Chapter 6 - Section 6.2

Monopoly

Market Power, Pricing Strategies, and Effects on Consumers

Why Monopolists Face Downward-Sloping Demand

Unlike perfectly competitive firms, a monopolist IS the market. The firm's demand curve is the entire market demand curve, which slopes downward. This fundamental difference gives monopolists pricing power but also creates trade-offs.

Key Characteristics of Monopoly Demand

Downward-Sloping

To sell more units, the monopolist must lower the price. Higher prices mean fewer sales.

Price Maker

The monopolist chooses the price-quantity combination, not just accepts market price.

No Close Substitutes

Consumers can't easily switch to alternative products, giving the firm market power.

Trade-Off

Can charge high prices OR sell high quantities, but not both simultaneously.

Why Marginal Revenue Lies Below Demand

For a monopolist, Marginal Revenue (MR) < Price. The MR curve lies below the demand curve. This is one of the most important distinctions between monopoly and perfect competition.

Why This Happens: A Simple Example

Suppose a monopolist currently sells 10 units at $100 each (total revenue = $1,000)

Scenario: Sell One More Unit

To sell the 11th unit, the monopolist must lower the price to $95 for ALL units

New Revenue: 11 units × $95 = $1,045

Old Revenue: 10 units × $100 = $1,000

Marginal Revenue = $1,045 - $1,000 = $45

Why MR ($45) < Price ($95):

  • Gain: +$95 from selling the 11th unit
  • Loss: -$50 from lowering price on the first 10 units (10 × $5 price cut)
  • Net MR = $45

Lowering price to sell more has a revenue-reducing effect on existing sales!

Key Takeaway: A monopolist's marginal revenue from an additional unit equals the price of that unit minus the revenue lost from lowering the price on all previous units. This is why the MR curve lies below the demand curve.

How Monopolists Maximize Profit (MR = MC)

Like all firms, monopolists maximize profit by producing where MR = MC. However, unlike competitive firms, the monopolist then charges a price above marginal cost based on the demand curve.

Step-by-Step Process

1

Find MR = MC: Determine the profit-maximizing quantity where marginal revenue equals marginal cost

2

Go up to demand: From that quantity, look up to the demand curve to find the price consumers will pay

3

Calculate profit: Profit = (P - ATC) × Quantity, shown as a shaded rectangle on the graph

Critical Difference from Perfect Competition

Perfect Competition:

P = MR = MC
Firms charge price equal to marginal cost

Monopoly:

MR = MC, but P > MR
Price is above marginal cost

This price markup above MC represents the monopolist's market power

How Monopolies Affect Price, Output, and Consumers

Compared to perfect competition, monopolies produce negative outcomes for society:

Higher Prices

Monopolists charge P > MC, extracting more from consumers than competitive firms

Lower Output

Monopolists restrict output below the socially optimal level to keep prices high

Deadweight Loss

Society loses potential gains from trade—allocative inefficiency harms welfare

Consumer Impact

Less Consumer Surplus: Higher prices transfer wealth from consumers to the monopolist

Reduced Choice: Lower output means fewer products available in the market

Less Innovation (potentially): Without competitive pressure, monopolists may have less incentive to innovate, though patent-based monopolies can drive R&D

Monopoly Profit-Maximization Graph Reference

A typical monopoly graph would display:

Curves Shown:

  • • Downward-sloping Demand curve (D)
  • • Marginal Revenue curve (MR) below D
  • • U-shaped Marginal Cost curve (MC)
  • • Average Total Cost curve (ATC)

Key Points:

  • • MR = MC intersection determines quantity
  • • Price set on demand curve above MR = MC
  • • Profit rectangle: (P - ATC) × Q
  • • Deadweight loss triangle shown

The graph visually demonstrates how monopolists produce less and charge more than competitive firms, creating economic inefficiency.

Explore Real-World Applications

You've completed the core economic theory. Now see how these concepts apply to real markets and current events.

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