I wonder if this HFT/flashorder thing going was used to buy equity cheap from retirees who sold on the bottom by manipulating stocks lower.
Or it could be a coincidence. Most people usually expect a drop in September, and right on cue, the manipulators dropped it in the first couple of days to get people nice and short. Then they ran it up. The market will do whatever it takes to screw the most people that it can. The fact that HFT stopped around the same time could be just a coincidence.