Organization that underwrites insurance policies. There are two principal types of insurance companies: mutual and stock. A mutual company is owned by its policy owners, who elect a board of directors that is responsible for its operation. A stock company is owned by its stockholders. In a mutual company, profits take the form of policy dividends, or refunds of part of premiums paid, which are distributed to policy owners. Profits in a stock company take the form of stockholders dividends, which are distributed to stockholders.