
                                       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):  October 25, 2005
                          (Date of earliest event reported)

            Indymac MBS, Inc. (as Depositor under the Pooling and Servicing
                Agreement, dated as August 1, 2005, providing for the
               issuance of IndyMac INDX Mortgage Loan Trust 2005-AR21
                Mortgage Pass-Through Certificates, Series 2005-AR21)
                 (Exact name of registrant as specified in charter)


                                         DELAWARE
                     (State or Other Jurisdiction of Incorporation)

               333-127556-02                         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
     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:  Oct 28, 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 October 25, 2005.



IndyMac INDX Mortgage Loan Trust 2005-AR21

Mortgage Pass-Through Certificates
Mortgage Pass-Through Certificates
2005-AR21

October 25, 2005 Distribution

				External Parties						Table of Contents

													Page
				Seller									Page
				Seller						1. Certificate Payment Report					2
				IndyMac Bank						1. Certificate Payment Report					2
				IndyMac Bank						2. Collection Account Report					4
										2. Collection Account Report					4
										3. Credit Enhancement Report					6
										4. Collateral Report					7
				Certificate Insurer(s)						5. Delinquency Report					10
				Certificate Insurer(s)						5. Delinquency Report					10
										6. REO Report					15

										7. Foreclosure Report					16
										8. Prepayment Report					17
										9. Prepayment Detail Report					20
										9. Prepayment Detail Report					20
										10. Realized Loss Report					22
										11. Realized Loss Detail Report					25
				Servicer(s)						11. Realized Loss Detail Report					25
				Servicer(s)						12. Triggers and Adj. Cert. Report					26
				IndyMac Bank						12. Triggers and Adj. Cert. Report					26
				IndyMac Bank						13. Other Related Information					27
										13. Other Related Information					27


				Underwriter(s)
				Merrill Lynch


										Total Number of Pages					27
										Total Number of Pages

				Dates						Contacts

				Cut-Off Date:			August 01, 2005			Brent Hoyler
				Close Date:			August 30, 2005			Administrator
				First Distribution Date:			September 26, 2005			(714) 247-6322
										Brent.Hoyler@db.com
										Brent.Hoyler@db.com
										Address:
										1761 East St. Andrew Place, Santa Ana, CA 92705
				Distribution Date:			October 25, 2005
										Factor Information:			(800) 735-7777
				Record Date:			September 30, 2005			Factor Information:			(800) 735-7777
										Main Phone Number:			(714) 247-6000
										Main Phone Number:			(714) 247-6000

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






Page 1 of 27
IndyMac INDX Mortgage Loan Trust 2005-AR21

Mortgage Pass-Through Certificates
Mortgage Pass-Through Certificates
2005-AR21

October 25, 2005 Distribution
Certificate Payment Report
Current Period Distribution - REMIC II
					Prior												Current
	Class		Original		Principal						Total		Realized		Deferred		Principal
	Class		Original		Principal						Total		Realized		Deferred		Principal
Class	Type	Cur	Face Value		Balance		Interest		Principal		Distribution		Loss		Interest		Balance


					(1)		(2)		(3)		(4)=(2)+(3)		(5)		(6)		(7)=(1)-(3)-(5)+(6)

1-A-1	CSTR	$	94,734,000.00		93,241,354.35		409,032.76		1,312,857.63		1,721,890.39		0.00		0.00		91,928,496.72
1-A-1	CSTR	$	94,734,000.00		93,241,354.35		409,032.76		1,312,857.63		1,721,890.39		0.00		0.00		91,928,496.72
2-A-1	CSTR	$	309,392,000.00		305,506,429.68		1,406,210.25		4,654,073.38		6,060,283.63		0.00		0.00		300,852,356.30
3-A-1	CSTR	$	165,635,000.00		162,685,221.06		732,187.11		3,485,619.03		4,217,806.14		0.00		0.00		159,199,602.03
3-A-2	CSTR	$	12,742,000.00		12,515,078.86		56,325.83		268,142.35		324,468.18		0.00		0.00		12,246,936.51
3-A-3	CSTR	$	12,742,000.00		12,515,078.85		56,325.83		268,142.35		324,468.18		0.00		0.00		12,246,936.50
4-A-1	CSTR	$	134,269,000.00		134,049,688.23		611,597.36		2,570,489.33		3,182,086.69		0.00		0.00		131,479,198.90
4-A-2	CSTR	$	10,329,000.00		10,312,128.86		47,048.75		197,741.73		244,790.48		0.00		0.00		10,114,387.13
4-A-3	CSTR	$	10,329,000.00		10,312,128.85		47,048.75		197,741.73		244,790.48		0.00		0.00		10,114,387.12
A-R	R	$	100.00		0.00		0.00		0.00		0.00		0.00		0.00		0.00
B-1	SUB	$	19,605,000.00		19,588,547.02		88,956.33		2,377.41		91,333.74		0.00		0.00		19,586,169.61
B-2	SUB	$	11,202,000.00		11,192,599.02		50,828.30		1,358.41		52,186.71		0.00		0.00		11,191,240.61
B-3	SUB	$	6,401,000.00		6,395,628.13		29,044.09		776.22		29,820.31		0.00		0.00		6,394,851.91
B-4	SUB	$	5,601,000.00		5,596,299.51		25,414.15		679.21		26,093.36		0.00		0.00		5,595,620.30
B-5	SUB	$	4,000,000.00		3,996,643.11		18,149.72		485.06		18,634.78		0.00		0.00		3,996,158.05
B-6	SUB	$	3,203,489.08		3,200,800.56		14,535.61		388.47		14,924.08		0.00		0.00		3,200,412.09
P	SUB	$	100.00		100.00		13,873.70		0.00		13,873.70		0.00		0.00		100.00


Total			800,184,689.08		791,107,726.09		3,606,578.54		12,960,872.31		16,567,450.85		0.00		0.00		778,146,853.78
Total




Interest Accrual Detail Current Period Factor Information per $1,000 of Original Face-
									Orig. Principal		Prior							Current
									Orig. Principal		Prior							Current
	Period		Period						(with Notional)		Principal						Total	Principal
	Period		Period
Class	Starting		Ending		Method		Cusip		Balance		Balance		Interest		Principal		Distribution	Balance

									(1)		(1)		(2)		(3)		(4)=(2)+(3)	(5)
1-A-1	09/01/05		09/30/05		A-30/360		45660LYA1		94,734,000.00		984.243823		4.317698		13.858357		18.176055	970.385466
2-A-1	09/01/05		09/30/05		A-30/360		45660LYB9		309,392,000.00		987.441271		4.545076		15.042643		19.587719	972.398628
3-A-1	09/01/05		09/30/05		A-30/360		45660LYC7		165,635,000.00		982.191089		4.420485		21.043976		25.464462	961.147113
3-A-2	09/01/05		09/30/05		A-30/360		45660LYD5		12,742,000.00		982.191089		4.420486		21.043977		25.464462	961.147113
3-A-3	09/01/05		09/30/05		A-30/360		45660LYE3		12,742,000.00		982.191089		4.420486		21.043977		25.464462	961.147112
4-A-1	09/01/05		09/30/05		A-30/360		45660LYF0		134,269,000.00		998.366624		4.555015		19.144325		23.699340	979.222299
4-A-2	09/01/05		09/30/05		A-30/360		45660LYG8		10,329,000.00		998.366624		4.555015		19.144325		23.699340	979.222299
4-A-3	09/01/05		09/30/05		A-30/360		45660LYH6		10,329,000.00		998.366623		4.555015		19.144325		23.699340	979.222298
A-R	09/01/05		09/30/05		A-30/360		45660LYJ2		100.00		0.000000		0.000000		0.000000		0.000000	0.000000
B-1	09/01/05		09/30/05		A-30/360		45660LYK9		19,605,000.00		999.160776		4.537431		0.121265		4.658696	999.039511
B-2	09/01/05		09/30/05		A-30/360		45660LYL7		11,202,000.00		999.160777		4.537431		0.121265		4.658696	999.039512
B-3	09/01/05		09/30/05		A-30/360		45660LYM5		6,401,000.00		999.160776		4.537430		0.121265		4.658696	999.039511
B-4	09/01/05		09/30/05		A-30/360		45660LYP8		5,601,000.00		999.160777		4.537431		0.121266		4.658697	999.039511
B-5	09/01/05		09/30/05		A-30/360		45660LYQ6		4,000,000.00		999.160778		4.537430		0.121265		4.658695	999.039513
B-6	09/01/05		09/30/05		A-30/360		45660LYR4		3,203,489.08		999.160753		4.537431		0.121265		4.658695	999.039488
P	09/01/05		09/30/05		A-30/360		45660LYN3		100.00		1,000.000000		138,737.000000		0.000000		138,737.000000	1,000.000000




