I trade futures and options with IB, whenever I trade I check the time and sales off the legs if a combo is traded. Why is it often the case the time and sales don't match the trade prices shown at the time? for the individual legs, and much more often the whole combo time and sales. fortunately most of the time I am the beneficiary by a significant margin. eg other day by up to 40%! but why is there this mismatch?