%

Paid Off - 360

Apr-01-05

121305942 1

263,200.00

262,572.77

Aug-15-05

5.583%

IL - 80.00%

Paid Off - 360

May-09-05

121173957 1

288,800.00

288,947.58

Oct-11-05

5.265%

CO - 80.00%

Paid Off - 360

Apr-28-05

121311108 1

360,000.00

359,142.10

Jul-20-05

5.433%

NY - 51.43%

Paid Off - 360

May-04-05

121181089 1

316,000.00

316,514.96

Oct-04-05

5.715%

CA - 80.00%

Paid Off - 360

Apr-18-05

121313842 1

321,000.00

320,671.39

Jul-21-05

5.633%

MA - 72.95%

Paid Off - 360

Apr-25-05

121196890 1

315,000.00

315,293.02

Sep-19-05

5.765%

CO - 75.00%

Paid Off - 360

Apr-21-05

121005018 2

1,000,000.00

998,851.56

Jul-22-05

5.483%

PA - 54.05%

Paid Off - 360

Apr-04-05

121200266 1

300,000.00

300,491.84

Sep-28-05

5.715%

VA - 66.67%

Paid Off - 360

Apr-12-05

121080817 2

600,000.00

599,568.33

Aug-01-05

6.183%

CA - 74.53%

Paid Off - 360

Mar-23-05

121222374 1

307,000.00

308,415.85

Sep-21-05

6.915%

CA - 76.75%

Paid Off - 360

Apr-11-05

121148677 2

560,000.00

558,665.49

Jul-20-05

5.633%

FL - 80.00%

Paid Off - 360

Apr-21-05

121230765 1

121,600.00

121,624.97

Oct-04-05

5.965%

FL - 80.00%

Paid Off - 360

May-12-05

121172247 2

386,250.00

385,838.53

Aug-05-05

5.583%

NJ - 75.00%

Paid Off - 360

Apr-22-05

121236631 1

258,700.00

259,060.70

Sep-27-05

6.315%

CA - 74.99%

Paid Off - 360

May-01-05

121236289 2

412,500.00

412,232.04

Aug-11-05

6.083%

CA - 75.00%

Paid Off - 360

Apr-28-05

121239485 1

285,000.00

285,824.91

Sep-22-05

6.215%

CA - 75.00%

Paid Off - 360

Apr-25-05

121246090 2

574,000.00

573,483.96

Aug-04-05

5.783%

CA - 71.75%

Paid Off - 360

Apr-21-05

121245724 1

240,000.00

239,546.72

Sep-27-05

6.615%

NJ - 64.86%

Paid Off - 360

May-09-05

121272683 2

410,000.00

409,443.94

Aug-09-05

5.233%

CA - 64.06%

Paid Off - 360

Apr-25-05

121249232 1

241,500.00

241,756.13

Sep-21-05

6.115%

CA - 68.03%

Paid Off - 360

May-05-05

121276767 2

520,000.00

519,359.58

Jul-26-05

5.383%

CA - 80.00%

Paid Off - 360

Apr-22-05

121253481 1

315,000.00

315,990.85

Sep-20-05

6.315%

CA - 72.41%

Paid Off - 360

Apr-15-05

121387848 2

370,800.00

370,047.45

Aug-09-05

5.883%

VA - 74.16%

Paid Off - 360

May-18-05

121268912 1

245,000.00

244,432.01

Sep-27-05

6.615%

VA - 73.13%

Paid Off - 360

May-09-05

121304903 1

244,750.00

244,677.81

Oct-13-05

5.665%

MD - 84.98%

Paid Off - 360

May-04-05

121307905 1

164,000.00

164,050.84

Sep-28-05

5.665%

WA - 58.57%

Paid Off - 360

May-04-05

121327284 1

270,000.00

269,809.56

Sep-27-05

6.015%

PA - 75.00%

Paid Off - 360

May-04-05

121342045 1

200,000.00

196,054.85

Sep-19-05

5.915%

CA - 28.57%

Paid Off - 360

May-01-05

120443984 2

450,755.00

450,759.33

Sep-26-05

5.065%

CA - 75.00%

Paid Off - 360

Apr-06-05

120765252 2

393,750.00

395,754.76

Sep-23-05

5.815%

CA - 75.00%

Paid Off - 360

Jan-12-05

121070661 2

1,357,000.00

1,359,735.46

Oct-03-05

5.865%

CA - 67.85%

Paid Off - 360

Apr-12-05

121183147 2

500,000.00

502,515.06

Sep-20-05

7.065%

CA - 80.00%

Paid Off - 360

Apr-15-05

121194536 2

796,000.00

795,916.43

Sep-21-05

6.665%

NJ - 80.00%

Paid Off - 360

Apr-14-05

121207848 2

371,250.00

372,138.12

Oct-13-05

6.015%

CA - 75.00%

Paid Off - 360

Apr-01-05

121210079 2

412,500.00

337,706.76

Sep-21-05

5.565%

IL - 66.00%

Paid Off - 360

Apr-26-05

121210603 2

1,383,000.00

1,384,226.76

Oct-03-05

5.415%

CA - 69.15%

Paid Off - 360

Apr-26-05

121213048 2

514,500.00

515,085.38

Sep-23-05

5.515%

CA - 70.00%

Paid Off - 360

Apr-22-05

121222749 2

400,000.00

400,650.72

Oct-06-05

5.715%

CA - 69.57%

Paid Off - 360

Apr-21-05

121249279 2

461,972.00

460,665.27

Oct-10-05

6.015%

CA - 76.23%

Paid Off - 360

Apr-22-05

121262288 2

450,000.00

450,737.75

Sep-29-05

5.715%

CA - 55.56%

Paid Off - 360

Apr-19-05

121263653 2

