Patrick J. Heron - 12 Sep 2024 Form 3 Insider Report for MBX Biosciences, Inc. (MBX)

Role: Director, 10%+ Owner
Signature: /s/ Richard Bartram, attorney-in-fact
Issuer symbol: MBX
Transactions as of: 12 Sep 2024
Net transactions value: $0
Form type: 3
Filing time: 12 Sep 2024, 19:20:21 UTC
Previous filing: 10 Sep 2024
Next filing: 17 Sep 2024
SEC: View on sec.gov

Derivative Securities (e.g., puts, calls, warrants, options, convertible securities)

Type	Sym	Class	Transaction	Value $	Shares	Change %	* Price $	Shares After	Date	Underlying Class	Amount	Exercise Price	Ownership	Footnotes
holding	MBX	Series A Convertible Preferred Stock							12 Sep 2024	Common Stock	1,574,005		By Frazier Life Sciences X, L.P.	F1, F2
holding	MBX	Series B Convertible Preferred Stock							12 Sep 2024	Common Stock	2,353,769		By Frazier Life Sciences X, L.P.	F1, F2

* An asterisk sign (*) next to the price indicates that the price is likely invalid.

Explanation of Responses:

Id	Content
F1	Each share of Series A Convertible Preferred Stock, Series B Convertible Preferred Stock and Series C Convertible Preferred Stock (collectively, the "Preferred Stock") is convertible into Common Stock on a one-for-12.0221 basis at any time at the option of the holder, and will automatically convert into the number of shares shown in Column 3 immediately prior to the closing of the Issuer's initial public offering. The Preferred Stock has no expiration date.
F2	These securities are held of record by Frazier Life Sciences X, L.P. ("FLS X"). FHMLS X, L.P. is the general partner of FLS X, and FHMLS X, L.L.C. is the general partner of FHMLS X, L.P. The Reporting Person and James Topper, M.D., Ph.D., are the sole managing members of FHMLS X, L.L.C. and share voting and investment power of the securities held by FLS X, and as a result, may be deemed to have beneficial ownership over such securities. The Reporting Person and Dr. Topper disclaim beneficial ownership of such securities except to the extent of their pecuniary interest therein.

Content

Each share of Series A Convertible Preferred Stock, Series B Convertible Preferred Stock and Series C Convertible Preferred Stock (collectively, the "Preferred Stock") is convertible into Common Stock on a one-for-12.0221 basis at any time at the option of the holder, and will automatically convert into the number of shares shown in Column 3 immediately prior to the closing of the Issuer's initial public offering. The Preferred Stock has no expiration date.

These securities are held of record by Frazier Life Sciences X, L.P. ("FLS X"). FHMLS X, L.P. is the general partner of FLS X, and FHMLS X, L.L.C. is the general partner of FHMLS X, L.P. The Reporting Person and James Topper, M.D., Ph.D., are the sole managing members of FHMLS X, L.L.C. and share voting and investment power of the securities held by FLS X, and as a result, may be deemed to have beneficial ownership over such securities. The Reporting Person and Dr. Topper disclaim beneficial ownership of such securities except to the extent of their pecuniary interest therein.

Remarks:

Exhibit 24 - Power of Attorney