CEO of MBX Biosciences (MBX) receives RSUs and stock options

Rhea-AI Filing Summary

MBX Biosciences President & CEO P. Kent Hawryluk reported new equity awards. On February 2, 2026, he received 35,250 shares of common stock in the form of restricted stock units at $0 per share, bringing his directly held common stock to 699,506 shares.

He was also granted a stock option to buy 164,500 shares of common stock at an exercise price of $39.07 per share, expiring on February 2, 2036, vesting in 48 equal monthly installments starting March 2, 2026. In addition, 468,277 shares are held indirectly by the P. Kent Hawryluk Revocable Trust, for which he serves as trustee.

Insider Trade Summary

3 transactions reported

Mixed 3 txns

Insider Hawryluk P. Kent

Role President & CEO

Type	Security	Shares	Price	Value
Grant/Award	Stock option (right to buy)	164,500	$0.00	--
Grant/Award	Common Stock	35,250	$0.00	--
holding	Common Stock	--	--	--

Holdings After Transaction: Stock option (right to buy) — 164,500 shares (Direct); Common Stock — 699,506 shares (Direct); Common Stock — 468,277 shares (Indirect, By Trust)

Footnotes (1)

1. 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. 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. 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.

Form 4 Insider Transactions: What Each Field Means →

SEC Form 4

FORM 4

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934
or Section 30(h) of the Investment Company Act of 1940

OMB APPROVAL

OMB Number:			3235-0287
Estimated average burden
hours per response:			0.5

Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

1. Name and Address of Reporting Person^*

Hawryluk P. Kent

(Last) (First) (Middle)

C/O MBX BIOSCIENCES, INC.

11711 N. MERIDIAN STREET, SUITE 300

(Street)

CARMEL IN 46032

(City) (State) (Zip)

2. Issuer Name and Ticker or Trading Symbol
MBX Biosciences, Inc. [ MBX ]

5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

X	Director		10% Owner
X	Officer (give title below)		Other (specify below)
	President & CEO

3. Date of Earliest Transaction (Month/Day/Year)
02/02/2026

4. If Amendment, Date of Original Filed (Month/Day/Year)

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	3. Transaction Code (Instr. 8)		4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
			Code	V	Amount	(A) or (D)	Price
Common Stock	02/02/2026		A		35,250(1)	A	$0	699,506	D
Common Stock								468,277	I	By Trust(2)

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	4. Transaction Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares
Stock option (right to buy)	$39.07	02/02/2026		A		164,500		(3)	02/02/2036	Common Stock	164,500	$0	164,500	D

Explanation of Responses:

1. 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.

2. 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.

3. 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.

	/s/ Richard Bartram, attorney-in-fact	02/03/2026
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.

FAQ

What insider transactions did MBX Biosciences (MBX) report for its CEO?

P. Kent Hawryluk reported new equity grants. He received 35,250 restricted stock units of MBX common stock at $0 per share and a stock option for 164,500 shares at $39.07, plus reported updated direct and trust-held share balances.

How many MBX Biosciences (MBX) shares does the CEO hold after this Form 4?

After the reported grants, Hawryluk directly holds 699,506 MBX shares. He also reports indirect ownership of 468,277 shares held by the P. Kent Hawryluk Revocable Trust, where he serves as trustee and notes a limited beneficial ownership disclaimer.

What are the terms of the MBX Biosciences (MBX) stock options granted to the CEO?

The CEO received a stock option for 164,500 MBX shares at $39.07. The option vests in forty-eight equal monthly installments beginning March 2, 2026, and expires on February 2, 2036, contingent on his continued service through each vesting date.

How do the MBX Biosciences (MBX) RSUs granted to the CEO vest?

The 35,250 MBX restricted stock units vest over four years. They vest in equal quarterly installments over a four-year period, with each vesting event conditioned on P. Kent Hawryluk’s continued service with the company on the applicable vesting date.

What indirect MBX Biosciences (MBX) holdings are reported for the CEO?

Indirect holdings total 468,277 MBX shares held by a trust. These shares are in the P. Kent Hawryluk Revocable Trust, dated January 25, 2011, for which he is trustee, and he disclaims beneficial ownership except for any pecuniary interest.

What is the significance of the Form 4 filed for MBX Biosciences (MBX)?

The Form 4 updates insider ownership details for MBX’s CEO. It records new grants of restricted stock units and stock options, as well as current direct and trust-held share balances, providing transparency into his equity-based compensation and ownership structure.