632,000.00

631,296.64

Sep-29-05

5.765%

CA - 80.00%

Paid Off - 360

Apr-19-05

121287947 2

456,000.00

454,650.38

Sep-27-05

5.915%

FL - 80.00%

Paid Off - 360

Apr-29-05

Page 18 of 24

IndyMac INDX Mortgage Loan Trust 2005-AR12

Mortgage Pass-Through Certificates

Realized Loss Report for August 25, 2005 Distribution

Realized Loss Report for October 25, 2005 Distribution

Realized Loss Report - Collateral

COLLATERAL REALIZED LOSSES

GROUP 2

GROUP 1

TOTAL

Current

Number of Loans Liquidated

Collateral Realized Loss/(Gain) Amount

Net Liquidation Proceeds

Cumulative

Number of Loans Liquidated

Collateral Realized Loss/(Gain) Amount

Net Liquidation Proceeds

Note: Collateral Realized Loss Amount may include adjustments to loans liquidated in prior periods.

Current Realized Losses

0.00

Supplemental Losses (Recoveries)

0.00

Current Net Realized Losses (Recoveries)

0.00

Prior Cumulative Realized Loss

0.00

Current Net Realized Loss (Recoveries)

0.00

Current Cumulative Realized Loss

0.00

Class B-1 Write Down Amount

0.00

Class B-2 Write Down Amount

0.00

Class B-3 Write Down Amount

0.00

Class B-4 Write Down Amount

0.00

Class B-5 Write Down Amount

0.00

Class B-6 Write Down Amount

0.00

Class B-7 Write Down Amount

0.00

Class B-8 Write Down Amount

0.00

Class B-9 Write Down Amount

0.00

Class B-10 Write Down Amount

0.00

Group 1

3 Months Moving Average

Group 2

Collateral Loss Severity Approximation by Groups

Collateral Loss Severity Approximation

Page 19 of 24

IndyMac INDX Mortgage Loan Trust 2005-AR12

Mortgage Pass-Through Certificates

Realized Loss Report for August 25, 2005 Distribution

Realized Loss Report for October 25, 2005 Distribution

Realized Loss Report - Collateral

DEFAULT SPEEDS

GROUP 2

GROUP 1

TOTAL

MDR

0.00%

3 Months Avg MDR

0.00%

12 Months Avg MDR

Avg MDR Since Cut-off

0.00%

CDR

0.00%

3 Months Avg CDR

0.00%

12 Months Avg CDR

Avg CDR Since Cut-off

0.00%

SDA

0.00%

3 Months Avg SDA Approximation

0.00%

12 Months Avg SDA Approximation

Avg SDA Since Cut-off Approximation

0.00%

Loss Severity Approximation for Current Period

3 Months Avg Loss Severity Approximation

12 Months Avg Loss Severity Approximation

Avg Loss Severity Approximation Since Cut-off

Group 1

Group 2

CDR by Groups

Total CDR

SDA by Groups

Total SDA

Page 20 of 24

IndyMac INDX Mortgage Loan Trust 2005-AR12

Mortgage Pass-Through Certificates

Realized Loss Report for August 25, 2005 Distribution

Realized Loss Report for October 25, 2005 Distribution

Realized Loss Report - Collateral

Group 1

Group 2

CDR Avg since Cut-Off by Groups

Total CDR Avg since Cut-Off

SDA Avg since Cut-Off by Groups

Total SDA Avg since Cut-Off

COLLATERAL REALIZED LOSS CALCULATION METHODOLOGY

Monthly Default Rate (MDR): (Beg Principal Balance of Liquidated Loans)/(Total Beg Principal Balance)

Conditional Default Rate (CDR): 1-((1-MDR)^12)

SDA Standard Default Assumption: CDR/IF(WAS<61,MIN(30,WAS)*0.02,MAX(0.03,MIN(30,WAS)*0.02-0.0095*(WAS-60)))

Average MDR over period between nth month and mth month (AvgMDRn,m): [(1-MDRn) * (1-MDRn+1) *…….*(1-MDRm)]^(1/months in period n,m)

Average CDR over period between the nth month and mth month (AvgCDRn,m): 1-((1-AvgMDRn,m)^12)

Average SDA Approximation over period between the nth month and mth month:

AvgCDRn,m/IF(Avg WASn,m<61,MIN(30,Avg WASn,m)*0.02,MAX(0.03,MIN(30,Avg WASn,m)*0.02-0.0095*(Avg WASn,m-60)))

Average WASn,m: (WASn + WASn+1 +…….+ WASm )/(number of months in the period n,m)

Loss Severity Approximation for current period: sum(Realized Loss Amount)/sum(Beg Principal Balance of Liquidated Loans)

Average Loss Severity Approximation over period between nth month and mth month: Avg(Loss Severityn,m)

Note: Default rates are calculated since deal issue date and include realized gains and additional realized losses and gains from prior periods.

