Herfindahl-Hirschman index

The Herfindahl-Hirschman index (HHI), better known as the Herfindahl index, is a statistical measure of concentration. It has achieved an unusual degree of visibility for a statistical index because of its use by the competition regulators to analyse the competitive effects of mergers. The aim of such an evaluation is to ascertain if sanctioning the proposed merger would result in an appreciable adverse effect on competition (AAEC) or not. Alt Indices uses financial as well as non-financial data from regulated sources to compute the HHI benchmarks.