第10章 市场势力：垄断与买方垄断

第10章 市场势力：垄断与买方垄断 第10章 市场势力:垄断与买方垄断 第10章 市场势力: 垄断与买方垄断 Chapter 1 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 Chapter 1 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 Chapter 1 完全竞争 完全竞争回顾 P = LMC = LRAC 长期内只存在正常利润或经济利润为零 大量生产者和消费者 同质化产品 充分信息 企业是价格的接受者 Chapter 1 完全竞争 Q Q P P 市场 单个企业 D S Q0 P0 P0 D = MR = P q0 LRAC LMC Chapter 1 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 Chapter 1 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。 Chapter 1 完全垄断 确定边际收入 作为唯一的生产者, 垄断企业面对整个市场 假定企业的需求为: P = 6 - Q Chapter 1 总收入、边际收入及平均收入 $6 0 $0 --- --- 5 1 5 $5 $5 4 2 8 3 4 3 3 9 1 3 2 4 8 -1 2 1 5 5 -3 1 价格 数量 总收入 边际收入 平均收入 P Q TR MR AR Chapter 1 平均收入和边际收入 Q 0 1 2 3 P 1 2 3 4 5 6 7 4 5 6 7 平均收入 (需求) 边际收入 Chapter 1 完全垄断 观察 1) 只有降价才能增加销售量 2) MR < P 3) 与完全竞争比较 不需要降价就能增加销售量 MR = P Chapter 1 完全垄断 完全垄断企业的产量决策 当 MR = MC 时利润达到最大化 或 Chapter 1 利润最大化 当产量低于 MR = MC 时，收入的减少大于成本的减少 (MR > MC). 当产量高于 MR = MC 时，收入的增加小于成本的增加(MR < MC) 完全垄断企业的产量决策 Chapter 1 利润最大化 利润减少 P1 Q1 利润减少 MC AC Q P D = AR MR P* Q* P2 Q2 Chapter 1 完全垄断 定价法则 可以将边际收入等于边际成本的原理转化为一个简单实用的法则 其过程可说明如下: Chapter 1 定价法则 Chapter 1 定价法则 Chapter 1 定价法则 Chapter 1 定价法则 = 边际成本加价在价格中所占比例 【(P-MC)/P】 8. 加价等于需求价格弹性的倒数。 Chapter 1 定价法则 假设: Chapter 1 完全垄断 完全垄断与完全竞争的价格比较: 完全垄断 P > MC 完全竞争 P = MC Chapter 1 完全垄断 完全垄断与完全竞争的价格比较: 需求价格弹性越大，价格越接近于边际成本 Chapter 1 完全垄断 需求变化 在完全竞争市场中, 市场供给曲线由边际成本决定; 对于完全垄断企业, 产量由边际成本和需求曲线共同决定; Chapter 1 需求变动导致价格变动但产量不变 D2 MR2 D1 MR1 Q MC P P2 P1 Q1= Q2 Chapter 1 需求变动导致产量变动但价格不变 D1 MR1 MC P MR2 D2 P1 = P2 Q1 Q2 Q Chapter 1 完全垄断 观察 需求变化通常导致价格及需求量都发生变化; 完全垄断市场没有供给曲线; Chapter 1 完全垄断 观察 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; 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; Chapter 1 垄断 税收的效果 在垄断的情况下，价格的上升有时会超过税收. 确定税收的影响: t =定量税 MC = MC + t MR = MC + t :最优产量决策 Chapter 1 对垄断者课税的效果 Quantity $/Q MC D = AR MR Q0 P0 MC + tax t Q1 P1 价格的增加大于税收:P0P1 > t Chapter 1 对垄断者课税的效果 问题 假设:ed = 2 价格将变化多少? Chapter 1 对垄断者课税的效果 回答 Chapter 1 垄断 多工厂厂商 对许多企业而言，产品是在两个或更多的不同工厂里生产的，而这些工厂的 营运成本是不同的。 Chapter 1 Monopoly 多工厂厂商 确定总产量和每一工厂的产量: 各个工厂的边际成本应该相等 对每个工厂而言，边际成本应该等于边际收益。 Chapter 1 垄断 用代数方法推导 多工厂厂商 Chapter 1 垄断 用代数方法推导 多工厂厂商 Chapter 1 垄断 用代数方法推导: : 多工厂厂商 Chapter 1 垄断 用代数方法推导: Chapter 1 两个工厂时的生产 Quantity $/Q D = AR MR MC1 MC2 MCT MR* Q1 Q2 Q3 P* Chapter 1 两个工厂时的生产 观察 1) MCT = MC1 + MC2 2) 利润最大化的产量 在 QT 和 P* 处:MCT = MR = MR* 在 Q1 处:MR* = MC1 在 Q2 处:MR* = MC2 Q1 + Q2 = QT ，MR = MC1 = MC2 Quantity $/Q D = AR MR MC1 MC2 MCT MR* Q1 Q2 Q3 P* Chapter 1 垄断势力 垄断势力就是将价格定得高于边际成本的能力 Chapter 1 垄断势力 纯粹的垄断并不多见 然而，在有几个厂商的市场中，每个厂商好像都面临一条向下倾斜的需求曲 线，并因此在价格大于边际成本处生产。 Chapter 1 垄断势力 背景 有四个生产牙刷的厂商，每个厂商每天生产 5000 把牙刷，共 20000 把， 并以每把 1.50 元的价格出售。 Chapter 1 数量 10000 2.00 QA 价格 价格 1.50 1.00 20000 30000 3,000 5,000 7,000 2.00 1.50 1.00 1.40 1.60 当价格为1.50元时，市场需求的价格弹性为1.5。 市场需求 牙刷的需求 厂商 A 面临的需求曲线取决于它的产品与其他厂商的产品有多少差别以及 厂商之间竞争的激烈程度。 * Chapter 1 数量 10000 2.00 QA 价格 价格 1.50 1.00 20000 30000 3,000 5,000 7,000 2.00 1.50 1.00 1.40 1.60 当价格为1.50元时，市场需求的价格弹性为1.5。 