NAIC 2025 Market Share Report | Top 25 Medical Professional Liability Insurers
The National Association of Insurance Commissioners has issued its annual Market Share Data Reports for both the Property & Casualty Insurance Marketplace, as well as for the Life & Fraternal Insurance Marketplace. As in past iterations, the data offered here reflects a compiled list of market share data based upon filings of countrywide premium submitted to the NAIC from Property & Casualty insurers as reported on the State Page of the NAIC’s annual statement for insurers.
Once collected, the data is compiled into a report listing the cumulative market share data for the seven major lines of insurance in the United States: All lines; Private Passenger Personal Auto; Commercial Auto; Workers’ Compensation; Medical Professional Liability; Homeowners’ Multi-Peril; and Other Liability (excluding auto liability).
With approximately 97.92% of P&C insurers reporting, the industry recorded approximately $1.06 trillion in Direct Premiums Written in 2024. The top 10 P&C insurers account for 51.40% of the total market share, reflecting a continued concentration of market share among the largest carriers.
Private passenger auto insurance remains the dominant line of business, with $344.11 billion in direct premiums written, representing approximately 35% of all reported P&C premiums.
Key takeaways from this year’s Medical Professional Liability Market Share Report
The following are three key takeaways from this year’s market share reports courtesy of Chat GPT:
1. Berkshire Hathaway Dominates with Nearly 18% Market Share
Berkshire Hathaway Group led the sector with $2.2 billion in direct premiums written, representing 17.72% of the total market. Its dominant share is more than 70% higher than its closest competitor, the Doctors Company Group.
2. Market Share is Highly Concentrated Among Top Carriers
The top five groups alone account for over 44% of the total U.S. medical professional liability insurance market. This includes Berkshire Hathaway, Doctors Co, CNA, ProAssurance, and MAG Mutual.
3. Premium Growth Remains Concentrated Despite a Fragmented Tail
After the top 10 groups, market share drops below 2% per group. The 25th-ranked company, MICA Group, holds just 0.73% of market share, illustrating how competitive dynamics shift beyond the top tier and how smaller mutuals, RRGs, and specialty writers continue to operate in regional or niche spaces.
The Top 25 P&C Insurers by Countrywide Premium – Medical Professional Liability Insurers
| Rank | Group/Company Name | Direct Premiums Written | Direct Premiums Earned | Direct Loss to EP Ratio (%) | Market Share (%) | Cumulative Market Share (%) | |
|---|---|---|---|---|---|---|---|
 |
1 | BERKSHIRE HATHAWAY GRP | 2,213,998,844 | 2,180,963,418 | 49.00 | 17.72 | 17.72 |
 |
2 | DOCTORS CO GRP | 1,267,764,164 | 1,233,116,521 | 44.35 | 10.14 | 27.86 |
 |
3 | CNA INS GRP | 757,207,091 | 726,112,027 | 36.25 | 6.06 | 33.92 |
 |
4 | PROASSURANCE CORP GRP | 679,670,466 | 687,649,921 | 45.18 | 5.44 | 39.36 |
 |
5 | MAG MUT INS GRP | 599,176,531 | 598,415,397 | 52.83 | 4.79 | 44.15 |
 |
6 | COVERYS GRP | 476,478,279 | 492,690,775 | 54.36 | 3.81 | 47.96 |
 |
7 | LIBERTY MUT GRP | 454,792,147 | 413,955,830 | 45.94 | 3.64 | 51.60 |
 |
8 | MCIC VT A RECIP RRG | 449,756,768 | 449,759,650 | 105.26 | 3.60 | 55.20 |
 |
9 | CURI HOLDINGS GRP | 411,919,973 | 398,233,708 | 53.44 | 3.30 | 58.50 |
 |
10 | CHUBB LTD GRP | 241,822,724 | 232,631,444 | 70.49 | 1.94 | 60.43 |
 |
11 | ISMIE GRP | 217,119,087 | 213,398,933 | 46.47 | 1.74 | 62.17 |
 |
12 | WR BERKLEY CORP GRP | 199,690,592 | 205,688,399 | 53.52 | 1.60 | 63.77 |
 |
13 | COPIC GRP | 192,510,138 | 187,465,588 | 44.96 | 1.54 | 65.31 |
 |
14 | PRI GRP | 186,934,534 | 178,353,503 | 54.89 | 1.50 | 66.81 |
 |
15 | FAIRFAX FIN GRP | 175,909,998 | 162,239,846 | 48.77 | 1.41 | 68.21 |
 |
16 | STATE VOLUNTEER MUT INS CO | 153,038,003 | 150,757,204 | 42.44 | 1.22 | 69.44 |
 |
17 | PHYSICIANS INS A MUT GRP | 149,167,486 | 146,220,127 | 56.84 | 1.19 | 70.63 |
 |
18 | CORE SPECIALTY INS HOLDINGS | 120,537,711 | 86,191,614 | 124.36 | 0.96 | 71.60 |
 |
19 | NATIONAL GRP | 113,065,904 | 109,623,754 | 39.97 | 0.90 | 72.50 |
 |
20 | MARKEL GRP | 104,382,434 | 101,897,027 | 38.58 | 0.84 | 73.34 |
 |
21 | ARCH INS GRP | 103,876,206 | 100,388,232 | 37.68 | 0.83 | 74.17 |
 |
22 | NCMIC GRP | 98,467,196 | 98,599,761 | 31.38 | 0.79 | 74.95 |
 |
23 | MOUNTAIN LAUREL RRG INC | 92,926,000 | 80,795,000 | 62.69 | 0.74 | 75.70 |
 |
24 | MUNICH RE GRP | 92,625,166 | 103,316,158 | 69.47 | 0.74 | 76.44 |
 |
25 | MICA GRP | 91,402,561 | 93,179,519 | 44.17 | 0.73 | 77.17 |
| INDUSTRY TOTAL | 12,497,284,962 | 12,200,800,230 | 52.86 | 100.00 | 100.00 |
Past NAIC Market Share Reports
For those interested in revisiting or comparing this year’s data with the NAIC Market Share Reports from past years, links to each of those reports are below:
