A. An oligopoly market exists when barriers to entry result in a few producers.
         1. Products may be homogeneous or differentiated.
         2. Examples include many industrial products such as steel and consumer goods like soda. 
         3. Automobile, steel, game consoles and other oligopolistic industries lost monopoly power
             because of the foreign invasion beginning in the 1970's.
             a. Eventually American companies became more competitive.
             b. The price was lower real wages for manufacturing workers.
             c.  The oligopolistic nature of the video game consol market
         4. Concentration ratios measure the amount of total output controlled by a few firms.
             a. eight-firm concentration ratio - Amosweb is Economics ..
             b. four-firm concentration ratio -Amosweb
        5. Readings
             a. Six movie studios movie studios receive 90% of American film revenues.
              b. The television industry is mostly an oligopoly of five companies: Disney/ABC , CBS
              c. NBC Universal Time Warner and News Corporation See Concentration of media ownership .
              d. Four major music companies receive 80% of recording revenues.
              e. Four wireless providers control 89% of the cellular telephone market.
              f. There are just six major book publishers.
              g. Healthcare insurance in the United States consists of very few insurance companies controlling
                  major market share in most states. For example, California's insured population of 20 million is
                  the most competitive in the nation and 44% of that market is dominated by two insurance 
                  companies,  Anthem and Kaiser Permanente.
              h. Anheuser-Busch and Miller Coors control about 80% of the beer industry.   
        B.  Three well-defined pricing models exist
              1. Kinked demand  
              2. Collusive pricing
              3. Price leadership  Please