A stop order is an order to buy or sell a security such that when the security trades at its designated stop price it becomes a market order to be executed at the best price available. Because the stop order is a market order, there are trading situations where the stop order could be executed at a price that is significantly higher or lower than the stop price.

Stop orders are not permitted on Canadian, OTC Bulletin Board or OTC Pink Marketplaces. Stop orders are often used to limit loss or lock in gains on profitable long or short positions.