CIE A-Level Economics: Characteristics of Oligopoly | 寡头垄断市场特征

📚 CIE A-Level Economics: Characteristics of Oligopoly | 寡头垄断市场特征

Oligopoly is one of the most important and realistic market structures in A-Level economics. It describes a market dominated by a few large firms, where strategic interaction and interdependence shape every decision. Understanding its characteristics is essential for analysing real-world industries such as banking, airlines, telecommunications and supermarkets.

寡头垄断是 A-Level 经济学中最重要且最贴近现实的市场结构之一。它描述了一个由少数大企业主导的市场，在这些市场中，战略互动和相互依存影响着每一个决策。理解其特征，对于分析银行业、航空业、电信业和超市等真实行业至关重要。

1. What Is Oligopoly? | 什么是寡头垄断？

Oligopoly is a market structure in which a small number of firms dominate the market, and each firm’s decisions directly affect the others. The word comes from Greek: ‘oligos’ means few and ‘polein’ means to sell. A common concentration ratio used to identify oligopoly is a five-firm concentration ratio exceeding 60%.

寡头垄断是一种由少数企业主导市场的市场结构，且每家企业的决策都会直接影响其他企业。该词源于希腊语：“oligos”意为少，“polein”意为售卖。识别寡头垄断常用的集中率指标是五企业集中率超过 60%。

Five-firm concentration ratio = (Sales of top 5 firms ÷ Total industry sales) × 100%

2. Few Firms, Large Market Share | 企业数量少，市场份额大

Oligopolistic markets are characterised by a handful of firms controlling a large proportion of total output. For example, in the UK grocery market, the largest four supermarkets account for over 60% of sales. This small number of firms gives each one significant market power, though less than a pure monopoly.

寡头垄断市场的特征是一小部分企业控制着总产出的很大比例。例如，在英国杂货市场中，最大的四家超市占据了超过 60% 的销售额。企业数量少使得每一家都拥有显著的市场力量，尽管小于完全垄断。

The small number of firms means that each firm’s output and pricing decisions are large enough to influence market conditions. Unlike perfect competition, where firms are price takers, oligopolistic firms are price setters, but their power is constrained by the reactions of rivals.

企业数量少意味着每家企业的产量和定价决策都足以影响市场状况。与完全竞争中的企业是价格接受者不同，寡头企业是价格制定者，但它们的权力受到竞争对手反应的制约。

3. Interdependence | 相互依存

Interdependence is the defining feature of oligopoly. Each firm must anticipate the reactions of its rivals before making decisions. For example, if one airline lowers its fares, other airlines may quickly match the price cut to avoid losing passengers. This creates a strategic game where every move is monitored and countered.

相互依存是寡头垄断的决定性特征。每家企业在做出决策之前，都必须预测竞争对手的反应。例如，如果一家航空公司降低票价，其他航空公司可能会迅速跟进降价，以避免失去乘客。这就形成了一种战略博弈，每一步行动都受到监视和反击。

The concept of interdependence can be contrasted with other market structures. In perfect competition, no single firm affects others. In monopoly, there are no rivals. In oligopoly, firms are mutually dependent: the success of one firm depends on the strategies of the others. This is why economists often use game theory to analyse oligopoly behaviour.

相互依存的概念可以与其他市场结构进行对比。在完全竞争中，没有一家企业会影响其他企业。在垄断中，没有竞争对手。在寡头垄断中，企业相互依赖：一家企业的成功取决于其他企业的战略。这就是经济学家常使用博弈论分析寡头行为的原因。

4. Barriers to Entry | 进入壁垒

Oligopolies are protected by high barriers to entry, which prevent new firms from easily competing. These barriers include economies of scale, legal patents, brand loyalty, control of essential inputs and high sunk costs. For example, the pharmaceutical industry requires massive research and development expenditure and regulatory approval, making entry extremely difficult.

寡头垄断受到高进入壁垒的保护，这些壁垒阻止新企业轻松进入竞争。这些壁垒包括规模经济、法定专利、品牌忠诚度、对关键投入品的控制以及高昂的沉没成本。例如，制药行业需要巨额研发支出和监管审批，这使得进入极其困难。

Economies of scale: large firms have lower average costs, making it hard for new entrants to compete on price.

规模经济：大企业的平均成本更低，使新进入者难以在价格上竞争。
High sunk costs: non-recoverable expenditures such as advertising and machinery deter potential entrants.

高沉没成本：诸如广告和机器等不可回收的支出，会阻止潜在进入者。
Patents and licences: legal protection grants exclusive rights to produce certain goods.

专利和许可：法律保护授予生产某些商品的专有权。
Brand loyalty: established firms benefit from consumer trust that new firms cannot easily replicate.

