The percentage of an industry or market's total sales that is earned by a particular company over a specified time period. Market share is calculated by taking the company's sales over the period and dividing it by the total sales of the industry over the same period. This metric is used to give a general idea of the size of a company to its market and its competitors. Taobiz explains Market Share Investors look at market share increases and decreases carefully because they can be a sign of the relative competitiveness of the company's products or services. As the total market for a product or service grows, a company that is maintaining its market share is growing revenues at the same rate as the total market. A company that is growing its market share will be growing its revenues faster than its competitors. Market share increases can allow a company to achieve greater scale in its operations and improve profitability. Companies are always looking to expand their share of the market, in addition to trying to grow the size of the total market by appealing to larger demographics, lowering prices, or through advertising. This calculation is sometimes done over specific countries such as Canada market share or US market share. Investors can obtain market share data from various independent sources (such as trade groups and regulatory bodies), and often from the company itself, although some industries are harder to measure with accuracy than others.