Natural monopoly

Topic: Market Structures, Market Failure and Competition · NCERT: Beyond NCERT

Meaning

A natural monopoly is an industry where one firm can supply the whole market more cheaply than two or more firms could. This happens because the industry has very large fixed costs (costs that do not change with output) and low running costs, so average cost (AC) keeps falling over the whole range of output that the market needs.

It matters because competition, which is the usual cure for monopoly, would waste money here. Building two railway tracks or two sets of power lines side by side makes no sense. So the government has to regulate the single firm or own it. How to set its price is a major policy question in power, gas, water and railways.

Key condition: AC falls as output rises → MC < AC → pricing at P = MC gives a loss.

Explanation

How it works: falling average cost

• Average cost (AC) is total cost divided by output. Marginal cost (MC) is the extra cost of producing one more unit.
• Big fixed cost, small cost per unit:
• Laying a gas pipeline network costs a very large amount at the start.
• Sending more gas through the same pipes adds very little cost.

• So each extra customer spreads the fixed cost more thinly, and AC falls.

• Why one firm is cheapest:

• Suppose two firms split the market. Each one pays the full fixed cost but serves only half the customers.
• Each firm's AC is then higher than one firm's AC would be.

• So the market "naturally" ends up with one firm. No law is needed to create this monopoly. It comes from scale economies (cost savings from large size), which smaller rivals cannot match.

• Examples: railway track, power transmission lines, city gas networks and water pipes.

The pricing problem

• When AC is falling, MC is always below AC. (If each extra unit costs less than the average, it pulls the average down.)
• Efficient pricing (P = MC):
• This gives the output that society values most, with no deadweight loss (DWL), meaning no lost gains from trade.

• But price < AC, so the firm makes a loss and cannot survive without a subsidy.

• Profit-maximising pricing (MR = MC):

• Marginal revenue (MR) is the extra revenue from selling one more unit.
• A private monopolist left alone would avoid the loss. It would cut output and charge P > MC.

• This brings back the DWL.

• So the regulator must choose between efficiency (P = MC) and financial viability (the firm covers its costs).

Worked example. TC = 840 + 10Q (fixed cost 840, MC = 10). Demand: P = 50 − 0.4Q.

Pricing rule	Output	Price	AC	Result
P = MC (efficient)	100	10	840/100 + 10 = 18.4	Loss = (18.4 − 10) × 100 = 840, the whole fixed cost
P = AC (average-cost pricing)	70	22	840/70 + 10 = 22	Zero economic profit (normal profit only). Output is below the efficient 100
Two-part tariff	100	Fixed charge (e.g. 84 users × ₹10 = 840) + ₹10 per unit	—	Covers all costs and reaches the efficient output

• How to read it: the loss under P = MC equals exactly the fixed cost. Every unit covers its own running cost (₹10), but nothing is left over to pay for the network. The two-part tariff fixes this by collecting the fixed cost separately.

Remedies: how regulators handle a natural monopoly

• Average-cost pricing (P = AC).
• The firm earns only normal profit (just enough to stay in business).

• It is financially viable, but output is below the efficient level, so some DWL remains.

• Two-part tariff.

• A fixed charge pays for the fixed cost of the network.
• A per-unit charge close to MC pays for use.

• Example: an electricity bill = fixed/demand charge + energy charge per kWh.

• Price cap (RPI − X).

• The regulator lets prices rise by inflation (RPI, the retail price index) minus an efficiency factor X.
• Example: inflation 5%, X = 2% → price may rise only 3%.

• The firm keeps any extra savings it makes, so it has a reason to cut costs.

• Public ownership. The State runs the network itself, as with Indian Railways track.

• Risk: a firm with no competition may suffer from X-inefficiency (Leibenstein, 1966). This means it stops keeping costs low, for example through overstaffing or poor upkeep.

• Unbundling. Separate the network (the natural monopoly part) from the service sold over it (where competition is possible). Several firms can then use one set of wires or pipes.

