When you short sell, your losses can be infinite. A short sale loses when the stock price rises and a stock is (theoretically, at least) not limited in how high it can go. For example, if you short 100 shares at $65 each hoping to make a profit but the shares increase to $90 apiece, you end up losing $2,500. On the other hand, a stock can't go below 0, so your upside is limited. Bottom line: you can lose more than you initially invest, but the best you can earn is a 100% gain if a company goes out of business and the stock loses its entire value.