The volatility of the stock market requires no introduction. It has long been acknowledged that the volatility is as much a reflection of non-economic factors as economic ones. An understanding of trends, based on both economic and non-economic factors, and the time that investors take to react to changes in the stock market can be the crucial difference between gains and losses in the stock market.
It is common for investors to buy stocks of companies in which they perceive the prize to go up, in small tranches, in order to ensure that the price does not go up at once, which would occur if investors purchased large blocks of shares at once. In order for this to work effectively and fairly, all investors have to be presented with the ability to place purchase or sell orders at prices that are uniformly communicated to all investors at one single point in time. Until 1998 this proposition was fairly routine since buyers and sellers traded on the floor of the stock exchanges.