In theory, vertical mergers can have both procompetitive and anticompetitive effects. Many early empirical studies found benefits for vertical relationships; but the seminal surveys of this literature are now over a decade old. We review the empirical evidence from the last decade on vertical integration—as well as that in two frequently cited surveys from the mid-2000s. Taken as a whole, the empirical evidence as to the change in welfare that is due to vertical mergers is decidedly mixed, and should certainly not be used as a basis for a presumption that most vertical mergers are procompetitive or harmless.

中文翻译：

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评估纵向合并的证据

理论上，纵向合并可以同时具有促进竞争和反竞争的效果。许多早期的实证研究发现了纵向关系的好处；但是对这些文献的开创性调查现在已经有十多年的历史了。我们回顾了过去十年关于垂直整合的经验证据——​​以及 2000 年代中期两次经常引用的调查中的证据。总的来说，关于由纵向合并引起的福利变化的经验证据显然是混合的，当然不应用作假设大多数纵向合并有利于竞争或无害的基础。