---
schema_version: "secwatch.filing_event.v1"
accession: "0001193125-25-220432"
form_type: "8-K"
ticker: "MBX"
cik: "0001776111"
company_name: "MBX Biosciences, Inc."
filed_at: "2025-09-26T23:59:59+00:00"
generated_at: "2026-05-17T05:34:53.673953+00:00"
event_type: "other_material"
sentiment: "neutral"
materiality_score: 0.6
calibrated_materiality_score: 0.6
confidence: "high"
source: SEC EDGAR
---

# MBX Biosciences raises $187.5M via public offering of 11.1M shares at $18.00

## Summary
- Offering of 11,108,055 shares at $18.00 per share; underwriters have 30-day option for up to 1,666,208 additional shares.
- Net proceeds of $187.5M; funds to advance three clinical-stage programs plus discovery R&D and corporate purposes.
- Underwriting agreement with J.P. Morgan and Jefferies as representatives; offering closed September 26, 2025.
- Registration statements on Form S-1 and S-1MEF became effective September 24, 2025.

## SEC filing metadata
- accession: 0001193125-25-220432
- form_type: 8-K
- ticker: MBX
- cik: 0001776111
- company_name: MBX Biosciences, Inc.
- filed_at: 2025-09-26T23:59:59+00:00
- event_type: other_material
- sentiment: neutral
- materiality_score: 0.6
- calibrated_materiality_score: 0.6
- confidence: high
- sec_items: 1.01, 9.01
- EDGAR index: https://www.sec.gov/Archives/edgar/data/1776111/000119312525220432/0001193125-25-220432-index.htm
- EDGAR primary document: https://www.sec.gov/Archives/edgar/data/1776111/000119312525220432/mbx-20250924.htm

## Machine-readable alternates
- HTML: https://secwatch.observer/filing/0001193125-25-220432
- JSON: https://secwatch.observer/filing/0001193125-25-220432.json
- Plain text: https://secwatch.observer/filing/0001193125-25-220432.txt

This AI-assisted summary is a reading aid. Review the linked SEC EDGAR filing before relying on any specific claim.