In finance, short selling or "shorting" is a way to profit from the decline in price of a security, such as stock or a bond. In contrast, investors who "go long" on an investment hope that the price will rise.
To profit from the stock price going down, short sellers can borrow a security and sell it, expecting that it will decrease in value so that they can buy it back at a lower price and keep the difference. The short seller owes his broker, who usually in turn has borrowed the shares from some other investor who is holding his shares long; the broker itself seldom actually purchases the shares to lend to the short seller.
For example, assume that shares in XYZ Company currently sell for $10 per share. A short seller would borrow 100 shares of XYZ Company, and then immediately sell those shares for a total of $1000. If the price of XYZ shares later falls to $8 per share, the short seller would then buy 100 shares back for $800, return the shares to their original owner, and make a $200 profit. This practice has the potential for an unlimited loss. For example, if the shares of XYZ that one borrowed and sold in fact went up to $25, the short seller would have to buy back all the shares at $2500, losing $1500.
However, the term "short selling" or "being short" is often used as a blanket term for all those strategies which allow an investor to gain from the decline in price of a security. Those strategies include buying options known as puts. A put option consists of the right to sell an asset at a given price; thus the owner of the option benefits when the market price of the asset falls. Similarly, a short position in a futures contract, or to be short a futures contract, means the holder of the position has the obligation to sell the underlying asset at a later date.