If you own a global or US index fund, you may be making a much bigger bet on artificial intelligence than you realise. That's one of the uncomfortable messages in the International Monetary Fund's latest Global Financial Stability Report. It names a sharp correction in AI-linked share prices as one of the most prominent risks facing the world's financial system.
This isn't a prediction that a crash is coming. It's a reminder that concentration risk tends to build quietly, and a good prompt to check what you actually own.
What the IMF said
According to coverage summarised by AI Affairs, citing The Guardian, the IMF's twice-yearly report highlights three prominent risks: an AI share-price correction, higher government borrowing costs and the threat of a major cyber-attack.
The key numbers are striking:
- Seven big technology stocks (Alphabet, Amazon, Apple, Meta, Microsoft, Nvidia and Tesla) now account for more than 35% of the S&P 500, up from 12% a decade ago.
- Their combined market value has risen by more than 50% over two years.
- Firms across the AI ecosystem accounted for roughly $21 trillion of the approximately $36 trillion rise in S&P 500 market value since late 2022, according to a separate IMF study.
The IMF warned that a fall in AI-related asset prices could spread well beyond the US. Asian markets would be most exposed outside the US, and investors in the UK and euro area could be hit through their US holdings.
Why the IMF is worried about how AI is financed
The report goes beyond high valuations. It points to the way AI companies are connected financially. A separate IMF study of 14 major US financing deals found about $300 billion of direct equity investment tied to $1.4 trillion in commitments for future revenue, averaging five years in length. Nine of those deals went on to attract more than $650 billion in additional debt.
In some of these arrangements, a tech company invests in an AI developer while also buying computing services from it. That ties the investment to expected sales within the same sector. If AI revenue disappoints, the IMF warns, companies could struggle to meet their commitments, and losses could spread across connected businesses.
The study also found that smaller GPU-focused cloud providers, sometimes called "neoclouds", had leverage above 600% and negative profitability. And it noted that the three largest private AI model companies were collectively valued at more than $2 trillion in August 2026, against combined revenue of less than $75 billion.
The IMF also identified borrowing by AI companies, hedge fund positions and retail investors borrowing to buy AI shares as possible sources of forced selling in a downturn.
Why index investors are more exposed than they think
Index funds weight companies by market value. When a handful of firms grow enormous, they automatically take up a bigger share of the fund. Someone who bought a "diversified" S&P 500 tracker a decade ago now has about a third of that money in seven companies, all closely tied to the same technology theme. Many global index funds are also heavily weighted to US stocks, so the same concentration carries over.
There's nothing wrong with owning these companies. Many are highly profitable. The issue is whether your portfolio reflects a choice you made deliberately or a drift you never noticed.
How to check your own concentration
- Look through your funds. Most fund providers publish top-ten holdings. Add up how much of each fund sits in the largest tech names.
- Count overlaps. A US index fund, a global fund, a tech fund and a few individual shares can all hold the same seven companies. Add them up across all your accounts.
- Include your job. If you work in tech, your income and perhaps your share options are already tied to the sector.
- Compare to your plan. Decide what share of your portfolio you're comfortable having in one theme, and see how far you've drifted.
Ways to spread risk, if you decide you need to
- Rebalance gradually towards your target mix rather than making one dramatic move.
- Consider equal-weight funds, which hold each company in an index in the same proportion. That reduces the influence of the biggest firms, though such funds behave differently and may cost more.
- Broaden geographically and by sector with funds covering smaller companies, other regions or less tech-heavy industries.
- Keep a bond and cash buffer sized to your time horizon, so you're never forced to sell shares in a slump.
- Avoid borrowing to invest in a single theme. Leverage is exactly the kind of thing the IMF flagged as an amplifier.
What not to do
Don't sell everything because of one warning. The IMF publishes risk assessments regularly, and markets can stay concentrated, or keep rising, for years. Timing a correction is notoriously hard, and selling out of the market can mean missing gains. The aim is balance, not panic.
A quick example
Imagine someone with half their portfolio in a US index fund, a quarter in a global fund and a quarter in a technology fund. Each looks reasonable on its own. Added together, though, the same handful of mega-cap companies may make up well over a third of everything they own, far more than they would have chosen deliberately.
The bottom line
The IMF's message is about resilience. AI may well transform the economy, but enthusiasm, borrowing and tangled financing deals can turn a normal pullback into something more painful. A short review of what you own, followed by a calm rebalance if it's needed, is the most practical response.
Disclaimer: This article is for general information and education only. It is not financial advice. Consider your own circumstances and speak to a qualified adviser before making investment decisions.
