™A sell stop triggered at $47 can become a market instruction and fill below $47 after a gap; the trigger is not a guaranteed execution price.
Orders & Market Structure
Stop order
An order that becomes a market order after a specified stop price is reached; execution price is not guaranteed.
Plain-English context
Put the definition to work.
A stop triggers a market order under the relevant rules; it does not guarantee that the sale occurs at the trigger.
Further reading and verification. Examples are hypothetical, not current quotes or recommendations. Product terms, tax treatment and market rules can change. FINRA — order types and execution