The theory of mutual funds is: nobody is supposed to be holding anything other than-- ... the ideal theory of mutual funds--is holding something other than this tangency portfolio.

共同基金定理是指：,所有人都应该持有-,理想的共同基金定理说,都应该持有这种切线投资组合。

耶鲁公开课 - 金融市场课程节选

That's the theory of efficient portfolio calculation.

这就是最优投资组合理论。

耶鲁公开课 - 金融市场课程节选

Now, underlying our theory is the idea that we measure the outcome of your investment in your portfolio by the mean of the return on the portfolio and the variance of the return on the portfolio.

而理论的基础是,我们通过计算,组合收益率的均值，和组合收益率的方差,来衡量一个投资组合的优劣。

耶鲁公开课 - 金融市场课程节选