Some Suggestions on How to Cheat the Auctioneer: Collusion in Auctions when Signals Are Affiliated.

First and second price collusive auction mechanisms from the literature on bid rigging within the independent private values model are extended to be applicable within the general symmetric model where signals are affiliated. A mechanism which allow information sharing is also proposed. The paper focus on ex post efficient cartel mechanisms which allows monetary transfers between members, and show the assumption of affiliation does not discourage collusion and that information sharing is both feasible and raises the gains of collusive behaviour.