The Effect of Management Design on the Portfolio Concentration and Performance of Mutual Funds
研究发现，主动管理型股票基金若将投资集中于每个行业板块的前一两只股票，其绩效会提升。单人管理的基金比多人管理的基金组合更集中、绩效更好、费用率更高；当管理设计从单人转为多人时，集中度、绩效和费用率均下降。
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.