Octave Specialty Group, Inc. is an insurance holding company focused primarily on the specialty property and casualty insurance business in the United States and the United Kingdom. It operates in two segments: Specialty Property and Casualty Insurance, which provides specialty program insurance with a focus on commercial and personal liability risks, and Insurance Distribution, which offers property, niche specialty risk, accident and health, miscellaneous specialty, reinsurance, surety, marine and energy, specialty auto, excess and surplus lines commercial package, professional lines, and directors' and officers' insurance. The company was formerly known as Ambac Financial Group, Inc. and changed its name to Octave Specialty Group, Inc. in November 2025. It was incorporated in 1991 and is headquartered in New York, New York.