Most investment underperformance is not caused by poor market conditions — it’s caused by predictable, avoidable investor mistakes. Understanding the most common portfolio errors and their solutions can significantly improve long-term outcomes.
1. Panic Selling During Market Falls
The mistake: Selling shares or ETFs when the market falls significantly — locking in losses and often missing the recovery.
Market falls are normal. The ASX has experienced falls of 10%+ many times and has always recovered to new highs over time. The 2008–09 Global Financial Crisis saw the ASX fall ~50%, then fully recover and exceed its prior peak within a few years.
The solution: Before investing, understand that your portfolio will fall 20–40% at some point. If you cannot tolerate this, reduce your allocation to shares and hold more bonds or cash. But do not sell after a fall has already occurred.
Key insight: Most investors who underperform the market do so because they sell low (after falls) and buy high (after rallies). This pattern is the single largest cause of retail investor underperformance.
2. Chasing Past Performance
The mistake: Buying assets or funds that performed strongly last year, expecting that performance to continue.
Research consistently shows that last year’s top-performing fund rarely leads the following year. Asset classes rotate in and out of favour — what led in 2021 may lag in 2022–24.
The solution: Choose your asset allocation based on your goals, time horizon, and risk tolerance — not last year’s return tables. Stick with broad, diversified, low-cost index ETFs rather than chasing thematic or sector-specific returns.
3. Home Country Bias
The mistake: Overweighting Australian shares relative to their global market weight. Australia represents approximately 2% of the global share market by capitalisation.
A common Australian portfolio error is holding 80%+ in Australian shares when Australia’s technology sector is tiny (ASX is dominated by banks and miners). This concentrates risk in a small market.
The solution: A 40% Australia / 60% international split is a commonly suggested starting point. The ASX does provide important franking credit benefits, but not at the expense of genuine global diversification.
4. Ignoring Fees
The mistake: Choosing a managed fund or super option with a 1–1.5% MER without recognising the compounding cost over decades.
A 1% fee difference on a $300,000 portfolio over 20 years represents hundreds of thousands of dollars in foregone wealth through compounding.
The solution: Use low-cost ETFs (VAS, VGS, A200, IWLD). Compare super fund fees using the government’s YourSuper comparison tool. Question any investment with an MER above 0.50% — what does it offer that a cheap index fund does not?
5. Not Diversifying (Concentration Risk)
The mistake: Holding too few assets — a single stock, one sector, one country, or one asset class.
Individual shares carry company-specific risk that disappears in a diversified portfolio. If you hold just CBA, NAB, BHP, and Telstra, your portfolio is vulnerable to sector or regulatory events.
The solution: Broad ETFs eliminate concentration risk automatically. VAS holds ~300 companies; VGS holds ~1,500. You can diversify the world with two ETFs.
6. Trying to Time the Market
The mistake: Waiting for the “right time” to invest, expecting to buy at the bottom. Holding cash while waiting for a better opportunity.
Decades of research shows that the average investor cannot consistently identify market tops and bottoms. Time in the market consistently beats timing the market.
The solution: Invest regularly (DCA) or invest available capital promptly. Holding excess cash in a savings account while waiting for a pullback typically underperforms immediate investment.
7. Neglecting Superannuation
The mistake: Ignoring super during working years — leaving default investment options, not checking employer contributions, not considering salary sacrifice.
Super is Australia’s most tax-advantaged investment structure (15% tax on income and gains in accumulation; 0% in pension). Neglecting it for 10–20 years is an extremely costly mistake.
The solution: Check your employer is paying SG contributions correctly (11.5% of salary in FY2024–25). Consider salary sacrificing additional contributions. Review your super investment option — many default Balanced options may be too conservative for younger investors.
8. Poor Tax Planning
The mistake: Selling assets after holding them 11 months (missing the 50% CGT discount), not using franking credits, ignoring asset location.
The solution: Hold assets 12+ months before selling. Maximise Australian shares (with franking) in personal accounts. Hold bonds and international shares in super where possible. Understand your CGT position before making sell decisions.
9. Not Having a Written Investment Plan
The mistake: Investing without a clear strategy — no target allocation, no rebalancing rules, no review schedule.
Investors without a plan are more likely to make emotional decisions: chasing performance, panic selling, over-trading.
The solution: Write a simple investment policy statement: target allocation, what you’ll buy, how often you’ll contribute, when you’ll rebalance, when you’ll review. It need not be long — even one page creates accountability.
10. Overcomplicating the Portfolio
The mistake: Holding 15–20 ETFs covering overlapping themes, individual shares, crypto, gold, REITs, and infrastructure — creating a portfolio too complex to manage effectively.
The solution: Two to three broad ETFs cover the world adequately. Complexity adds cost, maintenance, and often worse outcomes. Simple portfolios are easier to rebalance, easier to understand at tax time, and easier to stay disciplined with.
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Frequently Asked Questions
What is the biggest mistake Australian investors make? Panic selling during market downturns is consistently cited as the most damaging investor behaviour — converting temporary paper losses into permanent losses and missing recoveries. Ignoring super (especially salary sacrifice opportunities) is a close second for long-term wealth destruction.
Is it too late to start investing if I’m in my 40s or 50s? No — a 45-year-old investing for 20+ years still has a meaningful time horizon for growth. Starting late is far better than not starting. The key priorities at this stage are maximising super contributions and building outside-super investments simultaneously.
How many ETFs should I hold in a beginner portfolio? Two well-chosen ETFs (such as VAS + VGS) provide adequate global diversification for most investors. Adding a third for bonds (VAF) is a sensible step for investors approaching retirement or with conservative risk tolerance. Beyond three or four funds, marginal diversification benefit diminishes rapidly while complexity increases.
This article provides general financial information only. For advice tailored to your situation, speak with a licensed financial adviser through the ASIC financial advisers register or MoneySmart.