A stop-loss order is an order placed with a broker to buy or sell a specific stock once the stock reaches a certain price. A stop-loss is designed to limit an investor’s loss on a security position. For example, setting a stop-loss order for 10% below the price at which you bought the stock will limit your loss to 10%. Suppose you just purchased Microsoft (MSFT) at $20 per share. Right after buying the stock, you enter a stop-loss order for $18. If the stock falls below $18, your shares will then be sold at the prevailing market price.
Stop-limit orders are similar to stop-loss orders. However, as their name states, there is a limit on the price at which they will execute. There are then two prices specified in a stop-limit order: the stop price, which will convert the order to a sell order, and the limit price. Instead of the order becoming a market order to sell, the sell order becomes a limit order that will only execute at the limit price (or better).