In India

• Sectors with natural-monopoly features: railway track (Indian Railways), power transmission and distribution wires, city gas networks and water pipes.
• Sector regulators that set prices for the monopoly network:
• CERC (central) and SERCs (states) for electricity tariffs and network charges;
• PNGRB (2006) for petroleum pipelines and city gas distribution;

• AERA (2008) for airport tariffs.

• Two-part tariffs in practice: Indian electricity bills have a fixed/demand charge plus an energy charge per kWh. This is the textbook natural-monopoly remedy.

• Draft Electricity (Amendment) Bill, 2025:
• One discom (electricity distribution company) could supply power over another discom's network [4].
• Discoms must give open, non-discriminatory access (every supplier treated equally) to their networks, with charges set by the SERC [4].

• The idea: the wires stay a natural monopoly, but selling power becomes open to competition.

• Tariff Policy, 2016: every consumer category's tariff should be within ±20% of the average cost of supply [5]. This limits how much a regulated network can overcharge one group to subsidise another.

• Economy-wide check: under Section 4 of the Competition Act, 2002, being dominant is legal, but abusing a dominant position is not [3]. The CCI (set up with effect from 14 October 2003) enforces this [2].

Don't confuse with

• Legal (statutory) monopoly: this monopoly is created by a law that gives one body the sole right to supply. A natural monopoly comes from cost conditions (falling AC), not from law. Trap: the Post Office Act, 2023 removed the old exclusive privilege to carry letters. India Post's only exclusive privilege now is issuing postage stamps [1].
• Ordinary monopoly (from patents or control of a key resource): here the monopoly blocks rivals who could produce as cheaply. In a natural monopoly, breaking the firm up would raise costs, so the answer is regulation, not more rivals.
• Monopsony: a market with a single buyer (term coined by Joan Robinson, 1933). It holds down the price it pays. A natural monopoly is a single seller that could push up the price it charges.
• Perfect competition: firms are price takers and P = MC with no loss. In a natural monopoly, P = MC causes a loss, because MC < AC.

Prelims Hooks

• Natural monopoly: AC falls over the relevant range of output → MC < AC → P = MC means a loss equal to the unrecovered fixed cost.
• Four remedies: average-cost pricing, two-part tariff, RPI − X price cap, public ownership. Only the two-part tariff gives both efficient output and full cost recovery.
• RPI − X: with inflation 5% and X = 2%, the regulated price may rise only 3%.
• Average-cost pricing gives zero economic profit (normal profit only) but leaves some DWL.
• The Draft Electricity (Amendment) Bill, 2025 proposes that one discom may supply power over another discom's network, with open, non-discriminatory access and charges set by the SERC [4].
• Regulator–sector pairs: PNGRB – pipelines and city gas (2006); AERA – airport tariffs (2008); CERC/SERCs – electricity.

Mains Points

• Efficiency vs viability:
• P = MC is efficient but needs a subsidy, which is a burden on the budget.
• Average-cost pricing and price caps pay for themselves but leave some DWL.

• Two-part tariffs and network unbundling try to get both. An example is open access to discom wires under the Draft Electricity (Amendment) Bill, 2025 [4]. Use this in GS-III answers on infrastructure and discom losses.

• Public ownership vs regulated private supply:

• State ownership (e.g. Indian Railways track) avoids monopoly pricing but risks X-inefficiency (Leibenstein, 1966), such as overstaffing and poor upkeep.

• Independent regulators with RPI − X caps give firms a reason to cut costs. Their success depends on regulators having the capacity to do this well and being free from political pressure.

• Unbundling as reform:

• Keep the network (wires, pipes, track) as a regulated natural monopoly.
• Open the service sold over it to competition.
• Pair this with cost-reflective tariffs within the ±20% band of the Tariff Policy, 2016 [5] to protect both consumers and the network's finances.

Related concepts

• Monopoly
• X-inefficiency
• Price discrimination
• Monopsony
• Oligopsony
• Bilateral monopoly

Read more

• Monopoly, natural monopoly, monopsony and price discrimination