How to Rebalance Your ETF Portfolio in Australia

⚖️ What is portfolio rebalancing?🔗

When you set up an ETF portfolio, you choose a target allocation. Say 70% in a broad growth ETF and 30% in a defensive bond ETF. That split reflects your risk tolerance and your goals.

Markets do not stay still. After a strong run in equities, your growth ETF might climb to 78% of your portfolio while your defensive holding shrinks to 22%. Your actual risk exposure has quietly shifted, even though you did nothing.

🎯 The essential: Rebalancing is the act of restoring your original split. You are correcting for portfolio drift, the natural tendency of a portfolio to wander away from its target as different assets grow at different rates. It is not complicated, but it does take a bit of attention.

🎯 Why bother rebalancing?🔗

Two reasons, and they are both honest ones.

Risk creep. If growth assets keep outperforming, your portfolio gradually becomes riskier than you intended. A 70/30 investor who ignores drift for a few years might end up with an 85/15 portfolio. That is a meaningfully different risk profile, and it can hurt if markets fall sharply.

You systematically buy low and trim high. When you rebalance, you add to whatever has underperformed and trim whatever has run hard. That is the right direction. Whether it actually boosts long-term returns is a different question.

To be straight with you: the evidence on rebalancing improving returns is mixed. Some studies show a small benefit, others show it makes little difference after costs. The main reason to rebalance is risk management, not return chasing.

🗓️ The two main approaches🔗

Calendar-based rebalancing. You pick a date or two each year and check your allocation then. Many Australian investors do this in June or July, when they are already looking at their finances for tax time. It is simple, low effort, and easy to stick to. The downside is that a big market move between check-ins could leave you off-target for months.

Threshold-based rebalancing. Instead of checking on a schedule, you rebalance whenever any holding drifts more than a set amount from its target. A common starting point is a 5 percentage point band. If your target is 70% growth and it climbs to 76%, you act. If it only drifts to 73%, you leave it alone. It is more precise, but you need to check more often.

Combining both is the sweet spot for most people. Check on a schedule, say twice a year, but only act if a threshold has been breached. You are not reacting to every small wobble, but you are not ignoring a 10 percentage point drift either.

💸 The cheapest way to rebalance🔗

If you are still in the accumulation phase and adding money regularly, you have a powerful tool: direct your next contribution to the underweight holding. No selling, no brokerage on a sale, no CGT event. Just buy more of whatever has fallen behind.

Say your growth ETF has drifted high and your defensive ETF is underweight by $2,000. Your next $2,000 contribution goes entirely into the defensive ETF. Done. You have rebalanced without touching your existing units.

This works best when the drift is moderate and your contributions are meaningful relative to your portfolio size. For larger portfolios or bigger drifts, contributions alone may not be enough.

🔢 A worked example🔗

Illustrative example only. These figures are hypothetical and do not represent any real fund or return. You started with $50,000 split 70/30: $35,000 in a growth ETF and $15,000 in a defensive ETF. After a strong market run, your portfolio looks like this.

Your target was 70/30. You are now sitting at roughly 76/24. The drift has pushed you outside a 5 pp band, so it is time to act. To restore 70/30 on a $55,000 portfolio, you need $38,500 in the growth ETF and $16,500 in the defensive ETF, a shift of $3,500.

Option 1 (preferred): direct your next $3,500 of contributions entirely to the defensive ETF. No selling required. Option 2: sell $3,500 of growth ETF units and buy defensive ETF units. This restores the balance immediately but triggers a CGT event on the sale. Option 1 is almost always the better starting point.

🧾 When you have to sell, and the CGT catch🔗

Sometimes contributions are not enough. If your portfolio is large, or the drift is significant, you may need to sell to rebalance. Selling ETF units is a capital gains tax event in Australia. Here is what that means in plain terms.

CGT rules are personal and depend on your income, your cost base, and which units you sell, such as first in first out versus specific identification. Always speak to a registered tax agent before selling to rebalance. For the mechanics of how CGT works on investments, see our guide to capital gains tax on shares in Australia. This article does not constitute tax advice.

🧰 Tools to track your portfolio🔗

You do not need anything fancy. The goal is to make checking quick enough that you actually do it. A simple spreadsheet in Google Sheets or Excel works well: three columns for target %, current value, and current %. The spreadsheet does the maths and shows you the drift at a glance.

A portfolio tracker app such as Sharesight, popular with Australian investors, can automate a lot of this and help with tax reporting. That is an example, not an endorsement. Whatever you use, set a reminder. Twice a year is fine. The tool matters less than the habit.

⏱️ How often is enough?🔗

For most DIY ETF investors, once or twice a year is plenty. Over-tinkering is a real risk. Every sale generates brokerage, every sale of a profitable holding is a potential CGT event, and the more often you check, the more tempted you are to react to short-term noise.

If you are thinking about how your portfolio is structured, our guides on how many ETFs you should own and building a simple ETF portfolio are worth a read. The best rebalancing strategy is one you will actually follow. Simple and consistent beats clever and erratic every time.

❓ Frequently asked questions🔗