The Herfindahl-Hirschman Index (HHI) is a measure of the degree of concentration in an industry; it is defined as: \[HHI\ =\ \sum_{i=1}^n MS_i^2\] where: \(n\): number of firms in the industry \(MS_i\): market share of firm i (Technically, if there are more than 50 firms in the industry, the HHI sums over only the largest […]

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