The Evolution of Merger Enforcement Intensity: What Do the Data Show?

By John W. Mayo & Jeffrey Macher (Georgetown University)

A growing narrative in the popular press and among some academics has been that antitrust regulators have systematically relaxed existing antitrust law enforcement. This narrative has led to calls for reinvigorated enforcement and even the passage of new tougher antitrust legislation. The merits of this narrative and the corollary calls for antitrust reforms depend in part on whether the claim that antitrust regulators have become more relaxed in their enforcement efforts over time is correct. In this paper, we employ data from the United States antitrust agencies to examine one element of this claim. Specifically, we investigate whether antitrust regulators have become less likely to challenge proposed mergers over time. Our results indicate that, contrary to the popular narrative, the Agencies have become more likely to challenge proposed mergers over 1979-2017. Controlling for the number of merger proposals submitted to the antitrust agencies, we find that the likelihood of a merger challenge has more than doubled over this period. We explore reasons behind this increase, and find that increases in antitrust agencies’ budgets have led to enhanced merger enforcement intensity.

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