A sell order is an order instructing a broker or trading venue to sell a specified quantity of a share, bond, currency, derivative or other instrument. It is the counterpart of a buy order. A sell market order executes immediately against the highest bids available, while a sell limit order sets the lowest price the seller will accept and waits on the ask side of the order book until a buyer meets it. A sell stop order becomes active only if the price falls to a trigger level and is the usual form of a stop-loss order.
A sell order may close an existing holding or open a new position. Selling an instrument the seller does not own is short selling, which requires borrowing the instrument and in many markets must be flagged as a short sale when the order is entered.