Did tough antitrust policy lead to lower mark-ups in the US manufacturing industry?

This paper tests whether antitrust policy in the US has an impact on the price cost margin. Using a unique database the methodology developed by Domowitz et al. [Review of Economics and Statistics, 70 (1988) 55¯66] is applied to find estimates of the price cost margin. The estimates indicate presence of market power in many industries but also substantial heterogeneity of behaviour, both across time and industries. Finally, it confirms the hypothesis that mark-ups were lower when the antitrust policy was very tough.