Economic Definition of concentration oligopoly. Defined.
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Term concentration oligopoly Definition: Oligopoly is a market structure that contains a small number of relatively large firms, meaning oligopoly markets tend to be concentrated. A small number of large firms account for a majority of total output. Concentration unto itself is not necessarily bad, but it often leads to inefficient behavior, such as collusion and nonprice competition. Concentration is measured in three ways--market share, concentration ratio, Herfindahl index.