Portfolio rebalancing and asset allocation

Asset allocation is your chosen split across asset classes — typically equity, debt and sometimes others like gold — based on your goals, time horizon and tolerance for ups and downs. It's the single biggest driver of a portfolio's risk and return profile, more so than which specific fund or stock you pick. A longer horizon usually justifies more equity; a shorter one or a lower risk appetite tilts toward debt and stability.

Markets move at different speeds, so even a perfect starting mix wanders over time. When equity runs up, it grows to a larger share of the portfolio than you intended, quietly raising your risk; when it falls, your equity weight shrinks. Left alone, the portfolio you end up holding can look very different from the one you designed — often riskier, after a strong equity run, precisely when caution is warranted.

Rebalancing means periodically restoring your portfolio to its target allocation — trimming what has grown beyond its share and topping up what has fallen below. It's a disciplined, almost mechanical way to sell a little of what's expensive and buy a little of what's cheap, without relying on a market call. The point isn't to maximise return in any single year but to keep your risk where you intended it to be.

There are two common triggers: time-based (review on a set schedule, say once a year) and threshold-based (act when an asset class drifts beyond a set band from its target). Either works; the key is having a rule and following it rather than reacting to headlines. Bear in mind that selling to rebalance can have tax and cost implications, so factor those in — sometimes you can rebalance simply by directing fresh contributions to the underweight asset.

The biggest gains from rebalancing come from sticking with it, not from fine-tuning it. A sensible allocation you actually maintain beats an ideal one you abandon in a panic. Set an allocation that matches your goals, choose a rebalancing rule you'll follow, and let the process do the work of buying low and selling high for you. Revisit the allocation itself only when your goals or horizon genuinely change.