市场需求 牙刷的需求 DA MRA 由于竞争，厂商 A 看到的需求曲线的弹性要大得多(ed = 6)。但厂商 A 仍 然具有一些垄断势力，其所取的价格还是高于 MC 。 MCA * Chapter 1 垄断势力 垄断势力的测定 在完全竞争中: P = MR = MC 垄断势力下: P > MC Chapter 1 垄断势力 勒纳的垄断势力度 L = (P - MC)/P = 1/ed 勒纳指数(L)介于 0 到 1 之间 L 越大，垄断势力度越大。 ed 是厂商需求曲线的弹性，而不是市场需求曲线的弹性。 Chapter 1 垄断势力 垄断势力并不意味着高利润 利润取决于平均成本与价格的比较 思考 你能找出使用勒纳指数(L)来制定公共政策的困难之处吗? Chapter 1 垄断势力 定价的简单法则 具有垄断势力的厂商的定价 当需求弹性 ed 很大时，加价就小。 当需求弹性 ed 很小时，加价就大。 Chapter 1 需求弹性和价格加价 价格 价格 数量 数量 AR MR MR AR MC MC Q* Q* P* P* P*-MC 需求弹性越大，加价越小 * Chapter 1 加成定价:从超级市场到品牌裤子 超市 Chapter 1 加成定价:从超级市场到品牌裤子 便利店 Chapter 1 加成定价:从超级市场到品牌裤子 便利店具有更大的垄断势力 思考 便利店赚取的利润比超市高吗? 便利店 Chapter 1 加成定价:从超级市场到品牌裤子 设计师品牌裤子 需求弹性 ed = 3 到 4 价格大约高于边际成本 33 ~ 50% MC = 12 元/条 批发价 = 18 ~ 27 元/条 设计师品牌裤子的生产商 Chapter 1 录像带的价格 1985 1999 Title Retail Price($) Title Retail Price($) 紫雨 $29.98 Austin Powers $10.49 失落方舟的侵入者 24.95 A Bug’s Life 17.99 Jane Fonda Workout 59.95 There’s Something about Mary 13.99 The Empire Strikes Back 79.98 Tae-Bo Workout 24.47 An Officer and a Gentleman 24.95 Lethal Weapon 4 16.99 Star Trek: The Motion Picture 24.95 Men in Black 12.99 Star Wars 39.98 Armageddon 15.86 Chapter 1 录像带的价格 What Do You Think? 生产者应该降低价格去增加销售和收益吗? Chapter 1 垄断势力 垄断势力的来源 为什么有些厂商有相当的垄断势力，而其他厂商很少有或者没有? 厂商的垄断势力取决于其面临的需求弹性 Chapter 1 垄断势力 决定厂商需求弹性的因素有三个: 1) 市场需求弹性 2) 厂商的数量 3) 厂商之间的相互作用 Chapter 1 垄断势力的社会成本 垄断势力导致高价格和低质量 但是,垄断势力总体上会使消费者和生产者的福利变得更好还是更坏? Chapter 1 垄断势力的无谓损失 B A 损失的消费者剩余 无谓损失 因为高价格,消费者损失 A+B ,生产者获得 A-C. C Quantity AR MR MC QC PC Pm Qm $/Q Chapter 1 垄断势力的社会成本 寻租 厂商会花钱去获得垄断势力 游说 广告 形成过剩的生产能力 Chapter 1 垄断势力的社会成本 垄断的动机是为了获得利润. 消费者转移给厂商的消费者剩余越多,垄断势力越强. Chapter 1 垄断势力的社会成本 Example 1996 Archer Daniels Midland (ADM) successfully lobbied for regulations requiring ethanol be produced from corn Question Why only corn? Chapter 1 垄断势力的社会成本 价格管制 回忆:在竞争性市场中,政府的价格管制会产生无谓损失. Question: 垄断条件下如何? Chapter 1 价格管制 AR MR MC Pm Qm AC P1 Q1 Marginal revenue curve when price is regulated to be no higher that P1. If left alone, a monopolist produces Qm and charges Pm. If price is lowered to P3 output decreases and a shortage exists. For output levels above Q1 , the original average and marginal revenue curves apply. If price is lowered to PC output increases to its maximum QC and there is no deadweight loss. $/Q Quantity P2 = PC Qc P3 Q3 Q’3 Any price below P4 results in the firm incurring a loss. P4 Chapter 1 垄断势力的社会成本 自然垄断 由一个厂商生产全部的产品比由多个厂商来生产平均成本更低时. Chapter 1 自然垄断的价格管制 $/Q 当存在着外部规模经济时,自然垄断就出现了 Quantity Chapter 1 自然垄断的价格管制 MC AC AR MR $/Q Quantity 把价格定在 Pr , 产出最大化,利润为0. Qr Pr PC QC 若价格被管制为 PC, 厂商将回本并退出生产. Pm Qm 无管制,垄断者生产 Qm 要价 Pm. Chapter 1 垄断势力的社会成本 管制实践 估计厂商的成本和需求函数非常困难,因为它们取决于相关的市场状况 Chapter 1 垄断势力的社会成本 管制实践 一个可替代的工具--回报率管制 允许企业根据可获得的预期回报来设置最高价格. P = AVC + (D + T + sK)/Q, 这里 P = 价格, AVC = 平均可变成本 D = 折旧, T =税收 s = 允许的回报率, K = 厂商资本存量 Chapter 1 垄断势力的社会成本 管制实践 Using this technique requires hearings to arrive at the respective