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): July 2, 2018 (June 27, 2018)

EXPRESS SCRIPTS HOLDING COMPANY

(Exact name of registrant as specified in its charter)

Registrant’s telephone number, including area code 314-996-0900

Not Applicable

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:

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter).

Emerging growth company  ☐

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act.  ☐

Item 1.01 Entry into a Material Definitive Agreement

As previously announced, on March 8, 2018, Express Scripts Holding Company (the “Company”) entered into an Agreement and Plan of Merger (the “Merger Agreement”) with Cigna Corporation, a Delaware corporation (“Cigna”), Halfmoon Parent, Inc., a Delaware corporation and a direct wholly owned subsidiary of Cigna (“Holdco”), Halfmoon I, Inc., a Delaware corporation and a direct wholly owned subsidiary of Holdco (“Merger Sub 1”), and Halfmoon II, Inc., a Delaware corporation and a direct wholly owned subsidiary of Holdco (“Merger Sub 2”). As previously disclosed, subject to the conditions of the Merger Agreement, Cigna will acquire the Company in a cash and stock transaction through: (1) the merger of Merger Sub 1 with and into Cigna, with Cigna surviving as a direct wholly owned subsidiary of Holdco, and (2) the merger of Merger Sub 2 with and into the Company, with the Company surviving as a direct wholly owned subsidiary of Holdco.

On June 27, 2018, the Company and the other parties to the Merger Agreement entered into Amendment No. 1 to the Merger Agreement (“Amendment No. 1”). Pursuant to Amendment No. 1, upon closing of Cigna’s acquisition of the Company, Dr. Mark McClellan, the Director of the Robert J. Margolis, MD Center for Health Policy at Duke University, will join the board of directors of Holdco.

The foregoing description of Amendment No. 1 is not complete and is subject to and qualified in its entirety by reference to Amendment No. 1, a copy of which is attached hereto as Exhibit 2.1 and the terms of which are incorporated herein by reference.

FORWARD LOOKING STATEMENTS

Cautionary Notes on Forward Looking Statements

Information included or incorporated by reference in this communication, and information which may be contained in other filings with the Securities and Exchange Commission (the “SEC”) and press releases or other public statements, contains or may contain forward-looking statements. These forward-looking statements include, among other things, statements of plans, objectives, expectations (financial or otherwise) or intentions.

Forward-looking statements, including as they relate to Express Scripts Holding Company or Cigna Corporation, the management of either such company or the transaction, involve risks and uncertainties. Actual results may differ significantly from those projected or suggested in any forward-looking statements. Express Scripts Holding Company and Cigna Corporation do not undertake any obligation to release publicly any revisions to such forward-looking statements to reflect events or circumstances occurring after the date hereof or to reflect the occurrence of unanticipated events. Any number of factors could cause actual results to differ materially from those contemplated by any forward-looking statements, including, but not limited to, the risks associated with the following:

You should carefully consider these and other relevant factors, including those risk factors in this communication and other risks and uncertainties that affect the businesses of Express Scripts Holding Company and Cigna Corporation described in their respective filings with the SEC, including the preliminary joint proxy statement/prospectus contained in the Form S-4 of Halfmoon Parent, Inc. (“Holdco”), which was filed with the SEC on May 15, 2018 and amended on June 20, 2018, when reviewing any forward-looking statement. These factors are noted for investors as permitted under the Private Securities Litigation Reform Act of 1995. Investors should understand it is impossible to predict or identify all such factors or risks. As such, you should not consider either foregoing lists, or the risks identified in SEC filings, to be a complete discussion of all potential risks or uncertainties.

