Asset Allocation Decides Which Risks Get the Most Room
Last spring the plan said 60% stocks; this morning the account screen says 71%. Nobody bought a share — the market did the drifting, and asset allocation is the discipline of noticing.
Asset allocation is how a portfolio divides among broad groups: stocks, bonds, cash, and sometimes real estate or other assets. Research has long suggested that mix shapes more of a portfolio's behavior than any single fund pick.
Setting the mix
The right split follows the job the money has to do. A retirement account with thirty years to run can hold more stock than a house down payment needed in three.
Timeline is only half of it — the other half is risk tolerance, your honest capacity to watch the balance fall without abandoning the plan. Job security, debts, and other income all feed that answer.
The drift in numbers
Give a $100,000 portfolio a 60/30/10 target: $60,000 in stocks, $30,000 in bonds, $10,000 in cash. Each slice has a role — growth, income, and ready money.
Now let stocks climb to $80,000 while the rest stands still. The portfolio drifts to roughly 67% stocks, carrying more equity risk than anyone chose on purpose.
Rebalancing
Rebalancing pushes the mix back to target — selling some winners, buying what's lagged, or steering new contributions toward whatever's underweight. The point isn't predicting the next winner; it's keeping risk at the level you signed up for.
It isn't free, though. Selling in a taxable account can realize gains, so many investors rebalance with new money first or on a once-a-year schedule.
Allocation isn't diversification
A 60% stock slice invested in one company is still a concentrated bet. Diversification spreads holdings within each slice; allocation sets the size of the slices — a sturdy portfolio needs both.
Age formulas make tidy starting points, nothing more. A pension, a shaky job, or near-term spending can justify a mix the formula would never suggest.
For investor-focused guidance, see the SEC's asset-allocation guide.
Write your target mix down somewhere permanent — future you will need it on a red day.