
Who writes medical malpractice in Wisconsin
Ranked by direct premium written in 2024 from the Wisconsin market share report (every company, not a top-N list).
34 companies wrote medical malpractice in Wisconsin in 2024, $73.2M in direct premium. Continental Casualty Company led with 27.4%; the top five hold 85%. 59 companies are licensed for the line.
By Sam Alishahi, independent insurance broker · All lines in Wisconsin
The companies
| # | Company | NAIC | Home state | Status here | Premium | Share |
|---|---|---|---|---|---|---|
| 1 | Continental Casualty Company | 20443 | IL | Admitted (licensed) | $20.0M | 27.37% |
| 2 | MMIC Insurance, Inc. | 16942 | MN | Admitted (licensed) | $13.6M | 18.56% |
| 3 | ProAssurance Indemnity Company, Inc. | 33391 | AL | Admitted (licensed) | $13.5M | 18.40% |
| 4 | Medical Protective Company (The) | 11843 | IN | Admitted (licensed) | $11.9M | 16.21% |
| 5 | American Casualty Company of Reading, Pennsylvania | 20427 | PA | Admitted (licensed) | $2.9M | 4.01% |
| 6 | ProSelect Insurance Company | 10638 | NE | Admitted (licensed) | $2.6M | 3.55% |
| 7 | NCMIC Insurance Company | 15865 | IA | Admitted (licensed) | $1.9M | 2.56% |
| 8 | MAG Mutual Insurance Company | 42617 | GA | Admitted (licensed) | $1.2M | 1.68% |
| 9 | COPIC Insurance Company | 11860 | CO | Admitted (licensed) | $851,933 | 1.16% |
| 10 | Liberty Insurance Underwriters, Inc. | 19917 | IL | Admitted (licensed) | $790,078 | 1.08% |
| 11 | ACUITY, A Mutual Insurance Company | 14184 | WI | Admitted (licensed) | $610,527 | 0.83% |
| 12 | ProAssurance Insurance Company of America | 14460 | IL | Admitted (licensed) | $588,938 | 0.80% |
| 13 | Aspen American Insurance Company | 43460 | TX | Admitted (licensed) | $520,037 | 0.71% |
| 14 | Ace American Insurance Company | 22667 | PA | Admitted (licensed) | $482,457 | 0.66% |
| 15 | Cincinnati Insurance Company (The) | 10677 | OH | Admitted (licensed) | $334,380 | 0.46% |
| 16 | Great Divide Insurance Company | 25224 | ND | Admitted (licensed) | $292,056 | 0.40% |
| 17 | Berkshire Hathaway Specialty Insurance Company | 22276 | NE | Admitted (licensed) | $223,221 | 0.31% |
| 18 | ISMIE Mutual Insurance Company | 32921 | IL | Admitted (licensed) | $199,451 | 0.27% |
| 19 | Cincinnati Indemnity Company (The) | 23280 | OH | Admitted (licensed) | $152,772 | 0.21% |
| 20 | Fair American Insurance and Reinsurance Company | 35157 | NY | Admitted (licensed) | $112,735 | 0.15% |
| 21 | Fortress Assurance Corporation | 10801 | IL | Admitted (licensed) | $96,851 | 0.13% |
| 22 | Allied World Assurance Company (U.S.) Inc. | 22730 | NH | Admitted (licensed) | $73,446 | 0.10% |
| 23 | Church Mutual Insurance Company, S. I. | 18767 | WI | Admitted (licensed) | $53,930 | 0.07% |
| 24 | State Farm Fire and Casualty Company | 25143 | IL | Admitted (licensed) | $52,588 | 0.07% |
| 25 | NORCAL Insurance Company | 33200 | CA | Admitted (licensed) | $51,138 | 0.07% |
| 26 | Hartford Fire Insurance Company | 19682 | CT | Admitted (licensed) | $35,063 | 0.05% |
| 27 | Professional Solutions Insurance Company | 11127 | IA | Admitted (licensed) | $23,662 | 0.03% |
