No, you don't understand ran. I will try to help. You borrowed a $7 marble from your neighbor for a nominal fee with a promise to replace the borrowed marble at a later date and then you sold that marble immediately for market price. Now you are "short" because you have to replace the marble that you sold per your obligation. You want the price of marbles to go down because that is your profit minus the fees and capital gains taxes if you cash out of market.
Your bought rent on a marble and sold that rent contract for $7 and when you had to buy back for $5, you put $2 in your pocket and cancelled your obligation.
But what happens if it works the other way? What happens if you buy at $7 and sell the marble but then marble price goes above $7? Now you are you are losing money and you need to cover your obligation and that forces you to buy AND BUY FAST. That is called a cover buy and it drives up the price of a stock regardless of underlying value. Look at the volume on SHLD today. That was like 20x. Good traders see that sort of thing and they will front run it which is what happened today.
That trade was overloaded short. SHLD is still doomed. It is just that good traders took advantage of it and I am sure Eddie and Bruce through their various capital management operations. 30% is a massive market move for any stock.
My advice to anyone is look at the open interest option. SHLD was loaded short 70%. The Crock Market is a game much like a casino.
Is anyone really telling me that FaceBook has any actual underlying value? Twitter is worse. Uber is completely worthless. They will need attorneys. Uber is great short option.