Steven L. Hoerter - 22 Nov 2025 Form 4 Insider Report for MBX Biosciences, Inc. (MBX)

Role: Director
Signature: /s/ Richard Bartram, attorney-in-fact
Issuer symbol: MBX
Transactions as of: 22 Nov 2025
Net transactions value: $0
Form type: 4
Filing time: 25 Nov 2025, 08:50:28 UTC
Previous filing: 07 Nov 2025
Next filing: 06 Jan 2026
SEC: View on sec.gov

Reporting Owners (1)

Name	Relationship	Address	Signature	Signature date	CIK
Hoerter Steven L.	Director	C/O MBX BIOSCIENCES INC., 11711 N. MERIDIAN STREET, SUITE 300, CARMEL	/s/ Richard Bartram, attorney-in-fact	25 Nov 2025	0001533451

Derivative Securities (e.g., puts, calls, warrants, options, convertible securities)

Type	Sym	Class	Transaction	Value $	Shares	Change %	* Price $	Shares After	Date	Underlying Class	Amount	Exercise Price	Ownership	Footnotes
transaction	MBX	Stock option (right to buy)	Award	$0	+8,000		$0.000000	8,000	22 Nov 2025	Common Stock	8,000	$27.08	Direct	F1

* An asterisk sign (*) next to the price indicates that the price is likely invalid.

Explanation of Responses:

Id	Content
F1	The grant will vest in equal monthly installments over a one-year period from November 6, 2025, subject to the non-employee director's continued services to the Company.