Q. Where can I locate the concentration ratio and Herfindahl-Hirschman Index (HHI) for an industry?

Economic Census: Concentration Ratios (1992+) "classify industries by the percent of output accounted for by the largest 4, 8, 20 and 50 companies."

The Herfindahl-Hirschman Index (HHI) is calculated for the 50 largest companies (manufacturing industries only).

More information is available on the Concentration Ratios page of the Business & Economics -- Government Resources guide.