Following merger, an optimal mechanism discriminates against merging bidders with higher reserve prices and by allocating more often towards non-merging bidders. In this setting, we show that mergers always harm the auctioneer, benefit non-merging bidders, can increase total surplus, and have...

This chapter first reviews the economic theory underlying the unilateral competitive effects of mergers, focusing on the Cournot model, commonly applied to homogeneous products; the Bertrand model, commonly applied to differentiated consumer products; and models of auctions and bargaining,...