平台内市场结构设计——兼论网上外卖商业模式与管制

Intra-platform Market Structure Design:With Application to the Business Model and Regulation of Online Food Delivery Service

在撮合买卖双方交易的线上市场,平台通过最优定价和增值服务,可以影响商家进入,设计符合利润最大化的平台内市场结构。本文通过构建“双边平台+平台内商家竞争”的多方博弈模型,从理论上研究了平台内市场结构设计问题,得到以下四点结论:第一,平台在撮合交易之外,可以借助配送服务(在商家佣金与消费者配送费之间)实现交叉补贴定价,获得更高利润。第二,由于交叉补贴定价,平台介入会提高经济效率,与不存在平台时的商家自由进入竞争相比,平台内市场结构设计导致的商家数量更接近甚至可以达到社会最优。第三,平台交叉补贴定价模式的最优性受到竞争性配送市场、商家配送和定价能力等的影响,从而衍生出不同的商业模式。第四,政府管制平台对商家的佣金上限可能引起平台的策略性反应,依据平台具体商业模式而导致不同效果(利益再分配、无实际效果乃至效率损失)。本文模型及结论可以解释网上外卖平台的独特商业模式及管制效果。

This paper introduces the concept of“Intra-platform Market Structure Design”,emphasizing how a monopoly platform on an online marketplace that facilitates transactions between buyers and sellers can influence sellers'entry through optimal pricing and value-added services,thereby designing an internal market structure within the platform that maximizes profits.We develop a dynamic game theory model,combining sellers'Salop competition with platform design,to discuss how the platform affects sellers'entry and the efficiency of platform pricing.Based on the model,we derive the following main conclusions.First,beyond transaction facilitation,the platform can achieve cross-subsidy pricing through delivery services,thereby garnering higher profits(the delivery service itself may incur losses).In cross-subsidy pricing,the platform charges sellers commissions like ad-valorem tax and charges consumers delivery fees based on distance.Second,due to cross-subsidy pricing,a monopolistic platform's intervention can improve economic efficiency.Compared with a scenario where sellers enter freely without platform mediation,the equilibrium number of sellers resulting from the designed internal market structure of the platform is closer(or can even equal)to the first best.Third,the optimality of cross-subsidy pricing for a platform may be affected by the competitive delivery market and sellers'ability to deliver goods and discriminative pricing,leading to various business models.Fourth,imposing a regulatory cap on the commission rate charged by the platform to sellers may elicit strategic responses from the platform,leading to different impacts,such as redistribution of interests,zero impacts or even efficiency loss,according to specific business models of platforms.Compared with existing literature based on“platform governance”,the concept of“Intra-platform Market Structure Design”proposed in this paper focuses more on specific platform business models while also considering the platform's welfare effects.Additionally,it emphasizes the potential enhancement of competition efficiency among intra-platform sellers due to platform design.For instance,prior analyses of third-party platforms often assume the platform's role is limited to facilitating transactions.This paper further analyzes the role of delivery services and interprets them as a means to implement cross-subsidy pricing and price discrimination.The applied value of this paper lies in explaining the business model of online food delivery services.Compared with e-commerce platforms,third-party online food delivery platforms have a unique business model:in addition to transaction facilitation,they also provide delivery services,with their revenue mainly derived from delivery fees and commissions.Data analysis from leading online food delivery platforms in China shows that while the platforms are profitable overall,the delivery services themselves incur losses.The conclusions from our model help to elucidate this business model,particularly the impact of loss-making delivery businesses on platform profits and economic efficiency,and the potential effects of regulating the commission rates charged by platforms to sellers.In recent years,discussions have been intensified within the economics community regarding the development of the platform economy,especially concerning whether and how the government should regulate large Internet platforms.This paper offers the following major policy implications.First,it is crucial to fully recognize the crucial role of platforms in market structure design and their special economic principles to promote high-quality development of the platform economy.Second,to evaluate the effects of regulation on a platform,we should analyze the strategic responses induced by regulation and the further welfare impacts,including effects on competition within a platform.