纵向兼并的效应分析

采取对策论与微分技术在一般性假设下分析了纵向一体化的动机及其外部性。结果表明：（1）下游企业不仅存在主动兼并动机，而且还存在为降低其他企业纵向兼并对自身的负的外部性而进行的被动兼并动机；（2）不进行纵向市场圈定时的纵向兼并是促进市场竞争的，而当兼并后企业进行纵向市场圈定时，纵向兼并则会弱化市场竞争；（3）纵向兼并将导致上游企业利润增加；（4）参与兼并的下游企业效率越高，纵向兼并越可能是促进社会福利的。

Analysis on effects of vertical integration

Under some general assumptions, this paper applies tools of theroy of game and differential technology to investigating vertical integration motivations and externalities. The following results are shown: (1) downstream firms have not only the positive motives to engage in vertical integration but also the passive motives to engage in vertical integration in order to avoid the negative externalities put on by other downstream firms's vertical integration. (2) that the vertical integration is procompetitive or anticompetitive depends on whether or not the downstream firm engages in vertical foreclosure. (3) vertical integration of the downstream firm generally enhances profits of upstream firms. (4) Higher is efficiency of the downstream firm engaging in vertical integration, more possibly does the vertical integration enhance social welfare.