An Equilibrium Analysis of the Simultaneous Ascending Auction
2010/01/19
研討會日期 : 2010-01-19
時間 : 14:00
主講人 : 連淵湶博士
地點 : B110
演講者簡介 : 連淵湶博士為Ph.D. Economics，Stanford University (2007)。現為Postdoctoral Scholar in Economics, California Institute of Technology。其主要研究領域為Microeconomic Theory, Applied Microeconomics, Experimental Economics, Market Design, Financial Economics。現正申請本所研究職務中。
演講摘要 : We provide a general Bayes-Nash equilibrium analysis of the simultaneous ascending auction (SAA) when local bidders interested in a single item compete against global bidders with super-additive valuations for combinations of items. We first consider an environment where each local bidder values only a specific item, e.g. when a local bidder wants the license for the region where it has monopoly power. We show that bidders' drop-out levels are constrained efficient in the SAA, but unlike the Vickrey-Clarke-Groves (VCG) mechanism the SAA is not ex post efficient. Furthermore, due to the exposure problem, its revenue may be less than that of the VCG mechanism and may be decreasing in the number of bidders. Our techniques extend to large auctions with many items, and we show that the SAA and VCG mechanisms are efficiency and revenue equivalent in the limit. In contrast, in the sealed-bid second-price auction (SSA), the exposure problem causes inefficiencies even with many items. We also consider an environment where items are substitutes for local bidders so that price arbitrage will occur, as observed in many spectrum auctions. This environment, which combines substitutes and complements, results in an aggravated exposure problem and the SAA performs dramatically worse as a result. Finally, we consider an environment with medium-sized global bidders who demand fewer than all items. We show that global bidders divide the market at low prices when market sharing is feasible while they engage in mutually destructive bidding when there is a fitting problem. In both cases, the SAA results in inefficient outcomes.
