In a previous post, I showed how to calculate the global minimum variance portfolio using R and vanguard funds in my retirement account. It had an average annual return of 5.2% and volatility of 3.3% in the past 10 years. Because I’m holding those funds for a long term, at least 30 years. I don’t really mind a bigger volatility now. Instead, I really want a bigger return, say 10%. So I’ll set my target return as 10%, and find a portfolio that can achieve it. The resulting portfolio is called mean-variance efficient because it has the smallest volatility for the 10% target return.
Step 0. Load libraries and define helper functions.
Step 1. I choose assets from three broad classes: stocks, bonds, and commodities. For stocks, I choose funds that cover total US market, total international markets, and real estate. For bonds, I choose funds that invest in the total US bond market and inflation protected securities. For commodities, I choose funds that invest in gold and other precious metals and their mining companies and oil & gas and energy companies. First, I download the monthly adjusted closing price data of these funds between June 2000 and Oct 2014 from Yahoo.
Step 2. Calculate monthly continuously compounded returns as difference in log prices.
Step 3. Calculate annualized sample average returns of the underlying assets and the sample covariance matrix of the returns.
Step 4. Calculate the efficient portfolio with 10% as target return using a helper function written by Eric Zivot and Hezky Varon from U of Washington.