To be an oligopoly, the 4-firm concentration ratio must be at least 40%. ¨ Based on this rule of thumb, about 50% of U.S. manufacturing is oligopolistic. ¨ But, there are some shortcomings of concentration ratios
To be an oligopoly, the 4-firm concentration ratio must be at least 40%.¨ Based on this rule of thumb, about 50% of U.S. manufacturing is oligopolistic.¨ But, there are some shortcomings of concentration ratios