25 Largest Workers Compensation Insurers

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Workers compensation insurance is available from a broad range of insurers. This is evident from the latest (2017) list of the 25 largest workers compensation insurers in the United States. The list, which appears below, is derived from data published by the National Association of Insurance Commissioners (NAIC) in March, 2018. Most of the insurers on the list distribute their products through independent agents.

Varied Market

The workers compensation market is highly varied. The first three companies on the "top 25" list (Travelers, Hartford, and Zurich) are large multi-line insurers. These insurers provide many types of insurance coverages to businesses of all sizes. AmTrust, which is number four on the list, specializes in workers compensation and package policies for small to mid-sized companies. It is based in New York City and operates across the U.S.

Other insurers on the list, like W.R. Berkley and Markel, are specialty companies. W.R. Berkley owns approximately sixty insurance companies, each of which specializes in a certain type of business. For instance, Berkley Agribusiness focuses on commercial agriculture while Preferred Employers Insurance provides workers compensation insurance to businesses in California. Markel offers insurance programs designed for specific types of businesses, such as health clubs or schools. It also offers a small business program, which includes coverages like workers compensation and businessowners.

Workers Comp Specialists

Interestingly, some of the largest workers compensation insurers are state insurance funds. There are five state funds on the "top 25" list. These include the New York State Fund, the State Compensation Fund of California, SAIF (the state fund in Oregon), Pinnacol Assurance (the state fund in Colorado), and Texas Mutual. All five companies compete for business with private insurers in the standard market. All except SAIF operate their state's assigned risk plan. Assigned risk plans provide workers compensation coverage to employers that have not been able to obtain insurance from a standard insurer.

Such plans are essential because workers compensation insurance is mandatory in most states.

A few insurers on the list are workers compensation specialists but are not state insurance funds. These include Employers Group and ICW Group. Employers Group offers workers compensation coverage only. It operates in about forty states and focuses on small businesses. ICW Group sells only two commercial insurance coverages: workers compensation and earthquake. 

Blue Cross Blue Shield of Michigan, the only health insurer on the list, is the parent company of Accident Fund Group. The latter owns several subsidiaries, all of which sell workers compensation insurance only. Examples are United Heartland and CompWest.


The NAIC was established in 1871 to assist state regulators. It is an advisory organization rather than a regulatory agency. The NAIC sets standards and provides regulatory advice. It also creates model laws that states may adopt with or without modifications. The NAIC's model laws are an important time-saving tool for state regulatory agencies. They also facilitate the standardization of laws and regulations across the country.

The Top 25

The insurers on the "top 25" list appear in descending order based on net written premiums generated in 2017. The term net written premium means all policy premium collected by an insurer except for premium paid to a reinsurance company for reinsurance coverage. The written premium is the amount a policyholder is obligated to pay for a policy. Workers compensation premiums are paid in advance so the written premium is the amount the insured has paid upfront. Written premium differs from earned premium, which is the amount the insured has paid for the expired portion of the policy.

The earned premium is based on actual payrolls so it cannot be calculated until a final audit is performed.

Insurers' workers compensation premiums can fluctuate from year to year. Some changes may be deliberate. For instance, both AIG and Liberty Mutual have experienced a significant drop in workers compensation premiums in recent years. Both companies have stated that the decline was intentional, and reflected their decision to exit unprofitable business. 

One company that has permanently disappeared from the "top 25" list is ACE. In 2016, ACE purchased Chubb, and the combined company is using the Chubb name.

Rank Insurer 2017 Premium 2017 Market Share (%)
1 Travelers Group 4.356 bn 7.51
2 Hartford Group 3.407 bn 5.88
3 Zurich Ins. Group 2.923 bn 5.04
4 AmTrust Group 2.920 bn 5.04
5 Berkshire Hathaway 2.802 bn 4.83
6 Chubb Ltd. Group 2.459 bn 4.24
7 Liberty Mutual Group 2.447 bn 4.22
8 State Ins. Fund (NY) 2.278 bn 3.93
9 AIG 1.758 bn 3.03
10 Old Republic Group 1.458 bn 2.51
11 WR Berkley 1.412 bn 2.44
12 American Financial Grp. 1.367 bn 2.36
13 State Comp. Ins. Fund (CA) 1.360 bn 2.35
14 BCBS of MI Group 1.338 bn 2.31
15 Texas Mutual Ins. Co. 992 M* 1.71
16 Fairfax Financial Group 952 M 1.64
17 ICW Group 992 M 1.61
18 CNA Ins. Group 838 M 1.27
19 Employers Holding Group 720 M 1.24
20 Pinnacol Assurance 621 M 1.07
21 Starr Group 619 M 1.07
22 Arch Ins. Group 560 M .97
23 NJ Manufacturers Group 526 M .91
24 Markel Corp. Group 513 M .88
25 SAIF Corp. 498 M .86
Industry Total 57,983 bn