---
schema_version: "secwatch.filing_event.v1"
accession: "0001628280-25-043087"
form_type: "8-K"
ticker: "OSG"
cik: "0000874501"
company_name: "OCTAVE SPECIALTY GROUP INC"
filed_at: "2025-09-29T23:59:59+00:00"
generated_at: "2026-05-17T05:30:12.480864+00:00"
event_type: "m_and_a"
sentiment: "positive"
materiality_score: 0.85
calibrated_materiality_score: 0.85
confidence: "high"
source: SEC EDGAR
---

# Ambac completes $420M sale of legacy financial guarantee businesses to Oaktree

## Summary
- Sale of Ambac Assurance Corp and Ambac Assurance UK to Oaktree for $420M cash closed on September 29, 2025.
- Completion transforms Ambac into pure-play MGA and specialty insurance platform; CEO calls it defining moment.
- Issued Oaktree a warrant for 5,092,707 common shares with conversion options capped at $70M aggregate.
- Moelis & Company and Debevoise & Plimpton advised Ambac; BlackRock and Kirkland & Ellis advised Oaktree.

## SEC filing metadata
- accession: 0001628280-25-043087
- form_type: 8-K
- ticker: OSG
- cik: 0000874501
- company_name: OCTAVE SPECIALTY GROUP INC
- filed_at: 2025-09-29T23:59:59+00:00
- event_type: m_and_a
- sentiment: positive
- materiality_score: 0.85
- calibrated_materiality_score: 0.85
- confidence: high
- sec_items: 1.01, 2.01, 3.02, 7.01, 9.01
- EDGAR index: https://www.sec.gov/Archives/edgar/data/874501/000162828025043087/0001628280-25-043087-index.htm
- EDGAR primary document: https://www.sec.gov/Archives/edgar/data/874501/000162828025043087/ambc-20250929.htm

## Machine-readable alternates
- HTML: https://secwatch.observer/filing/0001628280-25-043087
- JSON: https://secwatch.observer/filing/0001628280-25-043087.json
- Plain text: https://secwatch.observer/filing/0001628280-25-043087.txt

## Key facts
- Equity Issuances
  OCTAVE SPECIALTY GROUP INC issued 5,092,707 shares of common stock of warrant to American Acorn Holdings, LLC (owned by funds managed by Oaktree Capital Management, L.P.) for $70 million in the aggregate.
  - Security: warrant
  - Shares: 5,092,707 shares of common stock
  - Purchaser: American Acorn Holdings, LLC (owned by funds managed by Oaktree Capital Management, L.P.)
  - Consideration: $70 million in the aggregate
  source text: with respect to the Warrant upon conversion of the Warrant (including conversions in connection with a Change of Control (as defined in the Letter Agreement)) will not exceed $70 million in the aggregate . The Warrant was, and the Warrant Shares will be, issued in reliance upon an exemption from registration pursuant to Section 4(a)(2) of the Securities Act. The
  evidence_url: https://www.sec.gov/Archives/edgar/data/874501/000162828025043087/0001628280-25-043087-index.htm
- M&A Transactions
  OCTAVE SPECIALTY GROUP INC completed a disposition involving Acorn for $420,000,000 in cash (closed 2025-09-29).
  - Action: disposition
  - Counterparty: Acorn
  - Consideration: $420,000,000 in cash
  - Closing: 2025-09-29
  source text: On September 29, 2025 , the Company completed its previously announced sale to Acorn of all of the issued and outstanding shares of common stock, par value $2.50 per share, of Ambac Assurance Corporation, a Wisconsin stock insurance company and wholly owned subsidiary of the Company (the “AAC Transaction”), for $420,000,000 in cash, subject to certain adjustments, pursuant to and upon the terms and subject to the conditions set forth in, the stock purchase agreement, dated as of June 3, 2024, as amended by the First Amendment, dated as of July 3, 2025 (together, the “AAC Sale Agreement”), by and between the Company and Acorn.
  evidence_url: https://www.sec.gov/Archives/edgar/data/874501/000162828025043087/0001628280-25-043087-index.htm

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