This paper uses the Nash bargaining model to examine the effects of the distribution system on firms purchasing multiple inputs. We show that network combination, that is, vertical integration between a manufacturer and a retail firm, does not always bring enterprise superiority to a non-integrated firm. Although classical economic theory articulates that vertically integrated firms typi-cally have an advantage over non-integrated firms in profits, as the former can eliminate double marginalization, this is not always the case if we consider a situation of multiple inputs trading.