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* SHEEHAN KEVIN J (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) Chief Executive Officer
	3. Date of Earliest Transaction (Month/Day/Year) 04/18/2006
	4. If Amendment, Date of Original Filed (Month/Day/Year) 04/20/2006	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	04/18/2006		A		4,222	A	$22.219	921,034	D
Common Stock	04/18/2006		A		1,902	A	$33.125	922,936	D
Common Stock	04/18/2006		A		1,516	A	$10.7579	924,452	D
Common Stock	04/18/2006		A		56,600	A	$7.5	981,052	D
Common Stock	04/18/2006		A		18,208	A	$10.7579	999,260	D
Common Stock	04/18/2006		S		4,222	D	$48.12	995,038	D
Common Stock	04/18/2006		S		1,902	D	$48.13	993,136	D
Common Stock	04/18/2006		S		1,516	D	$48.28	991,620	D
Common Stock	04/18/2006		S		56,600	D	$48.1466	935,020	D
Common Stock	04/18/2006		S		18,208	D	$48.0276	916,812	D
Common Stock	04/19/2006		S		74,000	D	$48.6635	842,812	D
Common Stock	04/20/2006		S		27,000	D	$48.5	815,812	D
Common Stock	04/20/2006		S		99,000	D	$48.5346	716,812	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)	$22.219	04/18/2006		M			4,222	08/15/2000(1)	11/12/2006	Common Stock	4,222	$0	1,212,620	D
Common Stock (right to buy)	$33.125	04/18/2006		M			1,902	01/16/2001(1)	11/12/2006	Common Stock	1,902	$0	1,210,718	D
Common Stock (right to buy)	$10.7579	04/18/2006		M			1,516	01/14/2000(1)	11/12/2006	Common Stock	1,516	$0	1,209,202	D
Common Stock (right to buy)	$7.5	04/18/2006		M			56,600	02/23/1999(1)	11/12/2006	Common Stock	56,600	$0	1,152,602	D
Common Stock (right to buy)	$10.7579	04/18/2006		M			18,208	01/14/2000(1)	11/12/2006	Common Stock	18,208	$0	1,134,394	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:

	Kevin J. Sheehan	04/24/2006
	** 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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