| 28 | Beazley Insurance Company, Inc. | 37540 | CT | Admitted (licensed) | $20,257 | 0.03% |
| 29 | Continental Insurance Company, (The) | 35289 | PA | Admitted (licensed) | $17,621 | 0.02% |
| 30 | American Home Assurance Company | 19380 | NY | Admitted (licensed) | $7,832 | 0.01% |
| 31 | Cincinnati Casualty Company (The) | 28665 | OH | Admitted (licensed) | $7,576 | 0.01% |
| 32 | Preferred Professional Insurance Company | 36234 | NE | Admitted (licensed) | $6,443 | 0.01% |
| 33 | CAMPMED CASUALTY \u0026 INDEMNITY COMPANY, INC. | 12260 | NH | Admitted (licensed) | $539 | 0.00% |
| 34 | National Union Fire Insurance Company of Pittsburgh, Pennsylvania | 19445 | PA | Admitted (licensed) | $181 | 0.00% |
Method and source
Source: the Wisconsin insurance regulator company list, read 2026-10-18. Admitted = union of two OCI 2025 Wisconsin Insurance Report documents joined by normalized name: Table E market share (every insurer with 2025 WI premium, all 48 lines incl. life/annuity/A&H; gives NAIC code + lines) and the Directory of Licensed Insurers as of 12/31/2025 (gives domicile, company type, year commenced in WI; no NAIC; https://oci.wi.gov/Documents/AboutOCI/2025_WIR_Directory.pdf). Join stats: {'exact': 1249, 'fuzzy': 3, 'unmatched_xlsx': 2, 'directory_rows': 2281, 'table_e_naic': 1254, 'directory_unmatched': 1029}. Rows with naic '' are directory-only (licensed but no 2025 WI premium or name not matched); rows with type '' are Table E only (name not matched to the directory). Type codes: AR=Accredited Reinsurer; CR=Certified Reinsurer; RJR=Reciprocal Jurisdiction Reinsurer; DSL=Domestic Surplus Line; FR=Fraternal Benefit Society; CC=Continuing Care Organization; CMO=Care Management Organization; HMO=Health Maintenance Organization; IRO=Independent Review Organization; LAH=Life and Accident and Health Company; LSP=Life Settlement Provider; RRG=Risk Retention Group; LSHO=Limited Service Health Organization; MC=Motor Club Plan; SCP=Service Contract Provider; PC=Property and Casualty Company; TI=Title Company; TM=Town Mutual of Wisconsin; VPP=Vehicle Protection Plan; WP=Warranty Plan. Filter P&C with type in {PC, RRG, DSL, TM, TI} or lines among the P&C lines (Table E sheets 34-48: FIRE, FARMOWNERS MULTIPLE PERIL, HOMEOWNERS MULTIPLE PERIL, COMMERCIAL MULTIPLE PERIL, MEDICAL MALPRACTICE, WORKERS COMPENSATION, EXCESS WORKERS COMPENSATION, OTHER LIABILITY, PRIVATE PASSENGER AUTO, COMMERCIAL AUTO, FIDELITY, SURETY, CREDIT, MORTGAGE GUARANTY, TITLE; sheet 33 STOP LOSS/EXCESS LOSS; line strings are the sheet titles, which differ slightly from the TOC). Directory also lists non-insurers (SCP, WP, VPP, MC, LSP, IRO, CC, CMO) and reinsurers (AR, CR, RJR); foreign domiciles are blanked. 'since' = year commenced business in WI. Wisconsin publishes no eligible surplus lines list (NRRA home-state rule; NAIC IID list for aliens), so surplus_lines is empty. "Premium" is direct premium written in the state for the year shown; "share" is that company's part of the state total for the line. A company can be licensed for a line and write none of it, and a surplus lines insurer can write a line without a state license for it.
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