Page 2 of 27
IndyMac INDX Mortgage Loan Trust 2005-AR21

Mortgage Pass-Through Certificates
Mortgage Pass-Through Certificates
2005-AR21

October 25, 2005 Distribution

Distribution to Date - REMIC II
																	Current


	Original				Unscheduled		Scheduled		Total		Total		Realized		Deferred		Principal

Class	Face Value		Interest		Principal		Principal		Principal		Distribution		Loss		Interest		Balance
	(1)		(2)		(3)		(4)		(5)=(3)+(4)		(6)=(2)+(5)		(7)		(8)		(9)=(1)-(5)-(7)+(8)
1-A-1	94,734,000.00		825,136.07		2,779,009.89		26,493.39		2,805,503.28		3,630,639.35		0.00		0.00		91,928,496.72
2-A-1	309,392,000.00		2,830,960.41		8,461,508.01		78,135.69		8,539,643.70		11,370,604.11		0.00		0.00		300,852,356.30
3-A-1	165,635,000.00		1,477,834.47		6,376,433.12		58,964.85		6,435,397.97		7,913,232.44		0.00		0.00		159,199,602.03
3-A-2	12,742,000.00		113,687.13		490,527.43		4,536.06		495,063.49		608,750.62		0.00		0.00		12,246,936.51
3-A-3	12,742,000.00		113,687.13		490,527.44		4,536.06		495,063.50		608,750.63		0.00		0.00		12,246,936.50
4-A-1	134,269,000.00		1,224,098.97		2,768,277.05		21,524.05		2,789,801.10		4,013,900.07		0.00		0.00		131,479,198.90
4-A-2	10,329,000.00		94,167.07		212,957.08		1,655.79		214,612.87		308,779.94		0.00		0.00		10,114,387.13
4-A-3	10,329,000.00		94,167.07		212,957.08		1,655.79		214,612.88		308,779.95		0.00		0.00		10,114,387.12
A-R	100.00		333.67		98.88		1.12		100.00		433.67		0.00		0.00		0.00
B-1	19,605,000.00		178,020.21		18,628.05		202.34		18,830.39		196,850.60		0.00		0.00		19,586,169.61
B-2	11,202,000.00		101,718.05		10,643.77		115.62		10,759.39		112,477.44		0.00		0.00		11,191,240.61
B-3	6,401,000.00		58,123.30		6,082.02		66.07		6,148.09		64,271.39		0.00		0.00		6,394,851.91
B-4	5,601,000.00		50,859.03		5,321.89		57.81		5,379.70		56,238.73		0.00		0.00		5,595,620.30
B-5	4,000,000.00		36,321.39		3,800.67		41.28		3,841.95		40,163.34		0.00		0.00		3,996,158.05
B-6	3,203,489.08		29,088.79		3,043.85		33.06		3,076.91		32,165.70		0.00		0.00		3,200,412.09
P	100.00		27,502.07		0.00		0.00		0.00		27,502.07		0.00		0.00		100.00


Total	800,184,689.08		7,255,704.83		21,839,816.23		198,018.98		22,037,835.22		29,293,540.05		0.00		0.00		778,146,853.78


Interest Detail - REMIC II
	Pass		Prior Principal				Non-		Prior		Unscheduled				Paid or		Current
	Pass		Prior Principal				Non-		Prior		Unscheduled				Paid or

	Through		(with Notional)		Accrued		Supported		Unpaid		Interest		Optimal		Deferred		Unpaid

Class	Rate		Balance		Interest		Interest SF		Interest		Adjustment		Interest		Interest		Interest
					(1)		(2)		(3)		(4)		(5)=(1)-(2)+(3)+(4)		(6)		(7)=(5)-(6)
1-A-1	5.26418%		93,241,354.35		409,032.76		0.00		0.00		0.00		409,032.76		409,032.76		0.00
2-A-1	5.52346%		305,506,429.68		1,406,210.25		0.00		0.00		0.00		1,406,210.25		1,406,210.25		0.00
3-A-1	5.40076%		162,685,221.06		732,187.11		0.00		0.00		0.00		732,187.11		732,187.11		0.00
3-A-2	5.40076%		12,515,078.86		56,325.83		0.00		0.00		0.00		56,325.83		56,325.83		0.00
3-A-3	5.40076%		12,515,078.85		56,325.83		0.00		0.00		0.00		56,325.83		56,325.83		0.00
4-A-1	5.47496%		134,049,688.23		611,597.36		0.00		0.00		0.00		611,597.36		611,597.36		0.00
4-A-2	5.47496%		10,312,128.86		47,048.75		0.00		0.00		0.00		47,048.75		47,048.75		0.00
4-A-3	5.47496%		10,312,128.85		47,048.75		0.00		0.00		0.00		47,048.75		47,048.75		0.00
A-R	0.00000%		0.00		0.00		0.00		0.00		0.00		0.00		0.00		0.00
B-1	5.44949%		19,588,547.02		88,956.33		0.00		0.00		0.00		88,956.33		88,956.33		0.00
B-2	5.44949%		11,192,599.02		50,828.30		0.00		0.00		0.00		50,828.30		50,828.30		0.00
B-3	5.44949%		6,395,628.13		29,044.09		0.00		0.00		0.00		29,044.09		29,044.09		0.00
B-4	5.44949%		5,596,299.51		25,414.15		0.00		0.00		0.00		25,414.15		25,414.15		0.00
B-5	5.44949%		3,996,643.11		18,149.72		0.00		0.00		0.00		18,149.72		18,149.72		0.00
B-6	5.44949%		3,200,800.56		14,535.61		0.00		0.00		0.00		14,535.61		14,535.61		0.00
P	0.00000%		100.00		0.00		0.00		0.00		0.00		0.00		13,873.70		0.00


Total			791,107,726.09		3,592,704.84		0.00		0.00		0.00		3,592,704.84		3,606,578.54		0.00



