P. Kent Hawryluk - 02 Feb 2026 Form 4 Insider Report for MBX Biosciences, Inc. (MBX)

Role: President & CEO, Director
Signature: /s/ Richard Bartram, attorney-in-fact
Issuer symbol: MBX
Transactions as of: 02 Feb 2026
Net transactions value: $0
Form type: 4
Filing time: 03 Feb 2026, 16:16:13 UTC
Previous filing: 28 Oct 2025
Next filing: 27 Feb 2026
SEC: View on sec.gov

Reporting Owners (1)

Name	Relationship	Address	Signature	Signature date	CIK
Hawryluk P. Kent	President & CEO, Director	C/O MBX BIOSCIENCES, INC., 11711 N. MERIDIAN STREET, SUITE 300, CARMEL	/s/ Richard Bartram, attorney-in-fact	03 Feb 2026	0001673991

Transactions Table

Type	Sym	Class	Transaction	Value $	Shares	Change %	* Price $	Shares After	Date	Ownership	Footnotes
transaction	MBX	Common Stock	Award	$0	+35,250	+5.3%	$0.000000	699,506	02 Feb 2026	Direct	F1
holding	MBX	Common Stock						468,277	02 Feb 2026	By Trust	F2

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	+164,500		$0.000000	164,500	02 Feb 2026	Common Stock	164,500	$39.07	Direct	F3

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

Explanation of Responses:

Id	Content
F1	Represents the grant of restricted stock units (RSUs). The RSUs will vest over a four (4) year period in equal quarterly installments, subject to the Reporting Person's continued service on such vesting date.
F2	Shares held by the P. Kent Hawryluk Revocable Trust dated January 25, 2011, of which the Reporting Person serves as trustee. The Reporting Person disclaims beneficial ownership except to the extent of any pecuniary interest therein, and this report shall not be deemed an admission that such shares are beneficially owned by him for Section 16 or any other purpose.
F3	The shares underlying this option vest and become exercisable in forty eight (48) equal monthly installments, beginning on March 2, 2026, subject to the Reporting Person's continued service on such vesting date.