A.M. BEST - assigns 15 different rating categories from A++ to F measuring a carrier's ability to meet their respective policyholder and other contractual obligations, and size categories ranging from I to IV.
Click here for insurance company ratings. 

MOODY'S - examines an insurance company's financial ability to meet its obligations to its policyholders.  Among the issues on which Moody's focuses is the management philosophy, the quality of its investment portfolio and its asset/liability structure.  It features ratings from Aaa to C. Click here Moody's  Insurance Company Watch List.

STANDARD & POORS - provides a review of an insurance company's claims-paying ability. Click here for Standard & Poors  insurance company's credit rating.

FITCH RATINGS - rates from an investors and policyholder standpoint addressing concerns such as claims-paying abilities, financial fundamentals, details regarding capitalization, debt ratings, leverage, and asset quality. Click here for Fitch insurance company ratings.