Topic 4.4 Notes – Monopolistic Competition

1. What Monopolistic Competition Is

Monopolistic competition sits between perfect competition and monopoly.

Core characteristics

• Many, various-sized firms → no single firm dominates the market.
• Product differentiation → goods are similar but not identical (brand, quality, location, service).
• Price makers → each firm faces a downward-sloping demand curve, so it chooses its price.
• Low barriers to entry and exit → firms can enter when profits exist and leave when losses persist.
• Non-price competition → advertising, branding, packaging, customer experience.
• Long-run normal profit → economic profit equals zero after entry and exit.

Real-world examples

• Fast food restaurants (McDonald’s vs. Chick-fil-A)
• Clothing brands (Nike and its swoosh logo)
• Hair salons, jewelers, furniture stores

It shares features with:

• Perfect competition → many firms, free entry
• Monopoly → demand > MR, price-setting power

2. Short-Run Profit Maximization and Graphs

In the short run, a monopolistically competitive firm acts like a small monopoly.

Profit Maximization

The firm:

1. Produces where MR = MC
2. Goes up to the demand curve to find price
3. Compares P to ATC at that quantity

Because demand slopes downward:

• MR lies below demand
• At the chosen quantity, P > MC → allocative inefficiency

The graph below shows a firm earning positive economic profit in the short run.

Monopolistic competition, short-run profit

Output is where MR intersects MC. Price is found by going up to the demand curve at that quantity. Because price is above ATC at that output, the firm earns economic profit.

Three Short-Run Outcomes

You should be comfortable calculating these areas from a graph or table. If price is 18 dollars, ATC is 14 dollars, and output is 200 units, profit equals $4 \times 200 = 800$ dollars.

Surplus and Deadweight Loss

• Consumer surplus = area under demand above price
• Producer surplus = area above MC below price
• Deadweight loss = triangle between demand and MC for units not produced

Efficient output occurs where P = MC. The firm instead produces where MR = MC, which means output is too low and price is too high.

That’s why imperfectly competitive prices don’t fully coordinate society’s resources.

3. Entry, Exit, and the Long Run

Low barriers drive the adjustment.

If Firms Earn Profit

• New firms enter
• More close substitutes exist
• Each firm’s demand and MR shift left
• Profit shrinks

If Firms Earn Losses

• Firms exit
• Fewer substitutes
• Demand shifts right
• Loss shrinks

Long-Run Equilibrium

In the long run:

• Demand is tangent to ATC
• $P = ATC$ → zero economic profit
• Still produces where MR = MC
• Not at minimum ATC

The tangency occurs on the downward-sloping part of ATC, not at its minimum. That is why the firm earns zero economic profit but still has excess capacity.

4. Inefficiency and Excess Capacity

Two inefficiencies remain in the long run.

Allocative Inefficiency

• $P > MC$
• Deadweight loss persists

Productive Inefficiency

• Firm does not produce at minimum ATC
• Produces a smaller output level
• Creates excess capacity

Excess capacity = difference between:

• Output at minimum ATC
• Actual long-run output

Firms could produce more at lower average cost, but demand for their specific differentiated product is limited.

5. Non-Price Competition and Product Differentiation

Because firms sell close substitutes, price is only part of the battle.

Common strategies:

• Brand identity (Nike swoosh)
• Customer service (Chick-fil-A reputation)
• Product attributes (quality, design)
• Advertising

Advertising typically:

• Shifts demand right
• Can make demand more elastic
• Creates temporary profit → entry → long-run zero profit again

On FRQs, advertising is usually shown as a rightward shift of demand and MR.