You chose an allocation, filled it with funds, and made it genuinely diversified. You’re not quite done — because the moment prices move, your carefully chosen mix quietly drifts away from its target. Rebalancing is how you nudge it back.
Suppose you set a 60/40 split of stocks to bonds. If stocks have a strong run and bonds are flat, the stock slice grows faster and takes up more of the pie. Example (illustrative): a 60/40 portfolio after a good year for stocks might quietly become 70/30 — without you buying a thing. That sounds like a win, but it means your portfolio is now riskier than you decided it should be: more exposed to the next stock downturn than your plan called for. Drift can go the other way too, leaving you more cautious than intended after a bad stretch for stocks.
Rebalancing means selling a little of whatever has grown too large and topping up whatever has shrunk, to return to your target — in the example, trimming stocks back from 70% to 60% and moving that money into bonds. Notice what it quietly forces you to do: sell some of what recently rose and buy some of what recently lagged. That’s an unglamorous, discipline-over-instinct habit, and it’s the opposite of chasing whatever’s hot.
Calendar rebalancing: check on a fixed schedule — say once or twice a year — and reset to target. Simple and easy to remember.
Threshold rebalancing: only act when a slice drifts past a set band — for example, if any part is more than 5 percentage points off its target. This reacts to what markets actually do rather than the calendar. Many people combine the two: glance on a schedule, but only trade if something has drifted meaningfully.
If you’re adding money regularly — the dollar-cost averaging habit from earlier — you can often rebalance just by directing each new contribution into whichever slice is currently underweight. That nudges the mix back toward target without selling anything, which sidesteps most trading costs and, in a taxable account, most tax events. Keeping costs low matters because they eat into compounding over time.
Selling to rebalance can trigger trading fees and, in a taxable account, a taxable gain — and the exact tax rules differ by country and account type, so this isn’t tax advice. Inside a tax-advantaged account, rebalancing trades usually don’t create an immediate tax bill. This is also where risk-per-trade thinking helps: rebalancing is a planned, whole-portfolio adjustment, not a reason to tinker constantly. Set a rule, follow it, and let the plan — not the headlines — drive your buying and selling.
This lesson is general investor education, not investment or tax advice. The 60/40-to-70/30 drift is illustrative arithmetic. Tax and trading-cost rules for selling to rebalance vary by country and by account type — check your national rules and a qualified professional.
There’s no single right answer. Many people check on a fixed schedule such as once or twice a year, only trading if a slice has drifted meaningfully off target — often a band like 5 percentage points. Rebalancing too often adds cost and effort for little benefit; this lesson describes the methods rather than prescribing a frequency.
In part, yes — and that’s the point. Rebalancing trims what has grown beyond your target and tops up what has lagged, which keeps your risk where you decided it should be. It’s a discipline-over-instinct habit, the opposite of piling into whatever is currently hot.
It can. Selling to rebalance may trigger trading fees and, in a taxable account, a taxable gain — and the rules vary by country and account type, so this isn’t tax advice. Directing new contributions to the underweight slice rebalances without selling, sidestepping most of those costs.
Investor education only — not investment advice, and never a promise of profit. Every investment can lose value.