Dates correspond to distribution dates.

Page 21 of 24

IndyMac INDX Mortgage Loan Trust 2005-AR12

Mortgage Pass-Through Certificates

Realized Loss Detail Report for August 25, 2005 Distribution

Realized Loss Detail Report for October 25, 2005 Distribution

Realized Loss Detail Report - Loans Liquidated During Current Distribution

SUMMARY

LOAN GROUP

Total Loan Count Current Losses = 0

Total Loan Count Revisions = 0

Loan Group 1 = Group 1

Total Prior Principal Balance = 0.00

Loan Group 2 = Group 2

Total Current Realized Loss Amount = 0.00

Total Revisions Amount = 0.00

Total Realized Loss Amount = 0.00

Total Net Liquidation Proceeds = 0.00

Note: Total Realized Loss Amount may include adjustments to loans liquidated in prior periods.

Loan Number

Current

State &

Prior

Realized

Cumulative

Loan

Note

LTV at

Original

Principal

Loss/(Gain)

Realized

Loan Group

Status

Rate

Origination

Term

Balance

Revisions

Loss/(Gain)

SPACE INTENTIONALLY LEFT BLANK

Page 22 of 24

IndyMac INDX Mortgage Loan Trust 2005-AR12

Mortgage Pass-Through Certificates

Triggers, Adj. Rate Cert. and Miscellaneous Report for August 25, 2005 Distribution

Triggers, Adj. Rate Cert. and Miscellaneous Report for October 25, 2005 Distribution

Triggers, Adj. Rate Cert. and Miscellaneous Report

TRIGGER EVENTS

GROUP 2

GROUP 1

TOTAL

Has the Optional Termination Date been reached?

Have the Sr. Prepay Step Down Cond been satisfied?

Has the Sr. Credit Supp. Depletion Date been reached?

ADJUSTABLE RATE CERTIFICATE INFORMATION

GROUP 2

GROUP 1

TOTAL

SPACE INTENTIONALLY LEFT BLANK

Componant Class Balances

Class A- PO-1 Beginning Balance

50.00

Class A- PO-1 Component Principal Amount

0.00

Class A- PO-1 Ending Balance

50.00

Class A- PO-2 Beginning Balance

50.00

Class A- PO-2 Component Principal Amount

0.00

Class A- PO-2 Ending Balance

50.00

CLASS A-X-1 IO-1 Beginning Notional Balance

513,654,438.10

Class A-X-1 IO-1 Ending Notional Amount

494,533,630.00

CLASS A-X-1 IO-2 Beginning Notional Balance

518,634,614.47

Class A-X-1 IO-2 Ending Notional Amount

499,276,840.10

ADDITIONAL INFORMATION

GROUP 2

GROUP 1

TOTAL

Current Senior Percentage

91.~~687101~~568659%

Next Senior Percentage

91.~~615659~~414532%

Current Subordinate Percentage

8.~~312899~~431341%

Next Subordinate Percentage

8.~~384341~~585468%

Current Senior Prepayment Percentage

100.000000%

Current Subordinated Prepayment Percentage

0.000000%

Page 23 of 24

IndyMac INDX Mortgage Loan Trust 2005-AR12

Mortgage Pass-Through Certificates

Other Related Information for August 25, 2005 Distribution

Other Related Information for October 25, 2005 Distribution

Other Related Information

ADDITIONAL INFORMATION

GROUP 2

GROUP 1

TOTAL

Scheduled principal

1 Month Prior

~~2,088~~0.2800

2 Months Prior

~~821,656~~0.9200

3 Months Prior

02,088.0028

4 Months Prior

0821,656.0092

5 Months Prior

0.00

6 Months Prior

0.00

7 Months Prior

0.00

8 Months Prior

0.00

9 Months Prior

0.00

10 Months Prior

0.00

11 Months Prior

0.00

12 Months Prior

0.00

Scheduled Principal on 60+ Day Delinquent Loans

1 Month Prior

0.00

2 Months Prior

0.00

3 Months Prior

0.00

4 Months Prior

0.00

5 Months Prior

0.00

6 Months Prior

0.00

7 Months Prior

0.00

8 Months Prior

0.00

9 Months Prior

0.00

10 Months Prior

0.00

11 Months Prior

0.00

12 Months Prior

0.00

Page 24 of 24

Filing Compare · IndyMac Indx Mortgage Loan Trust 2005-AR12