IMPORTANT INFORMATION ABOUT THE TRANSACTION AND WHERE TO FIND IT

This communication does not constitute an offer to buy or solicitation of an offer to sell any securities. In connection with the proposed transaction, on May 15, 2018, Holdco has filed a registration statement on Form S-4 that included a joint proxy statement of Cigna Corporation and Express Scripts Holding Company that also constitutes a prospectus of Holdco. The registration statement was amended on June 20, 2018. These materials have not yet been declared effective, are not yet final and may be amended. Cigna Corporation and Express Scripts Holding Company also plan to file other relevant documents with the SEC regarding the proposed transaction. INVESTORS AND SECURITY HOLDERS ARE URGED TO READ THE PRELIMINARY JOINT PROXY

STATEMENT/PROSPECTUS AND OTHER RELEVANT DOCUMENTS FILED WITH THE SEC, AND THE DEFINITIVE VERSIONS THEREOF (WHEN THEY BECOME AVAILABLE), CAREFULLY AND IN THEIR ENTIRETY BECAUSE THEY CONTAIN AND WILL CONTAIN IMPORTANT INFORMATION. You may obtain a free copy of the preliminary materials filed on May 15, 2018 and June 20, 2018, the definitive version of the joint proxy statement/prospectus (when it becomes available) and other relevant documents filed by Holdco, Cigna Corporation and Express Scripts Holding Company with the SEC at the SEC’s website at www.sec.gov. Copies of documents filed with the SEC by Cigna Corporation will be available free of charge on Cigna Corporation’s website at www.cigna.com or by contacting Cigna Corporation’s Investor Relations Department at (215) 761-4198. Copies of documents filed with the SEC by Express Scripts Holding Company will be available free of charge on Express Scripts Holding Company’s website at www.express-scripts.com or by contacting Express Scripts Holding Company’s Investor Relations Department at (314) 810-3115.

PARTICIPANTS IN THE SOLICITATION

Cigna Corporation (and, in some instances, Holdco) and Express Scripts Holding Company and their respective directors and executive officers may be deemed to be participants in the solicitation of proxies in respect of the proposed transaction under the rules of the SEC. Investors may obtain information regarding the names, affiliations and interests of directors and executive officers of Cigna Corporation (and, in some instances, Holdco) in Cigna Corporation’s Annual Report on Form 10-K for the year ended December 31, 2017, which was filed with the SEC on February 28, 2018, its definitive proxy statement for its 2018 Annual Meeting, which was filed with the SEC on March 16, 2018, and the preliminary joint proxy statement/prospectus contained in the Form S-4, which was filed by Holdco with the SEC on May 15, 2018 and amended on June 20, 2018. Investors may obtain information regarding the names, affiliations and interests of Express Scripts Holding Company’s directors and executive officers in Express Scripts Holding Company’s Annual Report on Form 10-K for the year ended December 31, 2017, which was filed with the SEC on February 27, 2018, its definitive proxy statement for its 2018 Annual Meeting, which was filed with the SEC on March 29, 2018, and the preliminary joint proxy statement/prospectus contained in the Form S-4, which was filed by Holdco with the SEC on May 15, 2018 and amended on June 20, 2018. You may obtain free copies of these documents at the SEC’s website at www.sec.gov. Copies of documents filed with the SEC by Cigna Corporation will be available free of charge on Cigna Corporation’s website at www.cigna.com or by contacting Cigna Corporation’s Investor Relations Department at (215) 761-4198. Copies of documents filed with the SEC by Express Scripts Holding Company will be available free of charge on Express Scripts Holding Company’s website at www.express-scripts.com or by contacting Express Scripts Holding Company’s Investor Relations Department at (314) 810-3115. Other information regarding the participants in the proxy solicitation and a description of their direct and indirect interests, by security holdings or otherwise, is contained in the joint proxy statement/prospectus and will be contained in other relevant materials to be filed with the SEC regarding the proposed transaction if and when they become available. Investors should read the preliminary joint proxy statement/prospectus, and the definitive version thereof (when it becomes available), carefully and in its entirety before making any voting or investment decisions.

NO OFFER OR SOLICITATION

This communication is for informational purposes only and not intended to and does not constitute an offer to subscribe for, buy or sell, the solicitation of an offer to subscribe for, buy or sell or an invitation to subscribe for, buy or sell any securities or the solicitation of any vote or approval in any jurisdiction pursuant to or in connection with the proposed transaction or otherwise, nor shall there be any sale, issuance or transfer of securities in any jurisdiction in contravention of applicable law. No offer of securities shall be made except by means of a prospectus meeting the requirements of Section 10 of the Securities Act of 1933, as amended, and otherwise in accordance with applicable law.

Item 9.01. Financial Statements and Exhibits.

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.

Dated: July 2, 2018