They take a small ask block and string it out to force the pps down. Then they take their buy orders and keep moving their bids lower and when they finally buy they tell their clients they executed their trade at the original ask and pocket the difference. The only thing that stops them is when the pps gets too low and stimulates increased buying at market price. If we were listed this would be harder for them to do because of execution time limits. If GP's large sell block last week would have went through at market we would be below $1 now, I guarantee it!