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 10, 2024

RHYTHM PHARMACEUTICALS, INC.

(Exact name of registrant as specified in its charter)

222 Berkeley Street

12th Floor

Boston, MA 02116

(Address of principal executive offices) (Zip Code)

Registrant’s telephone number, including area code: (857) 264-4280

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:

¨  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. 

On July 10, 2024, Rhythm Pharmaceuticals, Inc. (the “Company”) filed with the Securities and Exchange Commission (the “SEC”) a prospectus supplement to the prospectus included in the Company’s registration statement on Form S-3ASR (File No. 333-270233), filed with the SEC on March 2, 2023 (the “Registration Statement”), covering the resale from time to time by certain stockholders of up to an aggregate of 3,124,995 shares (the “Shares”) of the Company’s common stock, par value $0.001 per share, to satisfy registration rights that the Company granted to such stockholders in connection with the Company’s issuance and sale of 150,000 shares of the Company’s Series A Convertible Preferred Stock, par value $0.001 per share, for an aggregate purchase price of $150,000,000 on April 15, 2024.

A copy of the legal opinion of Latham & Watkins LLP relating to the validity of the Shares is filed herewith as Exhibit 5.1 and is incorporated herein by reference, and is filed with reference to, and is hereby incorporated by reference into, the Registration Statement.

Item 9.01. Financial Statements and Exhibits.

(d) Exhibits

SIGNATURES

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.