Stop-loss order (SL and SL-M)

A stop-loss order waits at the exchange until the price reaches a trigger, then becomes a live order to exit. An SL order becomes a limit order at a price you set. An SL-M order becomes a market order and fills at whatever price is available. Regular stop-loss orders expire at the end of the day.

An SL order protects you from a bad fill but may not fill at all if the price falls straight through its limit. An SL-M order always fills in a normal market but can fill well below the trigger. Not every broker offers SL-M on every segment.

If the stock opens below your trigger after a gap down, either order fills at or near the open, below where you planned.