Naïve Diversification and Regret When Investing
- by Mehmet E. Akgul
- August 16, 2018
Nearly all finance and investing books, writers, and academics mention diversification, periodic portfolio updates, rebalance illiquid holdings, and risk-adjusted performance evaluations. Do you think these finance professionals always implement these strategies to own their lives?
As you may guess from the beginning of the article they don’t. Jason Zweig, the writer of “Your Money & Your Brain”, asked Harry M. Markowitz, who holds Nobel Prize in economics in 1990 for having developed the theory of portfolio choice (a.k.a. Modern Portfolio Theory).
Dr. Markowitz's Portfolio Application In Real-World
Dr. Markowitz proved the importance of diversification. In modern portfolio theory, risk-averse investors allocate investments into diversified portfolios through mathematical formulations with mean-variance analysis and covariance between assets and/or asset classes. However, Dr. Markowitz told Mr. Zweig, that isn’t what he did:
Instead, I visualized my grief if the stock market went way up and I wasn't in it – or if it went way down and I was completely in it. My intention was to minimize my future regret. So, I split my contributions 50/50 between bonds and equities.
Modern Portfolio Theory
Dr. Markowitz has some of the following assumptions for the modern portfolio theory:
- An investor is risk-averse and rational.
- The investor’s utility function is concave and shows the diminishing marginal utility of wealth.
- Investment analysis is based on a single period, not a multi-period approach.
- An investor either maximizes his portfolio return for a given level of risk or maximizes his return for the minimum risk.
Conclusion
He apparently doesn’t take his own advice and represent regret behavior in the decision-making process as most investors do. We accept what risk-averse investors do with investment allocation, but we represent emotional and cognitive behavioral biases in our investments.
In order to overcome regret bias, investors’ education is necessary. Diversification and asset allocation help to reduce portfolio risk. Investors’ behavioral biases need to be considered in the portfolio management.