A sell-stop order, also known as a stop-loss order, is designed to stop a loss. If you hold a stock that is going down in price, you might place an order to sell the stock if it hits a certain price. Therefore, a sell-stop is placed at a price below the stock's current market price.

For example, if the stock is trading at BP 50, you might place a sell-stop order at BP 46.50. This order will not be executed until the stock trades at BP 46.50 or lower. Again, as soon as this happens, your broker will immediately execute the order for you at the current market price.