请教老师一个关于semivariance和variance的问题 attractive, 老师您好, assets, cannot

EricFang

老师您好，

您能帮忙解释一下Note中关于semivariance的如下描述吗？

Even though semivariance has the appealing intuition of measuring downside risk, mathematically it does not have the attractive properties that variance does (e.g., we cannot sum semivariance for a portfolio of assets).

非常感谢。