Form 8-K Boundless Bio, Inc. For: Jun 15

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

Boundless Bio, Inc.

(Exact Name of Registrant as Specified in Its Charter)

(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:

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 5.07 Submission of Matters to a Vote of Security Holders.

At the annual meeting of stockholders of Boundless Bio, Inc. (the Company) held on June 15, 2026 (the Meeting), two proposals were voted upon by the Company’s stockholders. The proposals are described in detail in the Company’s definitive proxy statement for the Meeting filed with the U.S. Securities and Exchange Commission on April 28, 2026. Below is a brief description of, and the final results of the votes for, each proposal.

Proposal 1: Each of the director nominees was elected as a Class II director to hold office until the Company’s 2029 annual meeting of stockholders, and until their respective successor is duly elected and qualified, by the votes set forth below.

Proposal 2: The Company’s stockholders ratified the appointment of KPMG LLP as the Company’s independent registered public accounting firm for the fiscal year ending December 31, 2026 by the votes set forth below.

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.