In a little more detail: A 'stop loss' order will sell once the share price falls below a threshold. It will sell using a market order, meaning whatever the c

In a little more detail: A 'stop loss' order will sell once the share price falls below a threshold. It will sell using a market order, meaning whatever the current best price might be. A 'stop limit' order will sell once the share prices falls below a threshold too, but will sell using a limit order, setting a minimum price that you're prepared to be paid. In a crashing market, stop loss orders can result in you selling stocks for pennies, regardless of their rational worth. Stop limit orders protect you from excessive price drops.