OSG

Octave Specialty Group, Inc.

A specialty property-and-casualty insurer, it pairs a distribution arm that places premiums across niche insurance lines with Everspan, a program carrier that works with managing general agents and is rated A- by A.M. Best. It began in 1971 as the American Municipal Bond Assurance Corporation (Ambac), a bond insurer that survived the 2008 crisis, then rebranded as Octave in 2025 after selling its legacy financial guarantee business. Its name borrows the musical octave, chosen to suggest distinct businesses working together in harmony.