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): September 16, 2024

Registrant’s telephone number, including area code: (919) 328-4400

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 (see General Instruction A.2. below):

¨ Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

¨ Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

¨ Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

¨ Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

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. ¨

Item 8.01 Other Events.

As previously disclosed, on August 21, 2024, Liquidia Corporation, a Delaware corporation (the “Company”) filed a lawsuit (the “FDA Suit”) in the U.S. District Court of the District of Columbia (the “District Court”) (Case No. 1:24-cv-02428) that challenged the recent decision by the U.S. Food and Drug Administration (the “FDA”) to grant 3-year new clinical investigation exclusivity (NCI exclusivity) to Tyvaso DPI. As also previously disclosed, on August 20, 2024, United Therapeutics Corporation (“United Therapeutics”) voluntarily dismissed, without prejudice, the complaint it had filed against the FDA in the District Court, challenging the FDA’s acceptance of Liquidia’s amended New Drug Application (the “NDA”) for YUTREPIA (treprostinil) inhalation powder (“YUTREPIA”) for review.

On September 16, 2024, United Therapeutics filed new cross-claims in the FDA Suit against the FDA, re-asserting its challenge to the FDA’s acceptance of Liquidia’s NDA for YUTREPIA. The Company intends to vigorously defend its ability to launch YUTREPIA and to defend itself against these allegations.

Item 9.01 Financial Statements and Exhibits.

(d) 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.