Just a point...you can do a sort of stop loss on the short side, call it a 'stop buy' for lack of a better term. 

With a stop loss you set a price and if the PPS drops to that level it triggers the stop and the shares are sold....with a short position a bear can set a price that is above where shares are currently trading, same idea in reverse....if the PPS climbs to that price the shares are bought and the short position is covered.