An oligopoly is a market form in which a market is dominated by a small number of sellers. For example, as of fourth quarter 2008, Verizon, AT&T, Sprint, and T-Mobile together control 97% of the US cellular phone market. Competition is limited in an oligopoly because barriers to entry are high.The most important barriers are government licenses, economies of scale, patents, access to expensive and complex technology, and strategic actions by incumbent firms designed to discourage or destroy nascent firms.
