Equilibrium Selections

This paper analyses the impact of multiple competitive equilibria and complete markets in a simple general equilibrium model. A random selection from the equilibrium correspondence of a finite exchange economy defines probability distributions on equilibrium prices. Asset markets allow traders to insure against the resulting uncertainty. If asset markets are complete, equilibrium selections are necessarily degenerate. The selection cannot be non- trivially random, and must assign probability one to particular equilibrium price vectors. In this case, asset prices reveal the choice of equilibrium price vectors and achieve the coordination of traders' expectations. If the asset market is incomplete, equilibrium selections can be non-degenerate, so that price uncertainty is self-fulfilling. A fully insured random selection defines an iterative procedure of reallocations which is Pareto improving at each step. The process converges to a Pareto optimum in finitely many steps. The key requirement is that the random selection be continuous, which is a generic condition for smooth exchange economies with strictly concave utility functions.