Page 3 of 27
IndyMac INDX Mortgage Loan Trust 2005-AR21

Mortgage Pass-Through Certificates
Mortgage Pass-Through Certificates
2005-AR21

October 25, 2005 Distribution
Collection Account Report
SUMMARY
SUMMARY
						Group 4		Group 3		Group 2		Group 1		Total
Principal Collections						2,967,774.73		4,023,239.49		4,655,924.92		1,313,933.17		12,960,872.31
Principal Withrawals						0.00		0.00		0.00		0.00		0.00
Principal Other Accounts						0.00		0.00		0.00		0.00		0.00
TOTAL NET PRINCIPAL						2,967,774.73		4,023,239.49		4,655,924.92		1,313,933.17		12,960,872.31
Interest Collections						768,746.74		919,825.51		1,535,117.28		444,169.55		3,667,859.07
Interest Withdrawals						-0.00		-0.00		-0.00		-0.00		-0.00
Interest Other Accounts						0.00		0.00		0.00		0.00		13,873.70
Interest Fees						-15,937.00		-17,649.30		-34,049.22		-7,518.71		-75,154.23
TOTAL NET INTEREST						752,809.75		902,176.21		1,501,068.05		436,650.84		3,606,578.54
TOTAL AVAILABLE FUNDS FOR DISTRIBUTION						3,720,584.48		4,925,415.70		6,156,992.97		1,750,584.01		16,567,450.85



PRINCIPAL - COLLECTIONS
PRINCIPAL - COLLECTIONS
							Group 4		Group 3		Group 2		Group 1		Total
Scheduled Principal Received							28,791.70		21,017.55		29,299.49		17,004.66		96,113.40
Curtailments							22,158.03		36,676.97		84,893.83		7,702.69		151,431.52
Prepayments In Full							2,916,825.00		3,965,544.97		4,541,731.60		1,289,225.82		12,713,327.39
Repurchased/Substitutions							0.00		0.00		0.00		0.00		0.00
Liquidations							0.00		0.00		0.00		0.00		0.00
Insurance Principal							0.00		0.00		0.00		0.00		0.00
Other Additional Principal							0.00		0.00		0.00		0.00		0.00
Delinquent Principal							-19,365.34		-15,135.58		-21,524.60		-13,788.57		-69,814.09
Realized Losses							-0.00		-0.00		-0.00		-0.00		-0.00
Advanced Principal							19,365.34		15,135.58		21,524.60		13,788.57		69,814.09
TOTAL PRINCIPAL COLLECTED							2,967,774.73		4,023,239.49		4,655,924.92		1,313,933.17		12,960,872.31


PRINCIPAL - WITHDRAWALS

SPACE INTENTIONALLY LEFT BLANK



PRINCIPAL - OTHER ACCOUNTS
PRINCIPAL - OTHER ACCOUNTS
						Group 4		Group 3		Group 2		Group 1		Total
TOTAL PRINCIPAL OTHER ACCOUNTS						0.00		0.00		0.00		0.00		0.00





Page 4 of 27
IndyMac INDX Mortgage Loan Trust 2005-AR21

Mortgage Pass-Through Certificates
Mortgage Pass-Through Certificates
2005-AR21

October 25, 2005 Distribution

INTEREST - COLLECTIONS
INTEREST - COLLECTIONS
						Group 4		Group 3		Group 2		Group 1		Total
Scheduled Interest						804,853.68		965,403.13		1,603,930.09		468,046.49		3,842,233.39
Repurchased/Substitution Interest						0.00		0.00		0.00		0.00		0.00
Liquidation Interest						0.00		0.00		0.00		0.00		0.00
Insurance Interest						0.00		0.00		0.00		0.00		0.00
Other Additional Interest						0.00		0.00		0.00		0.00		0.00
Prepayment Interest Shortfalls						-1,870.46		-3,455.25		-738.13		-344.55		-6,408.39
Delinquent Interest						-562,136.19		-704,562.93		-1,082,039.18		-358,323.75		-2,707,062.05
Compensating Interest						1,870.46		3,455.25		738.13		344.55		6,408.39
Civil Relief Act Shortfalls						-0.00		-0.00		-0.00		-0.00		-0.00
Interest Advanced						526,029.25		658,985.31		1,013,226.37		334,446.81		2,532,687.74
TOTAL INTEREST COLLECTED						768,746.74		919,825.51		1,535,117.28		444,169.55		3,667,859.07


INTEREST - WITHDRAWALS

SPACE INTENTIONALLY LEFT BLANK



INTEREST - OTHER ACCOUNTS
INTEREST - OTHER ACCOUNTS
						Group 4		Group 3		Group 2		Group 1		Total
Prepayment Charges														13,873.70
TOTAL INTEREST OTHER ACCOUNTS						0.00		0.00		0.00		0.00		13,873.70



INTEREST - FEES
INTEREST - FEES
						Group 4		Group 3		Group 2		Group 1		Total
Current Servicing Fees						15,455.74		17,064.64		33,098.06		7,228.39		72,846.83
Trustee Fees						481.25		584.66		951.17		290.32		2,307.40
TOTAL INTEREST FEES						15,937.00		17,649.30		34,049.22		7,518.71		75,154.23




Page 5 of 27
IndyMac INDX Mortgage Loan Trust 2005-AR21

Mortgage Pass-Through Certificates
Mortgage Pass-Through Certificates
2005-AR21

October 25, 2005 Distribution
Credit Enhancement Report
ACCOUNTS


SPACE INTENTIONALLY LEFT BLANK





INSURANCE

SPACE INTENTIONALLY LEFT BLANK



STRUCTURAL FEATURES

SPACE INTENTIONALLY LEFT BLANK



Page 6 of 27
IndyMac INDX Mortgage Loan Trust 2005-AR21

Mortgage Pass-Through Certificates
Mortgage Pass-Through Certificates
2005-AR21

October 25, 2005 Distribution
Collateral Report


COLLATERAL



							Group 4		Group 3		Group 2		Group 1		Total



Loan Count:


Original						567		376		1,544		365		2,852
Prior						566		371		1,528		359		2,824
Prefunding						0		0		0		0		0
Scheduled Paid Offs						-0		-0		-0		-0		-0
Full Voluntary Prepayments						-8		-7		-22		-5		-42
Repurchases						-0		-0		-0		-0		-0
Liquidations						-0		-0		-0		-0		-0
Current						558		364		1,506		354		2,782
Principal Balance:


Original						165,255,493.18		203,860,329.63		330,018,264.97		101,050,501.30		800,184,589.08
Prior						165,000,568.22		200,455,229.46		326,114,776.45		99,537,052.03		791,107,626.16
Prefunding						0.00		0.00		0.00		0.00		0.00
Scheduled Principal						-28,791.70		-21,017.55		-29,299.49		-17,004.66		-96,113.40
Partial Prepayments						-22,158.03		-36,676.97		-84,893.83		-7,702.69		-151,431.52
Full Voluntary Prepayments						-2,916,825.00		-3,965,544.97		-4,541,731.60		-1,289,225.82		-12,713,327.39
Repurchases						-0.00		-0.00		-0.00		-0.00		-0.00
Liquidations						-0.00		-0.00		-0.00		-0.00		-0.00
Current						162,032,793.49		196,431,989.97		321,458,851.53		98,223,118.86		778,146,753.85





PREFUNDING

SPACE INTENTIONALLY LEFT BLANK






Page 7 of 27
IndyMac INDX Mortgage Loan Trust 2005-AR21

Mortgage Pass-Through Certificates
Mortgage Pass-Through Certificates
2005-AR21

October 25, 2005 Distribution

CHARACTERISTICS
CHARACTERISTICS
						Group 4		Group 3		Group 2		Group 1		Total
Weighted Average Coupon Original						5.85263%		5.78265%		5.90445%		5.64925%		5.83049%
Weighted Average Coupon Prior						5.85263%		5.78265%		5.90445%		5.64925%		5.83049%
Weighted Average Coupon Current						5.85346%		5.77926%		5.90188%		5.64268%		5.82810%
Weighted Average Months to Maturity Original						358		358		357		357		357
Weighted Average Months to Maturity Prior						358		358		357		357		357
Weighted Average Months to Maturity Current						357		357		356		356		357
Weighted Avg Remaining Amortization Term Original						358		358		357		357		357
Weighted Avg Remaining Amortization Term Prior						358		358		357		357		357
Weighted Avg Remaining Amortization Term Current						357		357		356		356		357
Weighted Average Seasoning Original						1.78		2.09		2.86		2.79		2.43
Weighted Average Seasoning Prior						1.78		2.09		2.86		2.79		2.43
Weighted Average Seasoning Current						2.71		2.99		3.83		3.72		3.37









