SEC Form 4

FORM 4		UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934 or Section 30(h) of the Investment Company Act of 1940	OMB APPROVAL OMB Number: 3235-0287 Estimated average burden hours per response: 0.5
	Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

1. Name and Address of Reporting Person* MANCUSO ROBERT D (Last) (First) (Middle) INVESTORS BANK & TRUST COMPANY 200 CLARENDON STREET (Street) BOSTON MA 02116 (City) (State) (Zip)	2. Issuer Name and Ticker or Trading Symbol INVESTORS FINANCIAL SERVICES CORP [ IFIN ]	5. Relationship of Reporting Person(s) to Issuer (Check all applicable) Director 10% Owner X Officer (give title below) Other (specify below) Senior Vice President
	3. Date of Earliest Transaction (Month/Day/Year) 02/23/2006
	4. If Amendment, Date of Original Filed (Month/Day/Year)	6. Individual or Joint/Group Filing (Check Applicable Line) X Form filed by One Reporting Person Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	3. Transaction Code (Instr. 8)		4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
			Code	V	Amount	(A) or (D)	Price
Common Stock	02/23/2006		S		3,011	D	$46.4	145,307	D
Common Stock	02/23/2006		S		6,450	D	$46.42	138,857	D
Common Stock	02/23/2006		S		2,000	D	$46.45	136,857	D
Common Stock	02/23/2006		S		2,000	D	$46.5	134,857	D
Common Stock	02/23/2006		S		3,000	D	$46.53	131,857	D
Common Stock	02/23/2006		S		7,905	D	$46.54	123,952	D
Common Stock	02/23/2006		S		2,500	D	$46.56	121,452	D
Common Stock	02/23/2006		S		1,000	D	$46.59	120,452	D
Common Stock	02/23/2006		S		3,000	D	$46.6	117,452	D
Common Stock	02/23/2006		S		2,500	D	$46.61	114,952	D
Common Stock	02/23/2006		S		1,000	D	$46.63	113,952	D
Common Stock	02/23/2006		S		1,000	D	$46.64	112,952	D
Common Stock	02/23/2006		S		2,500	D	$46.65	110,452	D
Common Stock	02/23/2006		S		2,134	D	$46.67	108,318	D
Common Stock	02/23/2006		S		1,000	D	$46.72	107,318	D
Common Stock	02/23/2006		S		1,000	D	$46.81	106,318	D
Common Stock	02/23/2006		M		3,010	A	$31.665	109,328	D
Common Stock	02/23/2006		M		3,158	A	$31.665	112,486	D
Common Stock	02/23/2006		M		416	A	$31.09	112,902	D
Common Stock	02/23/2006		M		23,405	A	$31.665	136,307	D
Common Stock	02/23/2006		M		6,450	A	$31.09	142,757	D
Common Stock	02/23/2006		M		1,884	A	$31.09	144,641	D
Common Stock	02/23/2006		M		429	A	$31.665	145,070	D
Common Stock	02/23/2006		M		4,134	A	$34.75	149,204	D
Common Stock	02/23/2006		M		868	A	$34.75	150,072	D
Common Stock	02/23/2006		M		7,582	A	$34.79	157,654	D
Common Stock	02/23/2006		M		1,584	A	$34.79	159,238	D

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	4. Transaction Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares
Common Stock (right to buy)	$31.665	02/23/2006		M			3,010	11/14/2001(1)	11/14/2011	Common Stock	3,010	$0	388,733	D
Common Stock (right to buy)	$31.665	02/23/2006		M			3,158	11/14/2001(1)	11/14/2011	Common Stock	3,158	$0	385,575	D
Common Stock (right to buy)	$31.09	02/23/2006		M			416	11/12/2002(1)	11/12/2012	Common Stock	416	$0	385,159	D
Common Stock (right to buy)	$31.665	02/23/2006		M			23,405	11/14/2001(1)	11/14/2011	Common Stock	23,405	$0	361,754	D
Common Stock (right to buy)	$31.09	02/23/2006		M			6,450	11/12/2002(1)	11/12/2012	Common Stock	6,450	$0	355,304	D
Common Stock (right to buy)	$31.09	02/23/2006		M			1,884	11/12/2002(1)	11/12/2012	Common Stock	1,884	$0	353,420	D
Common Stock (right to buy)	$31.665	02/23/2006		M			429	11/14/2001(1)	11/14/2011	Common Stock	429	$0	352,991	D
Common Stock (right to buy)	$34.75	02/23/2006		M			4,134	11/13/2000(1)	11/13/2010	Common Stock	4,134	$0	348,857	D
Common Stock (right to buy)	$34.75	02/23/2006		M			868	11/13/2000(1)	11/13/2010	Common Stock	868	$0	347,989	D
Common Stock (right to buy)	$34.79	02/23/2006		M			7,582	11/17/2003(1)	11/17/2013	Common Stock	7,582	$0	340,407	D
Common Stock (right to buy)	$34.79	02/23/2006		M			1,584	11/17/2003(1)	11/17/2013	Common Stock	1,584	$0	338,823	D

Explanation of Responses:

1. Options granted pursuant to the Company's 1995 Stock Plan and became exercisable on the date of the grant.

Remarks:

	Robert D. Mancuso	02/27/2006
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
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