Editing Concentration ratio (section)

{{Short description|Mathematical ratios used to quantify concentration of market shares in industries}}
{{for|the chemistry and biology concept|Dilution ratio}}
{{Use dmy dates|date=November 2014}}

In [[economics]], '''concentration ratios''' are used to quantify [[market concentration]] and are based on companies' [[market share]]s in a given industry. 

A concentration ratio (CR) is the sum of the percentage market shares of (a pre-specified number of) the largest firms in an industry. An ''n''-firm concentration ratio is a common measure of market structure and shows the combined market share of the ''n'' largest firms in the market. For example, if ''n'' = 5, ''CR''<sub>5</sub> defines the combined market share of the five largest firms in an industry.  

{{citation needed span|date=June 2023|text=Competition economists and competition authorities typically employ concentration ratios (CR<sub>''n''</sub>) and the [[Herfindahl-Hirschman Index]] (HHI) as measures of market concentration.}}