Page 8 of 27
IndyMac INDX Mortgage Loan Trust 2005-AR21

Mortgage Pass-Through Certificates
Mortgage Pass-Through Certificates
2005-AR21

October 25, 2005 Distribution

ARM CHARACTERISTICS
ARM CHARACTERISTICS
						Group 4		Group 3		Group 2		Group 1		Total
Weighted Average Margin Original						2.70891%		2.59291%		2.54633%		2.56878%		2.59461%
Weighted Average Margin Prior						2.70891%		2.59291%		2.54633%		2.56878%		2.59461%
Weighted Average Margin Current						2.70885%		2.59026%		2.54679%		2.57026%		2.59456%
Weighted Average Max Rate Original						11.73149%		11.26616%		11.43325%		11.47740%		11.45785%
Weighted Average Max Rate Prior						11.73149%		11.26616%		11.43325%		11.47740%		11.45785%
Weighted Average Max Rate Current						11.73214%		11.25417%		11.43172%		11.47477%		11.45480%
Weighted Average Min Rate Original						0.13604%		0.10379%		0.17383%		0.12940%		0.14257%
Weighted Average Min Rate Prior						0.13604%		0.10379%		0.17383%		0.12940%		0.14257%
Weighted Average Min Rate Current						0.13625%		0.10555%		0.17521%		0.12716%		0.14339%
Weighted Average Cap Up Original						1.09289%		1.72703%		2.33536%		1.84526%		1.86189%
Weighted Average Cap Up Prior						1.09289%		1.72703%		2.33536%		1.84526%		1.86189%
Weighted Average Cap Up Current						1.09302%		1.72461%		2.31647%		1.67053%		1.83006%
Weighted Average Cap Down Original						1.09289%		1.72703%		2.33536%		1.84526%		1.86189%
Weighted Average Cap Down Prior						1.09289%		1.72703%		2.33536%		1.84526%		1.86189%
Weighted Average Cap Down Current						1.09302%		1.72461%		2.31647%		1.67053%		1.83006%




SERVICING FEES & ADVANCES

							Group 4		Group 3		Group 2		Group 1		Total




Current Servicing Fees						15,455.74		17,064.64		33,098.06		7,228.39		72,846.83
Delinquent Servicing Fees						36,106.93		45,577.62		68,812.81		23,876.94		174,374.30
TOTAL SERVICING FEES						51,562.68		62,642.26		101,910.87		31,105.33		247,221.14


Total Servicing Fees						51,562.68		62,642.26		101,910.87		31,105.33		247,221.14
Compensating Interest						-1,870.46		-3,455.25		-738.13		-344.55		-6,408.39
Delinquent Servicing Fees						-36,106.93		-45,577.62		-68,812.81		-23,876.94		-174,374.30
COLLECTED SERVICING FEES						13,585.29		13,609.39		32,359.93		6,883.84		66,438.45


Total Advanced Interest						526,029.25		658,985.31		1,013,226.37		334,446.81		2,532,687.74
Total Advanced Principal						19,365.34		15,135.58		21,524.60		13,788.57		69,814.09
Aggregate Advances with respect to this Distribution						545,394.59		674,120.89		1,034,750.97		348,235.38		2,602,501.83





ADDITIONAL COLLATERAL INFORMATION
						Group 4		Group 3		Group 2		Group 1		Total
Prepayment Interest Shortfall (PPIS)						1,870.46		3,455.25		738.13		344.55		6,408.39
Compensating Interest						-1,870.46		-3,455.25		-738.13		-344.55		-6,408.39
Net Prepayment Interest Shortfall (PPIS)						0.00		0.00		0.00		0.00		0.00
Weighted Average Net Mortgage Rate						5.474961%		5.400764%		5.523459%		5.264180%		5.470677%




Page 9 of 27
IndyMac INDX Mortgage Loan Trust 2005-AR21

Mortgage Pass-Through Certificates
Mortgage Pass-Through Certificates
2005-AR21

October 25, 2005 Distribution
Delinquency Report

	TOTAL
					< 1 PAYMENT		1 PAYMENT		2 PAYMENTS		3+ PAYMENTS		TOTAL
	DELINQUENT		Balance				13,478,556.73		711,600.00		0.00		14,190,156.73
			% Balance				1.73%		0.09%		0.00%		1.82%
			# Loans				38		4		0		42
			% # Loans				1.37%		0.14%		0.00%		1.51%
	FORECLOSURE		Balance		0.00		0.00		0.00		0.00		0.00
			% Balance		0.00%		0.00%		0.00%		0.00%		0.00%
			# Loans		0		0		0		0		0
			% # Loans		0.00%		0.00%		0.00%		0.00%		0.00%
	BANKRUPTCY		Balance		0.00		0.00		0.00		0.00		0.00
			% Balance		0.00%		0.00%		0.00%		0.00%		0.00%
			# Loans		0		0		0		0		0
			% # Loans		0.00%		0.00%		0.00%		0.00%		0.00%
	REO		Balance		0.00		0.00		0.00		0.00		0.00
			% Balance		0.00%		0.00%		0.00%		0.00%		0.00%
			# Loans		0		0		0		0		0
			% # Loans		0.00%		0.00%		0.00%		0.00%		0.00%
	TOTAL		Balance		0.00		13,478,556.73		711,600.00		0.00		14,190,156.73
			% Balance		0.00%		1.73%		0.09%		0.00%		1.82%
			# Loans		0		38		4		0		42
			% # Loans		0.00%		1.37%		0.14%		0.00%		1.51%









Page 10 of 27
IndyMac INDX Mortgage Loan Trust 2005-AR21

Mortgage Pass-Through Certificates
Mortgage Pass-Through Certificates
2005-AR21

October 25, 2005 Distribution


	GROUP 1
					< 1 PAYMENT		1 PAYMENT		2 PAYMENTS		3+ PAYMENTS		TOTAL
	DELINQUENT		Balance				1,890,284.78		0.00		0.00		1,890,284.78
			% Balance				1.92%		0.00%		0.00%		1.92%
			# Loans				6		0		0		6
			% # Loans				1.69%		0.00%		0.00%		1.69%
	FORECLOSURE		Balance		0.00		0.00		0.00		0.00		0.00
			% Balance		0.00%		0.00%		0.00%		0.00%		0.00%
			# Loans		0		0		0		0		0
			% # Loans		0.00%		0.00%		0.00%		0.00%		0.00%
	BANKRUPTCY		Balance		0.00		0.00		0.00		0.00		0.00
			% Balance		0.00%		0.00%		0.00%		0.00%		0.00%
			# Loans		0		0		0		0		0
			% # Loans		0.00%		0.00%		0.00%		0.00%		0.00%
	REO		Balance		0.00		0.00		0.00		0.00		0.00
			% Balance		0.00%		0.00%		0.00%		0.00%		0.00%
			# Loans		0		0		0		0		0
			% # Loans		0.00%		0.00%		0.00%		0.00%		0.00%
	TOTAL		Balance		0.00		1,890,284.78		0.00		0.00		1,890,284.78
			% Balance		0.00%		1.92%		0.00%		0.00%		1.92%
			# Loans		0		6		0		0		6
			% # Loans		0.00%		1.69%		0.00%		0.00%		1.69%










