Asset Allocation by Age: How to Split Stocks and Bonds

Asset allocation is the decision that matters more than which specific funds you pick. A 25-year-old with 100% stocks and a 62-year-old with 100% stocks are in completely different positions — one of them is fine, the other could be forced to sell at the worst possible time.

The classic rule is simple. The math behind why it works takes a few minutes to understand.

The Basic Framework: Why It Changes With Age

Stocks grow more over long periods but swing dramatically in the short term. The S&P 500 has lost 30–50% in some years. If you're 30 and your portfolio drops 40%, you've lost no real money — you haven't sold, and you have decades for it to recover.

Bonds grow less but fluctuate less. If you're 63 and the market drops 40% the year before you retire, that's a crisis — you might need to sell at the bottom.

Asset allocation is about matching your investment risk to your actual time horizon.

Age-Based Rules of Thumb

Classic rule: Hold (100 − your age)% in stocks.

• Age 30: 70% stocks, 30% bonds
• Age 50: 50% stocks, 50% bonds
• Age 65: 35% stocks, 65% bonds

Modern adjustment (people live longer): Use (110 − age) or even (120 − age).

• Age 30: 80–90% stocks
• Age 50: 60–70% stocks
• Age 65: 45–55% stocks

Most target-date funds use the 110-minus-age approach as a base. I tend to think the modern adjustment is more appropriate — a 65-year-old today may live to 90. Too much in bonds too early can mean running out of money.

Allocation by Decade

20s: Go Aggressive

This is the one time in your financial life where you should be comfortable watching your portfolio drop 30% without panic. You have 40+ years ahead of you. Every bear market in history has eventually been followed by new highs.

Target: 90–100% stocks (broad index funds)

• US Total Market: 60%
• International: 30%
• Bonds: 0–10%

30s: Slightly Moderate

Same philosophy as 20s, maybe add a small bond position if it helps you sleep during crashes. The key is not selling.

Target: 80–90% stocks

• US Total Market: 55%
• International: 25%
• Bonds: 10–20%

40s: Start Adding Stability

Still primarily stocks, but increasing bond allocation to buffer against sequence-of-returns risk (the risk of a crash right before retirement).

Target: 70–80% stocks

• US Total Market: 50%
• International: 20%
• Bonds: 20–30%

50s: Real Risk Management

The decade when asset allocation decisions become truly consequential. A market crash at 55 with 90% in stocks could delay retirement by years.

Target: 55–65% stocks

• US Total Market: 40%
• International: 15–20%
• Bonds: 35–45%

60s+: Capital Preservation

You need income and stability. Still hold meaningful stocks — you may have 25+ retirement years ahead — but volatility protection matters more.

Target: 40–55% stocks

• US Total Market: 30–40%
• International: 10–15%
• Bonds: 45–60%

The Easy Version: Target-Date Funds

If the above feels like too many decisions, a target-date fund does this automatically. Pick the fund closest to your expected retirement year (e.g., "Target 2050 Fund") and it manages allocation as you age.

The main downside: expense ratios are slightly higher than holding three individual index funds yourself (0.1–0.15% vs 0.03%). On $100,000, that's $70–120/year. A reasonable price for autopilot.

What Actually Goes Wrong

People tend to get allocation wrong in two ways:

1. Too conservative too early — being 70% bonds at 35 means missing decades of stock market growth
2. Too aggressive too late — being 90% stocks at 62 means a bad market year can derail your retirement date

Neither failure mode is permanent if you catch it in your 40s. It gets harder to fix in your late 50s.

The Bottom Line

• Stocks grow more, bonds protect against short-term crashes — the balance shifts with age
• In your 20s–30s: 80–100% stocks; start adding bonds in your 40s–50s
• Use the "120 minus age" rule as a modern starting point for longer lifespans
• Target-date funds automate this; holding 3 index funds is cheaper and equally effective
• Review your allocation at major life events (new job, marriage, near retirement) — not every month

Use our Retirement Calculator to see how different stock/bond allocations affect your projected retirement balance.