An insurer owned entirely by its policyholders is a

A mutual insurer is an insurance company that is owned entirely by its policyholders. This ownership structure means that the policyholders have a stake in the company, and they can share in its profits, often through dividends or reduced premiums. The primary purpose of a mutual insurer is to provide benefits to its policyholders rather than to shareholders, which is typically the case in stock insurance companies.

In contrast, a captivating insurer is not a recognized term in the insurance industry, while coinsurers typically refer to partners in the risk-sharing arrangement of underwriting insurance policies. A reinsurer, on the other hand, offers insurance to other insurers to help them manage risk and is not owned by policyholders. Therefore, mutual insurers represent a unique model focused on the interests and benefits of the individuals who hold policies with the company.