Active Share and the Three Pillars of Active Management: Skill, Conviction, and Opportunity
提出主动份额的新公式，强调其仅受与基准重叠持仓的影响，并说明如何根据主动份额调整费用比率，结论是主动份额对主动管理基金绩效重要，投资者不应为低主动份额基金支付过高费用。
This article relates Active Share to the fund manager’s individual stock-picking skill, conviction, and opportunity. I propose a new formula for Active Share that emphasizes that a fund’s Active Share is reduced only through overlapping holdings with its benchmark. I show why and how to adjust the expense ratio for the level of Active Share and the cost of investing in the benchmark. I conclude that Active Share matters for the performance of actively managed funds. Investors should not pay (too) much for low–Active Share funds, which generally underperform. But there is no evidence that high–Active Share funds as a group have underperformed, and patient managers with high Active Share have been quite successful.