Annuities provide a stream of payments and are generally classified as insurance because they are issued by insurance companies, are regulated as insurance, and require the same kinds of actuarial and investment management expertise that life insurance requires. Annuities and pensions that pay a benefit for life are sometimes regarded as insurance against the possibility that a retiree will outlive his or her financial resources. In that sense, they are the complement of life insurance and, from an underwriting perspective, are the mirror image of life insurance.