Scoring Unilateral Effects with the GUPPI: The Approach of the New Horizontal Merger Guidelines

The US Department of Justice and the Federal Trade Commission released the 2010 Horizontal Merger Guidelines on August 19, 2010. This note explains the approach set out in the 2010 Merger Guidelines to evaluate a merger’s potential for unilateral competitive effects by calculating a “gross upward pricing pressure index” or GUPPI.