Legally, the determination is often more complex. The higher the concentration ratio, the greater the market power of the leading firms. One commonly used concentration ratio is the four-firm concentration ratio, which consists of the combined market share of the four largest firms, as a percentage, in the total industry. The concentration ratio of an industry is used as an indicator of the relative size of leading firms in relation to the industry as a whole. There could be only two firms in a duopolistic market, each with 50% share or there could be three firms in the industry each with 33% share or 100 firms each with 1% share. Market shares within an industry might not exhibit a declining scale. A market share of less than 35%, held by one brand, product or service, is not an indicator of strength or dominance and will not raise anti-competitive concerns by government regulators.A market share of over 35% but less than 60%, held by one brand, product or service, is an indicator of market strength but not necessarily dominance.A company, brand, product, or service that has a combined market share exceeding 60% most probably has market power and market dominance.Although there are no hard and fast rules governing the relationship between market share and market dominance, the following are general criteria : Market share is not a perfect proxy of market dominance. A declining scale of market shares is common in most industries: that is, if the industry leader has say 50% share, the next largest might have 25% share, the next 12% share, the next 6% share, and all remaining firms combined might have 7% share. This is the percentage of the total market served by a firm or brand. There are several ways of measuring market dominance. In defining market dominance, one must see to what extent a product, brand, or firm controls a product category in a given geographic area. There is often a geographic element to the competitive landscape. Dominant positioning is both a legal concept and an economic concept and the distinction between the two is important when determining whether a firm's market position is dominant. Market dominance is a measure of the strength of a brand, product, service, or firm, relative to competitive offerings, exemplified by controlling a large proportion of the power in a particular market.