A "stop order" is an order to sell or buy securities at the market when a certain price (the "stop price") is reached. The term means the same as "stop-loss order". Usually, such orders are made by an investor in order to limit the investor's loss if the stock price starts to fall. For example, if an investor buys IBM stock at $90 per share, the investor might enter a stop order with its broker to sell the shares if the price of IBM shares drops to $80 per share.