Director Heron Patrick J bought $11,999,988 worth of shares (666,666 units at $18.00) (SEC Form 4)
$MBX
Biotechnology: Pharmaceutical Preparations
Health Care
| 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 |
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| 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*
(Street)
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2. Issuer Name and Ticker or Trading Symbol
MBX Biosciences, Inc. [ MBX ] |
5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)
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3. Date of Earliest Transaction
(Month/Day/Year) 09/26/2025 | ||||||||||||||||||||||||||
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4. If Amendment, Date of Original Filed
(Month/Day/Year) |
6. Individual or Joint/Group Filing (Check Applicable Line)
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| Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned | ||||||||||
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| 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 | 09/26/2025 | P | 666,666 | A | $18 | 5,219,440 | I | By Frazier Life Sciences X, L.P.(1) | ||
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Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities) | |||||||||||||||
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| 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 | ||||||||
1. Name and Address of Reporting Person*
(Street)
Relationship of Reporting Person(s) to Issuer
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1. Name and Address of Reporting Person*
(Street)
Relationship of Reporting Person(s) to Issuer
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1. Name and Address of Reporting Person*
(Street)
Relationship of Reporting Person(s) to Issuer
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1. Name and Address of Reporting Person*
(Street)
Relationship of Reporting Person(s) to Issuer
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1. Name and Address of Reporting Person*
(Street)
Relationship of Reporting Person(s) to Issuer
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| Explanation of Responses: |
| 1. The shares reported herein are held of record by Frazier Life Sciences X, L.P. FHMLS X, L.P. is the general partner of Frazier Life Sciences X, L.P. and FHMLS X, L.L.C. is the general partner of FHMLS X, L.P. James N. Topper and Patrick J. Heron are the sole managing members of FHMLS X, L.L.C. and share voting and investment power over the shares held by Frazier Life Sciences X, L.P. Dr. Topper and Mr. Heron disclaim beneficial ownership of such securities except to the extent of their pecuniary interest therein. |
| /s/ Steve R. Bailey, Attorney-in-Fact For Patrick J. Heron | 09/30/2025 | |
| By Steve R. Bailey, CFO of FHMLS X, L.L.C., GP of FHMLS X, L.P., GP of Frazier Life Sciences X, L.P. | 09/30/2025 | |
| By Steve R. Bailey, CFO of FHMLS X, L.L.C., GP of FHMLS X, L.P. | 09/30/2025 | |
| By Steve R. Bailey, CFO of FHMLS X, L.L.C. | 09/30/2025 | |
| /s/ Steve R. Bailey, Attorney-in-Fact For James N. Topper | 09/30/2025 | |
| ** 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. | ||