Public Policy to Promote Competition — AP Microeconomics
1. What is Public Policy to Promote Competition? ★☆☆☆☆ ⏱ 3 min
Public policy to promote competition refers to government actions designed to prevent anti-competitive business practices, reduce harmful concentration of market power, and eliminate the deadweight loss (DWL) that arises from uncompetitive markets. This topic accounts for 18-22% of the total AP Microeconomics exam score, appearing regularly on both multiple-choice and free-response sections.
Policy makers balance two competing goals: on one hand, concentrated market power leads to higher prices, lower output, and DWL compared to competitive outcomes. On the other hand, some markets have such large economies of scale that a single producer (a natural monopoly) is more efficient than multiple competing firms, so policy must adjust to this tradeoff.
2. Measuring Market Concentration ★★☆☆☆ ⏱ 4 min
To make informed policy decisions, regulators first measure how much market power is concentrated in the largest firms of an industry. Two standard metrics tested on AP Microeconomics are the 4-firm concentration ratio ($CR_4$) and the Herfindahl-Hirschman Index (HHI).
CR_4 = \sum_{i=1}^4 s_i
HHI = \sum_{i=1}^n s_i^2
HHI is more informative than $CR_4$ because it accounts for inequality of market shares. The U.S. Department of Justice (DOJ) uses the following thresholds for merger evaluation: HHI < 1500 = unconcentrated, 1500-2500 = moderately concentrated, >2500 = highly concentrated. Mergers that raise HHI by more than 100 points in highly concentrated markets are usually challenged.
Exam tip: Always use whole number percentages (not decimals) for market shares when calculating HHI for AP questions. If you use decimals (e.g., 0.4 instead of 40), your answer will be 10,000 times too small, and you will lose points.
3. Antitrust Policy and Merger Evaluation ★★★☆☆ ⏱ 4 min
Antitrust policy refers to laws and regulatory actions designed to break up harmful existing monopolies, block anti-competitive mergers, and prohibit collusive or predatory business practices that reduce competition.
- **Collusion**: Explicit or implicit agreements between competing firms to fix prices, limit output, or divide markets, which act like a joint monopoly and create large DWL.
- **Predatory pricing**: Setting prices below average variable cost with the explicit goal of driving competitors out of the market, so the firm can raise prices to monopoly levels once competition is eliminated.
When evaluating mergers, regulators balance the potential loss of consumer surplus from higher market power against potential efficiency gains from lower average costs (from economies of scale or synergies between merging firms). If the expected DWL from higher prices exceeds the efficiency gains, regulators block the merger; if efficiency gains are larger, they approve.
Exam tip: Always calculate total efficiency gains on all output produced by the merged firm, not just the change in output. A common mistake is only multiplying cost savings by the reduction in output, which understates total gains.
4. Natural Monopoly Regulation ★★★★☆ ⏱ 5 min
Two common price regulation rules are tested on AP Microeconomics:
- **Marginal cost pricing**: Regulators set price equal to marginal cost ($P=MC$), which achieves the allocatively efficient outcome that eliminates DWL. For a natural monopoly, ATC is falling, so $MC < ATC$, meaning the firm will earn negative economic profit and exit unless the government provides a subsidy.
- **Average cost pricing**: Regulators set price equal to average total cost ($P=ATC$), which allows the firm to earn zero economic profit (a normal rate of return) and stay in business. This outcome is not allocatively efficient (has some DWL) but avoids the need for a government subsidy.
Exam tip: On FRQ graph questions, remember that marginal cost pricing for a natural monopoly intersects demand below the ATC curve, resulting in a loss. If you draw the intersection above ATC, you will lose points.
5. Deregulation ★★★☆☆ ⏱ 3 min
Deregulation is the removal or reduction of government rules, price controls, and legal entry barriers in an industry, to allow increased competition and lower prices for consumers. Deregulation is typically pursued when technological change has eliminated the natural monopoly conditions that originally justified regulation.
Deregulation works well when entry barriers are low enough that new firms can enter and compete, leading to lower prices, higher output, and reduced DWL. However, deregulation can lead to worse outcomes if the market remains a natural monopoly after deregulation: unregulated monopoly pricing will create higher DWL than regulated average cost pricing.
Exam tip: Deregulation is not always the correct policy; always check whether the market still has natural monopoly characteristics. If it does, unregulated market power will lead to higher DWL than regulation.
Common Pitfalls
Why: Students confuse decimal and percentage scaling, which is standard for regulatory HHI calculations on the AP exam.
Why: Students associate concentration with bad outcomes and incorrectly generalize this to all cases.
Why: Students confuse regulation of a regular monopoly with a natural monopoly, where ATC is always falling over the relevant output range.
Why: Students generalize antitrust rules for unregulated monopolies to all monopolies, regardless of cost structure.
Why: Students confuse concentration ratios with other metrics that use averages.
Why: Students associate low prices from large firms with predatory behavior, but competitive firms cut prices to reflect lower costs.