If I sell a stock that I don't have, am I required to buy it before a certain amount of time?
I don't actually have any of this stock. Apparently, it's quite common strategy This is called naked short selling. It's not illegal per se, but there can be some major penalties so you should call your broker and ask them these questions. Intentionally naked short selling is not looked upon favorably. They'll probably try to recommend you a safer shorting system by which: