10-寡头垄断

Chapter 10 Oligopoly • Imperfect competition refers to those market structures that fall between perfect competition and pure monopoly. • Imperfect competition includes industries in which firms have competitors but do not face so much competition that they are price takers. BETWEEN MONOPOLY AND PERFECT COMPETITION • Types of Imperfectly Competitive Markets – Oligopoly • Only a few sellers, each offering a similar or identical product to the others. – Monopolistic Competition • Many firms selling products that are similar but not identical. Figure 1 The Four Types of Market StructureFigure 1 The Four Types of Market StructureFigure 1 The Four Types of Market StructureFigure 1 The Four Types of Market Structure • Tap water • Cable TV Monopoly (Chapter 15) • Novels • Movies Monopolistic Competition (Chapter 17) • Tennis balls • Crude oil Oligopoly (Chapter 16) Number of Firms?Number of Firms?Number of Firms?Number of Firms? Perfect • Wheat • Milk Competition (Chapter 14) Type of Products?Type of Products?Type of Products?Type of Products? Identical products Differentiated products One firm Few firms Many firms MARKETS WITH ONLY A FEW SELLERS • Because of the few sellers, the key feature of oligopoly is the tension between cooperation and self-interest. • Characteristics of an Oligopoly Market – Few sellers offering similar or identical products – Interdependent firms – Best off cooperating and acting like a monopolist by producing a small quantity of output and charging a price above marginal cost A Duopoly ExampleA Duopoly ExampleA Duopoly ExampleA Duopoly Example • A duopoly is an oligopoly with only two members. It is the simplest type of oligopoly. Table 1 The Demand Schedule for WaterTable 1 The Demand Schedule for WaterTable 1 The Demand Schedule for WaterTable 1 The Demand Schedule for Water A Duopoly ExampleA Duopoly ExampleA Duopoly ExampleA Duopoly Example • Price and Quantity Supplied • The price of water in a perfectly competitive market would be driven to where the marginal cost is zero: • P = MC = $0 • Q = 120 gallons • The price and quantity in a monopoly market would be where total profit is maximized: • P = $60 • Q = 60 gallons A Duopoly ExampleA Duopoly ExampleA Duopoly ExampleA Duopoly Example • Price and Quantity Supplied • The socially efficient quantity of water is 120 gallons, but a monopolist would produce only 60 gallons of water. • So what outcome then could be expected from duopolists? The Market for WaterThe Market for WaterThe Market for WaterThe Market for Water Quantity of OutputQuantity of OutputQuantity of OutputQuantity of Output0 CostCostCostCost $120 $60 60 MC is constant and = $0.MC is constant and = $0.MC is constant and = $0.MC is constant and = $0. 120 DemandDemandDemandDemand Marginal Marginal Marginal Marginal RevenueRevenueRevenueRevenue In a competitive market, quantity would equal 120 and P = MC = $0. A monopoly would produce 60 gallons and charge $60. Note that P > MC. Total industry output Total industry output Total industry output Total industry output with a with a with a with a duopolyduopolyduopolyduopoly will will will will probably exceed 60, probably exceed 60, probably exceed 60, probably exceed 60, but be less than 120.but be less than 120.but be less than 120.but be less than 120. Competition, Monopolies, and CartelsCompetition, Monopolies, and CartelsCompetition, Monopolies, and CartelsCompetition, Monopolies, and Cartels • The duopolists may agree on a monopoly outcome. • Collusion • An agreement among firms in a market about quantities to produce or prices to charge. • Cartel • A group of firms acting in unison. Competition, Monopolies, and CartelsCompetition, Monopolies, and CartelsCompetition, Monopolies, and CartelsCompetition, Monopolies, and Cartels • Although oligopolists would like to form cartels and earn monopoly profits, often that is not possible. Antitrust laws prohibit explicit agreements among oligopolists as a matter of public policy. The Equilibrium for an OligopolyThe Equilibrium for an OligopolyThe Equilibrium for an OligopolyThe Equilibrium for an Oligopoly • A Nash equilibrium is a situation in which economic actors interacting with one another each choose their best strategy given the strategies that all the others have chosen. The Equilibrium for an