Reminds me of a story where one of the major investment banks figured out (with some pretty advanced statistical models) that certain buyers of stocks set bought in certain intervals to avoid getting pushed up into a higher price. For example, say Sun Life was to buy 100k stocks of Microsoft stock. Rather than buying all 100k at once for a price of 23.45 - 23.60 per stock they would split it up into 5 orders of 20k stock that would execute on the 11th minute of the hour. The investment bank would see what was going on, based on Sun's past actions, and would temporarily long MSFT stock for 60 seconds before the order went through and make a tiny bit of profit.