Page 11 of 27
IndyMac INDX Mortgage Loan Trust 2005-AR21

Mortgage Pass-Through Certificates
Mortgage Pass-Through Certificates
2005-AR21

October 25, 2005 Distribution

	GROUP 2
					< 1 PAYMENT		1 PAYMENT		2 PAYMENTS		3+ PAYMENTS		TOTAL
	DELINQUENT		Balance				3,782,411.90		711,600.00		0.00		4,494,011.90
			% Balance				1.18%		0.22%		0.00%		1.40%
			# Loans				16		4		0		20
			% # Loans				1.06%		0.27%		0.00%		1.33%
	FORECLOSURE		Balance		0.00		0.00		0.00		0.00		0.00
			% Balance		0.00%		0.00%		0.00%		0.00%		0.00%
			# Loans		0		0		0		0		0
			% # Loans		0.00%		0.00%		0.00%		0.00%		0.00%
	BANKRUPTCY		Balance		0.00		0.00		0.00		0.00		0.00
			% Balance		0.00%		0.00%		0.00%		0.00%		0.00%
			# Loans		0		0		0		0		0
			% # Loans		0.00%		0.00%		0.00%		0.00%		0.00%
	REO		Balance		0.00		0.00		0.00		0.00		0.00
			% Balance		0.00%		0.00%		0.00%		0.00%		0.00%
			# Loans		0		0		0		0		0
			% # Loans		0.00%		0.00%		0.00%		0.00%		0.00%
	TOTAL		Balance		0.00		3,782,411.90		711,600.00		0.00		4,494,011.90
			% Balance		0.00%		1.18%		0.22%		0.00%		1.40%
			# Loans		0		16		4		0		20
			% # Loans		0.00%		1.06%		0.27%		0.00%		1.33%










Page 12 of 27
IndyMac INDX Mortgage Loan Trust 2005-AR21

Mortgage Pass-Through Certificates
Mortgage Pass-Through Certificates
2005-AR21

October 25, 2005 Distribution

	GROUP 3
					< 1 PAYMENT		1 PAYMENT		2 PAYMENTS		3+ PAYMENTS		TOTAL
	DELINQUENT		Balance				5,136,732.30		0.00		0.00		5,136,732.30
			% Balance				2.62%		0.00%		0.00%		2.62%
			# Loans				9		0		0		9
			% # Loans				2.47%		0.00%		0.00%		2.47%
	FORECLOSURE		Balance		0.00		0.00		0.00		0.00		0.00
			% Balance		0.00%		0.00%		0.00%		0.00%		0.00%
			# Loans		0		0		0		0		0
			% # Loans		0.00%		0.00%		0.00%		0.00%		0.00%
	BANKRUPTCY		Balance		0.00		0.00		0.00		0.00		0.00
			% Balance		0.00%		0.00%		0.00%		0.00%		0.00%
			# Loans		0		0		0		0		0
			% # Loans		0.00%		0.00%		0.00%		0.00%		0.00%
	REO		Balance		0.00		0.00		0.00		0.00		0.00
			% Balance		0.00%		0.00%		0.00%		0.00%		0.00%
			# Loans		0		0		0		0		0
			% # Loans		0.00%		0.00%		0.00%		0.00%		0.00%
	TOTAL		Balance		0.00		5,136,732.30		0.00		0.00		5,136,732.30
			% Balance		0.00%		2.62%		0.00%		0.00%		2.62%
			# Loans		0		9		0		0		9
			% # Loans		0.00%		2.47%		0.00%		0.00%		2.47%










Page 13 of 27
IndyMac INDX Mortgage Loan Trust 2005-AR21

Mortgage Pass-Through Certificates
Mortgage Pass-Through Certificates
2005-AR21

October 25, 2005 Distribution

	GROUP 4
					< 1 PAYMENT		1 PAYMENT		2 PAYMENTS		3+ PAYMENTS		TOTAL
	DELINQUENT		Balance				2,669,127.75		0.00		0.00		2,669,127.75
			% Balance				1.65%		0.00%		0.00%		1.65%
			# Loans				7		0		0		7
			% # Loans				1.25%		0.00%		0.00%		1.25%
	FORECLOSURE		Balance		0.00		0.00		0.00		0.00		0.00
			% Balance		0.00%		0.00%		0.00%		0.00%		0.00%
			# Loans		0		0		0		0		0
			% # Loans		0.00%		0.00%		0.00%		0.00%		0.00%
	BANKRUPTCY		Balance		0.00		0.00		0.00		0.00		0.00
			% Balance		0.00%		0.00%		0.00%		0.00%		0.00%
			# Loans		0		0		0		0		0
			% # Loans		0.00%		0.00%		0.00%		0.00%		0.00%
	REO		Balance		0.00		0.00		0.00		0.00		0.00
			% Balance		0.00%		0.00%		0.00%		0.00%		0.00%
			# Loans		0		0		0		0		0
			% # Loans		0.00%		0.00%		0.00%		0.00%		0.00%
	TOTAL		Balance		0.00		2,669,127.75		0.00		0.00		2,669,127.75
			% Balance		0.00%		1.65%		0.00%		0.00%		1.65%
			# Loans		0		7		0		0		7
			% # Loans		0.00%		1.25%		0.00%		0.00%		1.25%









Page 14 of 27
IndyMac INDX Mortgage Loan Trust 2005-AR21

Mortgage Pass-Through Certificates
Mortgage Pass-Through Certificates
2005-AR21

October 25, 2005 Distribution
REO Report
Loan Number			Original		Stated				Current		State &

														First
&			Principal		Principal		Paid to		Note		LTV at		Original		Payment

Loan Group			Balance		Balance		Date		Rate		Origination		Term		Date




TOTAL


Page 15 of 27
IndyMac INDX Mortgage Loan Trust 2005-AR21

Mortgage Pass-Through Certificates
Mortgage Pass-Through Certificates
2005-AR21

October 25, 2005 Distribution
Foreclosure Report
Loan Number			Original		Stated				Current		State &

														First
&			Principal		Principal		Paid to		Note		LTV at		Original		Payment

Loan Group			Balance		Balance		Date		Rate		Origination		Term		Date




TOTAL


Page 16 of 27
IndyMac INDX Mortgage Loan Trust 2005-AR21

Mortgage Pass-Through Certificates
Mortgage Pass-Through Certificates
2005-AR21

October 25, 2005 Distribution
Prepayment Report

VOLUNTARY PREPAYMENTS
VOLUNTARY PREPAYMENTS

							Group 4		Group 3		Group 2		Group 1		Total




Current


Number of Paid in Full Loans						8		7		22		5		42
Number of Repurchased Loans						0		0		0		0		0
Total Number of Loans Prepaid in Full						8		7		22		5		42
Curtailments Amount						22,158.03		36,676.97		84,893.83		7,702.69		151,431.52
Paid in Full Balance						2,916,825.00		3,965,544.97		4,541,731.60		1,289,225.82		12,713,327.39
Repurchased Loans Balance						0.00		0.00		0.00		0.00		0.00
Total Prepayment Amount						2,938,983.03		4,002,221.94		4,626,625.43		1,296,928.51		12,864,758.91

Cumulative


Number of Paid in Full Loans						9		12		37		10		68
Number of Repurchased Loans						0		0		1		1		2
Total Number of Loans Prepaid in Full						9		12		38		11		70
Paid in Full Balance						3,138,825.00		7,349,604.96		7,986,186.63		2,468,305.72		20,942,922.31
Repurchased Loans Balance						0.00		0.00		256,000.00		313,600.00		569,600.00
Curtailments Amount						25,148.61		34,054.19		257,237.91		10,853.22		327,293.93
Total Prepayment Amount						3,163,973.61		7,383,659.15		8,499,424.54		2,792,758.94		21,839,816.24










