We study when equilibrium prices can aggregate information in an auction market with a large population of traders. Our main result identifies a property of information---the betweenness property---that is both necessary and sufficient for information aggregation. The characterization provides...

In this paper, we examine the optimal mechanism design of selling an indivisible object to one regular buyer and one publicly known buyer, where inter-buyer resale cannot be prohibited. The resale market is modeled as a stochastic ultimatum bargaining game between the two buyers. We fully...

A crucial assumption in the optimal auction literature is that each bidder's valuation is known to be drawn from a unique distribution. In this paper we study the optimal auction problem allowing for ambiguity about the distribution of valuations. Agents may be ambiguity averse (modeled using...

This paper develops a methodology for characterizing expected revenue from auctions when bidders' types come from an arbitrary distribution. In particular, types may be multidimensional, and there may be mass points in the distribution. One application extends existing revenue equivalence...

It is well-known that the ability of the Vickrey-Clarke-Groves (VCG) mechanism to implement efficient outcomes for private value choice problems does not extend to interdependent value problems. When an agent's type affects other agents' utilities, it may not be incentive compatible for him to...

I study the canonical private value auction model for a single good without the quasilinearity restriction. I assume only that bidders are risk averse and the indi- visible good for sale is a normal good. I show that removing quasilinearity leads to qualitatively different solutions to the...

I show that a unique equilibrium exists in an asymmetric two-player all-pay auction with a discrete signal structure, correlated signals, and interdependent valuations. The proof is constructive, and the construction can be implemented as a computer program and be used to derive comparative...

Using a mechanism design framework, we characterize how a profit-maximizing intermediary can design matching markets when each agent is privately informed about his quality as a partner. Sufficient conditions are provided that ensure a version of positive assortative matching (what we call...

I study collusion between two bidders in a general symmetric IPV repeated auction, without communication, side transfers, or public randomization. I construct a collusive scheme, endogenous bid rotation, that generates a payoff larger than the bid rotation payoff.

In this paper we consider equilibrium behavior in a Dutch (descending price) auction when the bidders are uninformed of their valuations with probability q and can acquire information about their valuation with a positive cost during the auction. We assume that the information acquisition...