The insurance industry is typified by insurers belonging to a number of different organizational forms. Stock insurers are corporations owned by the shareholders of the firm. The shareholders hire managers to run the company and the insurance product is sold to customers who may or may not be shareholders in the firm.
Mutual insurers are companies that are owned by their customers.
Any policyowner of the company also owns a portion of the company. Reciprocal insurers or reciprocal exchanges are insurance companies where the policyowners of the exchange agree to insure one another. They are very similar to mutual companies. HMO's or Health Maintenance Organizations are companies that provide comprehensive health care coverage to their customers. HMO's, in their simplest form, provide prepaid health care coverage.