Final answer:
Judgment by market share is the traditional basis for antitrust violation conclusions when a company controls a large portion of the market, but modern antitrust regulation requires a more detailed and sophisticated analysis.
Step-by-step explanation:
Antitrust law enforcement traditionally relied on measuring market share to determine a firm's control over a market. However, this approach has evolved to include a more detailed analysis of market dynamics and competition strategies. Antitrust regulators now use statistical tools and real-world evidence to estimate demand and supply curves, understand the nature of competition within an industry, and build statistical models to predict the effects of mergers or market dominance on consumer outcomes. The shift from simple market share counts to a nuanced assessment illustrates the complexity of applying antitrust laws. These newer methods still involve a certain degree of subjective judgment, but they are designed to offer a more accurate picture of whether a company's market dominance actually hinders competition or harms consumers.
It's significant to note that a high market share, such as 90 percent, might indicate monopoly power, but it is not automatically a violation of antitrust laws. Regulators must also consider other factors like barriers to entry, the level of competition within the broader market, and the potential benefits or disadvantages to consumers.