阿同学2019-05-14 23:02:03

The market portfolio (M) contains the optimal allocation of only risky assets and no risky assets. Let the S1 be the Sharpe ratio of this market portfolio. There exists a risk-free asset. Initially, an investor is fully (100%) invested in M with a portfolio Sharpe ratio of S1. Subsequently, the investor borrows 30% at the risk-free rate, such that she is 130% invested in the market portfolio (M) where this leverage portfolio has a Sharpe ratio of S2. After the leverage (i.e., borrowing at the risk-free rate to invest 30% in M, is the investor still on the efficient frontier and how do the Sharpe ratios? A No (no longer efficient), and S2 < S1. B No, but S2 = S1. C Yes(still efficient), but S2 < S1. D Yes, and S2 = S1. 为什么改变后还在有效前沿上啊