AP Microeconomics: Antitrust and Regulation (Sherman Act, Clayton Act, FTC)

AP Microeconomics – Antitrust and Regulation (Sherman Act, Clayton Act, FTC)

AP Microeconomics – Antitrust & Regulation (Sherman Act, Clayton Act, FTC)

What This Is

Antitrust and regulation refer to government policies that keep markets competitive by preventing firms from abusing monopoly power, engaging in collusion, or merging in ways that would harm consumers. On the AP exam you’ll need to identify when a market is likely to be “uncompetitive,” explain how the Sherman Act (prohibits monopolistic practices), the Clayton Act (targets anti?competitive mergers and exclusive dealing), and the role of the Federal Trade Commission (FTC) in enforcing these laws. Real?world example: In 2001 the U.S. Department of Justice sued Microsoft under the Sherman Act for bundling its Internet Explorer browser with Windows, arguing the practice stifled competition in the web?browser market.

Key Terms & Formulas

• Sherman Act (1890) – The first federal antitrust law; bans “every contract, combination…or conspiracy in restraint of trade” and makes monopolization illegal.
• Clayton Act (1914) – Supplements the Sherman Act; prohibits specific practices such as price?discrimination, exclusive dealing, and mergers that may substantially lessen competition.
• Federal Trade Commission (FTC) – Independent agency that enforces antitrust laws, reviews mergers, and can issue cease?and?desist orders.
• Herfindahl?Hirschman Index (HHI) – HHI =? (s?)² where s? is the market share (in percent) of firm i. HHI <?1,500 = competitive, 1,500?2,500 = moderately concentrated, >?2,500 = highly concentrated.
• Lerner Index (L) – L = (P – MC) / P; measures monopoly power. P = price, MC = marginal cost. The closer L is to 1, the greater the market power.
• Market Power – Ability of a firm to set price above marginal cost without losing all customers.
• Collusion – Two or more firms cooperate (explicitly or tacitly) to restrict output or raise prices; illegal under the Sherman Act.
• Horizontal Merger – Combination of firms that produce the same (or very similar) product; scrutinized under the Clayton Act for potential competition reduction.
• Vertical Integration – Firm expands into a different stage of production (e.g., a retailer acquiring a supplier); less likely to be blocked unless it forecloses competition.
• Graph: Antitrust “Market Concentration” – Axes: Horizontal = “Number of Firms” (or “Market Share” of each firm); Vertical = “HHI Value.” A right?shift (higher HHI) signals increasing concentration; a left?shift signals a more competitive market.

Step?by?Step / Process Flow

1. Identify the market problem – Is the issue a monopoly pricing, a merger, price?discrimination, or collusion?
2. Gather market data – Determine each firm’s market share (percentage).
3. Calculate HHI – Square each share, sum the squares. Compare the result to the FTC thresholds (1,500 competitive; >?2,500 highly concentrated).
4. Assess monopoly power – Compute the Lerner Index if price and marginal cost are given; a high L supports antitrust action.
5. Apply the appropriate law –
6. If a firm is monopolizing (pricing above MC, exclusive dealing), cite the Sherman Act.
7. If a merger raises HHI by >?200 points and pushes the market into the highly concentrated range, invoke the Clayton Act.
8. Conclude with policy recommendation – Suggest FTC action (e.g., block merger, impose cease?and?desist, require divestiture).

Common Mistakes

• Mistake: Treating a price increase by a monopolist as a “shift of the demand curve.”
  Correction: A price change is a movement along the demand curve; only a change in consumer preferences or income shifts the curve.

• Mistake: Confusing market share with HHI (thinking HHI = sum of shares).
  Correction: HHI squares each share before summing; this gives more weight to larger firms and better reflects concentration.

• Mistake: Assuming any vertical integration is illegal.
  Correction: Vertical integration is generally permissible unless it forecloses a critical input and harms competition.

• Mistake: Forgetting that the Sherman Act also covers “attempts” and “conspiracies” to restrain trade, not just completed monopolies.
  Correction: Even a “failed” collusion can be prosecuted if there is an agreement to fix prices.

• Mistake: Using the Lerner Index without confirming that the firm faces a downward?sloping demand curve.
  Correction: The Lerner Index only applies when price > MC; in perfectly competitive markets L = 0.

AP Exam Insights

1. FRQ Prompt Pattern: You’ll often be asked to “evaluate the likely antitrust outcome of a proposed merger between Firm A (30% market share) and Firm B (20%).” You must compute the post?merger HHI, compare the change to the 200?point rule, and discuss FTC considerations (efficiencies, entry barriers).
2. Graph Requirement: The exam may require you to sketch a “market concentration” graph showing pre? and post?merger HHI levels, labeling the competitive, moderate, and high?concentration zones.
3. Distinguishing Laws: Remember the Sherman Act targets behavior (monopolistic conduct, price?fixing), while the Clayton Act focuses on structure (mergers, exclusive dealing). AP questions often test this distinction.
4. Multiple?Choice Traps: Look for answer choices that mix up “price ceiling” with “antitrust regulation,” or that claim “higher HHI always means higher prices” – the relationship is likely but not guaranteed.

Quick Check Questions

1. MCQ: A firm with a market share of 40% merges with a firm that has a 15% share. The pre?merger HHI is 1,800. What is the post?merger HHI?
2. Answer: 2,425.

3. Explanation: Pre?merger HHI = 40² + 15² + (other firms’ shares²) = 1,600 + 225 + … = 1,800. After merger, the combined firm has 55% share-55² = 3,025. Replace the two old squares (1,600 + 225) with 3,025; new HHI = 1,800 – 1,825 + 3,025 = 2,425.

4. FRQ?style: “Explain why the FTC might block a horizontal merger that raises the HHI by 250 points and pushes the market into the highly concentrated range.”

5. Answer: Because the increase exceeds the 200?point threshold and the market becomes highly concentrated (>?2,500), indicating a substantial lessening of competition; the FTC would likely block it unless the firms can prove significant consumer?benefiting efficiencies.

6. MCQ: Which of the following actions would most likely be prosecuted under the Sherman Act?
   A) A firm’s exclusive contract with a supplier.
   B) Two airlines agreeing to fix ticket prices.
   C) A merger that raises HHI by 150 points.
   D) A retailer’s vertical integration.

7. Answer: B) Two airlines agreeing to fix ticket prices.
8. Explanation: The Sherman Act prohibits price?fixing agreements (collusion), whereas the other options relate to the Clayton Act or are generally permissible.

Last?Minute Cram Sheet

1. Sherman Act – bans monopolistic behavior (price?fixing, monopoly).
2. Clayton Act – bans anti?competitive structure (mergers, exclusive dealing).
3. HHI Formula:? (market?share %)²; >?2,500 = highly concentrated.
4. Lerner Index: (P?–?MC)/P; measures monopoly power.
5. 200?point rule: FTC blocks a merger if HHI rises >?200 points and post?merger HHI >?2,500.
6. FTC – reviews mergers, can issue cease?and?desist orders, and enforces both Acts.
7. Horizontal merger – same?product firms; most scrutinized under Clayton.
8. Vertical integration – different production stages; usually allowed unless it forecloses competition.
9. Collusion – illegal agreement to restrict output or raise price; prosecuted under Sherman.
10. Supply?side vs. Demand?side shift: “Higher concentration” (HHI ?) is a shift of the market?structure curve, not a movement along a demand curve.

Good luck – you’ve got the tools; now apply them on the exam!