Monopoly Revision Sheet

1. 📌 Essentials

• Monopoly: one firm with no close substitutes, market power
• Market share > 25% raises regulatory concern
• Price setter: facing downward-sloping demand curve
• Revenue: TR = P × Q; AR = P; MR always less than P
• Profit maximization where MR = MC; set price from demand
• Monopoly profit: (P − ATC) × Q
• Deadweight loss results from underproduction
• Price discrimination: charging different prices based on consumer willingness
• Natural monopolies: lower costs due to economies of scale
• Regulation often involves setting P = MC, risking losses
• Anti-trust laws: prevent abuse of monopoly power
• Market power stems from barriers, resource control, or government rights
• Welfare impact: monopolies reduce consumer surplus, create deadweight loss

2. 🧩 Key Structures & Components

• Demand curve — downward-sloping; determines P and Q
• Total Revenue (TR) — P × Q
• Average Revenue (AR) — TR / Q, equals demand curve
• Marginal Revenue (MR) — ΔTR / ΔQ; always less than P for monopolies
• Profit maximization point — MR = MC
• Barriers to entry — resource control, legal rights, economies of scale
• Price discrimination — selling to segments at different prices
• Regulatory agencies — enforce competition laws
• Natural monopoly — achieved through economies of scale
• Government policies — regulation, public ownership, or laissez-faire