Asset allocation is the decision of how to divide your investment portfolio among major asset classes — most importantly stocks and bonds. It is widely considered the single most important determinant of long-term investment returns and risk. The age-based approach, popularized by the '110 minus age' rule, offers a simple, disciplined way to set that split and adjust it over time.
The age-based rule explained
The core idea is that your equity exposure should decline as you age. The rule says to hold (110 − your age)% in stocks and the remainder in bonds. A 30-year-old holds 80% stocks and 20% bonds; a 60-year-old holds 50% stocks and 50% bonds. The logic is straightforward: younger investors have decades to recover from market downturns, so they can afford the higher volatility of stocks in exchange for higher expected returns. As retirement approaches, the priority shifts to preserving capital, so the allocation tilts toward bonds.
Choosing 110, 120, or 130
The base number is a risk dial. 110 minus age is the most conservative and suits cautious investors. 120 minus age is a common middle ground that reflects longer life expectancies and the need for growth to outpace inflation over a longer retirement. 130 minus age is aggressive, appropriate for investors with high risk tolerance, long horizons, or other income sources in retirement. There is no single correct answer — the right base depends on your goals, time horizon, and comfort with volatility.
Why allocation matters more than selection
Research consistently shows that asset allocation explains the vast majority of the variation in portfolio returns over time — far more than individual security selection or market timing. A portfolio's risk and return profile is set largely by its stock-to-bond mix. This is why target-date funds, which automate an age-based glide path, have become the default choice in most retirement plans: they enforce a sensible allocation without requiring the investor to make ongoing decisions.
Practical guidance
Use this calculator to find your target split, then implement it with low-cost index funds or a target-date fund that matches your horizon. Rebalance at least annually to keep your actual allocation close to your target, and revisit the split whenever your age, goals, or risk tolerance change. Remember that the age rule is a starting point — your personal circumstances should always inform the final decision.