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): March 25, 2016

PINNACLE ENTERTAINMENT, INC.

(Exact name of registrant as specified in its charter)

Registrant’s Telephone Number, including area code: (702) 541-7777

N/A

(Former name or former address, if changed since last report)

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 July 20, 2015, Pinnacle Entertainment, Inc., a Delaware corporation (the “Company”), Gaming and Leisure Properties, Inc., a Pennsylvania corporation (“GLPI”), and Gold Merger Sub, LLC, a Delaware limited liability company and a wholly owned subsidiary of GLPI (“Merger Sub”), entered into an Agreement and Plan of Merger (the “Merger Agreement”), on the terms and subject to the conditions of which, at the effective time of the Merger, the Merger Sub will be merged with and into the Company (the “Merger”), with Merger Sub surviving the Merger.

As a result of continuing discussions among the parties, on March 25, 2016, the Company, GLPI and Merger Sub entered into Amendment No. 1 to the Merger Agreement (“Amendment No. 1”), pursuant to which the End Date (as defined in the Merger Agreement) has been extended to April 30, 2016 from March 31, 2016. The closing of the transactions is expected to occur following receipt of all required regulatory approvals and satisfaction of other customary closing conditions, which the Company anticipates will occur in April 2016.

Other than as expressly modified pursuant to Amendment No. 1, the Merger Agreement, which was previously filed as Exhibit 2.1 to the Current Report on Form 8-K filed with the Securities and Exchange Commission (the “SEC”) by the Company on July 23, 2015, remains in full force and effect as originally executed on July 20, 2015. The foregoing description of Amendment No. 1 and the transactions contemplated thereby does not purport to be complete and is subject to, and qualified in its entirety by, the full text of Amendment No. 1, which is attached hereto as Exhibit 2.1 to this Current Report on Form 8-K and is incorporated herein by reference.

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Forward Looking Statements

All statements included in this press release, other than historical information or statements of historical fact, are “forward-looking statements” within the meaning of Section 27A of the Securities Act of 1933 and Section 21E of the Securities Exchange Act of 1934. Words such as, but not limited to, “believes,” “expects,” “anticipates,” “estimates,” “intends,” “plans,” “could,” “may,” “will,” “should,” and similar expressions are intended to identify forward-looking statements. Such forward-looking statements, may include, without limitation, statements regarding the transaction between PNK and GLPI whereby PNK would sell its real estate assets to GLPI and spin-off PNK’s operations into a new public company; receipt of regulatory approvals and the consummation of the transaction and the timing thereof. All forward-looking statements rely on a number of assumptions, estimates and data concerning future results and events and are subject to a number of uncertainties and other factors, many of which are outside PNK’s control that could cause actual results to differ materially from actual those reflected in such statements. There is no assurance that a transaction with GLPI will be completed on any particular timeframe or at all. Accordingly, PNK cautions that the forward-looking statements contained herein are qualified by these and other important factors and uncertainties that could cause results to differ materially from those reflected by such statements. For more information on the potential factors, please review PNK’s filings with the Securities and Exchange Commission, including, but not limited to, its Annual Report on Form 10-K, its Quarterly Reports on Form 10-Q and its Current Reports on Form 8-K.

Additional Information

This communication shall not constitute an offer to sell or the solicitation of an offer to buy any securities, nor shall there be any sale of securities in any jurisdiction in which such offer, solicitation or sale would be unlawful prior to registration or qualification under the securities laws of any such jurisdiction. No offering of securities shall be made except by means of a prospectus meeting the requirements of Section 10 of the U.S. Securities Act of 1933, as amended. In connection with the proposed transaction between GLPI and Pinnacle, GLPI has filed with the SEC a registration statement on Form S-4 (File No. 333-206649) that includes a definitive joint proxy statement of GLPI and Pinnacle that also constitutes a prospectus of GLPI. This communication is not a substitute for the joint proxy statement/prospectus or any other document that GLPI or Pinnacle may file with the SEC or send to their shareholders in connection with the proposed transaction. The registration statement on Form S-4 was declared effective by the SEC on February 16, 2016. Pinnacle mailed the definitive proxy statement/prospectus to its stockholders on or about February 16, 2016, and its stockholders approved the transaction on March 15, 2016. INVESTORS AND SECURITY HOLDERS ARE URGED TO READ THE FORM S-4, INCLUDING THE DEFINITIVE JOINT PROXY STATEMENT/PROSPECTUS FILED AND OTHER RELEVANT DOCUMENTS THAT WILL BE FILED WITH THE SEC IF AND WHEN THEY BECOME AVAILABLE, BECAUSE THEY WILL CONTAIN IMPORTANT INFORMATION. You may obtain free copies of the definitive joint proxy statement/prospectus and other relevant documents filed by GLPI and Pinnacle with the SEC at the SEC’s website at www.sec.gov. Copies of the documents filed with the SEC by GLPI are available free of charge on GLPI’s investor relations website at investors.glpropinc.com or by contacting GLPI’s investor relations representative at (203) 682-8211. Copies of the documents filed with the SEC by Pinnacle are available free of charge on Pinnacle’s investor relations website at investors.pnkinc.com or by contacting Pinnacle’s investor relations department at (702) 541-7777.

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SIGNATURES

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

Date: March 28, 2016

EXHIBIT INDEX

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