A system and method are provided for trading multiple tradeable objects. One example method includes displaying at least one combined quantity indicator representing a combined quantity associated with at least two tradeable objects, detecting an input associated with an order for a predetermined order quantity in relation to one of the combined quantity indicators, and allocating the order quantity between the at least two tradeable objects using at least one quantity allocation rule. In one example embodiment, a plurality of quantity allocation rules can be user-configurable, and different rules can be defined and applied in relation to different order types.