OligopolyThe Equilibrium for an OligopolyThe Equilibrium for an OligopolyThe Equilibrium for an Oligopoly • When firms in an oligopoly individually choose production to maximize profit, they produce quantity of output greater than the level produced by monopoly and less than the level produced by competition. • The oligopoly price is less than the monopoly price but greater than the competitive price (which equals marginal cost). Equilibrium for an OligopolyEquilibrium for an OligopolyEquilibrium for an OligopolyEquilibrium for an Oligopoly • Summary • Possible outcome if oligopoly firms pursue their own self-interests: • Joint output is greater than the monopoly quantity but less than the competitive industry quantity. • Market prices are lower than monopoly price but greater than competitive price. • Total profits are less than the monopoly profit. How the Size of an Oligopoly Affects the How the Size of an Oligopoly Affects the How the Size of an Oligopoly Affects the How the Size of an Oligopoly Affects the Market OutcomeMarket OutcomeMarket OutcomeMarket Outcome • How increasing the number of sellers affects the price and quantity: • The output effect: Because price is above marginal cost, selling more at the going price raises profits. • The price effect: Raising production will increase the amount sold, which will lower the price and the profit per unit on all units sold. How the Size of an Oligopoly Affects the How the Size of an Oligopoly Affects the How the Size of an Oligopoly Affects the How the Size of an Oligopoly Affects the Market OutcomeMarket OutcomeMarket OutcomeMarket Outcome • As the number of sellers in an oligopoly grows larger, an oligopolistic market looks more and more like a competitive market. • The price approaches marginal cost, and the quantity produced approaches the socially efficient level. GAME THEORY AND THE ECONOMICS OF COOPERATION • Game theory is the study of how people behave in strategic situations. • Strategic decisions are those in which each person, in deciding what actions to take, must consider how others might respond to that action. GAME THEORY AND THE ECONOMICS OF COOPERATION • Because the number of firms in an oligopolistic market is small, each firm must act strategically. • Each firm knows that its profit depends not only on how much it produces but also on how much the other firms produce. The PrisonersThe PrisonersThe PrisonersThe Prisoners’’’’ Dilemma Dilemma Dilemma Dilemma • The prisoners’ dilemma provides insight into the difficulty in maintaining cooperation. • Often people (firms) fail to cooperate with one another even when cooperation would make them better off. The PrisonersThe PrisonersThe PrisonersThe Prisoners’’’’ Dilemma Dilemma Dilemma Dilemma • The prisoners’ dilemma is a particular “game” between two captured prisoners that illustrates why cooperation is difficult to maintain even when it is mutually beneficial. Figure 2 The PrisonersFigure 2 The PrisonersFigure 2 The PrisonersFigure 2 The Prisoners’’’’ Dilemma Dilemma Dilemma Dilemma BonnieBonnieBonnieBonnie’’’’ s Decision s Decision s Decision s Decision ConfessConfessConfessConfess ConfessConfessConfessConfess Bonnie gets 8 years Clyde gets 8 years Bonnie gets 20 years Clyde goes free Bonnie goes free Clyde gets 20 years gets 1 yearBonnie Clyde gets 1 year Remain SilentRemain SilentRemain SilentRemain Silent RemainRemainRemainRemain SilentSilentSilentSilent ClydeClydeClydeClyde’’’’ssss DecisionDecisionDecisionDecision Oligopolies as a PrisonersOligopolies as a PrisonersOligopolies as a PrisonersOligopolies as a Prisoners’’’’ Dilemma Dilemma Dilemma Dilemma • The dominant strategy is the best strategy for a player to follow regardless of the strategies chosen by the other players. • Cooperation is difficult to maintain, because cooperation is not in the best interest of the individual player. Figure 3 Jack and JillFigure 3 Jack and JillFigure 3 Jack and JillFigure 3 Jack and Jill’’’’s Oligopoly Games Oligopoly Games Oligopoly Games Oligopoly Game JackJackJackJack’’’’ssss Decision Decision Decision Decision High High High High ProductionProductionProductionProduction High Production: 40 Gal.High Production: 40 Gal.High Production: 40 Gal.High Production: 40 Gal. Jack gets $1,600 profit Jill gets $1,600 profit Jack gets $1,500 profit Jill gets $2,000 profit Jack gets $2,000 profit Jill gets $1,500 profit Jack gets $1,800 profit Jill gets $1,800 profit Low Production: 30 gal.Low Production: 30 gal.Low Production: 30 gal.Low Production: 30 gal. LowLowLowLow ProductionProductionProductionProduction JillJillJillJill’’’’ssss DecisionDecisionDecisionDecision 40 gal.40 gal.40 gal.40 gal. 30 gal.30 gal.30 gal.30 gal. Oligopolies as a PrisonersOligopolies as a PrisonersOligopolies as a PrisonersOligopolies as a Prisoners’’’’ Dilemma Dilemma Dilemma Dilemma • Self-interest makes it difficult for the oligopoly to maintain a cooperative outcome with low production, high prices, and monopoly profits. Figure 4 An Arms-Race GameFigure 4 An Arms-Race GameFigure 4 An Arms-Race GameFigure 4 An Arms-Race Game Decision of the United States (U.S.)Decision of the United States (U.S.)Decision of the United States (U.S.)Decision of the United States (U.S.) ArmArmArmArm ArmArmArmArm U.S. at risk USSR at risk U.S. at risk and weak USSR safe and powerful U.S. safe and powerful USSR at risk and weak U.S. safe USSR safe DisarmDisarmDisarmDisarm DisarmDisarmDisarmDisarm Decision Decision Decision Decision of the of the of the of the Soviet Union Soviet Union Soviet Union Soviet Union (USSR)(USSR)(USSR)(USSR) Figure 5 A Common-Resource GameFigure 5 A Common-Resource GameFigure 5 A Common-Resource GameFigure 5 A Common-Resource Game ExxonExxonExxonExxon’’’’s Decision s Decision s Decision s Decision Drill TwoDrill TwoDrill TwoDrill Two WellsWellsWellsWells Drill Two WellsDrill Two WellsDrill Two WellsDrill Two Wells Exxon gets $4 million profit Chevron gets $4 million profit Chevron gets $6 million profit Exxon gets $3 million profit Chevron gets $3 million profit Exxon gets $6 million profit Chevron gets $5 million profit Exxon gets $5 million profit Drill One WellDrill One WellDrill One WellDrill One Well Drill OneDrill OneDrill OneDrill One WellWellWellWell ChevronChevronChevronChevron’’’’ssss DecisionDecisionDecisionDecision Why People Sometimes CooperateWhy People Sometimes CooperateWhy People Sometimes CooperateWhy People Sometimes Cooperate • Firms that care about future profits will cooperate in repeated games rather than cheating in a single game to achieve a one-time gain. PUBLIC POLICY TOWARD OLIGOPOLIES • Cooperation among oligopolists is undesirable from the standpoint of society as a whole because it leads to production that is too low and prices that are too high. Restraint of Trade and the Antitrust LawsRestraint of Trade and the Antitrust LawsRestraint of Trade and the Antitrust LawsRestraint of Trade and the Antitrust Laws • Antitrust laws make it illegal to restrain trade or attempt to monopolize a market. • Sherman Antitrust Act of 1890 • Clayton Antitrust Act of 1914 Controversies over Antitrust PolicyControversies over Antitrust PolicyControversies over Antitrust PolicyControversies over Antitrust Policy • Antitrust policies sometimes may not allow business practices that have potentially positive effects: • Resale price maintenance • Predatory pricing • Tying Controversies over Antitrust Policy Controversies over Antitrust Policy Controversies over Antitrust Policy Controversies over Antitrust Policy • Resale Price Maintenance (or fair trade) • occurs when suppliers (like wholesalers) require retailers to charge a specific amount • Predatory Pricing • occurs when a large firm begins to cut the price of its product(s) with the intent of driving its competitor(s) out of the market • Tying • when a firm offers two (or more) of its products together at a single price, rather than separately SummarySummarySummarySummary • Oligopolists maximize their total profits by forming a cartel and acting like a monopolist. • If oligopolists make decisions about production levels individually, the result is a greater quantity and a lower price than under the monopoly outcome. SummarySummarySummarySummary • The prisoners’ dilemma shows that self- interest can prevent people from maintaining cooperation, even when cooperation is in their mutual self-interest. • The logic of the prisoners’ dilemma applies in many situations, including oligopolies. SummarySummarySummarySummary • Policymakers use the antitrust laws to prevent oligopolies from engaging in behavior that reduces competition.