Questions: Natural Monopoly and Regulation

Question 1

A regulator sets price equal to marginal cost for a natural monopoly with declining long-run average cost. What outcome should the regulator expect?

• A. The firm earns zero economic profit and serves consumers efficiently
• B. The firm earns positive economic profit, since low prices attract more customers
• C. The firm suffers losses on every unit sold and will exit unless subsidized
• D. Deadweight loss is maximized because the price is set too low

Answer: (C)

When LRAC is still declining at the efficient output, marginal cost lies below average cost (MC < LRAC is what causes LRAC to decline). Setting P = MC means P < LRAC, so the firm earns negative economic profit — it loses money on every unit. Without a subsidy, the firm exits. This is the core regulatory dilemma: marginal-cost pricing is socially efficient but financially unsustainable. Option A describes the desired outcome but ignores the financial impossibility. Real utility regulation usually settles for average-cost pricing instead.

Question 2

A city has one water utility serving all households. A new firm tries to enter and compete. Which explanation best captures why competition is unlikely to succeed?

• A. The existing firm uses predatory pricing to drive out competitors
• B. Government licensing prevents new firms from entering
• C. High infrastructure fixed costs mean two firms would each face higher average costs than one firm serving the whole market
• D. Consumers prefer dealing with a single provider out of habit

Answer: (C)

A natural monopoly is a cost-structure phenomenon, not the result of predatory behavior or legal barriers. When fixed costs (pipes, treatment plants) are very high and marginal costs are low, a single firm spreading those fixed costs over all customers achieves much lower average cost than two firms each building their own infrastructure. Any entrant would have higher costs and would be undercut. This is what 'natural' means — the monopoly emerges from the economics of production, not from anticompetitive conduct. Option A describes a behavioral monopoly, which is a different concept.

Question 3

Average-cost pricing for a natural monopoly eliminates most deadweight loss.

• T. True
• F. False

Answer: False

Average-cost pricing (P = LRAC) sets price above marginal cost — the firm covers all costs including a normal return, but P > MC means consumers who would have bought at MC don't buy at the higher price. This creates a deadweight loss triangle, smaller than under unregulated monopoly pricing but still present. Only marginal-cost pricing (P = MC) eliminates deadweight loss, but it causes losses for the firm when LRAC is declining. Average-cost pricing is the practical compromise that accepts some deadweight loss in exchange for financial viability without subsidy.

Question 4

A natural monopoly can emerge even when the dominant firm has never engaged in predatory or anticompetitive behavior.

• T. True
• F. False

Answer: True

Natural monopoly is defined by cost structure: a single firm can serve the entire market at lower total cost than any combination of multiple firms. This occurs because of large economies of scale relative to market size — declining LRAC throughout the relevant output range. No predatory conduct is required. The market naturally converges to one firm because any competitor would face higher average costs and be undercut on price by the incumbent simply operating at greater scale. This is why 'natural' monopoly is contrasted with monopoly achieved through deliberate exclusion.

Question 5

Why can't a regulator simply require a natural monopoly to price at marginal cost, and what alternative do most real-world regulators use instead?

Model answer: When LRAC is declining at the relevant output, MC < LRAC. Setting P = MC means the firm earns less per unit than its average cost — it loses money and will shut down without a subsidy. Most regulators instead use average-cost pricing (P = LRAC), which allows the firm to earn zero economic profit (covering all costs including a fair return) while remaining financially viable. This accepts some deadweight loss (P > MC) in exchange for sustainability without subsidy.

The tradeoff is efficiency vs. viability. MC pricing is Pareto-efficient but requires the government to subsidize the firm indefinitely to cover its losses. Average-cost pricing ('fair rate of return' regulation) is the standard approach for electricity, water, and gas utilities: set rates to cover costs including an allowed return on capital, let the firm break even, accept the residual inefficiency. This is a genuine second-best solution — the first-best (MC pricing + subsidy) has its own political and fiscal costs, and the choice involves value judgments about who bears the burden.