Asset Allocation by Age: Why the 110-Minus-Age Rule Is Wrong
The classic 'stocks equals 110 minus your age' rule is a useful starting point and a terrible finishing point. Here is a better framework.
The rule, and why it became famous
The classic formula: subtract your age from 110 (or 100, depending on who is talking), and the result is your stock allocation percentage. A 30-year-old holds 80% stocks. A 60-year-old holds 50%. A 70-year-old holds 40%.
It became famous because it is simple, defensible, and approximately correct for the median worker who retires at 65 and dies at 78. It survives in financial-planning curricula because it gives a non-financially-literate audience an actionable number.
The problem: almost nobody is that median worker anymore. Longer lifespans, longer retirements, dual-earner households, defined-contribution plans replacing pensions — every assumption underlying the rule has changed in the last 40 years.
Why the rule under-allocates to stocks
A 65-year-old today has, on average, 20+ years of life ahead. A 70-year-old has 15+. That is a long enough horizon that holding 40% to 60% of a portfolio in bonds creates a real risk: inflation slowly destroys purchasing power over decades, and a heavily bond-weighted portfolio may not generate enough growth to last.
The historical record is unforgiving. A 30-year retirement with a 50/50 stock/bond split has a meaningfully higher chance of running out of money than the same retirement with 70/30 — because bonds, after inflation, often return close to zero.
The flip side: 80%+ stock allocations in late retirement create sequence-of-returns risk. A 40% market drop two years into retirement, combined with mandatory withdrawals, can permanently impair a portfolio. So the answer is not 'always more stocks' — it is 'enough stocks to outrun inflation, sized to your actual horizon.'
A better framework: time horizon over age
Replace age with time horizon. The relevant question is not 'how old are you?' but 'when will you need this money?' A 65-year-old planning to leave most of an account to grandchildren has a 30+ year horizon — much longer than the 65-year-old withdrawing 5% a year for living expenses.
Money you will not touch for 10+ years: aggressive (80%+ stocks). Volatility is irrelevant on a 10+ year horizon — stocks have never lost money over any rolling 20-year period in US history.
Money you will need in 3 to 10 years: balanced (50% to 70% stocks). Long enough that stocks should outperform, short enough that a bad year matters.
Money you will need in the next 3 years: conservative (mostly bonds and cash). The risk of a 30% drawdown right before you need to spend it is too high to take.
The bucket strategy
A practical implementation: split your portfolio into three buckets based on when you will need the money, and allocate each bucket according to its own horizon.
Bucket 1 (years 1 to 3): cash, money market funds, short-term Treasury bills. This is your spending money. Volatility-free, returns minimal, sleeps soundly.
Bucket 2 (years 4 to 10): bond funds, dividend-paying stocks, balanced funds. Moderate volatility, moderate growth. Refilled from Bucket 3 when stocks are up.
Bucket 3 (years 11+): stock index funds, REITs, growth-oriented assets. Maximum volatility, maximum long-run return. Left alone for decades to compound.
The bucket strategy is more work to maintain than a single allocation, but it makes the underlying logic explicit — and it makes it psychologically easier to ride out a 30% market drop when you know your spending money is safe in Bucket 1.
The two factors most people get wrong
Risk tolerance. The strict mathematical answer to allocation is one thing. The allocation you can actually hold through a 40% market crash without panic-selling is another. The second one matters more — a 'too conservative' portfolio you stick with beats an 'optimal' portfolio you abandon at the bottom.
Other income sources. Social Security, a pension, rental income, an annuity — these all function like bond exposure in your overall financial picture. A retiree with a pension covering 70% of expenses can hold a more aggressive portfolio than one fully dependent on withdrawals, because the pension is the bond allocation.
Frequently asked questions
What is a good stock-to-bond ratio for a 30-year-old?
For long-term retirement money with a 30+ year horizon, 90% to 100% stocks is mathematically defensible. The classic 80/20 split is reasonable for someone who wants more stability or has shorter-term goals mixed in.
Should retirees own 100% bonds?
Almost never. A typical retirement now lasts 20 to 30 years — long enough that inflation erodes a pure-bond portfolio. Most retirees benefit from holding 30% to 60% in stocks even in their 70s and 80s.
How often should I rebalance my portfolio?
Once a year is enough for most investors. Rebalancing more often adds friction and tax cost without meaningful benefit. The exception: if any asset class drifts more than 5 percentage points from its target, rebalance regardless of the calendar.
Where do REITs and international stocks fit in this framework?
Both count as 'stocks' in the stock-vs-bond split. Within the stock allocation, a common framework is 60% US, 25% international developed, 10% emerging markets, 5% REITs — but the right mix depends on your overall tax situation and existing exposures.