Problem: Consider a Treasury Bill with a rate of return of 5% and the following portfolios, which have been created by 2 stocks, S1 and S2:
Portfolio A: The weight for S1 and S2 = 0.2 and 0.8; Expected return = 0.15; Standard Dev.= 0.24
Portfolio B: The weight for S1 and S2 = 0.4 and 0.6; Expected return = 0.18; Standard Dev.= 0.31
Portfolio C: The weight for S1 and S2 = 0.5 and 0.5; Expected return = 0.19; Standard Dev.= 0.35
Portfolio D: The weight for S1 and S2 = 0.9 and 0.1; Expected return = 0.24; Standard Dev.= 0.45
You are informed that one of these portfolios is "optimal risky portfolio". Which of these portfolios should be optimal risky portfolio? Explain Why?