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Deals and M&A 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 |
|---|---|---|---|---|
| 25 | Arch InsuranceU.S. arm of Bermuda-based Arch Capital; specialty, E&S and (since buying Allianz's book in 2024) middle market P&C through brokers, MGAs and programs. | Specialty and E&S insurers | $5.61 billion | A+ (Superior) |
| 28 | SompoBermuda-based commercial arm of Japan's Sompo Holdings (formerly Endurance): casualty, property, professional lines, surety and crop through brokers. | Specialty and E&S insurers | $4.66 billion | A+ (Superior) |
| 36 | EverestBermuda-based reinsurer (NYSE: EG) that sold its retail commercial book to AIG in 2025; U.S. business now comes via E&S, program and specialty units. | Reinsurer-owned commercial insurers | $2.77 billion | A+ (Superior) |
| 37 | AF Group (Accident Fund)Lansing, Michigan workers' comp specialist (Accident Fund, United Heartland, CompWest) owned by Blue Cross Blue Shield of Michigan; sale to Enstar pending. | Workers' comp specialists and state funds | $2.73 billion | A (Excellent) |
| 40 | Core SpecialtyCincinnati specialty insurer built from StarStone U.S. in 2020; writes E&S and admitted casualty, property, Lancer auto, comp and bonds via brokers. | Specialty and E&S insurers | $2.47 billion | A (Excellent) |
| 42 | Argo Group and Farm Family (Clearbrook)Brookfield's U.S. P&C arm: Argo specialty casualty, E&S, garage and Rockwood comp through brokers, plus Farm Family farm and small business cover. | Specialty and E&S insurers | $2.21 billion | A- (Excellent) for Argo companies; A (Excellent) for Farm Family Insurance Group |
| 45 | QBE North AmericaU.S. arm of Australia's QBE, writing specialty casualty, financial lines, construction, large-account property, programs, A&H and crop via brokers and agents. | Specialty and E&S insurers | $2.05 billion | A (Excellent) |
| 47 | BeazleyLloyd's specialty insurer known for cyber, D&O and E&S property, acquired by Zurich on Oct. 1, 2026; sells through brokers on admitted, E&S and Lloyd's paper. | Specialty and E&S insurers | $1.94 billion | A (Excellent) |
| 53 | AccelerantA risk exchange whose insurers issue policies for 300-plus specialty MGAs insuring small and mid-sized businesses; a Thoma Bravo buyout is pending. | Program carriers and fronting insurers | $1.60 billion | A- (Excellent), under review with developing implications since August 2026 |
| 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) |
| 58 | Coaction SpecialtyNew Jersey specialty insurer (formerly ProSight) owned by TowerBrook and Further Global: E&S casualty and property, marine, energy, entertainment and D&O. | Specialty and E&S insurers | $1.51 billion | A- (Excellent) |
| 60 | Skyward SpecialtyHouston-based specialty insurer writing E&S, surety, professional lines, energy, programs, captives and stop-loss; bought Lloyd's platform Apollo in 2026. | Specialty and E&S insurers | $1.41 billion | A (Excellent) |
| 63 | FortegraJacksonville specialty insurer writing E&S and admitted programs through MGAs plus warranty and credit protection; owned by Korea's DB Insurance since May 2026. | Specialty and E&S insurers | $1.33 billion | A (Excellent) |
| 68 | Aspen InsuranceBermuda specialty insurer and reinsurer owned by Apollo funds from 2019 and by Sompo since February 2026; known for excess casualty, professional lines and E&S. | Specialty and E&S insurers | $1.18 billion | A+ (Superior) |
| 71 | James RiverNasdaq-listed E&S casualty writer for small and mid-size accounts, sold only through wholesalers, plus Falls Lake admitted comp; rated A-, negative outlook. | Specialty and E&S insurers | $1.13 billion | A- (Excellent), negative outlook |
| 81 | ProAssuranceBirmingham-based medical malpractice, med-tech products and workers' comp insurer, owned by The Doctors Company since June 2026 after a $1.3 billion takeover. | Medical and professional liability specialists | $927.0 million | A (Excellent) |
| 86 | Obsidian InsuranceGenstar-backed hybrid fronting carrier that issues policies for MGA and program administrator programs; Protective Life agreed to buy it in April 2026. | Program carriers and fronting insurers | $866.6 million | A- (Excellent), under review with positive implications |
| 87 | Vantage RiskBermuda specialty (re)insurer founded in 2020 that writes U.S. excess casualty, construction, healthcare and large property; owned by Howard Hughes since 2026. | Specialty and E&S insurers | $822.5 million | A- (Excellent), positive outlook |
| — | At-BayCyber, tech E&O and MPL insurer for small and midsize firms, sold through brokers on its own E&S paper. Munich Re agreed to buy it in August 2026. | Cyber specialists | — | A- (Excellent), under review with positive implications (At-Bay Specialty Insurance Company) |
| — | CoverWalletNew York insurtech agency founded in 2015, owned by Aon since January 2020. Its site now sends small business quote requests to Aon Affinity agents. | Small business specialists | — | — |
| — | NEXT InsuranceOnline small business insurer founded in 2016, owned outright by Munich Re's ERGO since July 2025 and now branded ERGO NEXT: GL, BOP, comp, auto and E&O. | Small business specialists | — | A+ (Superior) |
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.