The Structure of Equilibrium in an Asset Market with Variable Supply

We characterize the structure of Nash equilibria in asset market games with variable asset supply. In equilibrium, di®erent assets have dif- ferent returns, and (risk neutral) investors with di®erent wealth hold portfolios with di®erent structures. In equilibrium, an asset's return is inversely related to the elasticity of its supply. The larger an in- vestor, the more diversi¯ed is his portfolio. Smaller investors do not hold all the assets, but achieve higher percentage returns. More gen- erally, our results can be applied also to other \multi-market games" in which several players compete in several arenas simultaneously, like multi-market Cournot oligopolies, or multiple rent-seeking games.