Turns Out an Age-Old Investment Rule Is Just Plain Wrong
The biggest problems an investor faces are internal, not external. Your decision-making will have the biggest effect on your success over the long-term, regardless of what the market does. It’s been said human nature is a terrible investor. That’s because what we think is the natural choice often turns out to be the worst choice in the world of investment decisions.
For decades, many people who were trying to decide how much of their investments should be in stocks versus bonds/cash locked onto the “100 minus your age rule.” Simply put, the rule says subtract your current age from 100, and that’s how much should be in stocks. So, a 30-year-old should have 70% in stocks and a 70-year-old should have 30% in stocks. There are many reasons for the popularity of the rule, including that it is pretty simple to apply and it seems to jibe with human nature wherein the older we get the more conservative we should be in everything (think about that pool of water on the sidewalk that you use to run and jump over that you now walk around).
In recent years the “100 minus your age” rule was put through historical scenarios by some very well-respected financial analysts, including Bill Bengen, Wade Pfau and Michael Kitces. They all came to the same conclusion: Rather than decreasing your allocation of stocks as you age you should do the exact opposite and increase the allocation of stocks versus bonds each year of retirement. To be specific, you start retirement with a base stock allocation, let’s say 55% for example, and you increase that by one percentage point per year starting in year two of retirement. This technique is called the “increasing glide path” retirement planning.
While this might seem counterintuitive (good investing decisions often do) it really makes sense if you think about it. Your biggest challenge during your retirement years is not a volatile stock market. It’s inflation eating up your spending power, and stocks are the antidote to counter inflation. Between growth in stock prices and growth in dividends, stock values have risen faster than inflation for decades. Therefore, decreasing your allocation of stocks as you age is hampering the ultimate inflation slayer, and a bad idea. In addition, if it turns out that you had the bad luck of having a big stock market downturn early in your retirement, using the increasing glide path is in essence dollar cost averaging into a down market.
The proof is in the statistical pudding so to speak. Bill Bengen found that the increasing glide path approach increased the SAFEMAX withdrawal rate I wrote about last week from 4.68% to 4.84%. That is a substantial change and puts to bed the fallacy of the 100 minus your age rule.
Fun Fact: The oldest living verified person was Jean Calment of France who lived 122 years, 164 days. Currently, the oldest living person in the U.S. is Naomi Whitehead, who turned 115 last month. I’m sure you wouldn’t have to convince either of them about the effects of inflation over their lifetimes.