Pub. date: 2008 | Online Pub. Date: October 22, 2007 | DOI: 10.4135/9781412956260 | Print ISBN: 9781412916523 | Online ISBN: 9781412956260| Publisher:SAGE Publications, Inc.About this encyclopedia
Rogene A. Buchholz
The Herfindahl Index, often called the HerfindahlHirschman Index (HHI), is a measure of market concentration, which can be defined as the percentage of total industry sales that are contributed by the largest firms in an industry. The HHI is a measure of the size of firms in a given industry and an indicator of the degree of competition in that industry. It is a more sophisticated method of measuring market concentration than the more common method that uses the fourfirm concentration ratio (the percentage of industry sales made by the leading four firms in a given industry). This measure is of interest to antitrust authorities who are trying ...