This paper studies empirically the effect of ownership concentration on the risk and performance of commercial banks, controlling for shareholders protection laws, bank regulations, and other country and bank specific traits. The sample used comprises 795 banks of 47 countries, in the period from 1997 to 2007. Our main finding is the existence of a cubic relationship between ownership concentration and bank performance. Such evidence is supportive of theoretical hypotheses of effective monitoring at low levels of ownership concentration, expropriation or losses connected to managerial discretion at moderate ownership concentration, and high costs of expropriation at high levels of ownership concentration. We also find that ownership concentration is more important to increase the performance of banks with low concentrated ownership structures, when legal protection of shareholders is low, and that capital regulations stringency is effective in simultaneously reducing risk and improving performance of banks. Regarding bank risk, we find a U-shape relationship between ownership concentration and earnings volatility, supporting that shareholder’s incentive to take risk prevails when her equity stake is above a threshold.