Liberty Mutual is the sixth-largest property and casualty insurance company in the U.S., as of 2021. That year, it had 5 percent of the property/casualty insurance market share in terms of direct premiums written, according to the National Association of Insurance Commissioners and the Insurance Information Institute. Liberty Mutual also ranked sixth for private passenger auto insurance by direct premiums written, with a 5 percent U.S. market share. For commercial auto insurance, it came in third with 4 percent.