A dynamic trading game is examined in which two uninformed buyers engage in Bertrand-like competition to attempt to purchase a single object of uncertain quality from an informed seller. It is shown that there exists a unique perfect sequential equilibrium. The game is compared to an analogous bargaining game in which a single uninformed buyer makes offers to a single seller. Despite the fact that in the equilibrium of the competitive game, buyers compete away their surplus, it is shown that sellers can often gain a higher ex ante surplus in the bargaining game.

We prove—in the standard independent private-values model—that the outcome, in terms of interim expected probabilities of trade and interim expected transfers, of any Bayesian mechanism can also be obtained with a dominant-strategy mechanism.

We analyze optimal mechanisms in environments where sellers are privately informed about quality. A methodology is provided for deriving conditions that are necessary and sufficient to determine when two simple trading environments maximize either social or private surplus. The commonly used auction mechanism is frequently inefficient in procurement environments. Often, the optimal mechanism is simply to order potential suppliers and to tender take-it-or-leave-it offers to each sequentially. We completely characterize the environments in which either mechanism is optimal. In doing so, we develop a general methodology that determines when and if a given trading institution is optimal.