One Auction or Two: Simultaneous vs. Sequential Sales in Multi-unit Auctions

This paper explores whether an auctioneer can benefit by dividing his stock of items into identical lots and auctioning off the lots sequentially, rather than selling them all in one auction. As for most auction houses, the auctioneer is not a monopolistic seller who can choose how much to produce—he or she has a consignment from a seller, which he or she has to sell so as to maximize the expected revenue. If all bidders are not present at the start of an auction, there is an obvious reason for holding some items back. A less obvious reason has to do with the intensity of competition and it is this we focus on. The set of bidders is fixed, players are impatient and the auctioneer cannot commit not to (eventually) sell items below any reserve price announced at the beginning of the first auction. Given this framework, we show that there are parameter values under which sequential auctions are in fact better for the auctioneer. If there is uncertainty among the bidders about the total number of items available, this enables the auctioneer to do even better with a sequential auction under certain conditions. One Auction or Two: Simultaneous vs. Sequential Sales in Multi-unit Auctions