Diversification means spreading your investments across multiple assets so that no single investment can destroy your portfolio. It is the most fundamental principle of managing investment risk, and the good news for Australian investors is that it has never been easier or cheaper to achieve — a single ETF can provide exposure to thousands of companies around the world.
The Core Idea — “Don’t Put All Your Eggs in One Basket”
If you invest all your money in one company and that company collapses (as happened with companies like One.Tel, ABC Learning, and Babcock & Brown in Australia), you lose everything. If you own shares in 200 companies, one failure might reduce your portfolio by 0.5% — an inconvenience, not a disaster.
This is the essence of diversification: spreading the risk of any individual investment’s failure across many holdings so the impact of any single disaster is manageable.
Types of Diversification
1. Diversification Across Companies
The simplest form — rather than owning one or two ASX stocks, you own hundreds. ETFs make this automatic.
- VAS (Vanguard Australian Shares ETF) holds approximately 300 Australian companies
- DHHF (Betashares Diversified All Growth ETF) holds approximately 8,000 companies globally
2. Diversification Across Sectors
Australia’s stock market is heavily concentrated in banking (CommBank, ANZ, Westpac, NAB) and resources (BHP, Rio Tinto, Fortescue). A portfolio made up of only ASX stocks is not well diversified across sectors — it is extremely weighted to financials and materials.
ASX 200 sector breakdown (approximate):
| Sector | Weight in ASX 200 |
|---|---|
| Financials | ~29% |
| Materials (mining) | ~22% |
| Healthcare | ~12% |
| Consumer discretionary | ~7% |
| Real estate | ~7% |
| Other | ~23% |
International ETFs add technology, consumer staples, industrials, and energy sectors that are underrepresented on the ASX.
3. Geographic Diversification
Investing only in Australian shares means 100% exposure to the Australian economy. If Australia experiences a specific economic shock (a property crash, a commodity price collapse, a recession), a globally diversified portfolio is partially protected.
International ETFs like VGS (Vanguard MSCI International Shares ETF) provide exposure to 1,500+ companies across the US, Europe, Japan, and other developed markets.
Approximate geographic exposure of a fully diversified global portfolio:
| Country/Region | Approximate share |
|---|---|
| United States | ~60–65% |
| Europe | ~15–20% |
| Japan | ~6–8% |
| Australia | ~2% |
| Other developed markets | ~5–10% |
| Emerging markets | ~10–15% |
4. Asset Class Diversification
Spreading across different types of assets — shares, bonds, property, cash — provides additional protection because different asset classes tend to respond differently to economic conditions. When shares fall sharply, bonds have historically maintained or increased in value (though this relationship broke down during the 2022 rate-rise period).
5. Time Diversification
Dollar cost averaging — investing regularly over time rather than all at once — provides a form of time diversification, reducing the impact of investing at a peak.
How Much Diversification Is Enough?
Academic research suggests that most of the benefit of diversification is achieved with approximately 20–30 stocks in a single market. However, a 20-stock portfolio is still concentrated in the Australian market. For true diversification, global ETFs holding thousands of companies are more effective.
Practically, for Australian retail investors:
- 1–3 broad market ETFs is sufficient for excellent diversification
- Adding more ETFs beyond 3 rarely adds meaningful diversification benefit
- Individual stocks add concentration risk unless you hold many of them
Diversification and the Australian Home Bias Problem
Most Australians are heavily over-weighted in Australian assets:
- Super fund in Australian shares option
- Own their home (large concentrated property asset)
- Non-super portfolio also in Australian shares
This “home country bias” is risky. Australia’s market represents only ~2% of global market cap but many Australian portfolios hold 50–100% Australian shares. International ETFs address this.
What Diversification Cannot Do
Diversification reduces company-specific risk (the risk any individual company fails) and sector-specific risk (a whole industry collapsing). It cannot eliminate market risk — the risk that all shares fall at once. In the 2008 GFC and March 2020 COVID crash, even well-diversified global portfolios fell 35–55%. Diversification reduced the damage of individual failures; it did not prevent the general market decline.
Related Articles
- Growth vs Defensive Assets Explained
- Asset Allocation by Age Australia
- Best ETFs Australia (2026)
- Home Country Bias Australia
- Getting Started hub
- Investing hub
Frequently Asked Questions
Is a portfolio of 5 ASX stocks diversified? Partially — 5 stocks is more diversified than 1, but not well diversified. With only 5 stocks, any one of them failing would impact your portfolio by 20%. Additionally, if all 5 are Australian, you have no geographic diversification. Most investing frameworks suggest broad market ETFs (holding hundreds to thousands of companies) as the baseline for genuine diversification.
Does diversification mean lower returns? Not necessarily. Diversification primarily eliminates idiosyncratic (company-specific) risk without necessarily sacrificing expected return. The academic concept of the Efficient Market Hypothesis suggests that diversifiable risk is not compensated — so you do not need to take on concentration risk to achieve strong returns. Removing concentration risk through diversification does not reduce expected return; it reduces the risk of catastrophic loss.
Should I diversify across Australian and international ETFs? For most Australian investors, including both Australian and international shares in a portfolio reduces concentration in a single market. All-in-one ETFs like DHHF and VDHG do this automatically. Whether a DIY approach (separate VAS and VGS) or an all-in-one ETF is better depends on your preference for simplicity versus control.
This article provides general financial information only. For advice tailored to your situation, speak with a licensed financial adviser. You can find one through the ASIC financial advisers register or MoneySmart.