figures. The hearing process creates a regulatory lag that may benefit producers (1950s & 60s) or consumers (1970s & 80s). Question Who is benefiting in the 1990s? Chapter 1 买方垄断 A monopsony is a market in which there is a single buyer. An oligopsony is a market with only a few buyers. Monopsony power is the ability of the buyer to affect the price of the good and pay less than the price that would exist in a competitive market. Chapter 1 Monopsony Competitive Buyer Price taker P = Marginal expenditure = Average expenditure D = Marginal value Chapter 1 Competitive Buyer Compared to Competitive Seller Quantity Quantity $/Q $/Q AR = MR D = MV ME = AE P* Q* ME = MV at Q* ME = P* P* = MV P* Q* MC MR = MC P* = MR P* = MC Buyer Seller Chapter 1 Monopsonist Buyer ME S = AE The market supply curve is the monopsonist’s average expenditure curve Quantity $/Q MV Q*m P*m Monopsony ME > P & above S PC QC Competitive P = PC Q = Q+C Chapter 1 Monopoly and Monopsony Quantity AR MR MC $/Q QC PC Monopoly Note: MR = MC; AR > MC; P > MC P* Q* Chapter 1 Monopoly and Monopsony Quantity $/Q MV ME S = AE Q* P* PC QC Monopsony Note: ME = MV; ME > AE; MV > P Chapter 1 Monopoly and Monopsony Monopoly MR < P P > MC Qm < QC Pm > PC Monopsony ME > P P < MV Qm < QC Pm < PC Chapter 1 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. Chapter 1 Monopsony Power The degree of monopsony power depends on three similar factors. 1) Elasticity of market supply The less elastic the market supply, the greater the monopsony power. Chapter 1 Monopsony Power The degree of monopsony power depends on three similar factors. 2) Number of buyers The fewer the number of buyers, the less elastic the supply and the greater the monopsony power. Chapter 1 Monopsony Power The degree of monopsony power depends on three similar factors. 3) Interaction Among Buyers The less the buyers compete, the greater the monopsony power. Chapter 1 Monopsony Power: Elastic versus Inelastic Supply ME S = AE ME S = AE Quantity Quantity $/Q $/Q MV MV Q* P* MV - P* P* Q* MV - P* Chapter 1 Deadweight Loss from Monopsony Power Determining the deadweight loss in monopsony Change in seller’s surplus = -A-C Change in buyer’s surplus = A - B Change in welfare = -A - C + A - B = -C - B Inefficiency occurs because less is purchased A Quantity $/Q MV ME S = AE Q* P* PC QC B C Deadweight Loss Chapter 1 Monopsony Power Bilateral Monopoly Bilateral 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. The Social Costs of Monopsony Power Chapter 1 Monopsony Power Question In this case, what is likely to happen to price? The Social Costs of Monopsony Power Chapter 1 Limiting Market Power: The Antitrust Laws Antitrust Laws: Promote a competitive economy Rules and regulations designed to promote a competitive economy by: Prohibiting actions that restrain or are likely to restrain competition Restricting the forms of market structures