This question should matter to every Australian investor managing a multi-asset portfolio, yet most people never properly sit down and think it through. On the surface it sounds almost administrative — rebalancing is just tidying up your allocations, right? But the compounding effects over a decade or two are anything but trivial, and the answer genuinely depends on factors most people skip straight past.

Here is the direct answer: systematic rebalancing does not reliably produce higher raw returns than buy-and-hold drift. What it reliably produces is a more controlled risk profile and, critically, better risk-adjusted returns over long horizons. That distinction sounds like a technicality but it changes everything about how you should frame the decision.

CONCEPTRebalancing is primarily a risk management tool — the return benefits are secondary and context-dependent.
WARNINGFrequent rebalancing in taxable Australian accounts can trigger CGT events that erase any theoretical edge entirely.
KEY IDEAThreshold-based rebalancing (e.g. ±5% bands) historically outperforms calendar rebalancing on both cost and efficiency measures.

Think of it like maintaining a car. You can skip servicing for years and the car still drives — sometimes faster because you are not losing time in the workshop. But when something goes wrong, it goes very wrong. Buy-and-hold drift works similarly. During a prolonged equity bull run, a drifting portfolio looks brilliant. Then a correction arrives and suddenly you are holding 80% equities when you thought you had 60%.

60% 70% 80% 90% Yr1 Yr3 Yr5 Yr7 Yr10 Drifting equity % Rebalanced equity % Equity allocation drift in a bull market (illustrative)

Vanguard research across multiple market cycles found that the return difference between annually rebalanced and buy-and-hold portfolios was often less than 0.5% per annum before costs. The risk difference, measured by volatility and maximum drawdown, was considerably larger. For Australian multi-asset portfolios specifically, the ASX's long-run equity outperformance means drift tends to be aggressive — your 60/40 can become an 80/20 faster than you expect across a decade-long run. The Journal of Financial Economics literature on portfolio rebalancing mechanics consistently shows that threshold-based approaches — only rebalancing when an asset class breaches a set band — minimise unnecessary trading. This is especially relevant in Australia where the capital gains tax discount rules make timing of rebalancing trades genuinely meaningful. Combining threshold triggers with natural cash flows — dividends, contributions — is the approach most consistent with the strategic asset allocation evidence base.

The practical takeaway you can use today: check your current allocation against your target. If any asset class has drifted more than five percentage points, that is your signal to look at rebalancing — not because it guarantees better returns, but because you are likely holding more risk than you signed up for.

You built a portfolio for a reason. Drift quietly rewrites it without asking permission.

This content is for educational purposes only and does not constitute financial product advice. Past performance is not indicative of future results. Profit Logic Ltd (ACN 688 669 936) accepts no responsibility for errors or omissions in this content or anywhere on this website. Always seek advice from a licensed financial adviser before making investment decisions.