Sell stop order
A sell stop order (sell stop market) waits below the current price and, when price trades at its trigger, becomes a market sell.
Price 100, sell stop at 97: when price trades at 97 it sells at 97 or worse, more in a fast fall. It is the usual stop loss for a long, and can also enter a short on a break down. The opposite is a buy stop order.
Learn more: types of orders.