Good Oil Conference Presentation on website, page-84

Someone once said "who would sell now" - I think it was Aqua. The answer to that is the 3 day trader.

These traders try to keep their trades within a 3 day window as they don't have a lot of money to invest and use the 3 day grace period before they pay up. Say they buy 200,000 shares at 7.1 and put in a sell at 7.4 - if they sell they make $540 approx after broker costs. But, if the 3 days is almost up they will adjust their sell price e.g 7.2 will get them $ 140, 7.1 and they are up for just the broker costs, anything lower and they have to start digging deeper into their pockets but they dont have to have the full funds to invest.

This could also explain a constant turn over in the stock.