Berkshire Hathaway Inc. is a holding company owning subsidiaries engaged in a number of diverse business activities. The most important of these is the property and casualty insurance business conducted on both a direct and reinsurance basis through a number of subsidiaries. Included in this group of subsidiaries is GEICO, one of the five largest auto insurers in the United States, General Re, one of the four largest reinsurers in the world, and the Berkshire Hathaway Reinsurance Group.