What Can a 60/40 Portfolio Deliver?
Posted on: April 4, 2016
The 60/40 portfolio, one that consists of 60% equity and 40% bond, is very common. Most of my clients use a variation of this portfolio. Because of this, I want to understand how this portfolio performed in the past.
For this study, I use the S&P 500 for the equity portion and the 10 year treasury bond for the bond portion. The market data I use is from 1928 to 2015. Note that this period includes the Great Depression.
The portfolio is rebalanced every year to maintain the 60/40 allocation. Then I examine five return intervals: 1 year, 2 years, 5 years, 10 years and 20 years. For each return interval, I calculate the average return, best return and worst return.
| Interval | 1 year | 2 years | 5 years | 10 years | 20 years |
| Average | 8.55 | 8.55 | 8.55 | 8.55 | 8.55 |
| Best | 32.85 | 25.75 | 20.15 | 16.04 | 14.78 |
| Worst | -27.55 | -20.6 | -5.37 | 1.8 | 3.48 |
- The 60/40 portfolio can still be quite risky in the short term. Note that the worst returns for the 1 year and 2 year intervals are -27.55% and -20.6% respectively. These are steep losses nobody likes.
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The worst return for the 5 year interval is a much smaller -5.37%. It’s clear that the longer the investment horizon, the better the risk/reward ratio. In fact, after 1941, there has never been a 5 year interval that this portfolio has a negative return.
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Never in history did this portfolio ever produce a negative return in the 10 and 20 year interval.
Most people’s retirement investment horizon is 20 years. The worst 20 year return is an anemic 3.48%. The best is 14.78%. The average is 8.55%. Even the worst return will nearly double your money in 20 years!
If you invest consistently into the 60/40 portfolio during your working years and divest consistently during the the retirement years, that is, avoid lump sum investment and market timing, your long-term return will most likely be not as low as 3.48%, and not as high as 14.78%, but around the average of 8.55%.
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The Investment Scientist 
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