Financial instruments may be electronically traded according to any of three modes, including single instrument mode, correlated mode, and aggregated mode. One of more market depth representations showing current market price levels, Bids and Asks of the financial instrument(s) to be traded are displayed on a GUI window. The user mouses parallel to the market depth representation to a price level at which the user wishes to initiate a trade, and the moused-over price level is selected. All trade order parameters are pre-constructed either prior to selecting or upon selecting of a price level. The user then clicks a mouse button or initiates some other action of a user input device to place one or more orders.