Frazier Life Sciences Public Fund, L.P. - 26 Sep 2025 SCHEDULE 13D/A Report for MBX BIOSCIENCES, INC. Common Stock, $0.0001 par value per share (MBX)

Filing Manager
Frazier Life Sciences Public Fund, L.P.
Reporting Manager
Patrick J. Heron
Security
MBX BIOSCIENCES, INC. Common Stock, $0.0001 par value per share
Symbol
MBX
Shares outstanding
44,650,385 shares
Disclosed Ownership
5,224,095 shares
Ownership
12%
Form type
SCHEDULE 13D/A
Filing time
30 Sep 2025, 17:01:06 UTC
Date of event
26 Sep 2025
Previous filing
20 Aug 2025
SEC
View on sec.gov

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Quoteable Key Fact

"Frazier Life Sciences Public Fund, L.P. disclosed 12% ownership in MBX BIOSCIENCES, INC. Common Stock, $0.0001 par value per share (MBX) on 26 Sep 2025."

Quick Takeaways

  • Frazier Life Sciences Public Fund, L.P. filed SCHEDULE 13D/A for MBX BIOSCIENCES, INC. Common Stock, $0.0001 par value per share (MBX).
  • Disclosed ownership: 12%.
  • Date of event: 26 Sep 2025.

What Changed

  • Previous schedule filing date: 20 Aug 2025.
  • Current filing was accepted on 30 Sep 2025, 17:01.

Why This Matters

  • This page explains what this Schedule 13D/13G filing tells you before manager-level rows.
  • You can verify ownership claims directly against the original SEC filing.

Official SEC Source

Backed by Schedule 13D/13G

Beneficial ownership values are sourced from the original SEC Schedule 13D/13G filing.

See Original Filing

Reporting Managers (14)

Name Ownership Shares Owned sole voting power shared voting power Signature Title CIK
Frazier Life Sciences Public Fund, L.P. 2.5% 1,103,920 0 1,103,920 /s/ Steve R. Bailey By Steve R. Bailey, CFO of FHMLSP, L.L.C., GP of FHMLSP, L.P., GP of Frazier Life Sciences Public Fund, L.P. 0001863769
FHMLSP, L.P. 2.5% 1,103,920 0 1,103,920 /s/ Steve R. Bailey By Steve R. Bailey, CFO of FHMLSP, L.L.C., GP of FHMLSP, L.P. 0001879466
FHMLSP, L.L.C. 2.5% 1,103,920 0 1,103,920 /s/ Steve R. Bailey By Steve R. Bailey, CFO of FHMLSP, L.L.C. 0001879465
Frazier Life Sciences Public Overage Fund, L.P. 0.7% 325,653 0 325,653 /s/ Steve R. Bailey By Steve R. Bailey, CFO of FHMLSP Overage, L.L.C., GP of FHMLSP Overage, L.P., GP of Frazier Life Sciences Public Overage Fund, L.P. 0001913804
FHMLSP Overage, L.P. 0.7% 325,653 0 325,653 /s/ Steve R. Bailey By Steve R. Bailey, CFO of FHMLSP Overage, L.L.C., GP of FHMLSP Overage, L.P. 0001963247
FHMLSP Overage, L.L.C. 0.7% 325,653 0 325,653 /s/ Steve R. Bailey By Steve R. Bailey, CFO of FHMLSP Overage, L.L.C. 0001963248
Frazier Life Sciences X, L.P. 12% 5,219,440 0 5,219,440 /s/ Steve R. Bailey 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. 0001790879
FHMLS X, L.P. 12% 5,219,440 0 5,219,440 /s/ Steve R. Bailey By Steve R. Bailey, CFO of FHMLS X, L.L.C., GP of FHMLS X, L.P. 0001790880
FHMLS X, L.L.C. 12% 5,219,440 0 5,219,440 /s/ Steve R. Bailey By Steve R. Bailey, CFO of FHMLS X, L.L.C. 0001790811
Frazier Life Sciences XI, L.P. 0% 3,000 0 3,000 /s/ Steve R. Bailey By Steve R. Bailey, CFO of FHMLS XI, L.L.C., GP of FHMLS XI, L.P., GP of Frazier Life Sciences XI, L.P. 0001911592
FHMLS XI, L.P. 0% 3,000 0 3,000 /s/ Steve R. Bailey By Steve R. Bailey, CFO of FHMLS XI, L.L.C., GP of FHMLS XI, L.P. 0001911580
FHMLS XI, L.L.C. 0% 3,000 0 3,000 /s/ Steve R. Bailey By Steve R. Bailey, CFO of FHMLS XI, L.L.C. 0001911623
James N. Topper 12% 5,219,440 0 5,219,440 /s/ Steve R. Bailey By Steve R. Bailey, Attorney-in-Fact for James N. Topper, pursuant to a Power of Attorney, a copy of which was filed with the SEC on July 31, 2017 0001341382
Patrick J. Heron 12% 5,224,095 4,655 5,219,440 /s/ Steve R. Bailey By Steve R. Bailey, Attorney-in-Fact for Patrick J. Heron, pursuant to a Power of Attorney, a copy of which was filed with the SEC on July 31, 2017 0001365617

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