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 (Date of earliest event reported) September 5, 2014

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

Section 8 – Other Events

Item 8.01 Other Events.

As previously disclosed, on April 29, 2014, Exelon Corporation, a Pennsylvania corporation (“Exelon”), entered into an Agreement and Plan of Merger (the “Original Merger Agreement”) by and among Exelon, Purple Acquisition Corp., a Delaware corporation and a wholly owned subsidiary of Exelon (“Merger Sub”), and Pepco Holdings, Inc., a Delaware corporation (“PHI”). The Original Merger Agreement was amended and restated by the Amended and Restated Agreement and Plan of Merger, dated as of July 18, 2014, among Exelon, Merger Sub and PHI.

Under the provisions of the Hart-Scott-Rodino Act (HSR Act), Exelon and PHI may not complete their proposed merger until Exelon and PHI have made filings with the United States Department of Justice (DOJ) and the Federal Trade Commission and the applicable HSR Act waiting period has expired or been terminated. Exelon and PHI initially filed pre-merger notifications under the HSR Act on August 6, 2014. Following informal discussions with the DOJ, Exelon voluntarily withdrew its pre-merger notification filing effective on September 5, 2014, and plans to refile it on September 9, 2014. The withdrawal and refiling are procedural steps to provide the DOJ with an additional 30 days to complete its review of the proposed merger. Assuming refiling on September 9, the waiting period will expire at 11:59 p.m. Eastern Time on October 9, 2014, unless a request is made for additional information or documentary material or the review period is voluntarily extended or earlier terminated. Exelon and PHI will continue to work cooperatively with the DOJ as it conducts its review of the proposed merger. Exelon and PHI continue to expect to complete the merger in the second or third quarter 2015.

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Cautionary Statements Regarding Forward-Looking Information

This report contains certain forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995, that are subject to risks and uncertainties. The factors that could cause actual results to differ materially from the forward-looking statements made by Exelon include those factors discussed herein, as well as the items discussed in (1) Exelon’s 2013 Annual Report on Form 10-K in (a) ITEM 1A. Risk Factors, (b) ITEM 7. Management’s Discussion and Analysis of Financial Condition and Results of Operations and (c) ITEM 8. Financial Statements and Supplementary Data: Note 22; (2) Exelon’s Second Quarter 2014 Quarterly Report on Form 10-Q in (a) Part II, Other Information, ITEM 1A. Risk Factors; (b) Part 1, Financial Information, ITEM 2. Management’s Discussion and Analysis of Financial Condition and Results of Operations and (c) Part I, Financial Information, ITEM 1. Financial Statements: Note 17; and (3) other factors discussed in filings with the SEC by Exelon. Readers are cautioned not to place undue reliance on these forward-looking statements, which apply only as of the date of this report. Exelon does not undertake any obligation to publicly release any revision to its forward-looking statements to reflect events or circumstances after the date of this report.

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SIGNATURES

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

September 5, 2014