We consider differentiated duopolists that face symmetric linear demands and produce using Cobb–Douglas technologies with a monopolized input and a competitively supplied input. A merger between the input monopolist and either firm eliminates double marginalization but – unlike​ with fixed-proportions technologies – can lead to foreclosure and reduce welfare. The same can occur under a CES technology with greater input substitutability than Cobb–Douglas. With identical Cobb–Douglas technologies, the merged firm raises the rival’s cost by more, and the welfare effects are worse, when the input it controls constitutes a low rather than high share of input costs. With different technologies, the welfare effects can be non-monotonic in that input’s share of costs.

我们考虑了面对对称线性需求并使用Cobb–Douglas技术生产的具有垄断输入和竞争性供应输入的差异化双寡头。投入垄断企业和任一企业之间的合并消除了双重边缘化，但与固定比例技术不同的是，这可能导致丧失抵押品赎回权并减少福利。在CES技术下，与Cobb–Douglas相比，具有更高的输入替代性的情况也可能发生同样的情况。如果采用相同的Cobb–Douglas技术，则合并后的公司将竞争对手的成本提高更多，而当其控制的投入所占投入成本所占份额不高时，其福利效应则更糟。使用不同的技术，在投入的成本份额中，福利效应可能是非单调的。