Ten Years of the 2010 HMG: A Perspective from the Department of Justice

Ten years after their release, the 2010 Horizontal Merger Guidelines continue to reflect accurately current legal and economic principles of antitrust. Despite fears to the contrary, the Antitrust Division still relies on market shares and concentration—along with a wide range of other evidence—to determine whether a merger is likely to harm competition substantially. Similarly, market definition remains an essential ingredient to merger analysis, combining the quantitative rigor of the hypothetical monopolist test with the kinds of qualitative evidence that date back to Brown Shoe. The 2010 Horizontal Merger Guidelines have also contributed to courts’ increasing acceptance of the standard economic tools that are used to quantify the potential impact of horizontal mergers, including merger simulation and upward pricing pressure.