MBX Biosciences (MBX) director receives grant of 12,500 stock options at $30.91

Rhea-AI Filing Summary

MBX Biosciences director Steven L. Hoerter received a grant of stock options covering 12,500 shares of common stock. The options have an exercise price of $30.9100 per share and expire on June 4, 2036. According to the footnotes, the grant will vest in full on the earlier of the one-year anniversary of the grant date or the date of the company’s next annual meeting of stockholders, as long as he continues serving as a non-employee director.

After these transactions, Hoerter is reported as holding 11,938 shares of common stock directly and 20,000 shares indirectly through the Steven L Hoerter Revocable Trust dated November 2, 2018, where he serves as trustee and disclaims beneficial ownership except for any pecuniary interest.

Insights

Equity compensation analyst

Routine director option grant with standard vesting; no buy/sell signal.

This filing shows Steven L. Hoerter, a director of MBX Biosciences, receiving a grant of stock options for 12,500 shares at an exercise price of $30.9100, expiring on June 4, 2036. The grant is characterized as a compensation-related award, not a market purchase.

The options vest in full on the earlier of the one-year anniversary of the grant date or the next annual meeting of stockholders, contingent on continued service as a non-employee director. The filing also lists 11,938 common shares held directly and 20,000 shares held via a revocable trust, which Hoerter disclaims beneficial ownership of except for any pecuniary interest.

Because this is a standard equity incentive grant without open-market buying or selling, it is generally viewed as routine governance and compensation practice rather than a directional signal about the company’s share price. The informational value lies mainly in confirming ongoing use of stock-based director compensation.

Insider Trade Summary

3 transactions reported

Mixed 3 txns

Insider Hoerter Steven L.

Role null

Type	Security	Shares	Price	Value
Grant/Award	Stock option (right to buy)	12,500	$0.00	--
holding	Common Stock	--	--	--
holding	Common Stock	--	--	--

Holdings After Transaction: Stock option (right to buy) — 12,500 shares (Direct, null); Common Stock — 11,938 shares (Direct, null); Common Stock — 20,000 shares (Indirect, Trust)

Footnotes (1)

1. Shares held by the Steven L Hoerter Revocable Trust dated November 2, 2018, 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 grant will vest in full on the earlier of the one-year anniversary of the grant date or on the date of our next annual meeting of stockholders, subject to the non-employee director's continued services to the Company.

Key Figures

Option grant size: 12,500 shares Option exercise price: $30.9100 per share Option expiration date: June 4, 2036 +2 more

5 metrics

Option grant size 12,500 shares Stock options granted to director on June 4, 2026

Option exercise price $30.9100 per share Exercise price of newly granted stock options

Option expiration date June 4, 2036 Expiration of granted stock options

Direct common shares 11,938 shares Common stock held directly after reported transactions

Trust-held common shares 20,000 shares Common stock held via revocable trust after transactions

Key Terms

Stock option (right to buy), Grant, award, or other acquisition, Revocable Trust, Section 16

4 terms

Stock option (right to buy) financial

"security_title: "Stock option (right to buy)""

Grant, award, or other acquisition financial

"transaction_code_description: "Grant, award, or other acquisition""

Revocable Trust financial

"Steven L Hoerter Revocable Trust dated November 2, 2018"

A revocable trust is a legal arrangement where the person who creates it keeps control and can change or cancel the trust at any time, while naming who will manage and receive the assets later. Think of it like a flexible folder for your investments and property that can be relabeled or reworked as circumstances change; it matters to investors because it determines how ownership is recorded, how easily assets transfer on incapacity or death, and whether holdings bypass public probate proceedings.

Section 16 regulatory

"beneficially owned by him for Section 16 or any other purpose"

Section 16 is a U.S. securities law rule that governs the trading and disclosure obligations of company insiders — typically officers, directors and large shareholders — to promote transparency and deter unfair profit-taking. It requires insiders to publicly report their stock trades and allows companies or the issuer to reclaim quick, short-term profits from certain insider trades, like a scoreboard and a refund policy that help investors see and limit possible insider advantage.

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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^*

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)
06/04/2026

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)

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								11,938	D
Common Stock								20,000	I	Trust(1)

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)	$30.91	06/04/2026		A		12,500		(2)	06/04/2036	Common Stock	12,500	$0	12,500	D

Explanation of Responses:

1. Shares held by the Steven L Hoerter Revocable Trust dated November 2, 2018, 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.

2. The grant will vest in full on the earlier of the one-year anniversary of the grant date or on the date of our next annual meeting of stockholders, subject to the non-employee director's continued services to the Company.

	/s/ P. Kent Hawryluk, attorney-in-fact	06/05/2026
	** 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)

FAQ

What did MBX (MBX) director Steven L. Hoerter receive in this Form 4 filing?

Steven L. Hoerter received a stock option grant for 12,500 shares of MBX Biosciences common stock. The grant is compensation-related, not an open-market purchase, and gives him the right to buy shares at a fixed exercise price if he remains a director.

What is the exercise price and term of Steven Hoerter’s MBX stock options?

The granted stock options have an exercise price of $30.9100 per share and expire on June 4, 2036. This means Hoerter may choose to exercise the options at that price any time before the expiration date, once the options are vested.

How and when do the new MBX stock options granted to Steven Hoerter vest?

The stock options will vest in full on the earlier of the one-year anniversary of the grant date or the date of MBX’s next annual meeting of stockholders. Vesting is conditioned on Hoerter’s continued service as a non-employee director through that date.

How many MBX shares does Steven Hoerter hold directly and indirectly after this filing?

After the reported transactions, Hoerter is shown holding 11,938 MBX common shares directly and 20,000 shares indirectly through the Steven L Hoerter Revocable Trust. He serves as trustee of the trust and disclaims beneficial ownership except for any pecuniary interest.

Is Steven Hoerter’s MBX Form 4 transaction a market buy or sell of shares?

No, the Form 4 reflects a grant of stock options as compensation, not an open-market purchase or sale of MBX shares. The transaction code indicates a grant or award acquisition, which is a standard element of director equity compensation programs.