Understanding financial correlations and what it means for investors

Damien Boey | WAM

Financial markets have never been so intrinsically linked. In today’s environment, understanding how different asset classes exist in relation to one another is more important than ever when constructing diversified investment portfolios. One of the biggest shifts that has emerged in markets is in the correlation between fixed income assets and equities and how that changes the way traditional portfolios behave.

From my perspective, we now operate in a market where bonds and stocks are increasingly moving in sync. Historically, investors have relied on bonds to act as a counterbalance to equities, providing a natural hedge in multi-asset portfolios. However, when bonds and equities rise and fall together, that diversification benefit breaks down.

This regime of positive – and indeed rising – correlation is making financial conditions more favourable for investors. What may appear positive: asset prices up, volatility down, is in fact proving to expose passive allocations more than ever before. Portfolio construction now requires a more considered approach. A passive fund effectively requires bonds and stocks not to move together. It needs them to move sufficiently out of sync to smooth out returns and mitigate risk in times of heightened volatility. When that doesn’t happen, structural vulnerabilities in these passive models begin to turn cracks into chasms.

With the meteoric rise in passive investing strategies seen in the past decade, investors need to think differently about diversification. What does this mean? It means incorporating assets that behave more independently of the traditional bond - equity complex. Commodities, for example, have historically shown lower correlation to both bonds and stocks and can offer investors a valuable source of diversification when the traditional playbook stops working.

How the levered basis trade fits in

Another feature of today’s markets that requires focus is the levered basis trade - an advanced strategy that, while hidden in the plumbing of the financial system, has become central to how market conditions are maintained.

In simple terms, this trade involves sophisticated players using leverage against safe assets to keep bond yields low, which in turn supports asset prices and, to some extent, broader economic activity. The great irony here is that high inflation and high inflation uncertainty are, via these mechanisms, helping to drive down bond yields.

Here’s how WAM Income Maximiser investment team think about it:
To meet higher yield demands, asset managers are pushed into areas like corporate credit. That flow of capital helps create conditions where hedge funds can exploit pricing gaps between futures and underlying bonds - the classic “basis” trade. This process, supported by significant leverage, suppresses yields and dampens volatility.

None of this works without central bank support. The Federal Reserve’s role in providing liquidity is critical. What we have today is, in my view, remarkably robust plumbing designed to make the global cost of capital a lot lower than it otherwise would be.

As a result of its complexity, investors don’t always see this plumbing, but it matters. Hedge fund leverage, futures markets and central bank backstops together create a powerful force shaping interest rates and asset prices. If this trade were interrupted in a meaningful way, we could see serious reversal pressure. For now, the system has held up, and that has been a key stabilising factor in global markets that we have observed.

Private credit, artificial intelligence, CapEx, and growth

A third area to be watching closely is private credit and its relationship with economic growth - particularly as it relates to capital expenditure cycles driven by artificial intelligence (AI).

Private credit is playing a growing role in the financial system. There are real concerns building in this space - about risk, opacity and the potential for stress - but our view is that it’s not the end of the journey just yet. We are are cautious, but not catastrophic.

One of the important marriages we are seeing is between private credit and the AI CapEx cycle. You cannot get the AI CapEx cycle going without private credit being healthy. Many of the projects and infrastructure builds required to power AI - data centres, networking, hardware build-outs - rely heavily on private funding channels, not just public markets and traditional bank lending.

That means if private credit were to come under significant strain, the knock-on effects wouldn’t just be financial - but in fact would flow on to economies more broadly. Growth expectations, especially in tech-heavy and AI-related sectors, could be downgraded if funding dries up or becomes much more selective and expensive.

So, when we think about risk today, we don’t just need to think about defaults or spreads; we need to think about how a more reluctant credit environment could reshape long-term growth paths in key sectors.

Putting it all together

When you step back, a few themes emerge from all of this:

• Bonds and equities are more correlated than ever before, undermining traditional diversification.
• Market plumbing - particularly the levered basis trade supported by central bank liquidity - is playing an outsized role in keeping financial conditions easy.
• Private credit sits at the crossroads of financial stability and future growth, especially in AI-driven investment cycles.

For investors, this means we can’t rely on old rules of thumb. A simple 60/40 portfolio is not a magic bullet solution. We need to think more deliberately about where diversification really comes from, how hidden leverage and liquidity structures impact risk, and how credit conditions intersect with long-term growth themes like AI and the infrastructure that supports it.

Resilience today, in our view, is about adaptability: recognising new correlation regimes, understanding the interaction between public and private credit and being willing to rethink portfolio construction for the decade ahead.

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All prices and analysis at 16 December 2025.  This document was originally published in Livewire Markets on 16 December 2025. This information has been prepared by Wilson Asset Management (International) Pty Limited (ABN 89 081 047 118)(AFSL 247333). The content is distributed by WealthHub Securities Limited (WSL) (ABN 83 089 718 249)(AFSL No. 230704). WSL is a Market Participant under the ASIC Market Integrity Rules and a wholly owned subsidiary of National Australia Bank Limited (ABN 12 004 044 937)(AFSL No. 230686) (NAB). NAB doesn’t guarantee its subsidiaries’ obligations or performance, or the products or services its subsidiaries offer.  This material is intended to provide general advice only. It has been prepared without having regard to or taking into account any particular investor’s objectives, financial situation and/or needs. All investors should therefore consider the appropriateness of the advice, in light of their own objectives, financial situation and/or needs, before acting on the advice.  Past performance is not a reliable indicator of future performance.  Any comments, suggestions or views presented do not reflect the views of WSL and/or NAB.  Subject to any terms implied by law and which cannot be excluded, neither WSL nor NAB shall be liable for any errors, omissions, defects or misrepresentations in the information or general advice including any third party sourced data (including by reasons of negligence, negligent misstatement or otherwise) or for any loss or damage (whether direct or indirect) suffered by persons who use or rely on the general advice or information. If any law prohibits the exclusion of such liability, WSL and NAB limit its liability to the re-supply of the information, provided that such limitation is permitted by law and is fair and reasonable. For more information, please click here.