Stocks are partitioned in various ways. One common way is by the country where the company is domiciled. For example, Nestle, Roche, and Novartis are domiciled in Switzerland, so they are part of the Swiss stock market.

The size of the world stock market was estimated at about $36.6 trillion at the beginning of October 2008. The total world derivatives market has been estimated at about $791 trillion face or nominal value, 11 times the size of the entire world economy. The value of the derivatives market, because it is stated in terms of notional values, cannot be directly compared to a stock or a fixed income security, which traditionally refers to an actual value. Moreover, the vast majority of derivatives 'cancel' each other out (i.e., a derivative 'bet' on an event occurring is offset by a comparable derivative 'bet' on the event not occurring). Many such relatively illiquid securities are valued as marked to model, rather than an actual market price.

The stocks are listed and traded on stock exchanges which are entities of a corporation or mutual organization specialized in the business of bringing buyers and sellers of the organizations to a listing of stocks and securities together. Basically the stock market is an exchange place or a market that facilitates the trading of stocks. People participating in the stock markets range from some casual traders and investors who trade as a hobby, to large fund traders.

Generally considered major stock exchanges are the Amsterdam Stock Exchange, London Stock Exchange, New York Stock Exchange, Paris Bourse, and the Deutsche Börse (Frankfurt Stock Exchange) and Toronto Stock Exchange. In Africa, examples include Nigerian Stock Exchange, JSE Limited, etc. Asian examples include the Philippine Stock Exchange, the Singapore Exchange, the Tokyo Stock Exchange, the Hong Kong Stock Exchange, the Shanghai Stock Exchange, and the Bombay Stock Exchange. In Latin America, there are such exchanges as the BM&F Bovespa and the BMV. Australia has a national stock exchange, the Australian Securities Exchange, due to the size of its population. The stock exchange is based in Sydney.

Market participants include individual retail investors, institutional investors such as mutual funds, banks, insurance companies and hedge funds, and also publicly traded corporations trading in their own shares. Some studies have suggested that institutional investors and corporations trading in their own shares generally receive higher risk-adjusted returns than retail investors.