This paper proposes a perfectly competitive model of a market with adverse selection. Prices are determined by zero-profit conditions, and the set of traded contracts is determined by free entry. Crucially for applications, contract characteristics are endogenously determined, consumers may have multiple dimensions of private information, and an equilibrium always exists. Equilibrium corresponds to the limit of a differentiated products Bertrand game. We apply the model to establish theoretical results on the equilibrium effects of mandates. Mandates can increase efficiency but have unintended consequences. With adverse selection, an insurance mandate reduces the price of low-coverage policies, which necessarily has indirect effects such as increasing adverse selection on the intensive margin and causing some consumers to purchase less coverage.

The endowment effect, the tendency to value possessions more than non-possessions, is a well-known departure from rational choice and has been replicated in numerous settings. We investigate the universality of the endowment effect, its evolutionary significance, and its dependence on environmental factors. We experimentally test for the endowment effect in an isolated and evolutionarily relevant population of hunter-gatherers, the Hadza Bushmen of Northern Tanzania. We find that Hadza living in isolated regions do not display the endowment effect, while Hadza living in a geographic region with increased exposure to modern society and markets do display the endowment effect.