11.9 Problems: Introduction to Portfolio Theory
Exercise 4.4 Annual estimates of the GWN model parameters for
Boeing and Microsoft are given in the table below:
Boeing | Microsoft | |
---|---|---|
\(\mu\) | 0.149 | 0.331 |
\(\sigma^{2}\) | 0.069 | 0.136 |
\(\rho\) | -0.008 | -0.008 |
- Create the following portfolios.
- Combinations of Boeing and Microsoft (with \(x_{\text{{boeing}}}=-1,-0.9,...,2\) and \(x_{\text{{msft}}}=1-x_{\text{{boeing}}}\))
- Combinations of Boeing and T-bills (with \(x_{\text{{boeing}}}=0,0.1,...,2\))
- Combinations of Microsoft and T-bills (with \(x_{\text{{msft}}}=0,0.1,...,2\))
- Use an annual risk-free rate of \(3\%\) per year for the T-bill. For each portfolio, compute \(E(R_{p})\), var\((R_{p})\) and SD\((R_{p})\) using the appropriate formulas. For each portfolio, plot \(E(R_{p})\) vs. SD\((R_{p})\) and put these values on the same graph. Compute the Sharpe’s slope for Boeing and Microsoft. Which asset has the highest slope value?
- Compute the global minimum variance portfolio using the analytical formula (11.10).
- Make a bar chart showing the weights of Boeing and Microsoft in global minimum variance portfolio.
- Compute \(E(R_{p})\), var\((R_{p})\) and SD\((R_{p})\) for the tangency portfolio.
- Compute Sharpe’s slope for the tangency portfolio.
- Indicate the location of the tangency portfolio on the graph you created previously in question 1.
- Using a risk-free rate of \(3\%\) per year for the T-bill, compute the tangency portfolio using the analytic formula (11.16).
- Make a bar chart showing the weights of Boeing and Microsoft in the tangency portfolio.
- Compute \(E(R_{p})\), var\((R_{p})\) and SD\((R_{p})\) for the tangency portfolio.
- Compute the Sharpe’s slope for the tangency portfolio.
- Indicate the location of the tangency portfolio on the graph you created previously in question 1.
- Consider a portfolio that has \(10\%\) in the tangency portfolio and \(90\%\) in T-bills.
- In this portfolio, what is the percent invested in Boeing and what is the percent invested in Microsoft? Give a bar chart showing the percents invested in T-bills, Boeing and Microsoft.
- Compute \(E(R_{p})\), var\((R_{p})\) and SD\((R_{p})\) for this portfolio.
- Compute Sharpe’s slope for this portfolio.
- Indicate the location of the tangency portfolio on the graph you created previously in question 1.
- Find the efficicient portfolio (combination of T-bills and tangency portfolio) that has the same risk (SD) as Microsoft.
- In this portfolio, what is the percent invested in Boeing and what is the percent invested in Microsoft? Give a bar chart showing the percent invested in T-bills, Boeing and Microsoft.
- Compute \(E(R_{p})\), var\((R_{p})\) and SD\((R_{p})\) for this portfolio.
- Compute Sharpe’s slope for this portfolio.
- Indicate the location of the tangency portfolio on the graph you created previoulsy in question 1.
Exercise 4.5 (Real world portfolios revisited)
Re-do the real-world portfolio analysis using forward looking estimates: For each 5-year period use the previous 5-year period to estimate GWN model parameters and then do asset allocation.
compare results to those in the section.