Page 17 of 27
IndyMac INDX Mortgage Loan Trust 2005-AR21

Mortgage Pass-Through Certificates
Mortgage Pass-Through Certificates
2005-AR21

October 25, 2005 Distribution

VOLUNTARY PREPAYMENTS RATES
VOLUNTARY PREPAYMENTS RATES

							Group 4		Group 3		Group 2		Group 1		Total



SMM						1.78%		2.00%		1.42%		1.30%		1.63%
3 Months Avg SMM						0.96%		1.83%		1.30%		1.39%		1.37%
12 Months Avg SMM						0.96%		1.83%		1.30%		1.39%		1.37%
Avg SMM Since Cut-off						0.96%		1.83%		1.30%		1.39%		1.37%


CPR						19.40%		21.50%		15.76%		14.56%		17.86%
3 Months Avg CPR						10.96%		19.86%		14.49%		15.48%		15.30%
12 Months Avg CPR						10.96%		19.86%		14.49%		15.48%		15.30%
Avg CPR Since Cut-off						10.96%		19.86%		14.49%		15.48%		15.30%


PSA						3,577.48%		3,597.28%		2,055.26%		1,959.68%		2,648.77%
3 Months Avg PSA Approximation						2,437.35%		3,908.20%		2,166.15%		2,381.24%		2,637.13%
12 Months Avg PSA Approximation						2,437.35%		3,908.20%		2,166.15%		2,381.24%		2,637.13%
Avg PSA Since Cut-off Approximation						2,437.35%		3,908.20%		2,166.15%		2,381.24%		2,637.13%










Page 18 of 27
IndyMac INDX Mortgage Loan Trust 2005-AR21

Mortgage Pass-Through Certificates
Mortgage Pass-Through Certificates
2005-AR21

October 25, 2005 Distribution






PREPAYMENT CALCULATION METHODOLOGY

Single Monthly Mortality (SMM): (Voluntary partial and full prepayments + Repurchases + Liquidations )/(Beg Principal Balance - Sched Principal) Conditional Prepayment Rate (CPR): 1-((1-SMM)^12) PSA Standard Prepayment Model: CPR/(0.002min(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) Conditional Prepayment Rate (CPR): 1-((1-SMM)^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) Dates correspond to distribution dates. Note: Prepayment rates are calculated since deal issue date and include partial and full voluntary prepayments, liquidations, and repurchases.













Page 19 of 27
IndyMac INDX Mortgage Loan Trust 2005-AR21

Mortgage Pass-Through Certificates
Mortgage Pass-Through Certificates
2005-AR21

October 25, 2005 Distribution
Prepayment Detail Report
Prepayment Detail Report - Mortgage Loans Prepaid in Full During Current Distribution
Loan Number			Original							Current		State &		Type Prepayment		First
Loan Number			Original							Current		State &		Type Prepayment

&		Loan	Principal		Prepayment			Prepayment		Note		LTV at		&		Payment

Loan Group		Status	Balance		Amount			Date		Rate		Origination		Original Term		Date

120386597 2			82,400.00		82,396.53			14-Oct-2005		5.625%		GA - 80.00%		Paid Off - 360		01-Apr-2005
			82,400.00

