The practice of selling securities not owned by the seller. The seller will make a profit if the price of the securities falls between the date of the bargain and the delivery date so that, for the purposes of delivering the securities to the buyer, the seller can buy them at a lower price than it sold them for. At the time of the short sale, the seller may have borrowed, or agreed to borrow, the securities or it may not hold them at all (referred to as a naked short).