A topic in the Open Knowledge Graph — a free, open map of 15,290 topics and the order to learn them in.
Asset allocation (the percentage mix of stocks, bonds, real estate, and cash in a portfolio) should align with your time horizon and risk tolerance; regular rebalancing maintains this target allocation, enforces disciplined buying low and selling high, and reduces risk from concentration.
Take a risk tolerance questionnaire to determine your target allocation. Build a portfolio with index funds matching this allocation. Track it quarterly; when one asset class grows to ±5% of target, rebalance. Compare performance to a set-it-and-forget-it portfolio after 3-5 years.
Higher allocation to stocks is always better when a 90/10 portfolio crashes harder in downturns. You need dozens of holdings to diversify when three index funds provide adequate diversification. Rebalancing is market-timing when it's rule-based and forces you to do the opposite of crowd behavior.
From your work with tax-advantaged accounts, you know that *where* you hold investments matters for tax efficiency. This topic addresses *what* you hold — the mix of asset classes — and how to maintain that mix over time. Asset allocation is the single most powerful decision in long-term investing: research consistently shows that the split between stocks, bonds, and other asset classes explains the vast majority of a portfolio's long-run performance and volatility, more than which specific funds you choose.
The core logic draws on the risk-return tradeoff you've already studied. Stocks offer higher expected returns but with larger swings — a 60% drop in a crash is possible. Bonds offer lower expected returns but with smaller swings — they act as ballast when stocks fall. Your target allocation is the percentage split that aligns with two factors: your time horizon (how many years until you need the money) and your risk tolerance (how much you can stomach watching your portfolio fall without panic-selling). A 25-year-old saving for retirement might hold 90% stocks; a 60-year-old approaching retirement might hold 60% stocks and 40% bonds. There is no universally correct allocation — only the one you can stick with through downturns.
Here is where proportions come in directly. If your target is 80% stocks / 20% bonds and stocks have a great year, they might grow to represent 88% of your portfolio. You are now overexposed to stock risk — not because you chose to be, but because growth drifted your allocation. Rebalancing is the mechanical process of returning to target: selling the asset class that has grown above its target percentage and buying the one that has fallen below. This has two benefits. First, it controls risk — you avoid becoming unintentionally concentrated in whatever happened to perform well recently. Second, it enforces discipline: you are systematically selling high and buying low, the opposite of what emotional investors tend to do.
A practical rule of thumb is to rebalance when any asset class drifts more than 5 percentage points from its target, or to review and rebalance on a fixed schedule (annually is common). The discipline is the point. When stocks are surging and bonds look boring, rebalancing forces you to trim stocks and add bonds — exactly when every instinct says to keep riding the winner. When stocks crash and bonds are stable, rebalancing forces you to buy more stocks at depressed prices — exactly when every instinct says to flee. Done consistently over decades, this mechanical contrarianism is one of the few behavioral edges available to individual investors.