This paper uses data on manufacturing firms listed on the Tokyo Stock Exchange to evaluate whether firms that are part of Japanese financial groups (keiretsu) behave differently from other Japanese firms. The results from this analysis reject the hypothesis that these firms collude in order to raise profits. The data do suggest that keiretsu firms are heavily influenced by their banks to produce at levels beyond those warranted by pure profit maximization. These higher levels of output may also explain why entry into markets with strong keiretsu presence is often described as difficult.