1. Firm Supply: Market Structure & Perfect Competition

2. Firm Supply u How does a firm decide how much to supply at a given price? This depends upon the firm’s – goals; – technology; – market environment; and – competitors’ behaviour.

3. Market Environment u Are there many other firms? u How do other firms’ decisions effect the firm’s payoffs?

4. Market Environment u Monopoly: Just one seller that determines the quantity supplied/the market-clearing price. u Oligopoly: A very small number of firms, the decision of each influencing the payoffs of the other firms.

5. Market Environment u Dominant Firm: Many firms, but one much larger than the rest. The large firm’s decisions affect the payoffs of each small firm. Decisions by any one small firm do not noticeably effect the payoffs of any other firm.

6. Market Environment u Monopolistic Competition: Many firms each making a slightly different product. Each firm’s output level is small relative to the total. u Perfect Competition: Many firms, all making the same product. Each firm’s output level is very small relative to the total output level.

7. Perfect Competition Assumptions u There are many buyers and sellers, –each firm is a price-taker u Homogeneous product u Freedom of entry and exit u Perfect information

8. Perfect Competition u What is the demand curve faced by the firm?

9. Perfect Competition Q P Market Supply Market Demand pepe

10. Perfect Competition Q P Market Supply pepe p’ At a price of p’, zero is demanded from the firm. Market Demand

11. Perfect Competition Q P Market Supply pepe p’ p” At a price of p” the firm faces the entire market demand. At a price of p’, zero is demanded from the firm. Market Demand

12. Perfect Competition u Therefore, the demand curve faced by the individual firm is...

13. Perfect Competition Market Supply Market Demand Q P Firm’s Demand Curve P P* y

14. The Firm’s Short-Run Supply Decision? u Each firm is a profit-maximizer u Each firm choose its output level by solving

15. The Firm’s Short-Run Supply Decision? What does the solution y s * look like?

16. The Firm’s Short-Run Supply Decision?  (y) yys*ys* F.O.C. S.O.C.

17. The Firm’s Short-Run Supply Decision? The first-order maximum profit condition is That is, So at a profit maximum with y s * > 0, the market price p equals the marginal cost of production at y = y s *.

18. The Firm’s Short-Run Supply Decision? P y pepe ys*ys*y’ At y = y s *, p = MC and MC slopes upwards, y = y s * is profit- maximizing. MC s (y)

19. The Firm’s Short-Run Supply Decision? P y pepe ys*ys*y’ At y = y’, p = MC and MC slopes downwards, y = y’ is profit- minimizing. MC s (y)

20. The Firm’s Short-Run Supply Decision? P y pepe y’ So a profit- maximising supply level can lie only on the upwards sloping part of the firm’s MC curve. MC s (y) ys*ys*

21. The Firm’s Short-Run Supply Decision? u But not every point on the upward- sloping part of the firm’s MC curve represents a profit-maximum. u The firm will choose an output level y > 0 only if

22. The Firm’s Short-Run Supply Decision? u The firm will not supply any output if Shut Down Point: P = AVC(y)

23. The Firm’s Short-Run Supply Decision? AVC s (y) AC s (y) MC s (y) P y

24. The Firm’s Short-Run Supply Decision? AVC s (y) AC s (y) MC s (y) P y

25. The Firm’s Short-Run Supply Decision? AVC s (y) AC s (y) MC s (y) P y p  AVC s (y) The firm’s short-run supply curve

26. The Firm’s Short-Run Supply Decision? AVC s (y) AC s (y) MC s (y) The firm’s short-run supply curve Shutdown point P y

27. Short Run Market Supply Curve P Q Market Supply Curve is the sum of all the firms supply curves (  MC) S

28. The Firm’s Long-Run Supply Decision? u The long-run is the circumstance in which the firm can choose amongst all of its short-run circumstances. u How does the firm’s long-run supply decision compare to its short-run supply decisions?

29. The Firm’s Long-Run Supply Decision? u A competitive firm’s long-run profit function is u The long-run cost c(y) of producing y units of output consists only of variable costs since all inputs are variable in the long-run.

30. The Firm’s Long-Run Supply Decision? The firm’s long-run supply level decision is to maximise,

31. The Firm’s Long-Run Supply Decision? u Additionally, the firm’s economic profit level must not be negative, since the firm would exit the market in that case. Therefore,

32. The Firm’s Long-Run Supply Decision? MC(y) AC(y) y P

33. The Firm’s Long-Run Supply Decision? MC(y) AC(y) y P p > AC(y)

34. The Firm’s Long-Run Supply Decision? MC(y) AC(y) y P The firm’s long-run supply curve

35. Application: Tax Incidence In Perfect Competition Q P Market Demand Market Supply P C = P P No tax: P C = P P

36. Application: Tax Incidence In Perfect Competition Q P Market Demand Market Supply P A tax is introduced. PCPC This is the tax.

37. Application: Tax Incidence In Perfect Competition Q P Market Demand Market Supply P The tax creates a wedge between the price firms receive and the price consumers pays. The difference is the tax. PCPC This is the tax.

38. Application: Tax Incidence In Perfect Competition Q P Market Demand Market Supply P In the short run, the burden of the tax is shared (not necessarily on a 50/50 basis) between consumers and producers. PCPC This is the tax

39. Application: Tax Incidence In Perfect Competition In the short run, u The producers receives less for the product. u Some firms will continue to produce output at a loss once they are covering their average variable costs. u Some firms will experience losses and so exit the market. u The supply curve shifts to the left and the prices consumers and producers face increases.

40. Application: Tax Incidence In Perfect Competition In the Long Run, u Consumers pay all of the tax (100%) u Producers pay none of tax (0%) u There are no firms making losses