Lesson 5 of 9 · All lessons in this module
  1. Revenue, economic profit and the MR = MC ruleVideo lesson
  2. Breakeven, shutdown and exit decisionsVideo lesson
  3. Short-run and long-run costs: economies and diseconomies of scale
  4. The four market structures and what defines them
  5. Monopolistic competition: price, output and the long run
  6. Oligopoly: kinked demand, Cournot, Stackelberg and price leadershipVideo lesson
  7. Oligopoly strategy: Nash equilibrium, collusion and the long runVideo lesson
  8. Identifying market structure: elasticity, concentration ratios and HHI
  9. Integrated cases: reading a market from the data

Lesson 5 of 9 · 12 min

Monopolistic competition: price, output and the long run

A monopolistically competitive firm sets output where MR = MC and charges what its downward-sloping demand allows; easy entry then erodes any economic profit, leaving zero profit at a price above minimum average cost.

In short

  • Many firms sell close but differentiated substitutes; entry and exit are fairly cheap; firms have some pricing power and compete through advertising and branding.
  • Each firm faces a downward-sloping demand curve, so MR < price.
  • Optimal output: MR = MC; price comes from the demand curve. Short-run economic profit (or loss) is possible.
  • There is no well-defined supply curve: the quantity offered depends on the shape of demand, not only on MC.
  • Long run: entry shifts each firm's demand left until P = ATC (zero economic profit), but output is below the minimum-ATC level and price above minimum ATC.

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