Mediated Collusion
研究了在完全信息的第一价格采购拍卖中，中介通过推荐价格和惩罚机制促进合谋，发现披露更多出价信息和更大惩罚能提高合谋利润，并刻画了对称双投标人下的最优合谋均衡。
Cartels and bidding rings are often facilitated by intermediaries, who recommend prices/bids to firms and can impose penalties (such as reverting to competitive behavior in future interactions) if these recommendations are not followed. Motivated by such cases, we study correlated equilibria in first-price procurement auctions with complete information, where bidders who disobey their recommendations are penalized. Cartel-optimal profit is greater when more information about submitted bids is disclosed at auction and when the maximum penalty is larger. When only the winner’s identity is disclosed (or the winner’s identity and bid), cartels do not benefit from mediation. Our main result characterizes the cartel-optimal equilibrium with two symmetric bidders when both bids are disclosed. The optimal equilibrium involves extensive randomization and displays tied bids and high winning bids with positive probability, even when the maximum penalty is very small. The stationary mediation schemes we consider are always more profitable for the cartel than bid rotation.