UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, DC 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d)

of the Securities Exchange Act of 1934

Date of Report: May 28, 2013

POWERSHARES DB US DOLLAR INDEX TRUST

(Registrant)

POWERSHARES DB US DOLLAR INDEX BULLISH FUND

POWERSHARES DB US DOLLAR INDEX BEARISH FUND

(Co-Registrants)

(Exact Name of each Registrant as Specified in its Charter)

001-33314, 001-33317 and 001-33318

(Commission File Number(s))

(212) 250-5883

(Registrant’s telephone number, including area code)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrants under any of the following provisions (see General Instruction A.2. below):

(a) On May 28, 2013, the Board of Managers of DB Commodity Services LLC, the managing owner (the “Managing Owner”) of PowerShares DB US Dollar Index Trust, Powershares DB US Dollar Index Bullish Fund and PowerShares DB US Dollar Index Bearish Fund (collectively, the “Registrant”), on behalf of the Registrants, dismissed KPMG LLP (“KPMG”) as the independent registered public accounting firm for the Registrant, effective May 28, 2013.

The reports of KPMG on each of the Registrants’ financial statements as of and for the two most recent fiscal years (ending December 31, 2012 and December 31, 2011) did not contain an adverse opinion or a disclaimer of opinion, and were not qualified or modified as to uncertainties, audit scope or accounting principles.

During each of the Registrants’ two most recent fiscal years (ending December 31, 2012 and December 31, 2011) and during the period from the end of the most recently completed fiscal year through the date of this Form 8-K, there were no disagreements between any of the Registrants and KPMG on any matter of accounting principles or practices, financial statement disclosure or auditing scope or procedure, which disagreements, if not resolved to the satisfaction of KPMG, would have caused it to make a reference to the subject matter thereof in its report on the financial statements of the Registrants for such periods.

During each of the Registrants’ two most recent fiscal years (ended December 31, 2012 and December 31, 2011) and during the period from the end of the most recently completed fiscal year through the date of this Form 8-K, there were no “reportable events” (as defined in Regulation S-K Item 304(a)(1)(v)).

The Managing Owner, on behalf of the Registrants, has provided KPMG with a copy of the foregoing disclosures and has requested that KPMG furnish it with a letter addressed to the Securities and Exchange Commission stating whether it agrees with the statements made by the Registrants set forth above. A copy of KPMG’s letter dated May 30, 2013 is filed as Exhibit 16.1 to this Form 8-K.

(b) On May 28, 2013, The Board of Managers of the Managing Owner, on behalf of the Registrants, approved the engagement of PricewaterhouseCoopers LLP as the independent registered public accounting firm for the Registrants, effective May 28, 2013. During each of the Registrants’ two most recent fiscal years (ended December 31, 2012 and December 31, 2011) and during the period from the end of the most recently completed fiscal year through the date of this Form 8-K, PricewaterhouseCoopers LLP has not been engaged as either the principal accountant to audit any of the Registrants’ financial statements or as an independent accountant to audit a significant subsidiary of any of the Registrants and on whom KPMG was expected to express reliance in its report. In addition, during each of the Registrants’ two most recent fiscal years (ended December 31, 2012 and December 31, 2011) and during the period from the end of the most recently completed fiscal year through the date of this Form 8-K, neither the Registrants, the Managing Owner, nor anyone on their behalf consulted with PricewaterhouseCoopers LLP, on behalf of the Registrants, regarding the application of accounting principles to a specified transaction (either completed or proposed), the type of audit opinion that might be rendered on the Registrants’ financial statements, or any matter that was either the subject of a “disagreement,” as defined in Item 304(a)(1)(iv) of Regulation S-K and the instructions thereto, or a “reportable event,” as defined in Item 304(a)(1)(v) of Regulation S-K.

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, each registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

Date: May 30, 2013