Asymmetric English Auctions Revisited

I introduce a property of player’s valuations that ensures the existence of an ex post e¢ cient equilibrium in asymmetric English auctions. The use of this property has the advantage of yielding an ex post e¢ cient equilibrium without assuming di¤erentiability of valuations or that signals are drawn from a density. These technical, non economic, assumptions have been ubiquitous in the study of (potentially) asymmetric English auctions. Therefore, my work highlights the economic content of what it takes to obtain e¢ cient ex post equilibria. I generalize prior work by Echenique and Manelli (2006) and by Birulin and Izmalkov (2003). Relative to Krishna (2003), I weaken his single crossing properties, drop his di¤erentiability and densities assumptions, but I assume that one player’s valuation is weakly increasing in other players’signals, while he uses a di¤erent assumption (neither stronger nor weaker). Journal of Economic Literature Classi…cation Numbers: D44, D82