@darrellquock - My understanding of the 4% rule, as William Bengen initially conceived, is that you withdraw 4% in year one. In successive years, you take the amount from the previous year and adjust it by the inflation rate. It doesn’t go back to the 4% starting baseline, unless inflation takes you there by coincidence. So, for example, if you took $40k in year 1, and then in year 2 inflation is 5%, you take ($40k * 1.05 = $42k). In year 3, you start with what you took in year 2 ($42k), plus/minus inflation. Now, suppose in year 3 inflation is at 3%, your withdrawal would be ($42k * 1.03 = $43,260). And on it goes from there.
Bengen’s ideology was that markets and the economy will rise and fall, so a 50% increase in portfolio value this year may be followed by a 30% decrease next year, or multiple years of decline. I do not recall that Bengen ever adjusted the withdrawal rate based on the growth or decline of the portfolio. However, that has been a common criticism from various financial professionals.
Now, Bengen did tell us about his views on allocation, and his research clearly showed that a portfolio of no less than 50% in stocks worked best. He tested multiple allocation ratios (from 100% stock to 100% bonds). Based on the results, he settled on 75% stock, 25% intermediate-term Government bonds as the best ratio overall. As he stated, allocations of less than 50% or over 75% were counterproductive.
Having said that, bear in mind that Bengen’s research was based on 50-year cycles, from 1926 to 1994, with the specific intent of finding the safest withdrawal rate to make a retirement portfolio last for a minimum of 30 years.
The Trinity study confirmed Bengen’s findings that a portfolio allocation of 50% to 100% in stocks worked the best. But, you should also consider:
- Government bond rates have steadily declined since they peaked at 15+ percent in 1981, bottoming at 0.6% in 2020.
- Bond rates today are roughly what they were in the early 1960s, and interest rate cuts later this year may pull bond rates down again.
- Bengen used the S&P 500 for his stock allocation in his research and excluded any portfolio management fees or expenses.
- In follow-up studies, it was shown that the 4% withdrawal rate from a 75/25 portfolio ended with huge terminal portfolio values (the amount left in the portfolio after 30 years).
- 30 years is a long time, but with early retirement, a portfolio may have to last a lot longer. Conversely, if life expectancy is short, much higher withdrawal rates may be possible without exhausting the portfolio.
The last point is important to keep in mind if the portfolio owner is already retired and has a portfolio that is growing, but doesn’t anticipate spending it all before dying.
The standard disclaimer here is that history is not a good predictor of the future, so use your judgment to adjust accordingly.