120392973 2			79,900.00		79,879.08			06-Oct-2005		6.250%		AZ - 79.90%		Paid Off - 360		01-Jun-2005
120392973 2					79,879.08			06-Oct-2005		6.250%		AZ - 79.90%		Paid Off - 360		01-Jun-2005
120393094 2			64,000.00		63,996.67			21-Sep-2005		6.500%		FL - 80.00%		Paid Off - 360		01-May-2005
120393094 2					63,996.67			21-Sep-2005		6.500%		FL - 80.00%		Paid Off - 360		01-May-2005
120393098 2			128,480.00		128,480.00			28-Sep-2005		5.625%		FL - 80.00%		Paid Off - 360		01-Jun-2005
120393098 2					128,480.00			28-Sep-2005		5.625%		FL - 80.00%		Paid Off - 360		01-Jun-2005
120394374 4			274,000.00		274,000.00			21-Sep-2005		5.375%		CA - 66.83%		Paid Off - 360		01-Jun-2005
120394374 4					274,000.00			21-Sep-2005		5.375%		CA - 66.83%		Paid Off - 360		01-Jun-2005
120394799 2			210,000.00		209,695.66			05-Oct-2005		6.000%		OR - 65.00%		Paid Off - 360		01-Jun-2005
120394799 2					209,695.66			05-Oct-2005		6.000%		OR - 65.00%		Paid Off - 360		01-Jun-2005
120394853 2			148,000.00		148,000.00			13-Oct-2005		6.375%		AZ - 80.00%		Paid Off - 360		01-Jun-2005
120394853 2					148,000.00			13-Oct-2005		6.375%		AZ - 80.00%		Paid Off - 360		01-Jun-2005
120394925 3			400,000.00		400,000.00			10-Oct-2005		5.500%		CA - 62.00%		Paid Off - 360		01-Jun-2005
120394925 3					400,000.00			10-Oct-2005		5.500%		CA - 62.00%		Paid Off - 360		01-Jun-2005
120396255 1			152,800.00		152,800.00			14-Oct-2005		5.750%		CA - 80.00%		Paid Off - 360		01-May-2005
120396255 1					152,800.00			14-Oct-2005		5.750%		CA - 80.00%		Paid Off - 360		01-May-2005
120396339 1			290,800.00		289,575.82			13-Oct-2005		5.750%		IL - 79.89%		Paid Off - 360		01-Jun-2005
120396339 1					289,575.82			13-Oct-2005		5.750%		IL - 79.89%		Paid Off - 360		01-Jun-2005
120396491 1			142,400.00		142,400.00			21-Sep-2005		5.875%		AL - 80.00%		Paid Off - 360		01-Jun-2005
120396491 1					142,400.00			21-Sep-2005		5.875%		AL - 80.00%		Paid Off - 360		01-Jun-2005
120396531 2			266,950.00		266,222.08			27-Sep-2005		6.500%		FL - 95.00%		Paid Off - 360		01-Jul-2005
120396531 2					266,222.08			27-Sep-2005		6.500%		FL - 95.00%		Paid Off - 360		01-Jul-2005
120396547 2			195,000.00		193,198.89			21-Sep-2005		5.875%		WI - 60.94%		Paid Off - 360		01-Jun-2005
120396547 2					193,198.89			21-Sep-2005		5.875%		WI - 60.94%		Paid Off - 360		01-Jun-2005
120397491 2			311,000.00		310,110.11			04-Oct-2005		6.250%		CA - 80.00%		Paid Off - 360		01-Jul-2005
120397491 2					310,110.11			04-Oct-2005		6.250%		CA - 80.00%		Paid Off - 360		01-Jul-2005
120398263 3			512,000.00		512,000.00			28-Sep-2005		6.375%		CA - 80.00%		Paid Off - 360		01-Jul-2005
120398263 3					512,000.00			28-Sep-2005		6.375%		CA - 80.00%		Paid Off - 360		01-Jul-2005
120934373 4			429,453.00		429,453.00			28-Sep-2005		6.250%		CA - 90.00%		Paid Off - 360		01-Sep-2005
120934373 4					429,453.00			28-Sep-2005		6.250%		CA - 90.00%		Paid Off - 360		01-Sep-2005
120940116 4			219,900.00		219,900.00			05-Oct-2005		7.375%		FL - 79.97%		Paid Off - 360		01-Aug-2005
120940116 4					219,900.00			05-Oct-2005		7.375%		FL - 79.97%		Paid Off - 360		01-Aug-2005
121004683 2			350,000.00		350,000.00			30-Sep-2005		6.500%		CA - 67.96%		Paid Off - 360		01-May-2005
121004683 2					350,000.00			30-Sep-2005		6.500%		CA - 67.96%		Paid Off - 360		01-May-2005
121085703 4			207,492.00		207,492.00			23-Sep-2005		7.625%		FL - 95.00%		Paid Off - 360		01-Sep-2005
121085703 4					207,492.00			23-Sep-2005		7.625%		FL - 95.00%		Paid Off - 360		01-Sep-2005
121129142 2			168,315.00		168,315.00			14-Oct-2005		5.625%		TX - 90.98%		Paid Off - 360		01-Jun-2005
121129142 2					168,315.00			14-Oct-2005		5.625%		TX - 90.98%		Paid Off - 360		01-Jun-2005
121172436 2			145,000.00		144,199.11			07-Oct-2005		5.500%		CA - 63.60%		Paid Off - 360		01-May-2005
121172436 2					144,199.11			07-Oct-2005		5.500%		CA - 63.60%		Paid Off - 360		01-May-2005
121183266 2			307,150.00		307,150.00			05-Oct-2005		6.375%		CA - 80.00%		Paid Off - 360		01-Sep-2005
121183266 2					307,150.00			05-Oct-2005		6.375%		CA - 80.00%		Paid Off - 360		01-Sep-2005
121254431 2			220,871.00		220,871.00			11-Oct-2005		6.125%		FL - 90.00%		Paid Off - 360		01-Aug-2005
121254431 2					220,871.00			11-Oct-2005		6.125%		FL - 90.00%		Paid Off - 360		01-Aug-2005
121384372 4			325,000.00		325,000.00			20-Sep-2005		5.500%		CA - 65.00%		Paid Off - 360		01-Jul-2005
121384372 4					325,000.00			20-Sep-2005		5.500%		CA - 65.00%		Paid Off - 360		01-Jul-2005
121412424 2			99,920.00		99,920.00			07-Oct-2005		7.875%		NM - 80.00%		Paid Off - 360		01-Apr-2005
121412424 2					99,920.00			07-Oct-2005		7.875%		NM - 80.00%		Paid Off - 360		01-Apr-2005
121474144 3			975,000.00		975,000.00			16-Sep-2005		5.250%		HI - 59.09%		Paid Off - 360		01-Sep-2005
121474144 3					975,000.00			16-Sep-2005		5.250%		HI - 59.09%		Paid Off - 360		01-Sep-2005
121492711 3			460,000.00		460,000.00			14-Oct-2005		4.875%		CA - 80.00%		Paid Off - 360		01-Aug-2005
121492711 3					460,000.00			14-Oct-2005		4.875%		CA - 80.00%		Paid Off - 360		01-Aug-2005
121503166 4			502,980.00		502,980.00			27-Sep-2005		6.750%		CA - 80.00%		Paid Off - 360		01-Sep-2005
121503166 4					502,980.00			27-Sep-2005		6.750%		CA - 80.00%		Paid Off - 360		01-Sep-2005
121528240 2			316,000.00		316,000.00			05-Oct-2005		5.750%		CA - 80.00%		Paid Off - 360		01-Aug-2005
121528240 2					316,000.00			05-Oct-2005		5.750%		CA - 80.00%		Paid Off - 360		01-Aug-2005
121552462 4			577,000.00		577,000.00			30-Sep-2005		5.375%		HI - 51.75%		Paid Off - 360		01-Aug-2005
121552462 4					577,000.00			30-Sep-2005		5.375%		HI - 51.75%		Paid Off - 360		01-Aug-2005
121559944 2			188,824.00		188,824.00			14-Oct-2005		6.750%		NV - 95.00%		Paid Off - 360		01-Sep-2005
121559944 2					188,824.00			14-Oct-2005		6.750%		NV - 95.00%		Paid Off - 360		01-Sep-2005
121565357 2			164,000.00		163,755.82			10-Oct-2005		7.500%		CA - 80.00%		Paid Off - 360		01-Jul-2005
121565357 2					163,755.82			10-Oct-2005		7.500%		CA - 80.00%		Paid Off - 360		01-Jul-2005
121604329 2			209,758.00		209,758.00			30-Sep-2005		6.750%		FL - 90.00%		Paid Off - 360		01-Aug-2005
121604329 2					209,758.00			30-Sep-2005		6.750%		FL - 90.00%		Paid Off - 360		01-Aug-2005
121619977 2			359,000.00		359,000.00			04-Oct-2005		5.500%		SC - 48.51%		Paid Off - 360		01-Aug-2005
121619977 2					359,000.00			04-Oct-2005		5.500%		SC - 48.51%		Paid Off - 360		01-Aug-2005
121649737 1			223,200.00		223,200.00			10-Oct-2005		6.875%		FL - 80.00%		Paid Off - 360		01-Aug-2005
121649737 1					223,200.00			10-Oct-2005		6.875%		FL - 80.00%		Paid Off - 360		01-Aug-2005
121651733 3			397,800.00		397,800.00			10-Oct-2005		5.000%		FL - 72.33%		Paid Off - 360		01-Aug-2005
121651733 3					397,800.00			10-Oct-2005		5.000%		FL - 72.33%		Paid Off - 360		01-Aug-2005
121656043 2			307,000.00		306,959.65			03-Oct-2005		5.500%		CA - 60.79%		Paid Off - 360		01-Sep-2005
121656043 2					306,959.65					5.500%		CA - 60.79%		Paid Off - 360


Page 20 of 27
IndyMac INDX Mortgage Loan Trust 2005-AR21

Mortgage Pass-Through Certificates
Mortgage Pass-Through Certificates
2005-AR21

October 25, 2005 Distribution

Prepayment Detail Report - Mortgage Loans Prepaid in Full During Current Distribution
Loan Number			Original							Current		State &		Type Prepayment		First
Loan Number			Original							Current		State &		Type Prepayment

&		Loan	Principal		Prepayment			Prepayment		Note		LTV at		&		Payment

Loan Group		Status	Balance		Amount			Date		Rate		Origination		Original Term		Date

121684643 1			481,250.00		481,250.00			29-Sep-2005		5.125%		CA - 70.00%		Paid Off - 360		01-Sep-2005
			481,250.00

121694711 4			381,000.00		381,000.00			13-Oct-2005		5.875%		CA - 76.97%		Paid Off - 360		01-Aug-2005
121694711 4					381,000.00			13-Oct-2005		5.875%		CA - 76.97%		Paid Off - 360		01-Aug-2005
121704206 2			225,000.00		225,000.00			04-Oct-2005		5.500%		MI - 74.75%		Paid Off - 360		01-Aug-2005
121704206 2					225,000.00			04-Oct-2005		5.500%		MI - 74.75%		Paid Off - 360		01-Aug-2005
121707902 3			572,000.00		570,744.97			16-Sep-2005		5.500%		VA - 80.00%		Paid Off - 360		01-Aug-2005
121707902 3					570,744.97			16-Sep-2005		5.500%		VA - 80.00%		Paid Off - 360		01-Aug-2005
121837195 3			650,000.00		650,000.00			13-Oct-2005		5.625%		IL - 65.33%		Paid Off - 360		01-Sep-2005
121837195 3					650,000.00			13-Oct-2005		5.625%		IL - 65.33%		Paid Off - 360		01-Sep-2005


