Management Change/Compensation, Proxy Results (Form 8-K)

Item 5.02 Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers; Compensatory Arrangements of Certain Officers.

On June 4, 2026, MBX Biosciences, Inc. (the "Company") held its 2026 annual meeting of stockholders (the "Annual Meeting"). As further described under Item 5.07 below, the Company's stockholders approved the election of two Class II directors to serve for a three-year term ending at the annual meeting of stockholders to be held in 2029.

Item 5.07 Submission of Matters to a Vote of Security Holders.

The Company held its Annual Meeting on June 4, 2026. As of April 10, 2026, the record date for the Annual Meeting, there were 47,570,485 shares outstanding shares of the Company's common stock. The Company's stockholders voted on the following matters, which are described in detail in the Proxy Statement: (i) to elect two Class II director nominees, Patrick J. Heron. and Edward T. Mathers, to the Company's Board of Directors, each to hold office until the Company's 2029 annual meeting of stockholders and until their successors are duly elected and qualified, subject to their earlier death, resignation or removal ("Proposal 1") and (ii) to ratify the appointment of Ernst & Young LLP as the Company's independent registered public accounting firm for the fiscal year ending December 31, 2026 ("Proposal 2").

The Company's stockholders approved the Class II director nominees recommended for election in Proposal 1 at the Annual Meeting. The Company's stockholders voted for Class I directors as follows:

The Company's stockholders approved Proposal 2 to ratify the appointment of Ernst & Young LLP as the Company's independent registered public accounting firm for the fiscal year ending December 31, 2026. The votes cast at the Annual Meeting were as follows: