Central banks often use certain concentration indices in their official reports to determine the degree of intensity of competition, of which the most common are the concentration ratio and the Herfindahl-Hirschman index. It is important to emphasize that when calculating the value of these...

A rapidly growing literature has shown that market concentration among domestic firms has increased in the United States over the last three decades. Using confidential census data for the manufacturing sector, we show that typical measures of concentration, once adjusted for sales by foreign...