With the adoption of the 2020 Vertical Merger Guidelines, the U.S. antitrust agencies have updated their guidance on vertical mergers for the Twenty-First Century. Although economists have long recognized the procompetitive benefits most vertical mergers generate, the law has not always followed...

Market definition remains a critical part of most antitrust cases, despite attempts to obviate it. While many commentators have argued that a particular policy change may theoretically broaden or narrow antitrust markets, and thereby affect substantive antitrust enforcement, none has empirically...