Oligopolies exist widely in modern economies. However, due to the reasons just cited, most do not function as cartels. Still, since these markets have relatively few sellers and each has a significant share of market sales, in many cases the total market production by oligopoly firms is less than would be expected if the market were perfectly competitive, and prices will be somewhat higher.
From the point of theory, the expected operation of the firm in perfect competition or in monopoly/cartel is straightforward. Assuming the firm in the perfect competition sufficiently understands its production costs, it will increase volume up to the point where its marginal cost exceeds the price. For a monopolist or cartel, production should increase up to point where marginal cost equals marginal revenue.
Oligopolies fall somewhere in between perfect competition and a cartel. However, the prescription of how to set optimal production volume is considerably more complex than either of the extremes. Like the monopolist, the oligopoly firm is aware that significant changes in its production level will have a significant effect on the market supply quantity, requiring a change in the market price to be in agreement with a downward sloping demand curve. However, while the firm is aware its production decisions will affect the market price, it is difficult to forecast the actual impact on price, even if the firm knows the behavior of the market demand curve.
A major reason for the complexity in determining the optimal production level is that the firm does not know how its oligopoly competitors will respond to its production decisions. For example, suppose a firm looks at the current market price and decides based on the market demand curve that it could increase its production volume by 1000 units per day and make a greater profit, even if the price dropped according to the market demand curve. Other sellers in the market will see the action taken and may decide that if the price is dropping and market demand is increasing that they could benefit by increasing their production to take advantage. As a consequence, the total market volume may increase more than expected, prices will drop more than expected, and the resulting gain in profit will be less than what the initial firm expected when it did its analysis.
Trying to figure out how to deal with reactions of other sellers not only is a vexing problem for sellers in oligopolies but has been a difficult challenge for academic economists who try to develop theories of oligopoly. The scholarly literature of economics is filled with elaborate mathematical models that attempt to address oligopoly operation. Next we will consider some of the insights of these analyses without the mathematics.
One approach that economists have used to model the behavior of oligopoly firms, known as the Bertrand model or price competition, is to assume all firms can anticipate the prices that will be charged by their competitors. If firms can reasonably anticipate the prices that other firms will charge and have a reasonable understanding of market demand, each firm can determine how customers would react to its own price and decide what production level and price leads to highest profit. The soft drink market is an example of a market that could operate in this manner.
Another approach for modeling oligopoly behavior, known as the Cournot model or quantity competition, is to assume all firms can determine the upcoming production levels or operating capacities of their competitors. For example, in the airline industry, schedules and gate arrangements are made months in advance. In essence, the airlines have committed to a schedule, their flying capacities are somewhat fixed, and what remains is to make the necessary adjustments to price to use the committed capacity effectively.
In comparing models where firms anticipate price to those where firms anticipate production volume or capacity commitment, firms that anticipate quantity levels tend to operate at lower production levels and charge higher prices. This occurs because in a quantity competition model, firms subtract the planned operation of their rivals from the market demand curve and assume the residual is the demand curve they will face. This leads to the presumption that the price elasticity of their own demand is the same as the price elasticity of overall market demand, whereas in price competition models the elasticity of the firm’s own demand is seen as greater than the price elasticity of overall market demand (as was the case in the perfect competition model).
The number of selling firms also has an effect on the likely outcome of oligopoly competition. As the number of firms increases, the market equilibrium moves toward the equilibrium that would be expected in a perfectly competitive market of firms with the same aggregate production resources.
Another issue that can affect the prices and quantity volumes in an oligopoly market is the existence of a “leader” firm. A leader firm will make a decision on either its price or its volume/capacity commitment and then the remaining “follower firms” determine how they will react. An example of a leader firm in an industry might be Apple in the portable media player market. Apple decides on how it will price its iPod products and other manufacturers then decide how to price their products. Although the leader firm commits first in these models, in order to determine its own best course of action, it needs to anticipate how the follower firms will react to its decision.