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

April 29, 2014

Date of Report (Date of earliest event reported)

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 7 – Regulation FD

Item 7.01. Regulation FD Disclosure.

On April 30, 2014, Exelon Corporation (Exelon) and Pepco Holdings, Inc. (PHI) issued a joint news release announcing that they have entered into an Agreement and Plan of Merger, dated as of April 29, 2014, by and among Exelon, Purple Acquisition Corp., a wholly-owned subsidiary of Exelon (Merger Sub), and PHI, pursuant to which Merger Sub will be merged with and into PHI, with PHI continuing as the surviving corporation and becoming a wholly-owned subsidiary of Exelon (the Merger). The news release is attached to this report as Exhibit 99.1. This Form 8-K and the attached exhibits are provided under Items 7.01 and 9.01 of Form 8-K and are furnished to, but not filed with, the Securities and Exchange Commission.

A one-hour webcast teleconference will be held by Exelon and PHI for the financial community on April 30, 2014, at 11:00 A.M. Eastern Time. The call-in number in the U.S. and Canada is 800-690-3108, and the international call-in number is 973-935-8753. If requested, the conference ID number is 14743663. Media representatives are invited to participate on a listen-only basis. The call will be webcast and archived on Exelon’s and PHI’s websites: www.exeloncorp.com and www.pepcoholdings.com (select the Investors page of either site). The slides to be used in connection with the webcast teleconference are attached hereto as Exhibit 99.2.

Telephone replays will be available until May 14, 2014. The U.S. and Canada number for replays is 800-585-8367, and the international number is 404-537-3406. The conference ID number is 14743663.

The information required by Item 1.01, including a copy of the Agreement and Plan of Merger, will be filed in a separate Current Report on Form 8-K.

Section 9 – Financial Statements and Exhibits

Item 9.01. Financial Statements and Exhibits.

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Cautionary Statements Regarding Forward-Looking Information

Except for the historical information contained herein, certain of the matters discussed in this communication constitute “forward-looking statements” within the meaning of the Securities Act of 1933 and the Securities Exchange Act of 1934, both as amended by the Private Securities Litigation Reform Act of 1995. Words such as “may,” “might,” “will,” “should,” “could,” “anticipate,” “estimate,” “expect,” “predict,” “project,” “future”, “potential,” “intend,” “seek to,” “plan,” “assume,” “believe,” “target,” “forecast,” “goal,” “objective,” “continue” or the negative of such terms or other variations thereof and words and terms of similar substance used in connection with any discussion of future plans, actions, or events identify forward-looking statements. These forward-looking statements include, but are not limited to, statements regarding benefits of the proposed merger, integration plans and expected synergies, the expected timing of completion of the transaction, anticipated future financial and operating performance and results, including estimates for growth. These statements are based on the current expectations of management of Exelon Corporation (Exelon) and Pepco Holdings, Inc. (PHI), as applicable. There are a

number of risks and uncertainties that could cause actual results to differ materially from the forward-looking statements included in this communication. For example, (1) PHI may be unable to obtain shareholder approval required for the merger; (2) the companies may be unable to obtain regulatory approvals required for the merger, or required regulatory approvals may delay the merger or cause the companies to abandon the merger; (3) conditions to the closing of the merger may not be satisfied; (4) an unsolicited offer of another company to acquire assets or capital stock of Exelon or PHI could interfere with the merger; (5) problems may arise in successfully integrating the businesses of the companies, which may result in the combined company not operating as effectively and efficiently as expected; (6) the combined company may be unable to achieve cost-cutting synergies or it may take longer than expected to achieve those synergies; (7) the merger may involve unexpected costs, unexpected liabilities or unexpected delays, or the effects of purchase accounting may be different from the companies’ expectations; (8) the credit ratings of the combined company or its subsidiaries may be different from what the companies expect; (9) the businesses of the companies may suffer as a result of uncertainty surrounding the merger; (10) the companies may not realize the values expected to be obtained for properties expected or required to be sold; (11) the industry may be subject to future regulatory or legislative actions that could adversely affect the companies; and (12) the companies may be adversely affected by other economic, business, and/or competitive factors. Other unknown or unpredictable factors could also have material adverse effects on future results, performance or achievements of the combined company. Therefore, forward-looking statements are not guarantees or assurances of future performance, and actual results could differ materially from those indicated by the forward-looking statements. Discussions of some of these other important factors and assumptions are contained in Exelon’s and PHI’s respective filings with the Securities and Exchange Commission (SEC), and available at the SEC’s website at www.sec.gov, including: (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; and (2) PHI’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 15. In light of these risks, uncertainties, assumptions and factors, the forward-looking events discussed in this communication may not occur. Readers are cautioned not to place undue reliance on these forward-looking statements, which speak only as of the date of this communication. Neither Exelon nor PHI undertakes any obligation to publicly release any revision to its forward-looking statements to reflect events or circumstances after the date of this communication. New factors emerge from time to time, and it is not possible for Exelon or PHI to predict all such factors. Furthermore, it may not be possible to assess the impact of any such factor on Exelon’s or PHI’s respective businesses or the extent to which any factor, or combination of factors, may cause results to differ materially from those contained in any forward-looking statement. Any specific factors that may be provided should not be construed as exhaustive.

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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.

April 29, 2014

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