On the existence of efficient multilateral trading mechanisms with interdependent values

Abstract

This paper studies multilateral trading problems in which agents’ valuations for items are interdependent. Assuming that each agent’s information has a greater marginal effect on her own valuation than on the other agents’ valuations, the paper identifies a necessary and sufficient condition for the existence of trading mechanisms satisfying efficiency, ex-post incentive compatibility, ex-post individual rationality, and ex-post budget balance. The paper presents a trading mechanism that satisfies the four properties when the necessary and sufficient condition holds and shows that this mechanism maximizes the ex-post budget surplus among all efficient, ex-post incentive compatible, and ex-post individually rational trading mechanisms. The paper examines an environment where each agent can possess at most one unit of an item, and her information about the item is one-dimensional. It then extends the results to two general environments: the multiple units environment and the multidimensional information environment.