Antitrust Mini-Series 11 Structural Presumptions

Antirust authorities make presumptions (assumptions) about whether markets are competitive based primarily on a metric called the Herfindahl-Hirschman Index (HHI). This video illustrates how to calculate HHI and discusses what thresholders trigger antitrust review. This video also draws skepticism on the measure, since its calculation depends on properly defining the market, and since authorities keep changing the thresholds.