品牌忠诚度：成熟企业享有消费者信任，新企业难以复制。

5. Product Differentiation | 产品差异化

Oligopolistic firms often produce differentiated products. Goods may be physically similar, but firms use branding, design, packaging and quality variations to make them appear different. For example, in the smartphone market, Apple and Samsung offer distinct operating systems, ecosystems and designs, even though the core product is similar.

寡头企业通常生产差异化的产品。商品在物理上可能相似，但企业通过品牌、设计、包装和质量差异使其看起来不同。例如，在智能手机市场中，苹果和三星提供不同的操作系统、生态系统和设计，尽管核心产品相似。

Product differentiation gives each firm some degree of market power. It creates customer loyalty and makes demand less price-elastic. Firms can therefore charge slightly higher prices than perfect competitors without losing all their customers. However, differentiation also increases costs, as firms must invest in research, advertising and innovation.

产品差异化赋予每家企业一定程度的市场力量。它创造了客户忠诚度，使需求价格弹性降低。因此，企业可以比完全竞争者收取略高的价格，而不会失去全部客户。然而，差异化也增加了成本，因为企业必须投资于研发、广告和创新。

6. Non-Price Competition | 非价格竞争

Because oligopolistic firms may fear price wars, they often rely heavily on non-price competition. This includes advertising, product quality, after-sales service, loyalty schemes, improved features and extended warranties. For example, supermarkets compete through loyalty cards and home delivery services rather than simply cutting prices.

由于寡头企业可能担心价格战，它们往往严重依赖非价格竞争。这包括广告、产品质量、售后服务、忠诚度计划、改进的功能和延长保修期。例如，超市通过会员卡和送货上门服务进行竞争，而不仅仅是降价。

Non-price competition is a rational response to interdependence. If one firm lowers its price, rivals may match the cut, leaving everyone worse off. But if a firm improves quality or launches a better advertising campaign, rivals may find it harder to respond quickly. Non-price competition can therefore be a more sustainable source of competitive advantage.

非价格竞争是对相互依存的理性回应。如果一家企业降价，竞争对手可能跟进降价，最终使所有企业状况恶化。但如果一家企业提高质量或发起更有效的广告活动，竞争对手可能难以迅速回应。因此，非价格竞争可以成为更可持续的竞争优势来源。

7. Collusion and Cartels | 串谋与卡特尔

Interdependence creates an incentive for firms to collude. Collusion occurs when firms agree to coordinate their prices, output levels or market shares instead of competing. A formal agreement is known as a cartel. The most famous example is OPEC, which coordinates oil production among member countries to influence global prices.

相互依存为企业创造了串谋的激励。当企业同意协调价格、产量或市场份额而不是相互竞争时，就发生了串谋。正式协议被称为卡特尔。最著名的例子是 OPEC，它协调成员国的石油产量以影响全球价格。

Collusion can take two forms: overt collusion, where agreements are explicit and usually illegal, and tacit collusion, where firms indirectly follow a price leader without a formal agreement. However, collusion is often unstable. Each member faces the temptation to cheat by secretly lowering prices or increasing output to gain higher profits. This instability is a central topic in game theory.

串谋可以采取两种形式：公开串谋，即协议是明确且通常非法的；以及默契串谋，即企业无须正式协议就间接跟随价格领导者。然而，串谋往往是不稳定的。每个成员都面临通过秘密降价或增产以获取更高利润的诱惑。这种不稳定性是博弈论的核心议题。

8. Kinked Demand Curve and Price Rigidity | 弯折需求曲线与价格刚性

A well-known model of oligopoly is the kinked demand curve, which explains why prices in oligopolistic markets are often sticky or rigid. The model assumes that if a firm raises its price, rivals will not follow, so the firm loses many customers. But if the firm lowers its price, rivals will match the cut, so the firm gains few new customers. This creates a kink at the current price.

寡头垄断的一个著名模型是弯折需求曲线，它解释了为什么寡头市场价格往往是刚性的。该模型假设：如果一家企业提高价格，竞争对手不会跟进，因此该企业会失去大量客户；但如果该企业降价，竞争对手会跟进降价，因此该企业只能获得少量新客户。这就形成了当前价格处的一个弯折点。

The demand curve above the kink is elastic; below the kink it is inelastic.

Because of the kink, the marginal revenue curve has a vertical discontinuity. This means that even if costs change within a certain range, the profit-maximising price and output remain unchanged. The model therefore helps explain price stability, but it has been criticised for failing to explain how the initial price is determined.

