---
schema_version: "secwatch.filing_event.v1"
accession: "0001193125-26-407555"
form_type: "8-K"
ticker: "LXEO"
cik: "0001907108"
company_name: "Lexeo Therapeutics, Inc."
filed_at: "2026-09-29T20:20:33+00:00"
generated_at: "2026-10-12T13:50:24.420756+00:00"
event_type: "m_and_a"
sentiment: "neutral"
materiality_score: 0.6
calibrated_materiality_score: 0.6
confidence: "high"
source: SEC EDGAR
---

# Lexeo completes acquisition of Mantle Therapeutics for $5.3M cash and $3M stock plus contingent payments

## Summary
- Lexeo completed the Mantle Therapeutics acquisition on September 29, 2026, through the merger of Magma Merger Sub Inc. into Mantle.
- Upfront consideration was $5.3 million in cash and $3.0 million in Lexeo common stock, issued under Section 4(a)(2)/Regulation D exemption.
- Contingent payments include a $1.0 million additional cash payment and up to $12.0 million in milestone payments over 12 years tied to development and regulatory milestones.
- Mantle restricted stock vested and was cancelled, and Mantle SAFEs and convertible promissory notes were cancelled for applicable consideration or payoff.

## SEC filing metadata
- accession: 0001193125-26-407555
- form_type: 8-K
- ticker: LXEO
- cik: 0001907108
- company_name: Lexeo Therapeutics, Inc.
- filed_at: 2026-09-29T20:20:33+00:00
- event_type: m_and_a
- sentiment: neutral
- materiality_score: 0.6
- calibrated_materiality_score: 0.6
- confidence: high
- sec_items: 2.01, 3.02, 9.01
- EDGAR index: https://www.sec.gov/Archives/edgar/data/1907108/000119312526407555/0001193125-26-407555-index.htm
- EDGAR primary document: https://www.sec.gov/Archives/edgar/data/1907108/000119312526407555/lxeo-20260929.htm

## Machine-readable alternates
- HTML: https://secwatch.observer/filing/0001193125-26-407555
- JSON: https://secwatch.observer/filing/0001193125-26-407555.json
- Plain text: https://secwatch.observer/filing/0001193125-26-407555.txt

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