Clinching auctions with online supply

Auctions for perishable goods such as Internet ad inventory need to make real-time allocation and pricing decisions as the supply of the good arrives in an online manner, without knowing the entire supply in advance. In this work, we consider a multi-unit model where buyers have global budget constraints, and the supply arrives in an online manner. Our main contribution is to show that for this setting there is an individuallyrational, incentive-compatible and Pareto-optimal auction that allocates these units and calculates prices on the fly, without knowledge of the total supply. We do so by showing that the Adaptive Clinching Auction satisfies a supply-monotonicity property. Finally, while our main technical result concerns multi-unit supply, we propose a formal model of online supply that captures scenarios beyond multi-unit supply and has applications to sponsored search. (C) 2015 Elsevier Inc. All rights reserved.