Right now the stock is being shorted which means they are BORROWING shares assuming that the price is going down. They are then pushing the price down through small sells at the bid. This creates a SELLING bubble that makes it appear as if there is a great deal of SELLING PRESSURE and pushes the stock price down. The goal is to drop the price significantly because shorters make money like we do but they make it from the price going down. Once the price hits a level they are happy with they then have to BUY these shares back. Once they buy them back that is called covering and it forces the price of the stock back up. Normally the shorting is done over a period of time and the covering is done over a small period of time. Because of this, the covering can typically move the price higher in a short period of time than the shorting ever dropped it. The shorter relies on people getting out of the stock because they are frustrated with the low price. That's how they accumulate shares. If nobody sells they will either keep dropping the price to test the pain threshold of the longer term investors or they will start buying at the ask in order to get the shares. At which point the stock price rises. They make their money on the short. Now they are ready to make money on the rise.
Shorters make money two times over... we make it once. However shorters have no limit to how much they lose because if the price runs from .0001 to $1 they are going to eventually be forced to cover and will have to pay that high price. Lots of risk!