Pure Monopoly

At the opposite extreme from pure competition stands pure monopoly: a market with a single seller of a product that has no close substitutes. Where the competitive firm is a powerless price taker, the monopolist is a price maker with genuine control over the market. This chapter analyzes how a monopoly sets price and output, the cost it imposes on society, and the policy responses it invites.

Characteristics of Monopoly

A pure monopoly has several defining features: a single seller that is the entire industry; a unique product with no close substitutes; price-making power, since the firm's output decisions move the market price; and blocked entry, so that barriers prevent rivals from entering and competing away its profits.

Barriers to Entry

Monopoly persists only when entry is blocked. The main barriers to entry include:

• Economies of scale — When average cost keeps falling over the entire range of market demand, a single large firm can supply the market more cheaply than several smaller ones. This case is a natural monopoly, common in utilities like water and electricity.
• Legal barriers — Patents, copyrights, and government licenses grant exclusive rights to produce.
• Control of essential resources — Owning a key input can foreclose competition.
• Strategic barriers — Established firms may use pricing or other tactics to deter entry.

The Monopolist's Demand and Revenue

Because it is the whole industry, the monopolist faces the downward-sloping market demand curve. To sell more, it must lower the price — and not just on the marginal unit but on all units. As a result, marginal revenue is less than price (MR < P), and the marginal revenue curve lies below the demand curve. This single fact, that MR < P, is the source of every important difference between monopoly and competition.

Profit Maximization Under Monopoly

The monopolist follows the same fundamental rule as any firm: produce where MR = MC. But because marginal revenue is below price, the firm finds the profit-maximizing quantity where MR = MC and then charges the higher price that demand will bear for that quantity. Compared with a competitive industry, the monopolist produces less output and charges a higher price.

Crucially, monopoly power does not guarantee profit, and the monopolist does not charge "the highest possible price." It chooses the price-quantity combination that maximizes profit, constrained by demand and costs. Persistent economic profits are possible because blocked entry prevents the competition that would erode them.

The Costs of Monopoly

Monopoly is inefficient on the very standards that made competition attractive:

• Allocative inefficiency — Because the monopolist produces where price exceeds marginal cost (P > MC), output falls short of the efficient level. Some units that consumers value more than they cost to produce are never made, creating a deadweight loss to society.
• Productive inefficiency and X-inefficiency — The monopolist need not produce at minimum average total cost. Sheltered from competition, it may also let costs drift above the minimum through slack management, a waste known as X-inefficiency.
• Transfer of surplus — Monopoly pricing transfers income from consumers to the firm, raising distributional as well as efficiency concerns.

Price Discrimination

Under certain conditions a monopolist can practice price discrimination — charging different buyers different prices for the same product. This requires market power, the ability to segment buyers by their willingness to pay, and the ability to prevent resale between them. Examples include airline fares, student and senior discounts, and bulk pricing. Price discrimination lets the firm capture more consumer surplus as profit; interestingly, it can sometimes increase total output relative to single-price monopoly, with mixed effects on overall welfare.

Regulating Monopoly

Because monopoly imposes real costs, governments respond in several ways: enforcing antitrust laws to prevent or break up monopoly power, and regulating natural monopolies by setting price ceilings. Regulators face a dilemma in pricing: setting price equal to marginal cost achieves allocative efficiency but may force a natural monopoly to operate at a loss, while setting price equal to average total cost lets the firm break even but sacrifices some efficiency. The practical challenge of regulation is to capture the cost advantages of large scale while limiting the abuse of market power.

---

Next chapter: most real markets lie between competition and monopoly. We turn first to the structure closest to competition — monopolistic competition.

Further Listening & Reading

• 🎥 Maximizing Profit Under Monopoly (MRU) — why a monopolist restricts output and raises price.
• 🎥 Introduction to Price Discrimination (MRU) — charging different buyers different prices.
• 🎧 Planet Money: Monopoly, the Board Game and American Capitalism (NPR) — the surprising anti-monopoly origins of the famous game.