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

And the third, securities selection, speaks to how it is you manage each of your individual asset classes.

第三,证券选择,说的是如何管理,每个单独的资产类别

耶鲁公开课 - 金融市场课程节选