If there is a group of traders, let's say controlling about 50+ mil shares in total, using SBSH, ETRD, NITE, AUTO, this group could totally control the pps until there is buying pressure and a 100+ mil volume day.
They sell into the bids of there group and grab the shares of those who panic. Then they lower B/A and start again.
The day, SBSH disappeared as seller, AUTO came up, followed by NITE, but always ETRD on or near the top of the left side of the box.
edit: After a while they let the stock breathe and play the game again