As of 2018, two of the most famous of oligopoly in the US, and wireless communication technologies. In Canada, banking and wireless communications are oligopolies. In the world of oligopoly include computer and operating system developers for smartphones.
Oligopoly similar to a monopoly except that the market is controlled by several companies, not just one. For example, film production in the U.S. is dominated by six companies that earned $5.2 billion profit in 2016: time/Warner, Disney, 21st century Fox, NBC/universal, Sony and viacom. Also in 2018, the four wireless companies (Verizon, at&T, Sprint or, the mother) account for 98% of wireless revenues in the United States
Seven banks control the canadian banking industry: Royal Bank of Canada (RBC), TD Canada trust, Bank of Nova Scotia, Bank of Montreal (BMO), canadian Imperial commercial Bank (cibc), Desjardins group and national Bank of Canada. Bell, Rogers and Telus own over 90% of the canadian wireless market.
Worldwide, Windows, Mac OS and Linux, control almost the entire computer market for operating systems. Meanwhile, just two operating systems, Google Android and Apple iOS, more than 90% of the smartphone and tablet market share.
All of these examples are imperfect or differentiated oligopoly, as the products and services these companies offer, while often very similar, not exactly the same. This is in contrast to pure or perfect oligopoly, where competitors produce goods that are virtually identical. There are some really pure oligopoly, although the metallurgy, cement and aluminium industries considered to be close.
(For associated reading, see economic basics: competition, monopoly and Oligopoly.)