This paper analyzes simultaneous ascending auctions of two different items, viewed as complements by multi-item bidders. The finding is that such auctions overly concentrate the goods to a multi-item bidder and never overly diffuse them to single-item bidders. The main reason is that some...

We study the design of profit maximizing single unit auctions under the assumption that the seller needs to incur costs to contact prospective bidders and inform them about the auction. With independent bidders’ types and possibly interdependent valuations, the seller’s problem can be...