When the 1968 Merger Guidelines were drafted, both the economics and antitrust literatures addressed how competition could be softened when oligopolists anticipated the natural and predictable responses of their rivals to their competitive moves, such as price cuts or output expansion. But when economists developed new models of oligopoly behavior, and of coordinated effects in particular, the older ideas were dropped—until the 2010 Guidelines, when the older ideas were reincorporated along with the newer ones . Our article points out limitations of the workhorse repeated game model of oligopoly conduct for analyzing coordinated effects of mergers, and suggests ways to make that model more realistic . We also identify important research questions that are raised when attempting to account for oligopolists’ natural and predictable responses in evaluating the consequences of mergers, and suggest studying Stackelberg reactions as a way to make progress in doing so .

当1968年《合并指南》起草时，经济学和反托拉斯文献都谈到了寡头垄断者预期竞争对手对其竞争行为的自然和可预见的反应（例如降价或扩大产量）时，如何软化竞争。但是，当经济学家开发出新的寡头垄断行为模型，尤其是协同效应模型时，旧观念被抛弃了，直到《 2010年指南》将旧观念与新观念重新合并。本文指出了寡头行为的主力重复博弈模型在分析合并的协同效应方面的局限性，并提出了使该模型更加现实的方法。