You may be at the top of your game, but Zenith would like to remind you to please be wary of falls and other accidents. Zenith Insurance is an underwriter of workers' compensation policies. The firm is licensed to underwrite policies in 45 US states but does most of its business in California and Florida. It is one of the top workers' compensation providers in California. A network of independent agencies sells the company's products. Zenith Insurance is the primary subsidiary of insurance holding company Zenith National, which is itself a unit of Canadian property/casualty insurer Fairfax Financial.