Grinnell Mutual Reinsurance Company is a mutual reinsurance company based in Grinnell, Iowa, United States. The company operates in 15 states. On December 10, 2015, A.M. Best issued an 'A' (Excellent) rating and stable outlook for Grinnell Mutual. This was the 25th consecutive year Grinnell Mutual received an 'A' rating. Grinnell Mutual is the 114th largest property-casualty insurance company in the U.S. Grinnell Mutual is the largest direct reinsurer of farm mutual companies in North America. With its member mutuals, it has over $1 Billion in combined written premium and $132 Billion insurance in force.