If you're looking for business insurance you have plenty of options for insurers. Here are the largest 50 commercial insurance companies, ranked by market share.

Rank Commercial insurance company Market share %
1 Chubb 5.52
2 Travelers Companies Inc. 5.49
3 Liberty Mutual 5.12
4 American International Group 4.19
5 Zurich 4.18
6 CNA Financial Corp. 3.27
7 Berkshire Hathaway Inc. 2.94
8 Nationwide Mutual Group 2.65
9 Hartford Financial Services 2.55
10 Tokio Marine 2.12
11 American Financial Group Inc. 1.90
12 Assurant Inc. 1.89
13 W. R. Berkley Corp. 1.86
14 AmTrust Financial Services 1.84
15 Fairfax Financial 1.69
16 AXA 1.50
17 State Farm 1.39
18 Old Republic International Corp. 1.35
19 Markel Corp. 1.32
20 Progressive 1.31
21 Farmers Insurance Group of Cos 1.27
22 Allianz 1.26
23 Cincinnati Financial Corp. 1.21
24 FM Global 1.16
25 Arch Capital 1.15
26 QBE 1.06
27 Auto-Owners Insurance 1.02
28 Hanover Insurance Group Inc. 0.93
29 Sompo 0.86
30 Selective Insurance Group Inc. 0.80
31 State Insurance Fund Workers' Comp 0.75
32 STARR Cos. 0.74
33 Allstate Corp. 0.69
34 Erie Insurance 0.68
35 Everest Re 0.55
36 Munich Re 0.54
37 EMC Insurance Cos. 0.53
38 Swiss Re 0.51
39 Argo 0.49
40 AXIS 0.47
41 State Compensation Insurance Fund 0.45
42 Alleghany Corp. 0.44
43 AF Group 0.44
44 USAA 0.42
45 Sentry Insurance a Mutual Co. 0.42
46 Federated Mutual 0.41
47 Westfield Insurance 0.39
48 MGIC Investment Corp. 0.37
49 Aspen 0.37
50 OneBeacon Insurance 0.36
Source: S&P Global Market Intelligence. Market share based on direct premiums written for commercial insurance in 2017.