How the 2026 Budget Reopened the Diversification Debate

Recent discussions around the 2026 Federal Budget, portfolio diversification and global investing have prompted broader questions about how Australians allocate capital, the role of residential property in wealth creation, and whether domestic markets alone can meet the needs of a modern portfolio. Beneath each of those conversations, however, sits one of the oldest and most fundamental questions in investing: how should capital be balanced between concentration and diversification?

Every portfolio sits somewhere along that spectrum, whether intentionally or not. Some investors build wealth through large positions in a small number of assets they understand deeply, while others spread capital across multiple holdings, sectors and geographies to reduce dependence on any single outcome. Both approaches have generated exceptional results in different market environments, and both have produced disappointing outcomes when applied without discipline.

Diversification has often been described as the only free lunch in finance because it helps manage uncertainty and reduce reliance on any one investment theme, market or economic cycle. At the same time, some of the world’s most successful investors built extraordinary wealth through concentrated, high-conviction positions. Neither approach is inherently superior. Successful investing is often less about choosing concentration or diversification outright, and more about balancing conviction with risk management in a way that aligns with an investor’s objectives, time horizon and tolerance for volatility.

Australia Has Historically Rewarded Concentration

Australia’s investment environment has historically rewarded concentrated exposure. Residential property delivered strong long-term capital growth for decades, supported by favourable tax settings, declining interest rates and persistent housing demand. At the same time, the ASX benefited from strong banking profitability, commodity cycles and a stable domestic economy.

As a result, many Australian households gradually built portfolios concentrated in a relatively small number of themes:

• residential property
• domestic banks
• mining and resources
• Australian equities
• superannuation tied closely to local markets

That concentration often did not feel particularly risky because the strategy worked for such a long period of time. When an asset class consistently delivers strong returns across multiple economic cycles, familiarity gradually replaces caution.

This is one reason concentration risk can be difficult to recognise while conditions remain favourable. Many portfolios only appear concentrated once the environment supporting them begins to change.

The Case for Concentration

Concentration itself is not inherently negative. In many cases, it is precisely how significant wealth is created. Some of the most successful long-term wealth creators built their fortunes through highly concentrated positions. Warren Buffett famously argued that broad diversification is most necessary for investors who lack conviction or understanding, while many founders and entrepreneurs generated extraordinary wealth by committing capital heavily to a single business they knew intimately.

The logic behind concentration is compelling. If an investor genuinely possesses superior insight into a company, industry or asset, spreading capital too broadly can dilute the very advantage that justifies the investment. Concentrated portfolios may also offer stronger upside participation, greater simplicity and a deeper understanding of each holding.

But concentration demands a great deal in return. It requires not only conviction, but the ability to withstand sharp volatility, prolonged drawdowns and the possibility of being wrong. Even high-quality assets can experience severe declines when economic conditions, policy settings or market sentiment deteriorate. Concentrated portfolios can produce exceptional outcomes when conviction is well placed, but they can also magnify mistakes when assumptions prove incorrect.

This is the distinction often overlooked in discussions around concentrated investing. The issue is not that concentration is inherently wrong, but that it is rarely suitable as a default strategy without genuine expertise, discipline and risk tolerance.

For many households and portfolios, the challenge is not simply pursuing concentration, but recognising when concentration risk has developed unintentionally over time.

Diversification Is About Correlation, Not Just Number of Holdings

One of the most common misconceptions in investing is that diversification simply means owning a large number of assets. Academic research suggests the reality is more nuanced.

Studies by researchers including Edwin Elton and Martin Gruber found that a portfolio of roughly 20 to 30 reasonably uncorrelated stocks captures most of the diversification benefit available within an equity allocation. Beyond that point, additional holdings tend to reduce risk only marginally while increasing complexity, monitoring difficulty and transaction costs.

