Competing Combinatorial Auctions

We investigate whether revenue-maximizing auctioneers selling heterogeneous items will allow for combinatorial bidding in the presence of auctioneer competition. We compare the choice of auction format by two competing auctioneers with that of a single auctioneer. Bidders are heterogeneous in their demands, with some having synergies for items. We find that, even if a single auctioneer offers a combinatorial auction, competing auctioneers in a comparable setting will not. Instead, the competing auctioneers will segment the market by restricting allowable package bids in order to increase competition between bidders. This shows that itmight not be advantageous for an onlinemarket platform to offer combinatorial auctions as a design option to competing auctioneers.