In: Finance
Assume you manage a risky portfolio with an expected rate of return of 12% and a standard deviation of 21%. The T-bill rate is 3%. Your client decides to invest in your risky portfolio a proportion (y) of her total investment budget so that her overall portfolio will have an expected rate of return of 8%. What is the standard deviation of the rate of return on your client's portfolio? Convert your answer to percentages with two decimal points
Proportion invested in risky portfolio = y
Proportion invested in T bill = (1-y)
Expected rate of return for risky portfolio = 12% = 0.12
Return on T bill = 3% = 0.03
Expected rate of return on overall portfolio = 8% = 0.08
So
(Proportion invested in risky portfolio * Expected rate of return for risky portfolio) + (Proportion invested in T bill * Return on T bill) = Expected rate of return on overall portfolio
Putting the values
(y * 0.12) + ((1-y) * 0.03) = 0.08
y = 5/7
So, Proportion invested in risky portfolio = 5/7
Standard Deviation of T bill = 0
Standard Deviation of risky portfolio = 28% = 0.28
The standard deviation of the rate of return on your client's portfolio = Proportion invested in risky portfolio * Standard Deviation of risky portfolio
= 5/7 * 0.28
= 0.20 = 20.00%