TOTAL			12,720,643.00		12,713,327.39
TOTAL


Page 21 of 27
IndyMac INDX Mortgage Loan Trust 2005-AR21

Mortgage Pass-Through Certificates
Mortgage Pass-Through Certificates
2005-AR21

October 25, 2005 Distribution
Realized Loss Report

COLLATERAL REALIZED LOSSES



							Group 4		Group 3		Group 2		Group 1		Total


Current
Current



Number of Loans Liquidated						0		0		0		0		0
Collateral Principal Realized Loss/(Gain) Amount						0.00		0.00		0.00		0.00		0.00
Collateral Interest Realized Loss/(Gain) Amount						0.00		0.00		0.00		0.00		0.00
Net Liquidation Proceeds						0.00		0.00		0.00		0.00		0.00

Cumulative
Cumulative



Number of Loans Liquidated						0		0		0		0		0
Collateral Realized Loss/(Gain) Amount						0.00		0.00		0.00		0.00		0.00
Net Liquidation Proceeds						0.00		0.00		0.00		0.00		0.00





		Special Hazard Loss Coverage Amt														7,911,076.26
		Fraud Loss Coverage Amt														24,005,538.00
		Bankruptcy Loss Coverage Amt														316,641.00










Page 22 of 27
IndyMac INDX Mortgage Loan Trust 2005-AR21

Mortgage Pass-Through Certificates
Mortgage Pass-Through Certificates
2005-AR21

October 25, 2005 Distribution


DEFAULT SPEEDS



							Group 4		Group 3		Group 2		Group 1		Total



MDR						0.00%		0.00%		0.00%		0.00%		0.00%
3 Months Avg MDR						0.00%		0.00%		0.00%		0.00%		0.00%
12 Months Avg MDR						0.00%		0.00%		0.00%		0.00%		0.00%
Avg MDR Since Cut-off						0.00%		0.00%		0.00%		0.00%		0.00%


CDR						0.00%		0.00%		0.00%		0.00%		0.00%
3 Months Avg CDR						0.00%		0.00%		0.00%		0.00%		0.00%
12 Months Avg CDR						0.00%		0.00%		0.00%		0.00%		0.00%
Avg CDR Since Cut-off						0.00%		0.00%		0.00%		0.00%		0.00%


SDA						0.00%		0.00%		0.00%		0.00%		0.00%
3 Months Avg SDA Approximation						0.00%		0.00%		0.00%		0.00%		0.00%
12 Months Avg SDA Approximation						0.00%		0.00%		0.00%		0.00%		0.00%
Avg SDA Since Cut-off Approximation						0.00%		0.00%		0.00%		0.00%		0.00%


Loss Severity Approximation for Current Period						0.00%		0.00%		0.00%		0.00%		0.00%
3 Months Avg Loss Severity Approximation						0.00%		0.00%		0.00%		0.00%		0.00%
12 Months Avg Loss Severity Approximation						0.00%		0.00%		0.00%		0.00%		0.00%
Avg Loss Severity Approximation Since Cut-off						0.00%		0.00%		0.00%		0.00%		0.00%












Page 23 of 27
IndyMac INDX Mortgage Loan Trust 2005-AR21

Mortgage Pass-Through Certificates
Mortgage Pass-Through Certificates
2005-AR21

October 25, 2005 Distribution





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 24 of 27
IndyMac INDX Mortgage Loan Trust 2005-AR21

Mortgage Pass-Through Certificates
Mortgage Pass-Through Certificates
2005-AR21

October 25, 2005 Distribution
Realized Loss Detail Report
Loan Number			Current		State &				Prior		Realized				Cumulative
															Cumulative
&		Loan	Note		LTV at		Original		Principal		Loss/(Gain)		Realized		Realized

Loan Group		Status	Rate		Origination		Term		Balance		Revision		Loss/(Gain)		Loss/(Gain)
Loan Group		Status	Rate		Origination		Term		Balance		Revision		Loss/(Gain)		Loss/(Gain)




TOTAL



Page 25 of 27
IndyMac INDX Mortgage Loan Trust 2005-AR21

Mortgage Pass-Through Certificates
Mortgage Pass-Through Certificates
2005-AR21

October 25, 2005 Distribution
Triggers and Adj. Cert. Report
TRIGGER EVENTS
TRIGGER EVENTS
						Group 4		Group 3		Group 2		Group 1		Total
						Has Optional Termination Date Reached (0=No,1=Yes)								No
						Has Sr. Prepay Stepdown Condition Occurred
						Has Sr. Credit Supp. Depletion Date Occured								Yes
						Has Spl. Haz. Cov. Term. Date Occured (0=No,1=Yes)								No
						Has Fraud Loss Coverage Term. Date Occured								No
						Has Bankrpt Loss Cov. Term. Date Occured								No



ADJUSTABLE RATE CERTIFICATE INFORMATION

SPACE INTENTIONALLY LEFT BLANK



ADDITIONAL INFORMATION
ADDITIONAL INFORMATION
						Group 4		Group 3		Group 2		Group 1		Total
Current Senior Percentage						93.741463%		93.644541%		93.680646%		93.675021%
Current Subordinate Percentage						6.258537%		6.355459%		6.319354%		6.324979%
Senior Prepayment Percentage						100.000000%		100.000000%		100.000000%		100.000000%
Subordinate Prepayment Percentage						0.000000%		0.000000%		0.000000%		0.000000%




Page 26 of 27
IndyMac INDX Mortgage Loan Trust 2005-AR21

Mortgage Pass-Through Certificates
Mortgage Pass-Through Certificates
2005-AR21

October 25, 2005 Distribution
Other Related Information
ADDITIONAL INFORMATION
ADDITIONAL INFORMATION
						Group 4		Group 3		Group 2		Group 1		Total


Sched. Payments for 60+Day Delinquent Loans						0.00		0.00		0.00		0.00		0.00
Sched. Pmts - 60+Day Delinquent Loans, 1 Month Prior						0.00		0.00		0.00		0.00		0.00
Sched. Pmts - 60+Day Delinquent Loans, 2 Month Prior						0.00		0.00		0.00		0.00		0.00
Sched. Pmts - 60+Day Delinquent Loans, 3 Month Prior						0.00		0.00		0.00		0.00		0.00
Sched. Pmts - 60+Day Delinquent Loans, 4 Month Prior						0.00		0.00		0.00		0.00		0.00
Sched. Pmts - 60+Day Delinquent Loans, 5 Month Prior						0.00		0.00		0.00		0.00		0.00
Sched. Pmts - 60+Day Delinquent Loans, 6 Month Prior						0.00		0.00		0.00		0.00		0.00
Sched. Pmts - 60+Day Delinquent Loans, 7 Month Prior						0.00		0.00		0.00		0.00		0.00
Sched. Pmts - 60+Day Delinquent Loans, 8 Month Prior						0.00		0.00		0.00		0.00		0.00
Sched. Pmts - 60+Day Delinquent Loans, 9 Month Prior						0.00		0.00		0.00		0.00		0.00
Sched. Pmts - 60+Day Delinquent Loans, 10 Month Prior						0.00		0.00		0.00		0.00		0.00
Sched. Pmts - 60+Day Delinquent Loans, 11 Month Prior						0.00		0.00		0.00		0.00		0.00



Class B-1 Writedown Amount														0.00
Class B-2 Writedown Amount														0.00
Class B-3 Writedown Amount														0.00
Class B-4 Writedown Amount														0.00
Class B-5 Writedown Amount														0.00
Class B-6 Writedown Amount														0.00




Page 27 of 27

IndyMac INDX Mortgage Loan Trust 2005-AR21 8-K