Wellington Biomedical Innovation Master Investors (Cayman) II L.P. - Sep 12, 2024 Form 3 Insider Report for MBX Biosciences, Inc. (MBX)

Role: 10%+ Owner
Signature: Wellington Biomedical Innovation Master Investors (Cayman) II L.P., By: Wellington Management Company LLP, as Investment Adviser, /s/ Jennifer C. Boylan, Authorized Person
Stock symbol: MBX
Transactions as of: Sep 12, 2024
Transactions value $: $0
Form type: 3
Date filed: 9/12/2024, 07:52 PM
Previous filing: Nov 16, 2023
Next filing: Sep 17, 2024

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 B Preferred Stock							Sep 12, 2024	Common Stock	1.39M		Direct	F1
holding	MBX	Series C Preferred Stock							Sep 12, 2024	Common Stock	404K		Direct	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 B Preferred Stock is convertible into shares of the Issuer's Common Stock on a 12.0221-for-one basis at any time at the holder's election. Immediately prior to the closing of the Issuer's initial public offering, all such shares of Series B Preferred Stock will automatically convert into the number of shares of Common Stock of the Issuer shown in column 3. The Series B Preferred Stock has no expiration date.
F2	Each share of Series C Preferred Stock is convertible into shares of the Issuer's Common Stock on a 12.0221-for-one basis at any time at the holder's election. Immediately prior to the closing of the Issuer's initial public offering, all such shares of Series C Preferred Stock will automatically convert into the number of shares of Common Stock of the Issuer shown in column 3. The Series C Preferred Stock has no expiration date.

Content

Each share of Series B Preferred Stock is convertible into shares of the Issuer's Common Stock on a 12.0221-for-one basis at any time at the holder's election. Immediately prior to the closing of the Issuer's initial public offering, all such shares of Series B Preferred Stock will automatically convert into the number of shares of Common Stock of the Issuer shown in column 3. The Series B Preferred Stock has no expiration date.

Each share of Series C Preferred Stock is convertible into shares of the Issuer's Common Stock on a 12.0221-for-one basis at any time at the holder's election. Immediately prior to the closing of the Issuer's initial public offering, all such shares of Series C Preferred Stock will automatically convert into the number of shares of Common Stock of the Issuer shown in column 3. The Series C Preferred Stock has no expiration date.