A concentration matrix is a tool used to analyze the degree of concentration within a market or industry. It is typically used to identify the dominant players in the market and assess the level of competition.

One example of a concentration matrix is the Herfindahl-Hirschman Index (HHI), which is commonly used in antitrust cases to determine the level of concentration in a market. The HHI is calculated by adding the squared market share of each firm in the market, with a higher HHI indicating a higher level of concentration. For example, if a market consists of four firms with market shares of 25%, 25%, 25%, and 25%, the HHI would be 2,000, indicating a high level of concentration.

Another example of a concentration matrix is the Five Forces model, developed by Michael Porter. This model evaluates the level of competition in an industry by examining the intensity of rivalry among existing firms, the threat of new entrants, the bargaining power of suppliers and buyers, and the threat of substitute products or services. The Five Forces model can be used to assess the level of concentration in an industry, as well as the potential for new entrants and the bargaining power of different players in the market.

Overall, concentration matrices are useful tools for analyzing the competitive landscape of a market or industry. By identifying the dominant players and assessing the level of competition, firms can make informed decisions about their strategic positioning and potential for growth.