UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 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): November 7, 2013 (November 7, 2013)

REGENCY ENERGY PARTNERS LP

(Exact name of registrant as specified in its charter)

2001 Bryan Street, Suite 3700

Dallas, Texas 75201

(Address of principal executive offices, including zip code)

(214) 750-1771

(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 registrant under any of the following provisions:

On November 7, 2013, Regency Energy Partners LP, a Delaware limited partnership (the “Partnership”), together with RVP LLC, a Delaware limited liability company and a wholly owned subsidiary of the Partnership (“RVP”) and Regency GP LP, a Delaware limited partnership and the general partner of the Partnership (“Partnership GP”), entered into an amendment (the “Amendment”) to the Agreement and Plan of Merger (the “Merger Agreement”), dated as of October 9, 2013, with PVR Partners, L.P., a Delaware limited partnership (“PVR”), and PVR GP, LLC, a Delaware limited liability company and the general partner of PVR.

The Amendment provides that upon the terms and subject to the conditions set forth in the Merger Agreement, as amended by the Amendment, PVR will merge with and into the Partnership (the “Merger”), with the Partnership continuing its existence under Delaware law as the surviving entity in the Merger. The Partnership expects that, as a result of the Merger and upon the consummation thereof, it will directly assume, and succeed PVR as issuer of, PVR’s currently outstanding senior notes. Prior to the Amendment, the Merger Agreement had provided for the merger of RVP with and into PVR, with PVR continuing its existence under Delaware law as the surviving entity and PVR becoming a wholly owned subsidiary of the Partnership.

The Amendment is attached hereto as Exhibit 2.1 and is incorporated herein by reference.

(d) Exhibits.

IMPORTANT ADDITIONAL INFORMATION WILL BE FILED WITH THE SEC

INVESTORS AND SECURITY HOLDERS ARE URGED TO READ THE PROXY STATEMENT/PROSPECTUS AND THE REGISTRATION STATEMENT REGARDING THE TRANSACTION CAREFULLY WHEN THEY ARE AVAILABLE. These documents (when they become available), and any other documents filed by PVR or the Partnership with the SEC, may be obtained free of charge at the SEC’s website, at www.sec.gov. In addition, security holders will be able to obtain free copies of the proxy statement/prospectus (when available) from PVR by contacting Investor Relations by mail at Attention: Investor Relations, Three Radnor Corporate Center, Suite 301, 100 Matsonford Road, Radnor, Pennsylvania 19087.

PARTICIPANTS IN THE SOLICITATION

The Partnership and PVR, and their respective directors and executive officers, may be deemed to be participants in the solicitation of proxies in respect of the transactions contemplated by the Agreement and Plan of Merger. Information regarding the directors and executive officers of Regency GP LLC, the general partner of the Partnership’s general partner, is contained in the Partnership’s Form 10-K for the year ended December 31, 2012, which has been filed with the SEC. Information regarding PVR’s directors and executive officers is contained in PVR’s Form 10-K for the year ended December 31, 2012 and its proxy statement filed on April 25, 2013, which are filed with the SEC. A more complete description will be available in the registration statement and the proxy statement/prospectus to be filed in connection with the Merger.

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SAFE HARBOR FOR FORWARD-LOOKING STATEMENTS

Statements in this document regarding the proposed transaction between the Partnership and PVR, the expected timetable for completing the proposed transaction, future financial and operating results, benefits and synergies of the proposed transaction, future opportunities for the combined company and any other statements about the Partnership’s or PVR’s management’s future expectations, beliefs, goals, plans or prospects constitute forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. Any statements that are not statements of historical fact (including statements containing the words “believes,” “plans,” “anticipates,” “expects,” “estimates” and similar expressions) should also be considered to be forward-looking statements.

The Partnership and PVR cannot give any assurance that expectations and projections about future events will prove to be correct. Forward-looking statements are subject to a variety of risks, uncertainties and assumptions. These risks and uncertainties include the risks that the proposed transaction may not be consummated or the benefits contemplated therefrom may not be realized. Additional risks include: the ability to obtain requisite regulatory and unitholder approval and the satisfaction of the other conditions to the consummation of the proposed transaction, the ability of the Partnership to successfully integrate PVR’s operations and employees and realize anticipated synergies and cost savings, the potential impact of the announcement or consummation of the proposed transaction on relationships, including with employees, suppliers, customers, competitors and credit rating agencies, the ability to achieve revenue, DCF and EBITDA growth, volatility in the price of oil, natural gas, and natural gas liquids, declines in the credit markets and the availability of credit for the combined company as well as for producers connected to the combined company’s system and its customers, the level of creditworthiness of, and performance by counterparties and customers, the ability to access capital to fund organic growth projects and acquisitions, including significant acquisitions, and the ability to obtain debt and equity financing on satisfactory terms, the use of derivative financial instruments to hedge commodity and interest rate risks, the amount of collateral required to be posted from time-to-time, changes in commodity prices, interest rates, and demand for the combined company’s services, changes in laws and regulations impacting the midstream sector of the natural gas industry, weather and other natural phenomena, acts of terrorism and war, industry changes including the impact of consolidations and changes in competition, the ability to obtain required approvals for construction or modernization of facilities and the timing of production from such facilities, and the effect of accounting pronouncements issued periodically by accounting standard setting boards. Therefore, actual results and outcomes may differ materially from those expressed in such forward-looking statements.

These and other risks and uncertainties are discussed in more detail in filings made by the Partnership and PVR with the Securities and Exchange Commission, which are available to the public. The Partnership and PVR undertake no obligation to update publicly or to revise any forward-looking statements, whether as a result of new information, future events or otherwise.

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SIGNATURE

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.

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EXHIBIT INDEX

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