Asset allocation is how you split your capital across the major asset classes: stocks, bonds, cash and, in some portfolios, real estate, gold or others. It is the most important investment decision you will make — far ahead of picking individual stocks or timing your entries.
The classic studies (Brinson, Hood and Beebower) estimated that asset allocation explains around 90% of the variability of a portfolio's results over time. Stock selection and market timing — where many investors spend most of their energy — explain the rest.
The reason is simple: asset classes behave very differently. Stocks offer the highest expected return at the cost of deep falls (drawdowns of 30–50% every so often); bonds cushion; cash earns little but gives options. The mix determines how much your portfolio can fall and how much it can grow.
It depends on three factors:
The classic rule of thumb — "120 minus your age in stocks" — is a reasonable starting point (at 30: 90% stocks; at 60: 60%), though no formula replaces knowing your own tolerance.
| Profile | Stocks | Bonds | Plausible fall in a crisis |
|---|---|---|---|
| Conservative | 30% | 70% | ~10–15% |
| Balanced | 60% | 40% | ~20–30% |
| Aggressive | 90% | 10% | ~35–45% |
Once the split is set, periodic rebalancing keeps it in place, and the portfolio's volatility is essentially determined by it.
As a first reference, 120 minus your age. Adjust for your horizon and, above all, for the fall you can endure without selling: if a −40% would make you liquidate, your equity weight is too high.
As a style within equities: a dividend portfolio is still "stocks" for allocation purposes, although its volatility tends to be somewhat lower than the market's.
Almost never: only when your life changes (horizon, income, goals), not when the market does. Changing the split in the middle of a crash is the most expensive way to discover your real risk tolerance.