问题如下图：
选项：
A. 
B. 
C. 
解释：
为什么the variance of the total portfolio is 25%而不是100%？ 一共4个asset，单个asset应该是25%对吗？
NO.PZ2018011501000007 老师，根据Cov(Ri,Rp)=Cov(Ri,w1*R1+w2*R2+······+wi*Ri)=w1*Cov(Ri,R1)+w2*Cov(Ri,R2)+······+wi*σi^2,如果Cov(Ri,R1)，Cov(Ri,R2)......最小，且σi^2最小能够得出Cov(Ri,Rp)，但是这道题目中仅说了“The expectereturn of the mestic bonasset class is the lowest of the asset classes, anthe returns of the mestic bonasset class have the lowest covarianwith other asset class returns.“也就是说假设mestic bon第i个资产，那么题干说E(Ri)最小，且Cov(Ri,R1)，Cov(Ri,R2)......最小，并没有提到σi^2方差最小，这样严格意义上来说，会影响结论么？
equto 25%. greater th25%. C is correct. A risk parity asset allocation is baseon the notion theaasset class shoulcontribute equally to the totrisk of the portfolio. Bon have the lowest risk level anmust contribute 25% of the portfolio’s totrisk, so bon must overweighte(greater th25%). The equcontribution of eaasset class is calculateas: wi* Cov(ri,rp)= 1nσp2\frac1n\sigma_p^2n1σp2 where wi = weight of asset i Cov(ri,rp) = covarianof asset i with the portfolio n = number of assets σ2= varianof the portfolio In this example, there are four asset classes, anthe varianof the totportfolio is assumeto 25%; therefore, using a risk parity approach, the allocation to eaasset class is expecteto contribute (1/4 × 25%) = 6.25% of the totvariance. Because bon have the lowest covariance, they must have a higher relative weight to achieve the same contribution to risk the other asset classes.组合的方差是25%?这个怎么来的呢
请问关于risk parity什么时候用广义的risk parity公式，什么时候用狭义的公式？
请问风险平价公式最终目的不是求权重吗，可是公式里边用的是组合整体的方便，既然不知道权重，那这个组合收益和方差是怎么得到的呢？题如下图
