We develop a test for adverse selection and use it to examine private health insurance markets. In contrast to earlier papers that consider a purely private system or a system in which private insurance supplements a public system, we focus our attention on a system where privately funded health...

We study the consequences of imposing a minimum coverage in an insurance market where enrollment is mandatory and agents have private information on their true risk type. If the regulation is not too stringent, the equilibrium is separating in which a single insurer monopolizes the high risks...