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): June 27, 2024

RIGEL PHARMACEUTICALS, INC.

(Exact name of registrant as specified in its charter)

Delaware

(State or other jurisdiction of incorporation)

Registrant’s telephone number, including area code: (650) 624-1100

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 (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))

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. ¨

The information set forth in Item 5.03 of this Current Report on Form 8-K is incorporated by reference into this Item 3.03.

On June 27, 2024, Rigel Pharmaceuticals, Inc., a Delaware corporation (the “Company”), effected a one-for-10 reverse stock split (“Reverse Stock Split”) of the Company’s common stock, par value $0.001 (the “Common Stock”). As previously disclosed, at its annual meeting of stockholders held on May 24, 2024, the stockholders of the Company approved a proposal to authorize the Company’s Board of Directors (the “Board”) to amend the Company’s Amended and Restated Certificate of Incorporation (the “Charter”) to authorize the Board to effect the Reverse Stock Split at a ratio between 1:2 to 1:20 shares of Common Stock (the “Split Ratio Range”), with the final determination of a ratio within the Split Ratio Range to be approved by the Board following stockholder approval. On June 15, 2024, the Board approved the Reverse Stock Split at a ratio of one-for-10. Following such approval, the Company filed an amendment to its Charter (the “Amendment”) with the Secretary of State of the State of Delaware to effect the Reverse Stock Split, with an effective time of 12:01 a.m. Eastern Time on June 27, 2024. On June 27, 2024, the Common Stock began trading on a split-adjusted basis under a new CUSIP number, 766559702.

No fractional shares will be issued in connection with the Reverse Stock Split. Stockholders who would otherwise be entitled to a fractional share of Common Stock are instead entitled to a check representing the cash value equal to the fraction to which the stockholder would otherwise be entitled, multiplied by the closing price of the Common Stock, as reported by Nasdaq, on the last trading day prior to the effective date of the Reverse Stock Split.

The foregoing description of the Amendment does not purport to be complete and is qualified in its entirety by the full text of the Amendment, a copy of which is filed as Exhibit 3.1 to this Current Report on Form 8-K and is incorporated herein by reference.

(d) Exhibits.

Exhibit No.   Description

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.