In finance, being short in an asset means investing in such a way that the investor will profit if the market value of the asset falls. This is the opposite of the more common long position, where the investor will profit if the market value of the asset rises. An investor that sells an asset short is, as to that asset, a short seller.
There are a number of ways of achieving a short position. The most fundamental is physical selling short or short-selling, by which the short seller borrows an asset (typically a fungible security such as a share or a bond) and sells it. The short seller must later buy the same amount of the asset to return it to the lender. If the market price of the asset has fallen in the meantime, the short seller will have made a profit equal to the difference in price. Conversely, if the price has risen then the short seller will bear a loss. The short seller usually must pay a borrowing fee to borrow the asset (charged at a particular rate over time, similar to an interest payment) and reimburse the lender for any cash return (such as a dividend or interest) that would have been paid on the asset while borrowed.