Herfindahl index

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Herfindahl-Hirschman Index

An index of market concentration the U.S. Department of Justice uses to determine whether a monopoly is forming. The scale goes from zero to 10,000, with 10,000 indicating that a single company controls 100% of the market share in a given industry. An HHI of less than 1000 indicates a market with little concentration, which the Justice Department prefers. Any merger or acquisition leading to an increase of more than 100 when the HHI was previously greater than 1,800 may lead to antitrust action against the company involved.
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Fig. 83 Herfindahl index. The Herfindahl index (H) is the sum of the squared firm sizes, all measured as a proportion of total market size. In the figure, for market A, H = (0.12)2 X 5 + (0.08)2X 5 = 0.104. If all firms in the market are the same size, then the value of the index is equal to the reciprocal of the number of firms; thus, if there are 10 firms all of the same size, H = 0.1. The upper limit of the index is 1, which occurs when there is a monopoly. The figure shows that market B (H = 0.190), with a single dominant firm, is almost twice as concentrated as market A, despite the latter having fewer firms.

Herfindahl index

a measure of the degree of SELLER CONCENTRATION in a MARKET that takes into account the total number of firms in the market and their relative size distribution (share of total market output). See CONCENTRATION MARKET.
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Our primary measure of controlling shareholders' power is Herfindahl Ownership Concentration Index based on the five largest shareholders' equity stakes, following Demsetz and Lehn (1985) and many subsequent studies of ownership structure.
Deputy Trade Representative for the Generalized System of Preferences (GSP) Erland Herfindahl. U.S.
The delegation of Uzbekistan led by Vice Prime Minister Tanzila Narbaeva held talks with Erland Herfindahl, Deputy Assistant of U.S.
Finally, the Herfindahl index (the sum of squared share of exports within the respective two-digit ISIC industrial category) indicates the concentration of a particular industry at the five-digit level within its two-digit ISIC category.
To measure the business concentration of each firm we construct the Line Herfindahl variable, which has an average (median) value of 0.42 (0.37), indicating considerable diversification across lines of business (a value of 1 indicates a single line of insurance).
I use the Herfindahl Equity Index to measure equity concentration.
Several studies use the Herfindahl index to measure salary disparity, other studies use the standard deviation or coefficient of variation, while other studies use the Gini coefficient.
Trade Representative for the Generalized System of Preferences (GSP) Erland Herfindahl at a business forum, Kazinform reported.
Comparing an industry's selling intensity with the degree to which it is dominated by a few firms, as measured by the Herfindahl index, does not indicate a systematic relationship between the two measures across industries, suggesting that the story of customer capital is distinct from the story of market power (Figure 3).
To further explore the robustness of the diversity-stability relationship, we measure stability using four metrics (unemployment rate, population/employment ratio, concentration of establishments, and average weekly wages) and two measures of economic diversity (Herfindahl [[H.sub.i]] index and the log share [[L.sub.i]] index).
With respect to loan level diversity, the pool's loan level Herfindahl score is 31.7 (28.2 excluding structured credit assessed loans).
Also, the report maps the competition in each region using the Herfindahl index.