2017年asset allocation真题这个解释不太懂。
Although a simple comparison of the sharpe ratio seems to imply that adding emerging market equity would reduce RFCFs sharpe ratio, the addition of an asset class is beneficial if the new asset class s sharpe ratio is greater than the current portfolio s sharpe ratio multiplied by the correlation between the two.
为什么会这样，哪里讲过这个吗？
