Chapter 9 Perfect competition and monopoly: The limiting cases of market structure David Begg, Stanley Fischer and Rudiger Dornbusch, Economics, 6th Edition, McGraw-Hill, 2000 Power Point presentation by Peter Smith

Perfect competition many buyers and sellers firms take price as given Characteristics of a perfectly competition market many buyers and sellers so no individual believes that their own action can affect market price firms take price as given so face a horizontal demand curve the product is homogeneous perfect customer information free entry and exit of firms See Section 9-1 in the main text.

The supply curve under perfect competition (1) Above price P3 (point C), the firm makes profit above the opportunity cost of capital in the short run At price P3, (point C), the firm makes NORMAL PROFITS P1 £ Output SAVC SMC Q1 SATC P3 A C Q3 See Section 9-1 in the main text, and Figure 9-2.

The supply curve under perfect competition (2) Between P1 and P3, (A and C), the firm makes short-run losses, but remains in the market Below P1 (the SHUT-DOWN PRICE), the firm fails to cover SAVC, and exits P1 £ Output SAVC SMC Q1 SATC P3 A C Q3 See Section 9-1 in the main text, and Figure 9-2.

The supply curve under perfect competition (3) So the SMC curve above SAVC represents the firm’s SHORT-RUN SUPPLY CURVE showing how much the firm would produce at each price level. P1 £ Output SAVC SMC Q1 SATC P3 A C Q3 See Section 9-1 in the main text, and Figure 9-2.

The firm and the industry in the short run under perfect competition (1) SAC P £ Output SMC D=MR=AR q Output £ Q P SRSS D See Section 9-3 in the main text. Market price is set at industry level at the intersection of demand and supply – the industry supply curve is the sum of the individual firm’s supply curves.

The firm and the industry in the short run under perfect competition (2) £ Output SMC D=MR=AR q INDUSTRY Output £ Q P SRSS D SAC See Section 9-3 in the main text. The firm accepts price as given at P – and chooses output at q where SMC=MR to maximize profits

The firm and the industry in the short run under perfect competition (3) SAC Firm P £ Output SMC D=MR=AR q INDUSTRY Output £ Q P SRSS D SRSS1 P1 See Section 9-3 in the main text. At this price, profits are shown by the shaded area. These profits attract new entrants into the industry. As more firms join the market, the industry supply curve shifts to the right, and market price falls.

Long-run equilibrium Firm INDUSTRY P* £ q* £ Q P* D SRSS Output Output SAC P* £ Output SMC D=MR=AR q* Output £ Q P* SRSS D LRSS See Section 9-3 in the main text. The market settles in long-run equilibrium when the typical firm just makes normal profit by setting LMC=MR at the minimum point of LAC. Long-run industry supply is horizontal. If the expansion of the industry pushes up input prices (e.g. wages) then the long-run supply curve will not be horizontal, but upward-sloping.

Adjustment to an increase in market demand: the short run Suppose a perfectly competitive market starts in equilibrium at P0Q0. Output £ D SRSS Q0 P0 D' If market demand shifts to D'D' ... Q1 P1 in the short run the new equilibrium is P1Q1 ... See Section 9-4 in the main text. – adjustment is through expansion of individual firms along their SMCs.

Adjustment to an increase in market demand: the long run In the long run, new firms are attracted by the profits now being made here Output £ D SRSS Q0 P0 D' – and firms are able to adjust their input of fixed factors Q1 P1 And the market finally settles at P2Q2. Q2 P2 LRSS If wages are bid up by this expansion, the long-run supply schedule is upward- sloping Notice of course, that if wages are not pushed up by the expansion of the industry,then the LRSS will be horizontal, and we return to the original price P0. See Section 9-4 in the main text, and Figure 9-10.

Monopoly A monopolist: is the sole supplier of an industry’s product and the only potential supplier is protected by some form of barrier to entry faces the market demand curve directly Unlike under perfect competition, MR is always below AR. See Section 9-6 in the main text.

Profit maximization by a monopolist Profits are maximized where MC = MR at Q1P1. Output £ P1 Q1 MC AC D = AR MR MC=MR In this position, AR is greater than AC so the firm makes profits above the opportunity cost of capital AC1 shown by the shaded area See Section 9-6 in the main text, and Figure 9-13. Entry barriers prevent new firms joining the industry.

Comparing monopoly with perfect competition (1) Suppose a competitive industry is taken over by a monopolist: Output D MR SRSS LRSS £ Q1 P1 A Competitive equilibrium is at A, with output Q1 and price P1. To the monopolist, LRSS is the LMC curve, and SRSS is the SMC curve = LMC =SMC The monopolist maximizes profits in the short run at MR = SMC at P2Q2. Q2 P2 See Section 9-8 in the main text, and Figure 9-14.

Comparing monopoly with perfect competition (2) Suppose a competitive industry is taken over by a monopolist: D MR SRSS LRSS £ Q1 P1 A = LMC =SMC Q2 P2 In the long run, the firm can adjust other inputs ... At P3Q3. P3 Q3 to set MR = LMC See Section 9-8 in the main text, and Figure 9-14. Output

Comparing monopoly with perfect competition (3) So we see that monopoly compared with perfect competition implies: higher price lower output Does the consumer always lose from monopoly? Among other things, this depends on whether the monopolist faces the same cost structure there may be the possibility of economies of scale. See Section 9-8 in the main text.

A natural monopoly £ P1 LMC LAC Q1 This firm enjoys substantial economies of scale relative to market demand LAC declines right up to market demand the largest firm always enjoys cost leadership and comes to dominate the industry It is a NATURAL MONOPOLY LMC LAC D MR P1 £ Q1 Output Note: we return to this topic in a later chapter. See Section 9-8 in the main text, and Figure 9-15.

Discriminating monopoly Suppose a monopolist supplies two separate groups of customers with differing elasticities of demand e.g. business travellers may be less sensitive to air fare levels than tourists The monopolist may increase profits by charging higher prices to the businessmen than to tourists. Discrimination is more likely to be possible for goods that cannot be resold e.g. dental treatment See Section 9-9 in the main text.