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Casualty and Litigation insurers
- Global and national commercial carriers 15
- Regional carriers 20
- Personal-lines carriers that also insure businesses 9
- Specialty and E&S insurers 31
- Workers' comp specialists and state funds 7
- Medical and professional liability specialists 3
- Niche and affinity insurers 9
- Small business specialists 12
- Cyber specialists 3
- Program carriers and fronting insurers 6
- Reinsurer-owned commercial insurers 5
| # | Insurer | Type | Commercial premiums (2025) | AM Best |
|---|---|---|---|---|
| 56 | The Doctors CompanyPhysician-owned med mal insurer based in Napa, California, covering doctors, dentists, clinicians and hospitals. It bought ProAssurance in June 2026. | Medical and professional liability specialists | $1.55 billion | A (Excellent) |
Ranked by 2025 U.S. commercial lines direct premiums written: NAIC 2025 market share data for 17 commercial lines (states and U.S. territories), summed by insurance group. A group's premium in a line where it is outside NAIC's top 125 is not counted. Seven groups are left out because a business cannot buy from them or their premium in these lines is mostly consumer coverage: USAA, CSAA, the Ohio Bureau of Workers' Compensation, Florida's Citizens, the Texas FAIR Plan and windstorm pool, Assurant and Generali. Brands without a rank are well-known companies inside these groups or outside the top 100.