Efficient Market Structures Under Incomplete Information

In economies with incomplete information, laissez-faire price competition is not, in general, constrained Pareto efficient. But which market structures are? We consider an environment in which firms have private information about costs and consumers make discrete choices over goods. Surveying an expansive class of market structures, we show that the constrained efficient ones are equivalent to price competition, but with lump-sum transfers and yardstick price ceilings that depend on the prices of competing firms