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Monopoly Efficiency and Welfare Loss

Jul 26, 2025

Overview

This lecture discusses efficiency under monopoly compared to perfect competition, focusing on productive and allocative efficiency, and illustrates why monopolies are considered inefficient.

Efficiency Under Monopoly

  • Monopoly output is neither productive efficient (minimum cost) nor allocative efficient (maximizes societal well-being).
  • Productive efficiency occurs at the lowest point on the average total cost (ATC) curve, where marginal cost (MC) equals ATC.
  • In a monopoly, output is not at minimum ATC, meaning goods could be produced more cheaply.
  • Allocative efficiency happens when the value to consumers (demand) equals the cost of production (MC).
  • Monopolies underproduce because their profit-maximizing quantity is less than the allocatively efficient quantity.
  • The benefit to society of producing additional units exceeds the marginal cost, but the monopolist restricts output to maximize profit.

Deadweight Loss and Social Implications

  • Deadweight loss is the value of trades that do not occur because a monopoly restricts quantity.
  • The area between the monopoly output and the allocatively efficient output represents lost societal welfare.
  • Monopolies create higher producer surplus and lower consumer surplus compared to perfect competition.

Comparison: Monopoly vs. Perfect Competition

  • Perfect competition yields higher total surplus (consumer plus producer surplus) and no deadweight loss.
  • In perfect competition, the market supply equals marginal cost, and the market quantity is where demand meets supply.
  • Monopoly price is higher and quantity is lower than in perfect competition.

Key Terms & Definitions

  • Productive Efficiency — Producing at the minimum average total cost (ATC); no resources wasted.
  • Allocative Efficiency — Producing where the value to consumers (demand) equals the marginal cost (MC).
  • Deadweight Loss — The loss of societal welfare due to underproduction in monopoly.
  • Consumer Surplus — Benefit to consumers above what they pay for a good.
  • Producer Surplus — Profit to producers above their cost of production.

Action Items / Next Steps

  • Review lecture notes and the textbook on monopoly efficiency.
  • Prepare for this week’s quiz and assignment on market efficiency.