Oligopoly Market Structure ch 13

Jul 23, 2025

Overview

This lecture explains the characteristics, pricing, output, and profit potential of oligopoly market structure, highlighting the complexity from interdependent decision-making and the kinked demand curve.

Oligopoly Characteristics

  • Oligopoly is defined by a small number of sellers, each able to influence the market.
  • Products in an oligopoly can be identical (like oil) or differentiated (like cars).
  • High barriers to entry exist, making it difficult for new competitors to join.
  • Firms are mutually interdependent, meaning each firm's actions affect all others in the market.

Pricing, Output, and Profit in Oligopoly

  • Oligopoly results in higher prices than perfect competition, but lower than monopoly.
  • Firms can maintain profits in the long run due to barriers to entry.
  • Profit potential exists, but is less than that of a monopoly.

Kinked Demand Curve and Firm Behavior

  • The demand curve is kinked because firm behavior differs for price increases and decreases.
  • If a firm raises price, rivals do not follow, causing elastic demand and a large loss of customers.
  • If a firm lowers price, rivals match the decrease, causing inelastic demand and little gain in sales.
  • The kinked demand curve creates a marginal revenue curve with a discontinuity.

Profit Maximization in Oligopoly

  • Firms maximize profit where marginal revenue (MR) equals marginal cost (MC).
  • Marginal cost curve looks the same as in other market structures.
  • The firm chooses output (Q*) where MR=MC and uses the demand curve to set the highest price consumers will pay for Q*.
  • Short-run profits can be made, lost, or the firm can break even.
  • In the long run, entry barriers allow some profits to persist, though they may erode if new rivals enter.

Comparison to Other Market Structures

  • Oligopoly profits are sustainable but generally lower than monopoly profits.
  • Profits are protected by entry barriers but can be reduced by eventual new entry.

Key Terms & Definitions

  • Oligopoly — a market structure with a small number of firms, high entry barriers, and interdependent decision-making.
  • Kinked Demand Curve — a demand curve showing elastic demand for price increases and inelastic demand for price decreases.
  • Marginal Revenue (MR) — the additional revenue from selling one more unit of output.
  • Marginal Cost (MC) — the additional cost of producing one more unit of output.
  • Barriers to Entry — obstacles that make it difficult for new firms to enter a market.

Action Items / Next Steps

  • Prepare to study collusion, mergers, and antitrust in the next lecture.