Monopoly and Antitrust Policy: Principles of Microeconomics (Chapter 15 Study Notes)

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Monopoly and Antitrust Policy

Introduction to Monopoly

A monopoly is a market structure in which a single firm is the sole producer of a good or service that has no close substitutes. Monopolies arise when barriers to entry prevent other firms from entering the market, allowing the monopolist to exert significant control over price and output.

Monopoly: A firm that is the only supplier of a good or service with no close substitutes.
Barriers to Entry: Obstacles that make it difficult or impossible for new firms to enter a market.

Sources of Monopoly Power

Barriers to entry can be high enough to keep out competing firms for several reasons:

Legal Restrictions: Government laws or regulations may block entry, such as patents, copyrights, or government franchises.
Control of Essential Resources: A firm may control a resource necessary for production (e.g., De Beers and diamonds).
Network Externalities: The value of a product increases with the number of users (e.g., social media platforms, Blu-ray vs. HD DVD).
Natural Monopoly: Economies of scale are so large that one firm can supply the entire market at a lower cost than multiple firms.

Legal Restrictions

Patent: Exclusive right to produce a product for a period of time.
Copyright: Exclusive right to publish and sell a creation.
Government Franchise: Government designation that a firm is the sole provider of a good or service.

Control of Essential Resources

Example: De Beers controlled a large share of the world's diamond supply, limiting competition.

Network Externalities

Definition: The situation in which the usefulness of a product increases with the number of consumers who use it.
Examples: Internet Explorer vs. Netscape, social media evolution (IM, MySpace, Facebook, Twitter, Instagram), Blu-ray vs. HD DVD.

Natural Monopoly

Definition: A situation in which economies of scale are so large that one firm can supply the entire market at a lower average cost than two or more firms.
Examples: Utilities such as electricity (Penelec), water (Pennsylvania American Water), and natural gas (Dominion).

Practice Problem: Barriers to Entry

All of the following could help a firm gain market power and potentially act as a monopolist EXCEPT:

A. having significant diseconomies of scale.
B. securing a copyright from the U.S. Copyright Office.
C. securing a patent from the U.S. Patent and Trademark Office.
D. owning all the natural resources necessary for the production process.

Monopoly Pricing and Output Decisions

Single-Price Monopolists and Marginal Revenue (MR)

Monopolists face a downward-sloping demand curve and must lower the price to sell additional units. This affects total revenue (TR) and marginal revenue (MR).

Good Effect: Selling more units increases total revenue.
Bad Effect: Lowering the price reduces revenue received for all units sold.

Marginal Revenue Calculation

Marginal revenue is the change in total revenue from selling one more unit:

For a single-price monopolist, MR is less than price because selling more units requires lowering the price on all units sold.

Example: If a monopolist sells 100 units at $15 and 120 units at $10, the marginal revenue for increasing output from 100 to 120 units is:

TR at 100 units: $15 × 100 = $1500
TR at 120 units: $10 × 120 = $1200
MR = Change in TR / Change in Q = ($1200 - $1500) / (120 - 100) = -$300 / 20 = -$15 per unit

Relationship Between Demand and MR

The MR curve for a linear demand curve has twice the slope of the demand curve.
MR bisects the quantity axis halfway between zero and where the demand curve hits the axis.

Profit Maximization for a Monopolist

Monopolists are price makers, choosing both the price and quantity to maximize profit, unlike perfectly competitive firms which are price takers.

Profit maximization occurs where MR = MC (marginal cost).
To find the profit-maximizing quantity (Q*), locate the intersection of MR and MC.
To find the profit-maximizing price (P*), go up from Q* to the demand curve.

Graphical Representation

In perfect competition: Q* is where P = MC.
In monopoly: Q* is where MR = MC; P* is found on the demand curve at Q*.

Profit and Loss in Monopoly

Profit (or loss) is determined by the relationship between price (P), average total cost (ATC), and average variable cost (AVC).
If P > ATC, the firm earns profit; if P < ATC but P > AVC, the firm minimizes loss by operating; if P < AVC, the firm should shut down.

Economic Efficiency and Monopoly

Measuring Efficiency Losses from Monopoly

Monopoly reduces economic efficiency compared to perfect competition:

Consumer Surplus: Decreases under monopoly.
Producer Surplus: Increases for the monopolist, but total surplus is lower.
Deadweight Loss: Represents the reduction in economic efficiency due to monopoly pricing above marginal cost.

Comparing Monopoly and Perfect Competition

Perfect competition maximizes total surplus (consumer + producer surplus).
Monopoly restricts output and raises price, creating deadweight loss.

Government Policy Toward Monopoly

Antitrust Laws and Enforcement

Governments use antitrust laws to prevent monopolies and promote competition.

Collusion: Agreement among firms to fix prices or otherwise restrict competition.
Antitrust Laws: Laws aimed at preventing collusion and monopolization.

Important U.S. Antitrust Laws

Law	Purpose
Sherman Act (1890)	Prohibited "restraint of trade," including price fixing and collusion. Outlawed monopolization.
Clayton Act (1914)	Prohibited firms from buying stock in competitors and from having directors serve on boards of competing firms.
Federal Trade Commission Act (1914)	Established the FTC to help administer antitrust laws.
Robinson-Patman Act (1936)	Prohibited charging buyers different prices if the result would reduce competition.
Cellar-Kefauver Act (1950)	Toughened restrictions on mergers that would reduce competition.

Mergers

Horizontal Merger: Merger between firms in the same industry.
Vertical Merger: Merger between firms at different stages of production of a good.

Measuring Market Concentration: Herfindahl-Hirschman Index (HHI)

The HHI is used to measure market concentration and assess the impact of mergers:

HHI = sum of the squares of the market shares of all firms in the market.
Example: Four firms with market shares of 30%, 30%, 20%, and 20%: HHI =

HHI After Merger	Increase in HHI	Antitrust Action
Less than 1500	Any	Merger allowed
1500-2500	Less than 100	Merger not likely to be challenged
1500-2500	More than 100	Merger may be challenged
Greater than 2500	Less than 100	Merger unlikely to be challenged
Greater than 2500	100-200	Merger may be challenged
Greater than 2500	More than 200	Merger likely to be challenged

Practice Problem: Merger Types

If Del Monte merges with Heinz's tuna, pet food, soup, and baby food businesses, this represents a horizontal merger because both companies operate in the same industry and at the same stage of production.

Summary

Monopolies arise due to barriers to entry, control of resources, network externalities, and natural monopoly conditions.
Monopolists maximize profit by equating MR and MC, and set price based on the demand curve.
Monopoly leads to deadweight loss and reduced economic efficiency compared to perfect competition.
Government policies, including antitrust laws and merger guidelines, aim to limit monopoly power and promote competition.

Additional info: Some explanations and examples have been expanded for clarity and completeness.