Oligopoly is a setting in which a small number of individuals or firms restrict outputs and/or restrict prices to derive market returns. There is no exact upper limit on the number of individuals or firms involved in an oligopoly market structure, but the actions of one firm must have significant consequences on others in order for an oligopoly to exist.
Instances of oligopoly over the course of history include steel manufacturers, oil companies and wireless carriers. In each of these environments, high costs of entry allow for a select group of producers to dominate a market and obtain significant power in the pricing and production of goods and services.
