Herfindahl index for the US

The Herfindahl index (HHI) is a measure of market concentration and is calculated by summing the squares of the market shares of all firms in a particular industry. For the U.S. economy as a whole, the HHI can vary significantly by sector; for example, a highly concentrated market like telecommunications might have a higher HHI compared to a more competitive sector like retail. Generally, an HHI below 1,500 indicates a competitive market, while an index above 2,500 suggests high concentration. The HHI helps regulators assess potential monopolistic behaviors and the competitive landscape of various industries.