That's got the lowest possible standard deviation of expected return and that's 25% stocks and 75% bonds with this sample period.

这个组合预期回报的标准差最小,在这一点上，投资组合,由25%的股票和75%的债券构成。

耶鲁公开课 - 金融市场课程节选

You could always find a portfolio that had a higher expected return for the same standard deviation.

你总是可以找到一个投资组合,具有较高的预期回报,而标准差不变。

耶鲁公开课 - 金融市场课程节选