Market capitalization (market cap) is the market value at a point in time of the shares outstanding of a publicly traded company, being equal to the share price at that point of time times the number of shares outstanding. As outstanding stock is bought and sold in public markets, capitalization could be used as an indicator of public opinion of a company's net worth and is a determining factor in some forms of .
Market capitalization is used by the investment community in ranking the size of companies, as opposed to sales or total asset figures. It is also used in ranking the relative size of , being a measure of the sum of the market capitalizations of all companies listed on each stock exchange. (See .) In performing such rankings, the market capitalizations are calculated at some significant date, such as 30 June or 31 December.
The total capitalization of or economic regions may be compared to other economic indicators. The total market capitalization of all publicly traded companies in the world was US$51.2 trillion in January 2007 and rose as high as US$57.5 trillion in May 2008 before dropping below US$50 trillion in August 2008 and slightly above US$40 trillion in September 2008. In 2014 and 2015, global market capitalization was US$68 trillion and US$67 trillion, respectively.
Market cap is given by the formula , where MC is the market capitalization, N is the number of shares outstanding, and P is the closing price per share.
For example, if some company has 4 million shares outstanding and the closing price per share is $20, its market cap is then $80 million. If the closing price per share rises to $21, the market cap becomes $84 million. If it drops to $19 per share, the market cap falls to $76 million. This is in contrast to mercantile pricing where purchase price, average price and sale price may differ due to transaction costs.