It means no one is selling any shares for them to buy to cover the short position they took at a higher PPS. If they try to cover it would cause the PPS to climb. This could lead to a short squeeze (a panic buying buy the shorts) if the price started to climb rapidly and stay up. It could cause them to get margin calls or scared perhaps, at least in a normal short type play. I don't know about penny stocks.
News 
Market Data 
Discover 
