Exactly. It's slightly more complicated since you pay to borrow the shares, but that's exactly it in concept. It's risky as there are theoretically unlimited lo

Exactly. It's slightly more complicated since you pay to borrow the shares, but that's exactly it in concept. It's risky as there are theoretically unlimited losses (shares can keep going up, but they can only fall to $0). Another common, but less risky way to be short is through put options. You buy the right to sell shares at a given price. If you had a put for less $18 you have now lost all your money. Safe to say there will be a lot of money made and a lot of money lost tomorrow when options start trading.