DEFINITION of 'Duopoly'

A situation in which two companies own all or nearly all of the market for a given product or service. A duopoly is the most basic form of oligopoly, a market dominated by a small number of companies. A duopoly can have the same impact on the market as a monopoly if the two players collude on prices or output. Collusion results in consumers paying higher prices than they would in a truly competitive market and is illegal under U.S. antitrust law.


Boeing and Airbus have been called a duopoly for their command of the large passenger airplane market. Similarly, Amazon and Apple have been called a duopoly for their dominance in the e-book marketplace.

A closely related concept is a monopoly, a situation in which a single company dominates the market. The United States Postal Service, which is by law the sole provider of first-class mail services, is an example of a monopoly.

  1. Perfect Competition

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

    A market similar to a monopoly except that a large buyer not ...
  3. Monopoly

    A situation in which a single company or group owns all or nearly ...
  4. Oligopoly

    A situation in which a particular market is controlled by a small ...
  5. Price Fixing

    Establishing the price of a product or service, rather than allowing ...
  6. Antitrust

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