A principal allocates an object among a finite number of agents, each of whom values the object. Each agent has access to private information about the principal's payoff if he receives the object. There are no monetary transfers. The object is allocated based on the agents' reports. The...

This paper studies the design of ex ante efficient mechanisms in situations where a single object is for sale, and agents have positively interdependent values and can covertly acquire information at some cost before participating in a mechanism. We find that when the strength of...