AS FILED WITH THE SECURITIES AND EXCHANGE COMMISSION ON April 12, 2011

 REGISTRATION NOS. 333 -122901

 811 -21719

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

FORM N-1A

REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933	¨
PRE-EFFECTIVE AMENDMENT NO.	¨
POST-EFFECTIVE AMENDMENT NO.  142	ý
AND/OR
REGISTRATION STATEMENT UNDER THE INVESTMENT COMPANY ACT OF 1940	¨
AMENDMENT NO.  148	ý

INVESTMENT MANAGERS SERIES TRUST

(Exact Name of Registrant as Specified in Charter)

803 West Michigan Street

Milwaukee, WI 53233

(Address of Principal Executive Offices, including Zip Code)

Registrant's Telephone Number, Including Area Code: (414) 299-2295

Constance Dye Shannon

UMB Fund Services, Inc.

803 West Michigan Street

Milwaukee, WI 53233

(Name and Address of Agent for Service)

COPIES TO:

Michael Glazer

Bingham McCutchen LLP

355 South Grand Avenue, Suite 4400

Los Angeles, CA 90071-3106

It is proposed that this filing will become effective (check appropriate box):

ýimmediately upon filing pursuant to paragraph (b) of Rule 485; or

¨ on ______________, pursuant to paragraph (b) of Rule 485; or

¨60 days after filing pursuant to paragraph (a)(1) of Rule 485;

¨ on ______________  pursuant to paragraph (a)(1) of Rule 485; or

¨75 days after filing pursuant to paragraph (a)(2) of Rule 485; or

¨ on _________ pursuant to paragraph (a)(2) of Rule 485; or

¨ on  __________ pursuant to paragraph (a)(3) of Rule 485.

If appropriate, check the following box:

¨This post-effective amendment designates a new effective date for a previously filed post-effective amendment.

SIGNATURES

Pursuant to the requirements of the Securities Act of 1933, as amended, and the Investment Company Act of 1940, as amended, the Registrant certifies that it meets all of the requirements for effectiveness of this registration statement under rule 485(b) under the Securities Act of 1933 and has duly caused this Registration Statement to be signed on its behalf by the undersigned, duly authorized, in the City of Milwaukee and State of Wisconsin, on the 12th day of April, 2011.

INVESTMENT MANAGERS SERIES TRUST
By:	/s/ John P. Zader
	John P. Zader, President

Pursuant to the requirements of the Securities Act of 1933, as amended, this Registration Statement has been signed on the 12th day of April, 2011, by the following persons in the capacities set forth below.

Signature	Title
†
Ashley Toomey Rabun	Trustee
†
William H. Young	Trustee
†
Charles H. Miller	Trustee
/s/ John P. Zader
John P. Zader	Trustee and President
†	Trustee and Vice President
Eric M. Banhazl
/s/ Rita Dam
Rita Dam	Treasurer and Principal Financial and Accounting Officer

† By /s/Rita Dam                                                                                                       

Attorney-in-fact, pursuant to power of attorney previously filed

with Post-Effective Amendment No. 31 on February 1, 2008.

EXHIBIT INDEX

Exhibit	Exhibit No.
XBRL Instance Document	EX-101.INS
XBRL Taxonomy Extension Schema Document	EX-101.SCH
XBRL Taxonomy Extension Calculation Linkbase	EX-101.CAL
XBRL Taxonomy Extension Definition Linkbase	EX-101.DEF
XBRL Taxonomy Extension Labels Linkbase	EX-101.LAB
XBRL Taxonomy Extension Presentation Linkbase	EX-101.PRE