---
schema_version: "secwatch.filing_event.v1"
accession: "0000947484-23-000136"
form_type: "8-K"
ticker: "ACGL"
cik: "0000947484"
company_name: "ARCH CAPITAL GROUP LTD."
filed_at: "2023-12-21T23:59:59+00:00"
generated_at: "2026-06-07T09:39:07.552907+00:00"
event_type: "m_and_a"
sentiment: "neutral"
materiality_score: 0.5
calibrated_materiality_score: 0.5
confidence: "medium"
source: SEC EDGAR
---

# Arch Capital subsidiary to sell Castel Underwriting Agencies to Ryan Specialty Holdings

## Summary
- Arch Financial Holdings (UK) Ltd signed definitive agreement to sell Castel Underwriting Agencies Ltd.
- Buyer is a subsidiary of Ryan Specialty Holdings, Inc.; expected closing H1 2024 subject to approvals.
- Castel is a London-based managing general underwriting platform; no financial terms disclosed.
- Sale subject to regulatory approvals and customary closing conditions; no further details provided.

## SEC filing metadata
- accession: 0000947484-23-000136
- form_type: 8-K
- ticker: ACGL
- cik: 0000947484
- company_name: ARCH CAPITAL GROUP LTD.
- filed_at: 2023-12-21T23:59:59+00:00
- event_type: m_and_a
- sentiment: neutral
- materiality_score: 0.5
- calibrated_materiality_score: 0.5
- confidence: medium
- sec_items: 7.01
- EDGAR index: https://www.sec.gov/Archives/edgar/data/947484/000094748423000136/0000947484-23-000136-index.htm
- EDGAR primary document: https://www.sec.gov/Archives/edgar/data/947484/000094748423000136/acgl-20231221.htm

## Machine-readable alternates
- HTML: https://secwatch.observer/filing/0000947484-23-000136
- JSON: https://secwatch.observer/filing/0000947484-23-000136.json
- Plain text: https://secwatch.observer/filing/0000947484-23-000136.txt

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