The Effect of Management Design on the Portfolio Concentration and Performance of Mutual Funds

We show that the performance of actively managed equity mutual funds increases when portfolios are concentrated in the top one or two stocks within each industry sector. Funds managed by a single manager have much more concentrated portfolios, tend to perform better, and have higher expense ratios than funds managed by multiple managers. We observe that when a fund’s management design is changed from single manager to multiple managers, the portfolio’s within- and cross-sector concentration, performance, and expense ratios decrease.