Using the data in Example 5.6, find the weights in a portfolio with expected return μ_V = 46\% and compute the risk \sigma ^{2}_{V} of this portfolio.
Using the data in Example 5.6, find the weights in a portfolio with expected return μ_V = 46\% and compute the risk \sigma ^{2}_{V} of this portfolio.
First, we find compute μ_1 = 4\% and μ_2 = 16\% from the data in Example 5.6. Next, (5.7) and (5.1)
μ_V = w_1μ_1 + w_2μ_2, (5.7)
w_1 + w_2 =\frac{x_1S_1(0)+x_2S_2(0)}{V(0)} =\frac{V(0)}{V(0)}=1 (5.1)
give the system of equations
4w_1 + 14w_2 = 46,
w_1 + w_2 = 1,
for the weights w_1 and w_2. The solution is w_1= −3.2 and w_2 = 4.2. Finally, we use (5.7) with the values \sigma^{2}_{1} \cong 0.0184, \sigma^{2}_{2} \cong 0.0024 and ρ_{12}\cong −0.96309 computed in Example 5.6 to find the risk of the portfolio:
\sigma^{2}_{V} \cong (−3.2)^2 × 0.0184 + (4.2)^2 × 0.0024+2 × (−3.2) × 4.2 × (−0.96309) ×\sqrt{0.0184}\times \sqrt{0.0024}
\cong 0.40278.