As filed with the Securities and Exchange Commission on May 6, 2011

Registration Nos. 333-89822; 811-21114

U.S. SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

Form N-1A

REGISTRATION STATEMENT

UNDER

THE SECURITIES ACT OF 1933	x
Pre-Effective Amendment No.
Post-Effective Amendment No. 42

and/or

REGISTRATION STATEMENT

UNDER

THE INVESTMENT COMPANY ACT OF 1940	x
Amendment No. 50

ProShares Trust

(Exact name of Registrant as Specified in Trust Instrument)

7501 Wisconsin Avenue,

Suite 1000 Bethesda, MD 20814

(Address of Principal Executive Office) (Zip Code)

(240) 497-6400

(Area Code and Telephone Number)

Michael L. Sapir, CEO

ProShare Advisors LLC

7501 Wisconsin Avenue, Suite 1000

Bethesda, MD 20814

(Name and Address of Agent for Service)

with copies to:
John Loder, Esq.	Amy R. Doberman
c/o Ropes & Gray LLP	ProShare Advisors LLC
One International Place	7501 Wisconsin Avenue, Suite 1000
Boston, MA 02110	Bethesda, MD 20814

Approximate date of Proposed Public Offering:

It is proposed that this filing will become effective:

x immediately upon filing pursuant to paragraph (b)

¨ 60 days after filing pursuant to paragraph (a)(1)

¨ on              pursuant to paragraph (a)(1)

¨ 75 days after filing pursuant to paragraph (a)(2)

¨ on (date) pursuant to paragraph (a)(2) of rule 485.

If appropriate, check the following:

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

EXPLANATORY NOTE

This post-effective amendment relates only to the following series of ProShares Trust: ProShares Ultra High Yield and ProShares Ultra Investment Grade Corporate. No information relating to any other series or class of series of ProShares Trust is amended or superseded hereby.

SIGNATURES

Pursuant to the requirements of the Securities Act of 1933 and the Investment Company Act of 1940, the Registrant has duly caused this post-effective amendment (the “Amendment”) to its Registration Statement to be signed on its behalf by the undersigned, thereto duly authorized, in the City of Bethesda and the State of Maryland on May 6, 2011.

ProShares Trust
By:	/s/ Louis M. Mayberg
	Louis M. Mayberg

Pursuant to the requirements of the Securities Act of 1933, this Amendment to the Registration Statement has been signed below by the following persons in the capacities indicated.

Signature	Title	Date
/s/ Michael L. Sapir * Michael L. Sapir	Trustee, Chairman	May 6, 2011
/s/ Russell S. Reynolds, III * Russell S. Reynolds, III	Trustee	May 6, 2011
/s/ Michael Wachs * Michael Wachs	Trustee	May 6, 2011
/s/ Louis M. Mayberg * Louis M. Mayberg	President	May 6, 2011
/s/ Charles S. Todd
Charles S. Todd	Treasurer	May 6, 2011

* By:	/s/ Amy R. Doberman
	Amy R. Doberman
	As Attorney-in-fact

Date: May 6, 2011

EXHIBIT INDEX

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