Economics:Oligopoly Market Structure

Between the definitions of perfect competition and pure monopoly lie oligopolies and monopolistic competition. An oligopoly is where there are a few sellers with similar or identical products, such as hockey skates (Bauer, CCM). Monopolistic competition has many companies with similar but not identical products. Each firm has monopoly power over what it produces, but products are close substitutes, such as cigarettes, CDs, and computer games. Examples of oligopolies include crude oil businesses and auto manufacturers.
The main key to behaviour in an oligopoly, is that companies must take into account what other companies will do. In perfect competition, firms are price-takers and can ignore other firms. In a monopoly, there is only one firm, and it does not take into account what competitors will do. Oligopolists are torn between:
1. cooperating to increase profits by obtaining the monopoly outcome, or;
2. competing to try to gain an advantage over competitors.
Duopolies and Cartels
A duopoly is when there are only two businesses in a market. Their best outcome is to cooperate and agree to restrict output to the monopoly quantity, where price is greater than margical cost, and profit is maximized. A great example of a duopoly is Coca-Cola and Pepsi Co. Usually, a duopoly trying to maximize profits will produce more than a monopolist but less than a competitive industry. Duopolies come from collusion where firms agree to share output and set prices such as in a cartel.
A cartel is a group of companies acting in unison, such as OPEC. If the competing companies cannot agree, then they may end up with the competitive position with profits equal to zero. Cartels are known to restrict output quantities in order to raise prices, and consequently profits.
Size of an Oligopoly and the Market Outcome
Generally, the more companies in the industry, the harder it is to form a cartel and to enforce it. As the number of companies increases, the more the industry resembles a competitive outcome, since each company has a smaller effect on the outcome. The mentality where each company tends to think only of its own profits and strategic behaviour is reduced. Each company will increase production as long as price is greater than marginal cost. As the number of companies increases, we tend to move towards a perfectly competitive outcome.
Game Theory and Prisoners' Dilemma
Game theory is the study of how people behave in strategic situations (i.e. when they must consider the effect of other people’s responses to their own actions). In an oligopoly, each company knows that its profits depend on actions of other firms. This gives rise to the "prisoners’ dilemma".
The prisoners' dilemma is a particular game that illustrated why it is difficult to cooperate, even when it is in the best interest of both parties. Both players select their own dominant strategies for shortsighted personal gain. Eventually, they reach an equilibrium in which they are both worse off than they would have been, if they could both agree to select an alternative (non-dominant) strategy.