They banned short term trading in 2008 after the banking crisis, any city man worth his salt was making 60% profit everyday. Also there are shares you can buy at todays rate, that you pay for on a fixed date in the futher, in the weeks leading upto 9/11 there was an huge increase in the trading of united airlines and american airlines shares on the chicargo stock exchange. On the fixed date if the value of the shares have dropped you make the difference if they go up then you pay the difference. This is why you see fellas jumping out of windows in the city, they never had the money to pay for the shares, so its out the window or into jail