基于双边交易环境的中间商拍卖机制设计

Mediated Auction Design in the Two-sided Markets

本文探讨由中间商主导的双边市场交易环境下的中间商拍卖机制设计问题。首先,分析现有拍卖机制在实践中潜在的局限性,特别指出卖方伪装成竞拍者抬高报价的欺诈行为。然后,建立由固定或比例交易费以及支付上限两类参数刻画的中间商拍卖模型(MAFC),并证明MAFC机制具有买卖双方诚实报价、中间商期望预算平衡和防止卖方欺诈等良好的性质。最后,从社会福利、竞拍者剩余和卖方期望收益三个方面对中间商拍卖机制进行福利分析,并将其与理论基准Myerson最优拍卖机制以及考虑卖方欺诈的Yokoo et al.(2005)阈值价格双边机制(TPD)进行比较。结果表明,在竞拍者多于两人以及评估价值服从均匀分布的情形下,两类MAFC机制在社会福利和竞拍者剩余方面均优于最优拍卖机制和TPD机制;在卖者期望收益方面,固定交易费MAFC机制优于最优拍卖机制,最优拍卖机制优于比例交易费MAFC机制,两类MAFC机制均优于TPD机制。

This paper investigates the problems when putting the traditional auction theory into practice, and proposes the mediated auction mechanism in the two-side markets. By introducing the payment constraint in the double VCG auction with participation fee framework, we set up parameterized mediated auction models with （fixed or percentage） transaction fee and payment ceiling. We prove that these auction formats achieve truth telling of buyers and sellers, expected budget balance of mediator, and shill-bid proofness. First, we prove the existence of auction parameters in general case, and further discuss the implementation of mediated auction when the value of two players follows uniform distribution. Moreover, we make welfare analysis on the new auctions, and comparing them with optimal auction provided by Myerson （1981）, as the theoretical benchmark, and threshold price double auction （TPD） proposed by Yokoo et al. （2005）, which considers the false-name-bid problem. The results show that, from social welfare and bidders＇ expected surplus perspectives, both of two mediated auction formats are better than optimal auction and TPD auction; Fixed transaction fee auction format is better than optimal auction, and optimal auction is better than percentage transaction fee auction, however, two mediated auctions are better than simple auctions without optimal reservation price and TPD auction in terms of expected surplus of the seller. This paper lays the micro-economic foundation for the mediated auction design in the two sided markets.