Horizontal Merger Antitrust Enforcement at the DOJ: A Closer Look From 2005-2015

I manually collect data on all horizontal merger cases litigated by the Department of Justice (DOJ) between 2005-2015 from the DOJ\u27s website by reading the Complaint, Competitive Impact Statement, and Final Judgment for a total of 94 cases. I analyze how horizontal merger antitrust enforcement is impacted by the 2008 Great Recession and the enactment of the 2010 Horizontal Merger Guideline Revision. The total number of mergers litigated by the DOJ decreases from 2008-9 corresponding to the nadir of the Great Recession. The pro-interventionist 2010 Guidelines lead to an increase in merger litigation following its enactment. I use a linear regression to evaluate which factors impact the outcome of the cases following the institution of the Guidelines. I find that when the judge is appointed by a democratic president, the merger is more likely to be blocked, consistent with a pro-enforcement, democratic ideology. Additionally, as the number of anticompetitive reasons against merging increases, the DOJ (plaintiff) is more likely to win. The use of the Hypothetical Monopolist Test (HMT) increases following 2010, and is consisted with the Guidelines’ emphasis on the use of various economic formulas. However, I did not see an increase in the use of other economic formulas. Based on the rationale cited in the Competitive Impact Statement by the DOJ, antitrust litigation appears nonuniform and only minimally effected by the 2010 Guidelines