When a stock is "shorted", it means someone is gambling that the stock is going to drop in price in the near future. They're essentially "borrowing" the stock and selling it for a profit, and then if the stock does drop, they're able to buy it at the lower price for less than they sold it for, and use that cheaper stock to "return" what they borrowed. However, in the case of GameStop, the hedge fund morons short sold 140% of the available stocks on the market. The people at wallstreetbets aren't stupid, and started buying up as much GameStop stock as they could and refused to sell. This drives the price of the stock up, and eventually the short seller is going to have to replace those stocks at whatever price the market is at. This is called a "short squeeze". Shorting a stock anywhere near it's total number of shares is foolish. Going over 100% is suicidal. If a single owner had control of every share, he could set whatever price he wanted, and the short sellers would be forced to pay it. This is essentially what the wallstreetbets players are trying to do right now. They are all insisting on holding the stock until it breaks $500 a share.