Optimality and robustness of the English auction

In Milgrom and Weber's (1982, Econometrica 50, 1089-1122) "general symmetric model," under a few additional regularity conditions, the English auction maximizes the seller's expected profit within the class of all posterior-implementable trading procedures and fails to do so among all interim incentive-compatible procedures in which "losers do not pay." These results suggest that appropriate notions of robustness and simplicity which imply the optimality of the English auction for a risk-neutral seller must impose "bargaining-like" features on the set of feasible trading mechanisms. (C) 2000 Academic Press.