Oligopoly and Game Theory

An oligopoly is a market structure where a small number of large firms dominate the market, offering either homogeneous or differentiated products. Key characteristics include:

• Few large firms: A handful of companies account for a significant portion of market output.
• High barriers to entry: Significant obstacles, such as high capital costs, economies of scale, or strong brand loyalty, prevent new firms from easily entering the market.
• Interdependence: This is the defining feature. Each firm's decisions regarding price, output, advertising, and product development are highly dependent on the anticipated reactions of its rivals. This makes strategic planning crucial.
• Product differentiation: Products can be homogeneous (e.g., steel, cement) or differentiated (e.g., cars, soft drinks). Differentiation allows for some market power.
• Non-price competition: Firms often compete through advertising, branding, product innovation, and customer service rather than solely through price, due to the fear of price wars.

Collusion occurs when firms in an oligopoly cooperate to restrict competition, often by agreeing on prices, output levels, or market shares. The most formal type of collusion is a cartel, where firms openly and explicitly agree on these terms. Examples include OPEC (Organisation of the Petroleum Exporting Countries).

Why firms collude:

• To reduce uncertainty and risk in the market.
• To increase joint profits, acting like a single monopolist.
• To prevent new entrants.

Factors favouring collusion:

• Small number of firms.
• Similar production costs among firms.
• Homogeneous products.
• Effective monitoring of agreements.
• High barriers to entry.

Factors hindering collusion:

• Large number of firms.
• Significant cost differences.
• Differentiated products.
• Difficulty in detecting cheating.
• Strong anti-collusion laws (e.g., competition policy).
• Recessions, which increase the incentive to cheat to maintain sales.

Game theory is a powerful analytical tool used to understand strategic decision-making in situations of interdependence. It models interactions where the outcome for each player depends on the actions of all players. Key elements of a game include players, strategies, and payoffs.

The Prisoner's Dilemma is a classic game theory scenario that illustrates the challenges of cooperation in oligopolies. Consider two firms, A and B, deciding whether to 'cooperate' (maintain high prices) or 'defect' (lower prices). The payoff matrix shows the profits for each firm based on their combined decisions:

In this scenario, regardless of what the other firm does, each firm has an incentive to choose 'Low Price' (defect). If B chooses High Price, A gets £12m by choosing Low Price (£10m if High Price). If B chooses Low Price, A gets £4m by choosing Low Price (£2m if High Price). This leads to a Nash Equilibrium where both firms choose 'Low Price', resulting in lower joint profits (£4m each) than if they had both cooperated (£10m each). This explains why collusion is difficult to sustain even when it is mutually beneficial.