“Most Australian advised portfolios have never been stress tested for single name concentration at the index level,” Liptak explains. “What's coming is not a marginal shift but a structural one, and it's happening largely on autopilot.”

These changes in index inclusion methodologies by Nasdaq, S&P Dow Jones, and FTSE Russell mean that the top ten constituents of the S&P 500 could soon account for nearly half of the index's weight, up from around 40 per cent today. For Australian balanced portfolios, which typically allocate 20 to 25 per cent to international equities, this translates to a significant concentration of assets in a few mega-cap technology and aerospace companies.

“This level of concentration is something that most investors would never have consciously chosen,” Liptak adds.

The methodology changes are noteworthy. Nasdaq's revised rules, effective from May 1, 2026, allow newly listed top-40-by-market-cap companies to enter the Nasdaq 100 within 15 trading days. They have eliminated the minimum free-float requirement and permit up to a 3x float weighting multiplier for low-float stocks. Similarly, FTSE Russell has shortened post-IPO seasoning to five days, and S&P Dow Jones Indices is considering halving its seasoning period and waiving both the minimum investable weight factor and the four-quarter profitability test for the largest issuers.

Bloomberg Intelligence estimates that S&P 500 index funds would need to purchase nearly a fifth of SpaceX's available float within six months of its inclusion, with Russell 1000 and Nasdaq 100 trackers facing similar pressures.

“The risk is compounded by a layer of exposure that many advisers are failing to measure: indirect pre-IPO positions already sitting inside Australian superannuation funds’ private equity and venture capital allocations,” Liptak notes. “Super funds have been actively growing their PE and VC books, and a meaningful portion of that capital is deployed through global venture managers who hold late-stage positions in all three of these companies.”

The February 2026 funding round for Anthropic, which valued the company at $380 billion, saw participation from Coatue Management, Dragoneer, Founders Fund, Iconiq, D.E. Shaw, and others. These are the same managers that hold LP commitments from major Australian super funds, including Hostplus, AustralianSuper, and Australian Retirement Trust. SpaceX and OpenAI have similarly concentrated late-stage investor lists.

Critically, private positions do not unwind when the underlying companies list. Venture capital and private equity funds operate on 10 to 12-year horizons, meaning the pre-IPO exposure sits alongside new public market exposure. For some clients, post-IPO concentration may arise from three simultaneous sources: existing private market exposure through PE and VC, existing public market exposure through international equities, and additional mechanical exposure created by index inclusion.

Regulatory dynamics further entrench the problem. The Your Future, Your Super performance test, which benchmarks MySuper products against indices, has created a structural incentive for the largest Australian super funds to remain closely aligned with their benchmarks.

“The funds aren’t going to be the ones to push back against this,” Liptak asserts. “The mitigation will need to happen at the individual portfolio level.”

Liptak suggests five practical responses for advisers and allocators. The first is to measure look-through exposure across all vehicles, as most portfolios have not been constructed with aggregated single-name concentration in mind. Beyond measurement, he recommends updating concentration limits on a look-through basis, reassessing the passive-active mix in international equities, reconsidering the case for reducing home bias, and ensuring that alternative allocations provide genuinely differentiated exposure.

“Passive vehicles will automatically absorb whatever weight these companies get in the index. Active managers retain the discretion to underweight or exclude them. That makes the manager structure decision a direct portfolio call, not a neutral implementation detail,” Liptak explains.

“Within Datt Capital's investment universe, we view the structural characteristics of the Australian small and mid-cap segment as one practical diversification option. The universe of roughly 300 to 400 listed companies outside the ASX 50 is characterised by lower analyst coverage, less index-driven price formation, and returns more closely linked to business fundamentals than to global macro or index-flow dynamics,” he continues.

The Datt Absolute Return Fund and Datt Small Companies Fund are benchmark-aware but not benchmark-constrained, allowing portfolio construction to differ materially from index weights. This distinction becomes directly relevant for investors seeking to reduce automatic exposure to the largest US index constituents.

“We're not suggesting Australian small and mid-caps are a substitute for international equities - they're not. The more relevant point is that, in an environment where international equity exposure is becoming structurally more concentrated through factors beyond investors' control, the Australian small and mid-cap segment offers one of the few listed equity allocations that can provide a genuine structural offset,” Liptak concludes.