What 2026’s mega-cap AI listings mean for multi-asset portfolios

This feature was produced in partnership with AJ Bell.

As mega-cap AI IPOs reshape public markets, James Flintoft, Head of Investment Solutions at AJ Bell, explores the implications for multi-asset portfolios. Below, James highlights the growing influence of index construction, concentration risk and the need for active asset allocation as advisers navigate how and when clients gain exposure to the next wave of transformative listings

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The 2026 IPO window is shaping up to be less about the number of companies coming to market and more about their sheer scale. SpaceX’s record-breaking listing has already shown how a single company can challenge index providers, passive funds and portfolio constructors. The next wave could be even more relevant for advisers, with potential mega-cap listings from Anthropic and OpenAI, alongside SK Hynix’s planned Nasdaq ADR listing, bringing more of the artificial intelligence value chain into public markets.

For multi-asset portfolios, the challenge is not simply assessing whether these businesses are attractive investments. It is how, when and where clients gain exposure to them through multi-asset portfolios. That requires more than using indices as implementation tools. It requires understanding exactly how those indices are built, where risks are accumulating and when active asset allocation decisions are needed to keep portfolios properly balanced.

The striking feature of the 2026 IPO cycle is concentration. A ‘normal’ IPO market gives investors a broad pipeline of smaller and mid-sized businesses. This one is being dominated by a handful of very large companies linked to artificial intelligence, digital infrastructure, semiconductors and space-based communications.

That matters for multi-asset portfolios because the impact is not confined to stock pickers. Once companies of this size become eligible for major indices, they can quickly alter the shape of passive exposure. A client who owns a global equity tracker, a US equity tracker or a technology-heavy fund may gain exposure without making an active decision to buy the new listing.

That makes this a portfolio-construction issue rather than just a market-news story. Advisers need to know that the managers behind their multi-asset solutions are aware of the details: which indices are being used, how quickly new mega caps can enter them, what free-float or profitability rules apply, and whether apparently diversified portfolios are becoming more exposed to a narrow set of AI-related earnings streams.

The new route into AI exposure

Until recently, public-market exposure to artificial intelligence has largely come through listed enablers: Nvidia, Microsoft, Alphabet, Amazon and Meta in the US, TSMC in Taiwan, ASML in Europe, Samsung and SK Hynix in Korea, and China’s large internet platforms such as Tencent and Alibaba. Investors have owned the infrastructure, cloud platforms, semiconductor supply chain, applications layer and parts of the Chinese AI ecosystem, but have had limited direct access to the leading Western frontier AI labs themselves.

That could change if Anthropic and OpenAI come to market. Their expected listings would give public investors more direct exposure to foundation models, enterprise AI tools and consumer AI platforms. But that does not automatically make portfolios better diversified. In fact, it may do the opposite if those companies enter indices at very large weights while their revenues still depend on the same underlying demand for computational power, data centres and corporate AI adoption.

SK Hynix’s planned Nasdaq ADR listing is different, but just as relevant. It is already a major listed company in South Korea and one of the key suppliers of high-bandwidth memory used in AI systems. The proposed US listing, expected to raise around $29 billion, is designed to broaden its investor base and help fund semiconductor capacity expansion. AI exposure is therefore not just about software names. It also sits in memory chips, advanced packaging, power demand, data-centre infrastructure and supply-chain capital expenditure.

Why index rules matter

What matters in practice is not only whether a company lists, but which benchmark admits it first. Nasdaq, FTSE Russell, MSCI, CRSP and S&P do not all treat new listings in the same way. Some indices can include very large companies quickly if they meet size and liquidity requirements. Others apply profitability, trading-history or committee-based criteria that can delay inclusion.

That creates a gap between economic relevance and index ownership. A company can become one of the most valuable businesses in the world before it appears in a client’s S&P 500 tracker. Conversely, a global equity, Nasdaq or broader US market fund may pick it up much sooner.

This matters because many multi-asset portfolios use index funds or systematic building blocks underneath. But using indices does not make asset allocation passive. Two portfolios can both say they hold ‘US equities’ or ‘global equities’, while having very different exposures to new mega-cap IPOs depending on the index methodology, eligibility rules and rebalance schedule. The active decision is not only which market to own, but which index exposure is the most appropriate route into that market.

Why active asset allocation matters

There are three implications that active asset allocators need to manage. The first is concentration. US equity markets are already heavily influenced by a small group of technology and AI-related businesses. If Anthropic, OpenAI and other mega-cap AI names list at very high valuations, the concentration risk in global equity indices could rise further. That does not mean avoiding the theme, but it does mean being deliberate about how much of the portfolio’s risk budget is being allocated to it.

The second is overlap. A multi-asset portfolio may appear diversified across regions and asset classes, but the growth engine may still be linked to the same AI capital-expenditure cycle. US mega-cap software, Taiwanese semiconductors, Korean memory and Japanese automation can all be different expressions of the same underlying theme.

The third is sequencing. Early index inclusion can create forced buying from passive funds, but the initial free float of newly-listed mega caps may be limited. As lock-ups expire and index weights adjust, portfolios can acquire more exposure over time. The portfolio impact therefore can build gradually rather than appearing soon after the IPO date.

The adviser conversation

For advisers, this creates a valuable client conversation: how to capture the long-term AI opportunity thoughtfully, rather than simply chasing the first day of trading. Many diversified portfolios already have meaningful exposure through listed incumbents and the semiconductor supply chain, so the focus should be on ensuring that exposure is intentional, appropriately sized and balanced by assets that can behave differently if the AI cycle becomes more volatile.

That is where the multi-asset framework matters. Bonds and equity markets with little exposure to the AI theme, such as the UK, have a role if the dominant market narrative becomes too narrow. The fact that AI businesses are innovative does not remove the need for valuation discipline, diversification and risk control.

For investment managers, the task is to map where that exposure builds automatically, decide whether it is desirable at portfolio level, and use active asset allocation to manage the build-up of risk. Index funds can be efficient implementation vehicles, but they are not a substitute for judgement on valuation, concentration, regional balance and the overall role each asset class is playing.

The mega-cap IPOs and listings of 2026 are important because they are likely to change the public-market opportunity set. But they do not change the basic job of portfolio construction. Advisers still need multi-asset managers who can look through the index label, understand the construction rules underneath and make active decisions that capture long-term growth, all whilst managing valuation risk and avoiding over-reliance on a single market story.

AI may be the defining investment theme of this cycle, and the arrival of Anthropic and OpenAI would make it more visible in client portfolios. The role of multi-asset managers is to be across the detail of how that exposure enters portfolios, to decide how much is appropriate, and to ensure that visibility does not become accidental concentration.

For more information on AJ Bell’s range of multi-asset solutions, click here

This feature first appeared in the 2026 edition of Multi-Asset Fund Insights.

To explore the full report, please click here.