Monopoly: When One Firm Is the Market

A monopoly is the opposite extreme from perfect competition - a single firm with enough market power to restrict output and raise prices above the competitive level.

Perfect competition, covered in the previous lesson, sits at one end of a spectrum of market structures. Monopoly sits at the far opposite end: a market with a single seller and no close substitutes, giving that one firm substantial control over price.

What makes a monopoly possible

A monopoly exists when one firm is the sole supplier of a good or service with no close substitutes, and significant barriers prevent other firms from entering to compete it away - covered in more depth later in this module. Sources of monopoly power include control of an essential resource, government-granted exclusive rights like patents, and, importantly, situations where economies of scale, covered earlier in this module, make it inefficient or impractical for more than one firm to serve the market at all.

A natural monopoly describes this last case specifically: an industry where the economies of scale are so large relative to market demand that having a single producer serve the entire market is actually the most efficient outcome - think of water or electricity distribution infrastructure, where duplicating pipes or power lines across every neighborhood would be wastefully expensive.

Market power and its effect on price

Unlike a price-taking firm in perfect competition, a monopolist has market power - the ability to influence the market price by adjusting how much it produces. Because a monopolist faces the entire market’s downward-sloping demand curve alone, rather than a flat price set by competition, it can restrict output below the competitive level to push the price higher, generally earning economic profit even in the long run, since barriers to entry, covered later in this module, prevent new competitors from entering to compete that profit away.

Why a small town's only water utility isn't like the wheat farmer

Recall the wheat farmer from the previous lesson, powerless to affect the market price of wheat. Now consider a town's sole water utility, holding a natural monopoly over water pipes running to every home. Unlike the farmer, the utility faces the entire town's demand curve on its own - if it raises the price, it doesn't lose customers to a rival pipe network, because none realistically exists. This gives the utility genuine influence over price, which is exactly why natural monopolies like water and electricity utilities are usually subject to price regulation rather than left to set prices freely.

The cost of monopoly to society

Assuming monopoly is only a problem because prices are higher

It's tempting to think the entire problem with monopoly is simply that consumers pay more. That's part of it, but the deeper economic concern is that a monopolist restricting output below the competitive level creates deadweight loss, covered in the previous module's lesson on taxes - mutually beneficial trades that would have happened at the competitive price and quantity simply don't happen at all under monopoly. It's not just a transfer of money from consumers to the monopolist; some potential value is destroyed entirely, which is exactly the efficiency concern that motivates antitrust policy, covered later in this module.

Why not every monopoly gets the same treatment

Not all monopolies are treated the same way by policy. Natural monopolies are often allowed to exist but regulated, since breaking them up would be genuinely inefficient given the economies of scale involved. Patent-protected monopolies are deliberately created for a limited time to reward innovation, a trade-off covered further in the entrepreneurship module. Monopolies that emerge purely from anticompetitive behavior, by contrast, are the primary target of antitrust enforcement, covered later in this module.

Key takeaways

A monopoly is a market with a single seller and no close substitutes, protected by significant barriers to entry.
A natural monopoly arises when economies of scale make a single producer the most efficient outcome.
Market power lets a monopolist restrict output and raise price above the competitive level.
Monopoly creates deadweight loss, not just higher prices, by preventing some beneficial trades from occurring.
Different sources of monopoly power - natural, government-granted, or anticompetitive - are treated differently by policy.