1、第10章 市场势力市场势力: 垄断与买方垄断垄断与买方垄断 第第 10章章Slide 2 本章要讨论的问题本章要讨论的问题 垄断 垄断势力 垄断形成原因 垄断的社会成本 第第 10章章Slide 3 本章要讨论的问题本章要讨论的问题 买方垄断 买方垄断势力 限制市场势力: 反垄断法 第第 10章章Slide 4 完全竞争完全竞争 完全竞争回顾 lP = LMC = LRAC l长期内只存在正常利润或经济利润为零 l大量生产者和消费者 l同质化产品 l充分信息 l企业是价格的接受者 完全竞争完全竞争 Q Q PP市场市场单个企业单个企业 DS Q0 P0P0 D = MR = P q0 LRAC
2、LMC 第第 10章章Slide 6 完全垄断完全垄断 完全垄断 1) 一个生产者 许多消费者 2) 一种产品 (没有替代品) 3) 市场进入壁垒 第第 10章章Slide 7 完全垄断完全垄断 完全垄断企业是市场供给方，对其产品的销售能 够绝对控制。 当边际收入等于边际成本时，利润达到最大。 第第 10章章Slide 8 完全垄断完全垄断 确定边际收入 l作为唯一的生产者, 垄断企业面对整个市场 l假定企业的需求为: uP = 6 - Q 第第 10章章Slide 9 总收入、边际收入及平均收入总收入、边际收入及平均收入 $60$0- 515$5$5 42834 33913 248-12 1
3、55-31 价格价格 数量数量 总收入总收入 边际收入边际收入 平均收入平均收入 PQTRMRAR 第第 10章章Slide 10 平均收入和边际收入平均收入和边际收入 Q 0 1 2 3 P 1234567 4 5 6 7 平均收入平均收入 (需求需求) 边际收入边际收入 第第 10章章Slide 11 完全垄断完全垄断 观察 1) 只有降价才能增加销售量 2) MR MC). 当产量高于 MR = MC 时，收入的增加小于成本 的增加(MR MC l完全竞争 P = MC 第第 10章章Slide 22 完全垄断完全垄断 完全垄断与完全竞争的价格比较: l需求价格弹性越大，价格越接近于边际
4、成本 第第 10章章Slide 23 完全垄断完全垄断 需求变化 l在完全竞争市场中, 市场供给曲线由边际成 本决定； l对于完全垄断企业, 产量由边际成本和需求 曲线共同决定； 第第 10章章Slide 24 D2 MR2 D1 MR1 需求变动导致价格变动但产量不变需求变动导致价格变动但产量不变 Q MC P P2 P1 Q1= Q2 第第 10章章Slide 25 D1 MR1 需求变动导致产量变动但价格不变需求变动导致产量变动但价格不变 MC P MR2 D2 P1 = P2 Q1Q2 Q 第第 10章章Slide 26 完全垄断完全垄断 观察 l需求变化通常导致价格及需求量都发生变化
5、； l完全垄断市场没有供给曲线； 第第 10章章Slide 27 完全垄断完全垄断 观察 l在相同价格水平下，完全垄断企业可能生产 不同数量的产品； l在不同价格水平下，完全垄断企业可能生产 相同数量的产品； 第第 10章章Slide 28 Monopoly The Effect of a Tax lUnder monopoly price can sometimes rise by more than the amount of the tax. To determine the impact of a tax: lt = specific tax lMC = MC + t lMR = MC
6、 + t : optimal production decision 第第 10章章Slide 29 Effect of Excise Tax on Monopolist Quantity $/Q MC D = AR MR Q0 P0 MC + tax t Q1 P1 P Increase in P: P0P1 increase in tax 第第 10章章Slide 30 Question lSuppose: Ed = -2 lHow much would the price change? Effect of Excise Tax on Monopolist 第第 10章章Slide 31
7、 Answer What would happen to profits? tax. theby twice increases Price 22)(2 toincreases If 22If 1 1 tMCtMCP tMCMC MCPE E MC P d d Effect of Excise Tax on Monopolist 第第 10章章Slide 32 Monopoly The Multiplant Firm lFor many firms, production takes place in two or more different plants whose operating c
8、ost can differ. 第第 10章章Slide 33 Monopoly The Multiplant Firm lChoosing total output and the output for each plant: uThe marginal cost in each plant should be equal. uThe marginal cost should equal the marginal revenue for each plant. 第第 10章章Slide 34 Monopoly Algebraically: 21 22 11 Output Total 2Pla
9、nt for Cost excess profit is zero. Qr Pr PC QC If the price were regulate to be PC, the firm would lose money and go out of business. Pm Qm Unregulated, the monopolist would produce Qm and charge Pm. Regulating the Price of a Natural Monopoly 第第 10章章Slide 67 Regulation in Practice lIt is very diffic
10、ult to estimate the firms cost and demand functions because they change with evolving market conditions The Social Costs of Monopoly Power 第第 10章章Slide 68 Regulation in Practice lAn alternative pricing technique-rate-of-return regulation allows the firms to set a maximum price based on the expected
11、rate or return that the firm will earn. uP = AVC + (D + T + sK)/Q, where lP = price, AVC = average variable cost lD = depreciation, T = taxes ls = allowed rate of return, K = firms capital stock The Social Costs of Monopoly Power 第第 10章章Slide 69 Regulation in Practice lUsing this technique requires
12、hearings to arrive at the respective figures. lThe hearing process creates a regulatory lag that may benefit producers (1950s AR MC; P MC P* Q* 第第 10章章Slide 75 Monopoly and Monopsony Quantity $/Q MV ME S = AE Q* P* PC QC Monopsony Note: ME = MV; ME AE; MV P 第第 10章章Slide 76 Monopoly and Monopsony Mon
13、opoly lMR MC lQm PC Monopsony lME P lP MV lQm QC lPm PC 第第 10章章Slide 77 Monopsony Power A few buyers can influence price (e.g. automobile industry). Monopsony power gives them the ability to pay a price that is less than marginal value. 第第 10章章Slide 78 Monopsony Power The degree of monopsony power d
14、epends on three similar factors. 1) Elasticity of market supply uThe less elastic the market supply, the greater the monopsony power. 第第 10章章Slide 79 Monopsony Power The degree of monopsony power depends on three similar factors. 2) Number of buyers uThe fewer the number of buyers, the less elastic
15、the supply and the greater the monopsony power. 第第 10章章Slide 80 Monopsony Power The degree of monopsony power depends on three similar factors. 3) Interaction Among Buyers uThe less the buyers compete, the greater the monopsony power. ME S = AE ME S = AE Monopsony Power: Elastic versus Inelastic Sup
