The difference between earnings actually achieved and those that could have been obtained had circumstances and choices been different (e.g., if there had been fewer costs involved, less fees, little loss of time, etc.). In investment terms, the concept of foregone earnings concentrates on the difference in smaller fees. Over an extended period of time, recurring fees can be a significant drag on the value and growth of an investment instrument. This can also be true of one time fees if these are too large.