seems like automated trading algo's have learned to spot short interest or just large and/or many sell orders tick by tick and will, after a bit of market drop, buy purely on the offset or squeeze factor...almost a reversion to the mean based on squeezing sellers (selling as a profi trade rather than selling existing holdings)....and its strictly based on the fact that the market it pure shit and its fairly logical for a trader to sell right now...trading desks sell and then very large, Fed zero interest funded algo funds buy (and buy large) basically to squeeze any and all selling that has been done. This is done as an on-going algo strategy.