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A natural monopoly is when one firm has the ability to supply the entire market at lower prices than two or more firms. A natural monopoly faces downward-sloping average cost (AC) for the entire range for which demand is applicable. The reason for its downward-sloping AC curve is usually that the initial investment in the infrastructure of the firm is large, but once it is in place, the marginal cost (MC) of production is low, for example hydro power. This high establishment cost is a strong barrier to entry and a natural monopoly could undercut any would-be competitor so they could not survive. Natural monopolies often involve some kind of network, for example water, gas,phone, rail.
Equilibrium Output-Natural Monopoly
The rule for maximising profit or minimising a loss (the equlibrium) for a natural monopoly is the same as any other firm. The most profitable output or smallest loss is where marginal revenue (MR) equals marginal cost (MC). Any other position will result in a smaller profit or greater loss. Therefore, the equilibrium output is at a price of Pe and quantity Qe (determined from the intersection of the marginal cost and marginal revenue curves). At the equilibrium output Qe the natural monopoly is making a supernormal profit (of $100m) and produces less than what society or consumers desire. Operating at the equilibrium output position creates a deadweight loss of BFG because consumer surplus and producer surplus are not maximised. The natural monopoly is charging a price in excess of marginal cost (P > MC), this is called mark-up pricing. At the equilibrium output in perfect competition, price and marginal cost are the same. Sellers cannot charge higher prices because they would immediately lose sales to competitors. This is called marginal cost pricing and occurs in perfect competition where at the equilibrium output position price equals marginal cost (P = MC). A natural monopoly charges more and produces less than would be the case if the firm operated as a perfect competitor.
Policies concerning natural monopoly
One way a government can regulate a monopoly is by administering price controls that do not allow a natural monopoly to operate at its preferred equilibrium output position where marginal revenue equals marginal cost. For this monopoly the equilibrium output is at a price of $7 (Pe) and quantity of 50m (Qe). The aim of price controls is to benefit the consumer with lower price and a greater quantity. Average cost pricing is a way that the government can improve resource allocation because it increases total surpluses in the market and reduces the deadweight loss that would be associated with a natural monopoly operating at its equilibrium position (MR = MC). Average cost pricing regulates the firm to charge a price equal to average costs (P = AC). In this instance the price would be $4 (Pn) and the quantity would be 80m units (Qn). The natural monopoly would no longer be maximising profits because the marginal revenue is less than marginal cost, the firm is making marginal losses on the increased output. The firm would make a normal profit instead of a supernormal profit. Normal profit is a return to the entrepreneur sufficient to keep them in their present activity. A natural monopoly regulated to a situation where price equals average cost is able to earn a fair rate of return. The net deadweight loss to society is reduced but not eliminated, the deadweight loss is now the area HKG. The natural monopoly is making a normal profit so they may lack the funds to do R & D and be less innovative, this could be viewed as a negative impact on resource allocation of fixing the price. A price set to equal average cost is more socially desirable than the equilibrium output position because consumers experience a significant increase in consumer surplus due to the lower price and higher quantity consumed. Average cost pricing has the advantage over marginal cost pricing of not having to provide a subsidy to a natural monopoly to keep the firm operating.
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