Microeconomics
Oligopoly
Few large sellers — strategic interactions, game theory, often less competitive
Oligopoly is a market structure with few large sellers (typically 2-10) producing differentiated or homogeneous products. Key feature: strategic interaction — each firm's decisions affect others; they consider competitors' likely responses. Examples: airlines, automobiles, smartphones, soft drinks. Game theory analyzes oligopoly behavior. Possible outcomes: collusion (cooperative agreement, often illegal), price war (aggressive competition), price leadership (one firm sets, others follow), Cournot equilibrium. Welfare impact: usually less efficient than competition; may be efficient depending on structure.
- DefinitionFew large sellers (typically 2-10)
- Key featureStrategic interaction; consider competitors' responses
- ExamplesAirlines, autos, smartphones, soft drinks
- Tools usedGame theory, Cournot model
- Possible behaviorsCollusion, price war, leadership, competition
- WelfareUsually less efficient than competition
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Why oligopoly matters
- Major industries. Many real-world examples.
- Antitrust. Preventing excess market power.
- Game theory. Strategic interaction modeling.
- Innovation. R&D in concentrated industries.
- Public policy. Regulation of concentrated markets.
- Strategy. Business strategy in oligopolies.
- Education. Realistic market analysis.
Common misconceptions
- Same as monopoly. Multiple firms; competition possible.
- Always collude. Often compete intensely.
- Always inefficient. Sometimes natural; can be efficient.
- Stable. Constant strategic adjustment.
- Two firms only. Up to ~10.
- Always bad for consumers. Sometimes drives innovation, lower prices.
Frequently asked questions
What's oligopoly?
Market structure with few large sellers. Few enough that each firm's actions affect others. Typically 2-10 firms. Strategic interaction. Common: most major industries. Differs from monopoly (one seller) and perfect competition (many small sellers). Each firm: must consider competitors' likely responses to its decisions (strategic).
What strategic decisions?
Multiple. (1) Pricing: high price for collusion or low for competition? (2) Production: how much to produce? (3) Product differentiation: how distinct? (4) Advertising: how much to spend? (5) Innovation: invest in R&D? (6) Entry deterrence: keep new firms out? (7) Mergers: with competitors? Each: depends on what others do. Game theory analyzes.
What's the prisoner's dilemma in oligopoly?
Classic dilemma. Two firms can: cooperate (high prices, both profit) or defect (lower price, gain market share). If both cooperate: best total outcome. But each tempted to defect. If one defects, other should too. Both defect: worse total than cooperating. Hence: collusion difficult to maintain without enforcement.
What's collusion?
Firms agreeing to coordinate (prices, quantities, market shares). Often illegal (antitrust laws). Two types. (1) Explicit: formal cartel agreement. OPEC. (2) Tacit: implicit understanding without explicit communication. Examples: airlines following each other's price changes. Effectively monopoly: high prices, restricted output. Hard to maintain — incentive to defect.
What's a cartel?
Explicit collusive agreement. Coordinates pricing, output, market shares. Can exploit market power. Examples: OPEC (oil-producing countries), historical cartels (sugar, diamonds). Stability problems: members tempted to cheat (produce more, undercut). Cartel collapses if cheating undetected. Antitrust laws strictly prohibit cartels in most countries.
What's the Cournot model?
Theoretical model. Each firm chooses quantity assuming others' quantities fixed. Reach equilibrium where no firm wants to change quantity given others' choices. More firms → more output → lower price (closer to competition). Two firms: Cournot duopoly. Mathematical model widely used. Bertrand competition (price-based) gives different results.
When is it efficient?
Sometimes. (1) If firms compete intensely: closer to perfect competition. (2) Differentiated products: consumer choice. (3) Innovation incentives: scale matters for R&D. (4) Some natural oligopoly: high fixed costs make many firms inefficient. But: usually less efficient than competition. Antitrust: tries to prevent excess market power.