UNITED THERAPEUTICS Corp

(a) Entry into License Agreement Amendment

On November 3, 2026 (the Amendment Effective Date), we entered into the Arena Amendment, which amends the Exclusive License Agreement, dated November 15, 2018 (the License Agreement), with Arena. Under the License Agreement, we hold exclusive rights to develop, manufacture, and commercialize ralinepag.

In exchange for these rights, we agreed to pay Arena (1) an upfront payment of $800.0 million, which was paid on January 24, 2019; (2) a one-time milestone payment of $250.0 million upon the first marketing approval, if any, in the United States of an inhaled version of ralinepag to treat pulmonary arterial hypertension; (3) a one-time milestone payment of $150.0 million upon the first marketing approval, if any, in any of Japan, France, Italy, the United Kingdom, Spain, or Germany of an oral version of ralinepag for any indication; and (4) low double-digit, tiered royalties on net sales of any pharmaceutical product containing ralinepag as an active ingredient, subject to certain adjustments for third-party license payments.

Under the Arena Amendment, we paid Arena a lump-sum, non-refundable payment of $525.0 million on the Amendment Effective Date (the Royalty Substitution Payment) in exchange for the elimination of our obligation to pay royalties on net sales of any product containing ralinepag, including, if approved, ralinepag extended-release tablets and ralinepag DPI. Milestone payment obligations remain in place.

We expect to recognize the $525.0 million Royalty Substitution Payment as research and development expense, during the fourth quarter of 2026.

The foregoing description of the Arena Amendment does not purport to be complete and is qualified in its entirety by reference to the Arena Amendment, a copy of which is filed as Exhibit 10.1 to this Quarterly Report on Form 10-Q and incorporated herein by reference.

(c) Trading Plans

During the three months ended September 30, 2026, no director or Section 16 officer adopted orterminated any Rule 10b5-1 plans or non-Rule 10b5-1 trading arrangements (in each case, as defined in Item 408(a) of Regulation S-K).