ABSTRACTThis paper analyzes the impact of mergers on the alphas and betas of actual merged firms compared to those of the homemade mergers an investor could have created by buying proportional shares of the two firms. The results provide some evidence of merger synergy. Where alpha and beta shifts were observed, the evidence did not indicate that either the relative size of target firms or concurrent capital structure changes were related to these shifts as current theory suggests. There is weak evidence that nonconglomerate mergers were more frequently synergistic.