A dynamic model with many sellers and buyers is constructed. Agents failing to trade may trade in the next period. An equilibrium is found where sellers hold identical auctions and buyers randomize over the sellers they visit. The distribution of buyer valuations is endogenous. An auction with efficient reserve is an optimal mechanism from each seller's point of view, in spite of the ability of any seller to alter the distribution of buyer types participating in the seller's mechanism by altering the mechanism.

In models of asymmetric information, possession of private information leads to rents for the possessors. This induces mechanism designers to distort away from efficiency. The authors show that this is an artifact of the presumption that information is independently distributed. Rent extraction in a large class of mechanism design games is analyzed, and a necessary and sufficient condition for arbitrarily small rents to private information is provided. Additionally, the two-person bargaining game is shown to have an efficient solution under first-order stochastic dominance and a hazard rate condition. Similar conditions allow full rent extraction in Milgrom-Weber auctions.