that are allowable Chapter 1 Limiting Market Power: The Antitrust Laws Sherman Act (1890) Section 1 Prohibits contracts, combinations, or conspiracies in restraint of trade Explicit agreement to restrict output or fix prices Implicit collusion through parallel conduct Chapter 1 Limiting Market Power: The Antitrust Laws 1983 Six companies and six executives indicted for price of copper tubing 1996 Archer Daniels Midland (ADM) pleaded guilty to price fixing for lysine -- three sentenced to prison in 1999 Examples of Illegal Combinations Chapter 1 Limiting Market Power: The Antitrust Laws 1999 Roche A.G., BASF A.G., Rhone-Poulenc and Takeda pleaded guilty to price fixing of vitamins -- fined more than $1 billion. Examples of Illegal Combinations Chapter 1 Limiting Market Power: The Antitrust Laws Sherman Act (1890) Section 2 Makes it illegal to monopolize or attempt to monopolize a market and prohibits conspiracies that result in monopolization. Chapter 1 Limiting Market Power: The Antitrust Laws Clayton Act (1914) 1) Makes it unlawful to require a buyer or lessor not to buy from a competitor 2) Prohibits predatory pricing Chapter 1 Limiting Market Power: The Antitrust Laws Clayton Act (1914) 3) Prohibits mergers and acquisitions if they “substantially lessen competition” or “tend to create a monopoly” Chapter 1 Limiting Market Power: The Antitrust Laws Robinson-Patman Act (1936) Prohibits price discrimination if it is likely to injure the competition Chapter 1 Limiting Market Power: The Antitrust Laws Federal Trade Commission Act (1914, amended 1938, 1973, 1975) 1) Created the Federal Trade Commission (FTC) 2) Prohibitions against deceptive advertising, labeling, with retailer to exclude competing brands agreements Chapter 1 Limiting Market Power: The Antitrust Laws Antitrust laws are enforced three ways: 1) Antitrust Division of the Department of Justice A part of the executive branch--the administration can influence enforcement Fines levied on businesses; fines and imprisonment levied on individuals Chapter 1 Limiting Market Power: The Antitrust Laws Antitrust laws are enforced three ways: 2) Federal Trade Commission Enforces through voluntary understanding or formal commission order Chapter 1 Limiting Market Power: The Antitrust Laws Antitrust laws are enforced three ways: 3) Private Proceedings Lawsuits for damages Plaintiff can receive treble damages Chapter 1 Limiting Market Power: The Antitrust Laws Two Examples American Airlines -- Price fixing Microsoft Monopoly power Predatory actions Collusion Chapter 1 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. Chapter 1 Summary Monopoly power 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. Chapter 1 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. Chapter 1 End of Chapter 10 Market Power: Monopoly and Monopsony Chapter 1 1 2 2 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 1