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 22, 2026

United Therapeutics Corporation

(Exact Name of Registrant as Specified in its Charter)

Registrant’s telephone number, including area code: (301) 608-9292

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:

Securities registered pursuant to Section 12(b) of the Act:

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.   ¨

On July 22, 2026, the Board of Directors (the Board) of United Therapeutics Corporation (the Company), acting upon the recommendation of its Nominating and Governance Committee, increased the size of the Board to 13 members and appointed Victor Dzau, M.D., to serve as a member of the Board. The Board determined that Dr. Dzau will not serve on a Board committee initially.

There is no arrangement or understanding between Dr. Dzau and any other persons pursuant to which he was selected as a director of the Company. Since the beginning of the Company’s last fiscal year through the present, there have been no transactions with the Company, and there are currently no proposed transactions with the Company, in which the amount involved exceeds $120,000 and in which Dr. Dzau had or will have a direct or indirect material interest within the meaning of Item 404(a) of Regulation S-K.

In connection with Dr. Dzau’s appointment to the Board, the Company awarded him the following awards under the Company’s 2026 Stock Incentive Plan: (a) 380 restricted stock units and 1,190 stock options, representing his initial grant upon joining the Board, and (b) 350 restricted stock units and 1,110 stock options, which are pro-rata grants representing the remainder of the 2026-2027 Board service year. These awards were granted on July 22, 2026, in accordance with the Company’s standard non-employee director compensation program (the Director Compensation Program), as described in the Company’s definitive proxy statement for its 2026 annual meeting of shareholders, filed with the Securities and Exchange Commission (SEC) on April 29, 2026. Dr. Dzau will be provided further compensation for his services in accordance with the Director Compensation Program. Dr. Dzau and the Company also entered into the Company’s standard indemnification agreement for directors and executive officers, effective July 22, 2026, the form of which was filed with the SEC as Exhibit 10.1 to the Company’s Current Report on Form 8-K filed October 1, 2021.

A copy of the press release announcing Dr. Dzau’s appointment is being furnished as Exhibit 99.1 to this Current Report on Form 8-K and incorporated herein by reference.

The information in this Item 7.01 and Exhibit 99.1 attached hereto are being furnished and shall not be deemed “filed” for purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the Exchange Act), or otherwise subject to the liabilities of that section, nor shall it be deemed incorporated by reference in any filing under the Securities Act of 1933, as amended, or the Exchange Act as amended, regardless of any general incorporation language in such filing.

(d)    Exhibits

SIGNATURE

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