A filtering/stacking process that maximizes cancellation (according to certain mathematical criteria) of one type of event (a multiple in the case of horizontal stacking, a ghost in the case of uphole stacking), regardless of frequency content and at the same time reinforces another type of event (the primary). Application requires precise knowledge as to the time differences between the events on the records to be stacked (i.e., precise differential normal-moveout information for multiple cancellation, precise uphole data for ghost cancellation). For optimum wideband horizontal stacking, see Schneider et al. (1965). For optimum wideband uphole stacking, see Schneider et al. (1964).