由于弯折点的存在，边际收入曲线出现一个垂直的间断区间。这意味着即使成本在一定范围内变化，利润最大化的价格和产量也保持不变。因此，该模型有助于解释价格稳定性，但也被批评为未能解释初始价格是如何决定的。

9. Game Theory and Strategic Behaviour | 博弈论与战略行为

Game theory is widely used to analyse oligopolistic interdependence. Firms are viewed as players who choose strategies, and their payoffs depend on the choices of all players. The prisoner’s dilemma shows why two rational firms may not cooperate even if cooperation would make them better off. Each firm fears that if it cooperates, the other will cheat and gain an advantage.

博弈论被广泛用于分析寡头的相互依存。企业被视为选择策略的参与者，其收益取决于所有参与者的选择。囚徒困境表明，即使合作能让双方都变得更好，两个理性的企业也可能不会合作。每家企业都担心如果自己合作，对方会欺骗并因此获利。

In a simple duopoly game, two firms can choose high price or low price. The dominant strategy may be to choose low price, even though both would earn higher profits with a high price. Repeated games, however, can support cooperation through strategies such as ‘tit-for-tat’, where a firm rewards cooperation and punishes cheating. This explains why some oligopolies maintain stable prices over time.

在简单的双头博弈中，两家企业可以选择高价或低价。主导策略可能是选择低价，尽管双方都选择高价能获得更高利润。然而，重复博弈可以通过“以牙还牙”等策略支持合作，即企业奖励合作、惩罚欺骗。这解释了为什么一些寡头市场能够长期维持稳定的价格。

10. Examples of Oligopolies | 寡头垄断实例

Oligopolies exist in many industries around the world. In the UK, the banking sector is dominated by a handful of major banks; the energy market is controlled by a few large suppliers; and the airline industry is concentrated among a small number of carriers. In each case, the firms are highly interdependent and engage in non-price competition.

寡头垄断存在于全球许多行业中。在英国，银行业由少数大型银行主导，能源市场由几家大型供应商控制，航空业则集中在少数几家航空公司手中。在这些案例中，企业高度相互依存，并进行非价格竞争。

It is important to note that oligopoly can take different forms. A ‘pure oligopoly’ produces identical or near-identical products, such as cement or steel. A ‘differentiated oligopoly’ produces branded products such as cars, soft drinks or cosmetics. The nature of competition differs between these two forms, with differentiated oligopolies relying more on advertising and innovation.

需要注意的是，寡头垄断可以采取不同形式。“纯粹寡头垄断”生产相同或几乎相同的产品，如水泥或钢铁；“差异化寡头垄断”生产品牌产品，如汽车、软饮料或化妆品。这两种形式的竞争性质不同，差异化寡头更依赖广告和创新。

11. Evaluation of Oligopoly | 对寡头垄断的评价

Oligopoly has both advantages and disadvantages. On the positive side, large firms are able to achieve economies of scale, invest heavily in research and development, and engage in innovation. Competition through product quality and advertising can benefit consumers. In industries such as telecommunications and pharmaceuticals, oligopoly may be necessary to support high fixed costs and long-term investment.

寡头垄断既有优点也有缺点。从积极方面看，大型企业能够实现规模经济、大量投资于研发并进行创新。通过产品质量和广告进行的竞争可以使消费者受益。在电信和制药等行业，寡头垄断可能是支持高固定成本和长期投资的必要条件。

On the negative side, oligopolies may earn supernormal profits, charge higher prices and produce less output than would occur under perfect competition. Collusion can reduce consumer welfare, and barriers to entry protect inefficient firms. Price rigidity may prevent markets from adjusting quickly to changes in supply and demand. Governments often use competition policy to regulate anti-competitive behaviour.

从消极方面看，寡头企业可能赚取超额利润、收取更高的价格，并生产少于完全竞争条件下的产量。串谋会降低消费者福利，进入壁垒保护了低效率的企业。价格刚性可能阻碍市场对供需变化的快速调整。政府通常使用竞争政策来监管反竞争行为。

12. Conclusion | 结论

Oligopoly is a complex and fascinating market structure. Its key characteristics include few large firms, high barriers to entry, product differentiation, non-price competition, interdependence and the potential for collusion. The kinked demand curve and game theory provide useful analytical tools for understanding price rigidity and strategic behaviour. For A-Level students, mastering these features is essential for evaluating real-world market power and government policy.

寡头垄断是一种复杂而引人入胜的市场结构。其关键特征包括少数大企业、高进入壁垒、产品差异化、非价格竞争、相互依存以及串谋的可能性。弯折需求曲线和博弈论为理解价格刚性和战略行为提供了有用的分析工具。对于 A-Level 学生而言，掌握这些特征对于评估现实世界中的市场力量和政府政策至关重要。

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CIE A-Level Economics: Characteristics of Oligopoly | 寡头垄断市场特征