We study Dominant-Strategy Incentive-Compatible (DSIC) revenue-maximizing auctions (“optimal” auctions) for a single-item and correlated private values. We give tight bounds on the ratio of the revenue of the optimal Ex-Post Individually Rational (EPIR) auction and the revenue of the optimal...

Mean-preserving contractions are critical for studying Bayesian models of information design. We introduce the class of bi-pooling policies, and the class of bi-pooling distributions as their induced distributions over posteriors. We show that every extreme point in the set of all...

Two firms produce substitute goods of unknown quality. At each stage the firms set prices and a consumer with private information and unit demand buys from one of the firms. Both firms and consumers see the entire history of prices and purchases. Will such markets aggregate information? Will the...

A player inuences a collective outcome if his actions can change the probability of that outcome. He is Æ-pivotal if this change exceeds some threshold Æ. We study inuence in general environments with N players and arbitrary sets of signals. It is shown that inuence is maximized when players'...