16、ply Quantity Quantity $/Q$/Q MVMV Q* P* MV - P* P* Q* MV - P* 第第 10章章Slide 82 A Deadweight Loss from Monopsony Power Determining the deadweight loss in monopsony lChange in sellers surplus = -A-C lChange in buyers surplus = A - B lChange in welfare = -A - C + A - B = -C - B lInefficiency occurs beca
17、use less is purchased Quantity $/Q MV ME S = AE Q* P* PC QC B C Deadweight Loss 第第 10章章Slide 83 Monopsony Power Bilateral Monopoly lBilateral monopoly is rare, however, markets with a small number of sellers with monopoly power selling to a market with few buyers with monopsony power is more common.
18、 The Social Costs of Monopsony Power 第第 10章章Slide 84 Monopsony Power Question lIn this case, what is likely to happen to price? The Social Costs of Monopsony Power 第第 10章章Slide 85 Limiting Market Power: The Antitrust Laws Antitrust Laws: lPromote a competitive economy lRules and regulations designed
19、 to promote a competitive economy by: uProhibiting actions that restrain or are likely to restrain competition uRestricting the forms of market structures that are allowable 第第 10章章Slide 86 Sherman Act (1890) lSection 1 uProhibits contracts, combinations, or conspiracies in restraint of trade lExpli
20、cit agreement to restrict output or fix prices lImplicit collusion through parallel conduct Limiting Market Power: The Antitrust Laws 第第 10章章Slide 87 1983 lSix companies and six executives indicted for price of copper tubing 1996 lArcher Daniels Midland (ADM) pleaded guilty to price fixing for lysin
21、e - three sentenced to prison in 1999 Limiting Market Power: The Antitrust Laws Examples of Illegal Combinations 第第 10章章Slide 88 1999 lRoche A.G., BASF A.G., Rhone-Poulenc and Takeda pleaded guilty to price fixing of vitamins - fined more than $1 billion. Limiting Market Power: The Antitrust Laws Ex
22、amples of Illegal Combinations 第第 10章章Slide 89 Sherman Act (1890) lSection 2 uMakes it illegal to monopolize or attempt to monopolize a market and prohibits conspiracies that result in monopolization. Limiting Market Power: The Antitrust Laws 第第 10章章Slide 90 Clayton Act (1914) 1) Makes it unlawful t
23、o require a buyer or lessor not to buy from a competitor 2) Prohibits predatory pricing Limiting Market Power: The Antitrust Laws 第第 10章章Slide 91 Clayton Act (1914) 3) Prohibits mergers and acquisitions if they “substantially lessen competition” or “tend to create a monopoly” Limiting Market Power:
24、The Antitrust Laws 第第 10章章Slide 92 Robinson-Patman Act (1936) lProhibits price discrimination if it is likely to injure the competition Limiting Market Power: The Antitrust Laws 第第 10章章Slide 93 Federal Trade Commission Act (1914, amended 1938, 1973, 1975) 1) Created the Federal Trade Commission (FTC
25、) 2) Prohibitions against deceptive advertising, labeling, agreements with retailer to exclude competing brands Limiting Market Power: The Antitrust Laws 第第 10章章Slide 94 Antitrust laws are enforced three ways: 1) Antitrust Division of the Department of Justice uA part of the executive branch-the adm
26、inistration can influence enforcement uFines levied on businesses; fines and imprisonment levied on individuals Limiting Market Power: The Antitrust Laws 第第 10章章Slide 95 Antitrust laws are enforced three ways: 2) Federal Trade Commission uEnforces through voluntary understanding or formal commission
27、 order Limiting Market Power: The Antitrust Laws 第第 10章章Slide 96 Antitrust laws are enforced three ways: 3) Private Proceedings uLawsuits for damages uPlaintiff can receive treble damages Limiting Market Power: The Antitrust Laws 第第 10章章Slide 97 Two Examples lAmerican Airlines - Price fixing lMicros
28、oft uMonopoly power uPredatory actions uCollusion Limiting Market Power: The Antitrust Laws 第第 10章章Slide 98 Summary Market power is the ability of sellers or buyers to affect the price of a good. Market power can be in two forms: monopoly power and monopsony power. 第第 10章章Slide 99 Summary Monopoly p
29、ower is determined in part by the number of firms competing in the market. Monopsony power is determined in part by the number of buyers in the market. 第第 10章章Slide 100 Summary Market power can impose costs on society. Sometimes, scale economies make pure monopoly desirable. We rely on the antitrust laws to prevent firms from obtaining excessive market power. End of Chapter 10 Market Power: Monopoly and Monopsony
