This paper studies the relationship between firms' size and the number of their business partners by employing a unique data set covering about 820,000 Japanese firms. First, we find that the number of interfirm relationships, measured by the indegree, has a fat-tail distribution: the top 1 percent firms occupy about 50 percent of all interfirm relationships. Second, the indegree distribution for those firms with a large number of relationships, or "hub" firms, also exhibits a fat-tail, indicating the existence of "super-hub" firms. Third, larger firms tend to have more relationships, but the relationship between firms' size and the number of their indegree is not necessarily proportional. Firms already with a large number of relationships do not increase it with their size.
