Herfindahl-Hirschman Index - HHI

AAA

DEFINITION of 'Herfindahl-Hirschman Index - HHI'

A commonly accepted measure of market concentration. It is calculated by squaring the market share of each firm competing in a market, and then summing the resulting numbers. The HHI number can range from close to zero to 10,000. The HHI is expressed as:

HHI = s1^2 + s2^2 + s3^2 + ... + sn^2 (where sn is the market share of the ith firm).

The closer a market is to being a monopoly, the higher the market's concentration (and the lower its competition). If, for example, there were only one firm in an industry, that firm would have 100% market share, and the HHI would equal 10,000 (100^2), indicating a monopoly. Or, if there were thousands of firms competing, each would have nearly 0% market share, and the HHI would be close to zero, indicating nearly perfect competition.

The U.S. Department of Justice uses the HHI for evaluating mergers.

INVESTOPEDIA EXPLAINS 'Herfindahl-Hirschman Index - HHI'

The U.S. Department of Justice considers a market with a result of less than 1,000 to be a competitive marketplace; a result of 1,000-1,800 to be a moderately concentrated marketplace; and a result of 1,800 or greater to be a highly concentrated marketplace. As a general rule, mergers that increase the HHI by more than 100 points in concentrated markets raise antitrust concerns.

RELATED TERMS
  1. Perfect Competition

    A market structure in which the following five criteria are met: ...
  2. Antitrust

    The antitrust laws apply to virtually all industries and to every ...
  3. Oligopsony

    Similar to an oligopoly (few sellers), this is a market in which ...
  4. Cartel

    An organization created from a formal agreement between a group ...
  5. Oligopoly

    A situation in which a particular market is controlled by a small ...
  6. Merger

    The combining of two or more companies, generally by offering ...
Related Articles
  1. Economics

    Economics Basics

    Learn economics principles such as the relationship of supply and demand, elasticity, utility, and more!
  2. Trading Strategies

    Setting Vs. Getting: What Is A Price-Taker?

    Learn how the economic term "price taker" may separate investors from traders.
  3. Personal Finance

    Antitrust Defined

    Check out the history and reasons behind antitrust laws, as well as the arguments over them.
  4. Economics

    Understanding Perpetuity

    Perpetuity means without end. In finance, a perpetuity is a flow of money that will be received on a regular basis without a specified ending date.
  5. Fundamental Analysis

    What is a Null Hypothesis?

    In statistics, a null hypothesis is assumed true until proven otherwise.
  6. Economics

    How A Limited Government Affects A Country's Finances

    Countries with limited governments have fewer laws about what individuals and businesses can and can’t do. What's the net result?
  7. Investing Basics

    How Does Goodwill Affect Financial Statements?

    Goodwill is a bit of a paradox--intangible, yet it is recorded as an asset on the purchasing company's balance sheet.
  8. Investing Basics

    Using Normal Distribution Formula To Optimize Your Portfolio

    Normal or bell curve distribution can be used in portfolio theory to help portfolio managers maximize return and minimize risk.
  9. Investing Basics

    R-Squared

    Learn more about this statistical measurement used to represent movement between a security and its benchmark.
  10. Insurance

    The Government And Risk: A Love-Hate Relationship

    Though the U.S. government can help its citizens by subsidizing risky loans, the costs always come back to the taxpayers.

You May Also Like

Hot Definitions
  1. Interest Rate Risk

    The risk that an investment's value will change due to a change in the absolute level of interest rates, in the spread between ...
  2. Income Effect

    In the context of economic theory, the income effect is the change in an individual's or economy's income and how that change ...
  3. Price-To-Sales Ratio - PSR

    A valuation ratio that compares a company’s stock price to its revenues. The price-to-sales ratio is an indicator of the ...
  4. Hurdle Rate

    The minimum rate of return on a project or investment required by a manager or investor. In order to compensate for risk, ...
  5. Market Value

    The price an asset would fetch in the marketplace. Market value is also commonly used to refer to the market capitalization ...
  6. Preference Shares

    Company stock with dividends that are paid to shareholders before common stock dividends are paid out. In the event of a ...
Trading Center