MBX Biosciences (MBX) director awarded 12,500 stock options

Rhea-AI Filing Summary

MBX Biosciences, Inc. director Tiba Aynechi received a grant of stock options covering 12,500 shares of common stock as equity compensation. The options have an exercise price of $30.91 per share and expire on June 4, 2036. The grant will vest in full on the earlier of the one-year anniversary of the grant date or the company’s next annual meeting of stockholders, as long as the non-employee director continues to serve.

Insider Trade Summary

1 transaction reported

Mixed 1 txn

Insider Aynechi Tiba

Role null

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

Holdings After Transaction: Stock option (right to buy) — 12,500 shares (Direct, null)

Footnotes (1)

1. [object Object]

Key Figures

Options granted: 12,500 options Exercise price: $30.91 per share Underlying shares: 12,500 shares +2 more

5 metrics

Options granted 12,500 options Stock option grant to director Tiba Aynechi

Exercise price $30.91 per share Strike price for granted options

Underlying shares 12,500 shares Common stock underlying the options

Expiration date June 4, 2036 Option expiration for this grant

Post-grant derivative holdings 12,500 options Total options held following transaction

Key Terms

Stock option (right to buy), Common Stock, non-employee director, annual meeting of stockholders

4 terms

Stock option (right to buy) financial

"security_title: Stock option (right to buy)"

Common Stock financial

"underlying_security_title: Common Stock"

Common stock represents ownership shares in a company, giving investors a stake in its success and a say in important decisions through voting rights. It is the most common type of stock traded on markets and can provide income through dividends, as well as potential for value growth. For investors, holding common stock means sharing in the company’s profits and risks.

non-employee director financial

"subject to the non-employee director's continued services"

annual meeting of stockholders financial

"on the date of our next annual meeting of stockholders"

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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^*

Aynechi Tiba

(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

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		(1)	06/04/2036	Common Stock	12,500	$0	12,500	D

Explanation of Responses:

1. 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 insider transaction did MBX director Tiba Aynechi report on this Form 4 for MBX?

Tiba Aynechi reported receiving a grant of stock options for 12,500 shares of MBX Biosciences common stock. This is a compensation-related award, not an open-market stock purchase or sale.

What is the exercise price of the stock options granted to MBX director Tiba Aynechi?

The granted stock options have an exercise price of $30.91 per share. This means Aynechi can buy MBX Biosciences common stock at $30.91 once the options are vested and exercised.

When do Tiba Aynechi’s MBX Biosciences stock options vest?

The options will vest in full on the earlier of the one-year anniversary of the June 4, 2036 grant date or the next annual stockholder meeting. Vesting requires continued service as a non-employee director.

When do the MBX Biosciences stock options granted to Tiba Aynechi expire?

The stock options granted to Tiba Aynechi expire on June 4, 2036. After that expiration date, any unexercised options will no longer allow the director to purchase MBX Biosciences common stock.

How many MBX Biosciences derivative securities does Tiba Aynechi hold after this Form 4 transaction?

Following this grant, Tiba Aynechi holds 12,500 stock options as reported. These options each relate to one share of MBX Biosciences common stock upon exercise, subject to vesting conditions.