The critical detail, however, is correlation. Diversification is not determined by the number of holdings in a portfolio, but by how differently those holdings behave under varying market conditions. Adding another Australian bank to a portfolio already dominated by financials does little to diversify risk, even if the holdings count increases. The same applies to portfolios heavily concentrated in miners, property-linked exposures or domestic cyclicals.

This distinction matters particularly in Australia, where many portfolios carry overlapping exposures without fully recognising it. A household balance sheet consisting of residential property, Australian bank shares and employment income tied to the domestic economy may appear diversified on the surface, yet remains heavily exposed to the same underlying economic drivers, interest rate settings and policy conditions.

Concentration risk often becomes most visible when conditions change. During periods of market stress, assets linked to the same economic themes frequently move together, reducing the protection investors expected from holding multiple positions. Effective diversification, therefore, is not about owning more investments for the sake of it. It is about reducing reliance on a single outcome, sector, market or economic cycle.

What Genuine Diversification Looks Like in Practice

Effective diversification operates across multiple dimensions rather than within a single market or asset class alone. In practice, this may involve diversification:

• across sectors, reducing reliance on the performance of any one industry
• across geographies, recognising that economies and market cycles do not move in perfect synchronisation
• across asset classes including equities, fixed income, cash, infrastructure and alternatives
• across currencies and interest rate environments
• across liquidity profiles, balancing long-term growth assets with accessible capital

The distinction matters because portfolios with a large number of holdings can still remain highly concentrated beneath the surface. A portfolio containing dozens of Australian equities may continue to carry significant exposure to the same domestic economic conditions, banking system or commodity cycle. By contrast, a smaller portfolio spread across global equities, infrastructure, fixed income and alternative assets may provide broader diversification despite holding fewer individual positions.

This is why institutional portfolio construction tends to focus less on the number of holdings and more on the underlying risk factors driving returns. Large superannuation funds, sovereign wealth funds and family offices typically allocate capital across multiple asset classes, sectors and geographies to reduce vulnerability to policy changes, economic downturns, sector-specific weakness, regulatory shifts and interest rate cycles.

Diversification may not always maximise returns during periods when a concentrated investment theme is outperforming strongly. However, it can help portfolios remain more resilient across changing market environments and reduce the likelihood of long-term outcomes becoming overly dependent on a single investment thesis.

Finding the Right Balance

The strongest portfolios are rarely built around maximum concentration or maximum diversification. More often, successful long-term investing involves finding an appropriate balance between conviction and risk management.

Concentration and diversification are not inherently right or wrong. For investors with deep expertise, high conviction and the financial capacity to absorb significant volatility, concentrated positions may be entirely appropriate. For many other households and portfolios, broader diversification across asset classes, sectors and geographies remains the more reliable framework for managing long-term uncertainty.

The more important question is whether a portfolio is concentrated or diversified by design. Many Australian portfolios have gradually become concentrated through home bias, property exposure, sector weightings and inherited investment patterns rather than through deliberate strategic choice.

This is why many modern portfolios increasingly adopt “core and satellite” approaches. Core holdings may provide broad diversified exposure through domestic and international equities, ETFs or defensive assets, while smaller satellite positions allow for higher-conviction thematic or sector opportunities.

A balanced portfolio today may combine:

• Australian equities for income exposure
• Global equities for structural growth
• Fixed income for stability
• Infrastructure or alternatives for diversification
• Cash or liquid assets for flexibility

The appropriate balance ultimately depends on factors such as investment objectives, risk tolerance, liquidity requirements and time horizon. Younger investors with longer timeframes may tolerate greater concentration and volatility, while retirees often prioritise income stability, capital preservation and liquidity.

The objective is not maximum diversification, but diversification appropriate to the investor’s objectives, risk tolerance and broader strategy.



For those reassessing portfolio concentration, sector exposure or diversification opportunities, speak with an adviser to help clarify whether existing allocations remain aligned with broader long-term objectives. Concentration risk is often easiest to identify in hindsight. The portfolios that navigate changing market environments most effectively are usually those reviewed deliberately and adjusted before risks become fully visible.