MBX Biosciences, Inc. 13D

Frazier Life Sciences funds maintain an approximately 11–12% economic stake in MBX Biosciences via multiple vehicles, with this Amendment No. 3 reflecting internal fund and disclosure housekeeping rather than a change in stake size or activist plans.

Frazier Life Sciences funds and affiliates report holding an aggregate position of roughly 6.65 million shares of MBX Biosciences, Inc., including 1,429,573 shares (3.0%) held by Frazier Life Sciences Public Fund, L.P., 5,219,440 shares (10.8%) held by Frazier Life Sciences X, L.P., and 3,000 shares held by Frazier Life Sciences XI, L.P., with Heron and Topper sharing voting and investment power over the FLS X stake; this third amendment primarily reflects internal restructuring (a merger of a related overage fund into the public fund) and clarifies fund structures and financing sources, without indicating new activist intentions or material changes in ownership percentages.

Filing Facts

CIK

1776111

Ticker

MBX

Form

13D

Source Type

fda

Accession

0001231919-26-000851

Alert Tier

5