High valuations are only part of today’s market risk. Concentration, leverage and links between public and private markets deserve equal attention.

It is tempting to assess today’s financial markets by asking a familiar question: are valuations approaching the extremes seen during previous bubbles?

That comparison is useful, but it does not tell the whole story.

The more important issue is how risk has become concentrated across equities, debt and private markets. AI-related investment sits at the centre of much of that concentration.

For accountants and advisers watching economic conditions, the lesson is straightforward. Headline market multiples need to be considered alongside where capital is flowing, how investment is financed and how risks could spread.

AI has created an unusual concentration of market value

The AI investment cycle is one of the clearest examples.

A relatively small group of large technology companies now represents a substantial share of US equity market value and returns. Unlike many companies associated with the dot-com bubble, today’s largest technology businesses can also be highly profitable and cash-generative.

That distinction matters. But profitability alone does not remove valuation risk.

The concern is the scale of expectations being placed on future AI spending and returns. Large capital commitments are flowing through hyperscalers, semiconductor businesses, data centres and related infrastructure.

This creates a question that goes beyond whether AI will prove economically useful.

Can the eventual returns justify the amount of capital currently being committed?

If expected corporate returns fail to materialise, the consequences may reach beyond individual technology businesses. Hardware suppliers, data centres, energy providers, software businesses and financial markets are increasingly connected to the same investment cycle.

Market concentration can disguise wider risk

Traditional valuation measures also point towards historically expensive US equities.

Measures discussed during the webinar included cyclically adjusted price-to-earnings ratios, forward earnings multiples and market capitalisation relative to GDP. Several are at levels that invite comparisons with previous market peaks.

However, aggregate figures require care.

The current market is highly concentrated. A relatively small number of companies can therefore have an unusually large influence on index valuations and performance.

There is also an important geographical distinction.

UK and European equity valuations are less stretched than their US equivalents on some measures. Their indices contain greater exposure to sectors such as banks, energy, mining, consumer staples and industrial businesses, with less representation from the largest technology companies.

That does not make these markets immune to a global correction. It does mean the valuation story is not uniform.

The present excess appears particularly concentrated in US mega-cap technology and AI-related assets rather than global equities as a single asset class.

Debt markets may provide an earlier warning

Equities are only one part of the picture.

Global debt has grown across governments, businesses, financial institutions and households. At the same time, higher interest costs make that debt increasingly expensive to maintain.

This creates a difficult policy problem.

Governments have historically provided support when financial crises threaten the wider economy. Higher sovereign debt and interest costs may reduce the room available for similar interventions during another major downturn.

Debt markets can also respond to deteriorating conditions before equity investors do.

That makes movements in government bond yields, corporate credit spreads and credit risk particularly important when assessing whether financial stress is spreading.

The issue is therefore not simply how expensive equities have become. It is whether apparently separate risks across equity and debt markets are becoming connected.

Private markets add another layer

Private equity and private debt deserve similar attention.

When portfolio companies cannot be sold at acceptable valuations, investment managers can delay exits or move assets through continuation vehicles and secondary transactions.

These structures can serve legitimate purposes. But repeated recycling of assets can make underlying valuations and eventual exit prospects harder to assess.

Borrowing against portfolio valuations can add another layer of risk.

Commercial real estate has already demonstrated what can happen when underlying asset values face substantial pressure. Other private-market assets may encounter similar challenges if exits remain difficult or financing costs stay elevated.

For accountants advising businesses or assessing financial exposures, transparency matters as much as the headline valuation.

This is not simply another dot-com bubble

Historical comparisons are useful, but the current environment has its own characteristics.

Many technology leaders today have substantial revenues, profits and cash flows. That makes a direct comparison with speculative technology companies from the late 1990s incomplete.

At the same time, today's risks extend across more interconnected areas.

AI capital expenditure, public equities, corporate borrowing, private markets and infrastructure investment increasingly overlap. Passive investment and leverage may also affect how quickly market movements spread during periods of stress.

The result is a market that can look healthier on conventional measures while still carrying substantial structural risk.

What should accountants take from this?

The practical lesson is not to predict the precise timing of a correction. Market timing remains extremely difficult.

Instead, look beyond individual headline indicators.

