SCHEDULE Filed 2025-09-30 Event 2025-09-26 SEC 0001863769-25-000010 →

Frazier Life Sciences Public Fund, L.P. → MBX Biosciences, Inc. MBX

Stake: 11.70% Shares: 5,224,095 CUSIP: 55287L101 Class: Common Stock, $0.0001 par value per share

Item 4 — Purpose of Transaction

Not extracted from this filing — typically because it's an amendment (13D/A) and Item 4 is unchanged from the parent filing. Read the raw SEC filing →

Cross-References

Insider Activity (last 365d)

6 transactions

6 buys · 0 sales · 0 awards/exercises

Issuer Cluster

4 13D/G filings on this issuer

3 other filings besides this one

Filer Track Record

4 filings by this filer

3 other filings in the data moat

Short Interest · settle 2026-07-15

DTC 6.21

5,776,709 shares short · -2.0% vs prior

Institutional Consensus · 2025-12-31

Held by elite portfolio managers

1 holder · $21.47M

Point72 Asset Mgmt

Post-Filing Returns · since 2025-09-26 on MBX

+1 day

0.0%

+5 days

0.0%

+30 days

0.0%

+60 days

0.0%

+90 days

0.0%

+180 days

0.0%

Anchor price 62.00 on closest trading day on/after 2025-09-26. Source: Yahoo Finance daily adj_close (split + dividend adjusted).

Form 4 Insider Transactions · last 365d

Date	Insider	Role	Type	Shares	Price	Value
2026-06-04	Pescovitz Ora H.	director	Award	12,500	$30.91	$386K
2026-06-04	Heron Patrick J	director, 10%+ owner	Award	12,500	$30.91	$386K
2026-06-04	Stelzer Laurie	director	Award	12,500	$30.91	$386K
2026-06-04	Hoerter Steven L.	director	Award	12,500	$30.91	$386K
2026-06-04	Ryder Steven	director	Award	12,500	$30.91	$386K
2026-06-04	Aynechi Tiba	director	Award	12,500	$30.91	$386K

Other 13D/G Filings on MBX Biosciences, Inc.

Filed	Form	Filer	Stake	Shares
2026-06-24	SCHEDULE 13G	Paradigm Biocapital Advisors LP	—	—	view →
2025-09-30	SCHEDULE	ORBIMED ADVISORS LLC	9.00%	4,002,887	view →
2025-09-30	SCHEDULE	Norwest Venture Partners XVI, LP	4.80%	2,140,989	view →

Other Filings by Frazier Life Sciences Public Fund, L.P.

Filed	Form	Issuer	Stake	Shares
2026-05-21	SCHEDULE 13D/A	KalVista Pharmaceuticals, Inc.	2.30%	1,249,165	view →
2025-09-17	SCHEDULE	HilleVax, Inc.	—	—	view →
2023-09-27	SC	HilleVax, Inc.	—	—	view →

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