An interface for trading multiple tradeable objects includes a price axis or scale. A first indication of quantities represented in a market for a first tradeable object is displayed in association with the price axis or scale. A second indication of quantities represented in the market for a second tradeable object is displayed in association with the price axis or scale. The first tradeable object may be different than the second tradeable object. Alternatively, the first tradeable object and the second tradeable object may be the same, but the indications of quantity may be provided from different sources, such as different exchanges.