Consider concentration alongside valuation. Consider cash generation alongside capital commitments. Look at debt as well as equities, and examine the connections between listed companies, private markets and the wider economy.

Historical valuation measures can tell you when markets look unusual.

Understanding where the leverage, concentration and financial connections sit can tell you more about what might happen if conditions change.

Frequently asked questions

Are global stock markets currently in a bubble?

The webinar does not argue that all global markets are equally overvalued. Instead, it identifies particularly stretched valuations and market concentration in US equities, especially among large technology and AI-related companies. UK and European markets were presented as less stretched on some valuation measures. This makes the picture more complicated than describing global equities as one single bubble.

Why are investors comparing today’s market with the dot-com bubble?

High technology valuations and strong investor expectations around a transformative technology invite comparisons with the late-1990s dot-com period. However, there is an important difference. Many of today’s largest technology companies generate substantial revenues, profits and cash flows. The concern is therefore not simply whether these businesses are viable, but whether future returns can justify current valuations and investment levels.

Why is AI investment considered a financial-market risk?

The risk comes partly from the scale and concentration of investment associated with AI. Capital is flowing into areas including semiconductor manufacturing, data centres, computing infrastructure and related services. If expected returns disappoint, the effects could therefore extend beyond individual AI companies into suppliers, infrastructure businesses, lenders and investors exposed to the same investment cycle.

Does market concentration make stock markets more vulnerable?

Market concentration can increase vulnerability because a relatively small number of very large companies can drive a significant proportion of index performance and valuation. When market leadership becomes highly concentrated, difficulties affecting those companies can have consequences for investors who appear to hold broadly diversified index investments.

Are UK and European markets as highly valued as US equities?

Not according to the comparison presented in the webinar. UK and European markets were described as less stretched than US equities on some valuation measures. Their indices also contain different sector mixes, including greater exposure to banks, energy, mining, industrial companies and consumer staples. However, lower relative valuations would not necessarily protect them from the effects of a wider global market correction.

What market indicators can help identify unusually high valuations?

The webinar discusses several measures rather than relying on one indicator. These include cyclically adjusted price-to-earnings ratios, forward earnings multiples and comparisons between stock-market capitalisation and economic output. Such measures can provide historical context, but none can reliably identify when a market correction will occur.

Why does debt matter when assessing market risk?

Debt matters because financial risk is not confined to share prices. Governments, businesses, financial institutions and households can all face pressure when borrowing costs rise. High debt levels combined with higher interest costs may also constrain the ability of governments and businesses to respond when economic or financial conditions deteriorate.

Can bond and credit markets provide warning signs before equities?

The webinar suggests debt markets deserve close attention when assessing financial stress. Government bond yields, corporate credit spreads and changing perceptions of creditworthiness can reveal concerns about borrowing costs and repayment risk. These indicators should be considered alongside equity valuations rather than treating stock-market performance as a complete measure of financial conditions.

Why are private equity and private debt relevant to this discussion?

Private markets can make underlying financial risks more difficult to observe. When investments cannot be sold at acceptable valuations, managers may delay exits or use continuation vehicles and secondary transactions. Borrowing linked to portfolio valuations can add further risk. The webinar therefore argues that investors should consider liquidity, leverage and exit conditions alongside reported private-market valuations.

Could an AI-related downturn affect businesses outside the technology sector?

Potentially. The webinar's argument is that AI investment connects technology companies with semiconductor suppliers, data centres, energy infrastructure, lenders and other businesses. A significant reduction in investment or expected returns could therefore affect several connected sectors rather than remaining confined to companies directly developing AI products.

What should accountants and business advisers watch?

Accountants should look beyond headline equity indices when considering financial conditions. Relevant areas raised in the webinar include market concentration, corporate capital expenditure, debt and borrowing costs, credit-market conditions, private-market valuations and the connections between these areas. Together, they provide a broader view of financial risk than a single valuation multiple.

The contents of this article are meant as a guide only and are not a substitute for professional advice. The author/s accept no responsibility for any action taken, or refrained from, as a result of the material contained in this document. Specific advice should be obtained before acting or refraining from acting, in connection with the matters dealt with in this article. The information at the time of publishing was accurate and could be subject to final changes.