MBX Biosciences (MBX) director receives capped 2025 stock option grant

Filing Impact

(Neutral)

Filing Sentiment

(Neutral)

Form Type

4/A

Rhea-AI Filing Summary

MBX Biosciences director Steven L. Hoerter received a stock option grant as part of his non-employee director compensation. The options have an exercise price of $27.08 per share and expire on November 21, 2035. The grant vests in equal monthly installments over one year from November 6, 2025, and was adjusted so his 2025 equity compensation does not exceed $1,000,000 in aggregate grant date fair value under the company’s director compensation policy.

Insider Trade Summary

1 transaction reported

Mixed 1 txn

Insider Hoerter Steven L.

Role null

Type	Security	Shares	Price	Value
Grant/Award	Stock option (right to buy)	0	$0.00	--

Holdings After Transaction: Stock option (right to buy) — 0 shares (Direct, null)

Footnotes (1)

Pursuant to the Company's Non-Employee Director Compensation Policy, these grants were adjusted downward such that the non-employee Director's annual equity compensation in 2025 totals no more than $1,000,000 based on the aggregate grant date fair value as determined in accordance with FASB Topic ASC 718. 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.

Key Figures

Option exercise price: $27.08 per share Expiration date: November 21, 2035 Equity compensation cap: $1,000,000 +1 more

4 metrics

Option exercise price $27.08 per share Exercise price of director stock option grant

Expiration date November 21, 2035 Option expiration for director grant

Equity compensation cap $1,000,000 Maximum 2025 annual equity compensation based on grant date fair value

Vesting schedule length One year Equal monthly vesting from November 6, 2025

Key Terms

Non-Employee Director Compensation Policy, grant date fair value, FASB Topic ASC 718, vest in equal monthly installments

4 terms

Non-Employee Director Compensation Policy financial

"Pursuant to the Company's Non-Employee Director Compensation Policy, these grants were adjusted downward..."

grant date fair value financial

"annual equity compensation in 2025 totals no more than $1,000,000 based on the aggregate grant date fair value..."

The grant date fair value is the estimated dollar worth of a stock-based award (such as stock options or restricted shares) at the exact moment it is given to an employee or contractor. Investors care because companies use that value to record compensation expenses and to show how much potential ownership and earnings dilution those awards could create—think of it as the price tag placed on a gift card when it is handed over so the company can report the cost now.

FASB Topic ASC 718 financial

"aggregate grant date fair value as determined in accordance with FASB Topic ASC 718."

vest in equal monthly installments financial

"The grant will vest in equal monthly installments over a one-year period..."

Form 4 Insider Transactions: What Each Field Means →

04/22/2026 - 08:02 AM

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^*

Hoerter Steven L.

(Last)

(First)

(Middle)

C/O MBX BIOSCIENCES INC.

11711 N. MERIDIAN STREET, SUITE 300

(Street)

CARMEL

INDIANA

46032

(City)

(State)

(Zip)

UNITED STATES

(Country)

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
	Officer (give title below)	Other (specify below)

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
11/22/2025

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

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

4. If Amendment, Date of Original Filed (Month/Day/Year)
11/25/2025

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)
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	Code	V	Amount	(A) or (D)	Price		6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)

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)
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)	Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares	8. Price of Derivative Security (Instr. 5)		10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
Stock option (right to buy)	$27.08	11/22/2025		A		0⁽¹⁾		⁽²⁾	11/21/2035	Common Stock	0⁽¹⁾	$0	0⁽¹⁾	D

Explanation of Responses:

1. Pursuant to the Company's Non-Employee Director Compensation Policy, these grants were adjusted downward such that the non-employee Director's annual equity compensation in 2025 totals no more than $1,000,000 based on the aggregate grant date fair value as determined in accordance with FASB Topic ASC 718.

2. 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.

	/s/ P. Kent Hawryluk, attorney-in-fact	04/22/2026
	** 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.
* Form 4: SEC 1474 (03-26)

Source: View Original Filing on SEC EDGAR

FAQ

What insider transaction did MBX director Steven L. Hoerter report on Form 4/A for MBX?

Steven L. Hoerter reported receiving a stock option grant as non-employee director compensation. The options carry a $27.08 exercise price and expire November 21, 2035, with vesting in equal monthly installments over one year starting November 6, 2025.

What is the exercise price and expiration date of Steven Hoerter’s new MBX stock options?

The granted stock options have a $27.08 per share exercise price and an expiration date of November 21, 2035. These terms define the cost to purchase MBX common stock and the final date the options can be exercised if vested and outstanding.

How do Steven Hoerter’s MBX director options vest under this Form 4/A filing?

The grant will vest in equal monthly installments over a one-year period starting November 6, 2025. Vesting is conditioned on Mr. Hoerter’s continued service as a non-employee director, aligning his equity compensation with ongoing board participation during that year.

How does MBX’s Non-Employee Director Compensation Policy affect Hoerter’s 2025 equity awards?

Under MBX’s Non-Employee Director Compensation Policy, Hoerter’s grants were adjusted so his 2025 annual equity compensation totals no more than $1,000,000. This limit is based on aggregate grant date fair value calculated in accordance with FASB Topic ASC 718 accounting standards.

Is Steven Hoerter’s MBX Form 4/A transaction a market purchase or sale of common stock?

No, the Form 4/A reflects a grant of stock options as compensation, not a market purchase or sale of common shares. It records a derivative award with a $27.08 exercise price, vesting monthly over one year, subject to his continued service as a non-employee director.