Well, it can only be true if security selection and market timing detract from institutional returns or individual returns in the aggregate.

唯一的可能性就是证券选择,和市场时机选择,给机构和个人带来的是负的回报

耶鲁公开课 - 金融市场课程节选

Because we hold relatively stable, relatively well-diversified portfolios, security selection turns out not to be an important determinant of returns for most investors and market timing turns out not to be an important determinant of returns.

因为持有相对稳定,和相对分散的投资组合,证券选择不再是,决定投资者回报率的重要因素,而市场时机选择,也不会成为决定回报率的重要因素

耶鲁公开课 - 金融市场课程节选