MBX Biosciences medical chief sells 373 shares

The 373-share sale was made under a mandatory sell-to-cover agreement to cover tax obligations from restricted stock unit vesting.

Available on EDGAR 11/05/2026 - 04:10 PM EST Accepted by SEC EDGAR 11/05/2026 - 04:10 PM EST Learn about SEC filing dates

Rhea-AI Filing Summary

MBX Biosciences, Inc. Chief Medical Officer Salomon Azoulay sold 373 common shares on November 4, 2026, at a weighted average price of $53.96 per share. The sale covered tax obligations tied to restricted stock unit vesting under a mandatory sell-to-cover agreement; he directly held 14,026 shares afterward. No Rule 10b5-1 plan is reported.

Insider Trade Summary

Net Seller: 373 shares

Net Sell 1 txn

Insider Azoulay Salomon

Role Chief Medical Officer

Sold 373 shs ($20K)

Type	Security	Shares	Price	Value
Sale	Common Stock F1, F2	373	$53.96	$20K

Holdings After Transaction: Common Stock — 14,026 shares (Direct)

Footnotes (2)

1. F1. The sales reported on this Form 4 represent shares of common stock sold by the Reporting Person to cover tax obligations in connection with the vesting of restricted stock units, pursuant to a mandatory sell-to-cover agreement between the Reporting Person and the Company.
2. F2. The price reported in Column 4 is a weighted average price. These shares were sold on an aggregate basis for all Company participants, at prices ranging from $51.78 to $56.78, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer or the staff of the Securities and Exchange Commission, upon request, full information regarding the aggregate number of shares sold at each separate price within the range set forth in this footnote.

Key Figures

Common shares sold: 373 shares Weighted average sale price: $53.96 per share Aggregate sale price range: $51.78 to $56.78 per share +1 more

4 metrics

Common shares sold 373 shares November 4, 2026

Weighted average sale price $53.96 per share Sale on November 4, 2026

Aggregate sale price range $51.78 to $56.78 per share Shares sold on an aggregate basis for Company participants

Direct shares following sale 14,026 shares After the November 4, 2026 sale

Key Terms

sell-to-cover agreement, restricted stock units, weighted average price

3 terms

sell-to-cover agreement technical

"pursuant to a mandatory sell-to-cover agreement"

restricted stock units financial

"in connection with the vesting of restricted stock units"

Restricted stock units are a type of company reward where employees are promised shares of stock, but they only fully own these shares after meeting certain conditions, like staying with the company for a set time. They matter because they can become valuable assets and are often used to motivate employees to help the company succeed.

weighted average price financial

"The price reported in Column 4 is a weighted average price"

Weighted average price is the average price of a security where each trade or component is counted according to its size, so bigger trades pull the average more than smaller ones. Think of it like calculating the average cost of a grocery haul where items you bought more of have greater influence on the final per-item cost. Investors use it to understand the true average price paid or received, judge execution quality, and compare trading performance against market movement.

FAQ

AI-generated questions and answers. How Rhea-AI works. Not financial advice.

How many MBX shares did Salomon Azoulay sell, and at what price?

Salomon Azoulay sold 373 shares on November 4, 2026, at a weighted average price of $53.96 per share. The shares were sold on an aggregate basis for Company participants at prices ranging from $51.78 to $56.78.

AI-generated analysis. How Rhea-AI works. Not financial advice.

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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^*

Azoulay Salomon

(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)

	Director		10% Owner
X	Officer (give title below)		Other (specify below)
	Chief Medical Officer

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
11/04/2026

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	11/04/2026		S		373(1)	D	$53.96(2)	14,026	D

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

Explanation of Responses:

1. The sales reported on this Form 4 represent shares of common stock sold by the Reporting Person to cover tax obligations in connection with the vesting of restricted stock units, pursuant to a mandatory sell-to-cover agreement between the Reporting Person and the Company.

2. The price reported in Column 4 is a weighted average price. These shares were sold on an aggregate basis for all Company participants, at prices ranging from $51.78 to $56.78, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer or the staff of the Securities and Exchange Commission, upon request, full information regarding the aggregate number of shares sold at each separate price within the range set forth in this footnote.

	/s/ John W. Smither	11/05/2026
	** 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)