Objectives of chapter 7: Monopolistic competition Price and output in monopolistic competition

Chapter 7 by TITH Seyla 1

Objectives of chapter 7:

• Monopolistic competition• Price and output in monopolistic competition• Monopolistic competition and efficiency• Product variety• Oligopoly and its behavior- a game theory

overview• Three oligopoly models• Oligopoly and advertising• Oligopoly and efficiency

Chapter 7: Monopolistic Competition and Oligopoly


What Is Monopolistic Competition?

– Monopolistic competition is a market structure in which

A large number of firms compete. Each firm produces a differentiated product. Firms compete on product quality, price, and

marketing. Firms are free to enter and exit the industry.


Monopolistic Competition• Examples of Monopolistic Competition

– Producers of audio and video equipment, clothing, jewelry, computers, and sporting goods operate in monopolistic competition.


Price and Output in Monopolistic Competition

• The Firm’s Short-Run Output and Price Decision– A firm that has decided the quality of its

product and its marketing program produces the profit-maximizing quantity at which its marginal revenue equals its marginal cost (MR = MC).

– Price is determined from the demand curve for the firm’s product and is the highest price that the firm can charge for the profit-maximizing quantity.

– Figure 14.1 shows a firm’s economic profit in the short run.



– The firm in monopolistic competition operates likea single-price monopoly.

– The firm produces the quantity at which MR equals MC and sells that quantity for the highest possible price.

– It earns an economic profit (as in this example) when P > ATC.



• Long Run: Zero Economic Profit– In the long run, economic profit induces entry.– And entry continues as long as firms in the

industry earn an economic profit—as long as (P > ATC).

– In the long run, a firm in monopolistic competition maximizes its profit by producing the quantity at which its marginal revenue equals its marginal cost, MR = MC.



– As firms enter the industry, each existing firm loses some of its market share. The demand for its product decreases and the demand curve for its product shifts leftward.

– The decrease in demand decreases the quantity at which MR = MC and lowers the maximum price that the firm can charge to sell this quantity.

– Price and quantity fall with firm entry until P = ATC and firms earn zero economic profit.



– Figure 14.3 shows a firm in monopolistic competition in long-run equilibrium.



• Monopolistic Competition and Perfect Competition– Two key differences between monopolistic

competition and perfect competition are: Excess capacity Markup– A firm has excess capacity if it produces less

than the quantity at which ATC is a minimum.– A firm’s markup is the amount by which its

price exceeds its marginal cost.



– Firms in monopolistic competition operate with excess capacity in long-run equilibrium.

– Firms produce less than the efficient scale—the quantity at which ATC is a minimum.

– The downward-sloping demand curve for their products drives this result.



– Firms in monopolistic competition operate with positive markup.

– Again, the downward-sloping demand curve for their products drives this result.



– In contrast, firms in perfect competition have no excess capacity and no markup.

– The perfectly elastic demand curve for their products drives this result.


What Is Oligopoly?– Oligopoly is a market structure in which Natural or legal barriers prevent the entry of

new firms. A small number of firms compete.


What Is Oligopoly?• Barriers to Entry

– Either natural or legal barriers to entry can create oligopoly.

– Figure 15.1 shows two oligopoly situations.

– In part (a), there is a natural duopoly—a market with two firms.


What Is Oligopoly?

– In part (b), there is a natural oligopoly market with three firms.

– A legal oligopoly might arise even where the demand and costs leave room for a larger number of firms.


What Is Oligopoly?• Small Number of Firms

– Because an oligopoly market has a small number of firms, the firms are interdependent and face a temptation to cooperate.

– Interdependence: With a small number of firms, each firm’s profit depends on every firm’s actions.

– Cartel: A cartel and is an illegal group of firms acting together to limit output, raise price, and increase profit.

– Firms in oligopoly face the temptation to form a cartel, but aside from being illegal, cartels often break down.


Two Traditional Oligopoly Models• The Kinked Demand Curve Model

– In the kinked demand curve model of oligopoly, each firm believes that if it raises its price, its competitors will not follow, but if it lowers its price all of its competitors will follow.


Two Traditional Oligopoly Models

– Figure 15.2 shows the kinked demand curve model.

– The firm believes that the demand for its product has a kink at the current price and quantity.


Two Traditional Oligopoly Models– Above the kink,

demand is relatively elastic because all other firm’s prices remain unchanged.

– Below the kink, demand is relatively inelastic because all other firm’s prices change in line with the price of the firm shown in the figure.


Two Traditional Oligopoly Models

– The kink in the demand curve means that the MR curve is discontinuous at the current quantity—shown by that gap AB in the figure.


Two Traditional Oligopoly Models– Fluctuations in MC that

remain within the discontinuous portion of the MR curve leave the profit-maximizing quantity and price unchanged.

– For example, if costs increased so that the MC curve shifted upward from MC0 to MC1, the profit-maximizing price and quantity would not change.


Two Traditional Oligopoly Models– The beliefs that

generate the kinked demand curve are not always correct and firms can figure out this fact.

– If MC increases enough, all firms raise their prices and the kink vanishes.

– A firm that bases its actions on wrong beliefs doesn’t maximize profit.


Two Traditional Oligopoly Models• Dominant Firm Oligopoly

– In a dominant firm oligopoly, there is one large firm that has a significant cost advantage over many other, smaller competing firms.

– The large firm operates as a monopoly, setting its price and output to maximize its profit.

– The small firms act as perfect competitors, taking as given the market price set by the dominant firm.


Two Traditional Oligopoly Models– Figure 15.3 shows10 small firms in part (a).

The demand curve, D, is the market demand and the supply curve S10 is the supply of the 10 small firms.


Two Traditional Oligopoly Models– At a price of $1.50, the 10 small firms produce

the quantity demanded. At this price, the large firm would sell nothing.


Two Traditional Oligopoly Models– But if the price was $1.00, the 10 small firms

would supply only half the market, leaving the rest to the large firm.


Two Traditional Oligopoly Models– The demand curve for the large firm’s output is the

curve XD on the right.


Two Traditional Oligopoly Models– The large firm can set the price and receives a

marginal revenue that is less than price along the curve MR.


Two Traditional Oligopoly Models– The large firm maximizes profit by setting MR =

MC. Let’s suppose that the marginal cost curve is MC in the figure.


Two Traditional Oligopoly Models– The profit-maximizing quantity for the large firm

is 10 units. The price charged is $1.00.


Two Traditional Oligopoly Models– The small firms take this price and supply the

rest of the quantity demanded.


Two Traditional Oligopoly Models– In the long run, such an industry might become

a monopoly as the large firm buys up the small firms and cuts costs.

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Objectives of chapter 7: Monopolistic competition Price and output in monopolistic competition