There are a number of reasons why n-firm concentration ratios are important. First, they can be used to identify industries that are potentially anti-competitive. If a small number of firms have a large share of the market, they may be able to collude to fix prices or reduce output, which would harm consumers. Second, n-firm concentration ratios can be used to track changes in the level of competition in an industry. If the n-firm concentration ratio is increasing, it suggests that the industry is becoming more concentrated and potentially less competitive.

There are a number of real-world examples of industries with high n-firm concentration ratios. One example is the pharmaceutical industry. The top four firms in the pharmaceutical industry account for over 50% of the global market. This high level of concentration raises concerns about the potential for anti-competitive behavior, such as price-fixing.

Another example is the oil and gas industry. The top four firms in the oil and gas industry account for over 40% of the global market. This high level of concentration also raises concerns about the potential for anti-competitive behaviour.