Asset Allocation by Age and How to Rebalance
Asset Allocation by Age and How to Rebalance
How much of your money should sit in stocks versus bonds? It depends on your age, your goals, and your stomach for a bad year. That answer is unsatisfying, which is why a handful of well-worn rules of thumb exist to give you a starting number.
This article walks through the age-based rules, why the split matters more than picking winners, and how to rebalance without making it a chore you dread. None of it is financial advice. Use it as a framework to think with.
Why allocation beats stock picking
Decades of research land in the same place: how you split money across asset classes explains far more of your long-term result than which securities you buy. The Bogleheads investment philosophy treats allocation as the central decision and individual selection as an afterthought.
The intuition is simple. Stocks return more and swing harder. Bonds return less and soften the ride. Your mix sets both your growth and how much volatility you have to sit through to get it.
The "120 minus age" rule
The best-known shortcut subtracts your age from a fixed number to get your stock percentage. The classic version used 100. As lifespans stretched, advisors moved to 110 or 120.
The logic: the younger you are, the more time you have to ride out a crash, so you can hold more stocks. As your horizon shrinks, you move toward bonds to protect what you built.
| Age | 120 minus age (stocks) | Implied bonds | Rough risk posture |
|---|---|---|---|
| 25 | 95% | 5% | Aggressive growth |
| 35 | 85% | 15% | Growth |
| 45 | 75% | 25% | Balanced growth |
| 55 | 65% | 35% | Balanced |
| 65 | 55% | 45% | Conservative |
| 75 | 45% | 55% | Capital preservation |
Starting points, not commandments. A 35-year-old with unstable income might sensibly hold more bonds. A 60-year-old with a fat pension might hold more stocks. The rule uses one variable when the real decision involves several.
Glide paths, or how target-date funds do it
The "minus age" rule is the manual version of what target-date funds automate. A glide path is a schedule that lowers stock exposure as a target retirement year gets closer.
Vanguard, one of the largest managers of these funds, publishes research on how it builds those glide paths, weighing growth early against risk reduction near and into retirement. Its principles for investing success lay out the reasoning. The part worth stealing: the shift is gradual and rules-based, not a lurch when markets fall.
A glide path also keeps moving after retirement, not just up to it, because someone retiring at 65 may need the portfolio to last another 30 years. That is part of why "120 minus age" replaced "100 minus age."
See your whole portfolio first
None of these rules help if you cannot see your current allocation. Most people hold investments in several places: a workplace plan, a brokerage, maybe crypto and some cash. Your stock-to-bond ratio is the blend of all of them, not whatever one account shows you.
That is the argument in why seeing your full portfolio matters. You cannot rebalance toward a target you cannot measure. Step one is a complete, current view of where every dollar sits.
Hidden duplication is the related trap. Two funds in two accounts can hold the same underlying companies and quietly concentrate your risk. Knowing how to spot ETF overlap keeps you from believing you are diversified when you are not.
How to rebalance without stress
Rebalancing nudges your portfolio back to its target mix after markets push it out of line. Stocks surge, you drift from 80% to 88% stocks, and you are carrying more risk than you signed up for. Rebalancing trims the winners and tops up the laggards.
Two low-stress approaches cover most people.
- Calendar rebalancing. Check once or twice a year on a fixed date. Simple and unemotional.
- Threshold rebalancing. Act only when an asset class drifts past a set band, say 5 percentage points, from target. Less frequent, more responsive.
You do not need both. Pick one and let it run.
A simple rebalancing routine
- Record current values for every holding.
- Work out your actual stock, bond, and other percentages.
- Compare against your target for your age and situation.
- If something sits outside your comfort band, adjust. New contributions do the job with fewer taxes and fees than selling.
- Write the target down so future-you does not improvise.
Emotion is what wrecks rebalancing. The whole point is to buy what is cheap and trim what is expensive, which feels wrong every single time. A schedule takes the agonizing out of it.
The honest caveat
Age-based rules are crude on purpose. They ignore your other income, your debts, your job security, your goals, and how you actually behave when a balance drops. The SEC's investor education site has a level-headed primer on assessing your risk tolerance, worth reading before you anchor on any single number.
Treat the rules as a conversation with yourself. If your finances are complicated, a fee-only fiduciary can help you personalize.
Tracking your allocation in MyMoneyViz
To rebalance you need to see your mix, and to see your mix you need everything in one place. A portfolio tracker like MyMoneyViz covers 13+ asset types and shows allocation across the whole portfolio, so your real stock-to-bond ratio is on screen instead of buried in four logins.
Set a target allocation as a goal and watch your actual mix against it. Backfill your history and you can see how the allocation drifted through past market moves, which makes the case for rebalancing on a schedule feel a lot less theoretical.
The bottom line
Asset allocation by age gives you a sane default: more stocks when young, more bonds as retirement approaches, moved in steady steps rather than panicked jumps. Rebalancing keeps that plan intact when markets pull you off course.
Every rule assumes you can see what you own. Get your full portfolio in view with MyMoneyViz, set your target, and rebalance on a schedule instead of on a feeling.
