Workers' compensation costs remain a significant component of expenses for most companies, and finding the best workers' comp coverage at the most reasonable price is critical to helping businesses manage their bottom line. But which carriers have the biggest share of the market? The National Association of Insurance Commissioners (NAIC) has ranked the top 25 Workers' Compensation insurance companies and groups by market share of direct premiums written for 2016. Its latest report includes countrywide direct written premium for the top 25 groups and companies as reported on the State Page of the annual statement for insurers that report to the NAIC. This information serves as an indicator of the degree of market concentration in the Workers' Comp line of business as well as identifying leading insurance writers. Related: Understanding the relationship between workers' comp and SSDI For 2017, direct written premiums totaled $57.9 billion for the top 25 carriers, down slightly from 2016's $58.2 billion. The top 25 carriers accounted for 68.9% percent of the total direct premiums written, with the top 15 bringing in a little more than half at 57.39%, or about $33.3 billion. The top four carriers represent a little less than a quarter (23.47%) of total direct premiums written. The State Compensation Insurance Fund (California) dropped out of the top 10 to number 13, with the rest of the top 10 generally maintaining their positions from 2016. Travelers Group and Hartford Fire & Casualty Group retained their number 1 and number 2 positions from 2016 and 2015. Continue reading to find out which companies ranked in NAIC's list of top 10 Workers' Compensation companies and groups in 2017: Related: Top 10 workers' comp carriers for 2016, as ranked by NAIC