a stop order is an order that becomes a market order only when a specified price is reached. it can be used to write a new position or to exit an existing position. a buy-stop order as the name suggests is an instruction to buy foreign exchange at the market price once the market reaches your specified price or maximum, which is higher than the current market price. a sell-stop order is an instruction to sell the currency at the market price once the market reaches your specified price or minimum, which is below the current market price.