An order to fill a transaction at the most desirable price available, and as quickly as possible. At-best transactions can either be applied to equities or currencies where the trader would attempt to get the best possible price or rate respectively. 

|||This type of order is generally executed faster than a conditional order, such as a limit order. Because the ultimate price a trader receives for a share is subject to the current market price, the trader may wind up paying more (for a buy order) or receiving less (for a sell order) than expected.