 Market share is the percentage of a market (defined in terms of either units or revenue) accounted for by a specific entity..In a survey of nearly 200 senior marketing managers, 67% responded that they found the dollar market share metric very useful, while 61% found unit market share very useful.ncreasing market share is one of the most important objectives of business. The main advantage of using market share as a measure of business performance is that it is less dependent upon macroenvironmental variables such as the state of the economy or changes in tax policy.