A Comparison of Sequential and Simultaneous Auctions

Abstract. Sequential and simultaneous auctions are two important mechanisms for buying/selling multiple objects. These two mechanisms yield different out-comes (i.e., different revenues and also different profits to the winning bidders). Hence, both the auctioneer and the bidding agents want to know which mecha-nism is better for them. Given this, we compare the outcomes for these mecha-nisms for the following scenario. There are multiple similar objects for sale, each object is sold in a separate auction, and each bidder needs only one object. We use English auction rules and first determine equilibrium bidding strategies for each individual auction for the simultaneous and sequential cases. We do this for both common and private value objects by treating a bidder’s information about these values as uncertain. We then consider the case where the private and common values have a uniform distribution and compare the two mechanisms in terms of three key properties: a bidder’s ex-ante expected profit, the auctioneer’s expected cumulative revenue, and the total expected surplus. For both common and private value objects, our study shows the following result. The expected cumulative revenue and the expected total surplus is higher for the sequential mechanism. However, a bidder’s exante expected profit depends on the number of objects be-ing auctioned and the number of participating bidders, and it is sometimes higher for the sequential mechanism and sometimes for the simultaneous one.