We investigate the impact of institutional ownership and ownership concentration on firm stock return performance using panel data model. Our main ownership measures include; percentage of institutional ownership held by different institutions in a firm and percentage of a firm’s outstanding stocks held by the largest three block holders. We find that there is no significant relationship between either institutional ownership or ownership concentration and both ex post and ex ante return. Also, we find that there is negative and significant relationship between institutional ownership represented by some institutions and ex post risk, while the relationship is negative and significant only between institutional ownership by employee associations and ex ante risk. Ownership concentration has no effect on ex post risk but it has a positive and significant effect on ex ante risk. The results are consistent with some past studies from the literature
