As filed with the Securities and Exchange Commission on October 18, 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. 48

and/or

REGISTRATION STATEMENT

UNDER

THE INVESTMENT COMPANY ACT OF 1940

Amendment No. 56 x

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. c/o Ropes & Gray LLP One International Place Boston, MA 02110 Amy R. Doberman ProShare Advisors LLC 7501 Wisconsin Avenue, Suite 1000 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.

SIGNATURES

Pursuant to the requirements of the Securities Act of 1933, as amended (the “Securities Act”), and the Investment Company Act of 1940, as amended, the Registrant has duly caused this Post-Effective Amendment No. 48 to its Registration Statement to be signed on its behalf by the undersigned, thereunto duly authorized, in the City of Bethesda and the State of Maryland on October 18, 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	October 18, 2011
/s/ Russell S. Reynolds, III * Russell S. Reynolds, III	Trustee	October 18, 2011
/s/ Michael Wachs * Michael Wachs	Trustee	October 18, 2011
/s/ William D. Fertig*	Trustee	October 18, 2011
William D. Fertig
/s/ Louis M. Mayberg * Louis M. Mayberg	President	October 18, 2011
/s/ Charles S. Todd Charles S. Todd	Treasurer	October 18, 2011

* By:	/s/ Amy R. Doberman
	Amy R. Doberman
	As Attorney-in-fact
Date: October 18, 2011

EXHIBIT INDEX

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