Equilibrium in Insurance Markets with Asymmetric Information and Adverse Selection

This report examines possible outcomes of greater competition in insurance markets. The report describes the nature of insurance offerings in equilibrium if firms offer multiple policies; but it replaces the conventional assumption that each policy must earn nonnegative profits with the more realistic requirement that the portfolio of policies offered by the firm earn nonnegative profits in the aggregate. Theorems regarding the existence, optimality, and uniqueness of the subsidy equilibrium are presented, together with a simple characterization of the subsidy equilibrium and a comparison with existing equilibrium notions. Because the subsidy patterns, from low to high, that emerge under this formulation appear to characterize multiple-option insurance plans such as the Federal Employees Health Benefits Plan, this model may be more useful than conventional methods in the analysis of such plans.