By Clémence Rusek, senior investment strategist at Vontobel
A new wave of mega initial public offerings (IPOs) is set to dominate equity markets in 2026, driven in part by the artificial intelligence boom. SpaceX has completed a blockbuster IPO valued at $1.8trn, Anthropic and OpenAI are reportedly preparing for listings in 2026 and 2027 at valuations measured in trillions of dollars. Together, these offerings have the potential to mark one of the largest issuance cycles in market history.
The scale alone is enough to capture investor attention. If realised, the combined size of these AI-related listings could rival or even exceed some of the most iconic IPOs of the past decades.
The key question for investors is not simply how big these IPOs will be, but what they signal about the current stage of the equity cycle.
A surge in supply but not necessarily a market shock
At first glance, concerns about market absorption appear justified. A cluster of mega-cap IPOs and capital raises (Alphabet, Meta) arriving within a relatively short timeframe raises the spectre of equity supply overwhelming demand. However, the underlying data suggests otherwise. Proposed IPO structures are likely to involve only about 5% of total shares being floated initially, meaning the effective supply entering the market at listing may be considerably smaller than headline valuations imply.
Therefore, despite record headline figures, total expected equity supply is expected to represent only about 1% of total US market capitalisation, a level that remains below long-term averages. This suggests that from a purely technical perspective, markets are unlikely to face systemic pressure from new issuance alone.
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In other words, while individual deals may be unprecedented in size, the broader market has grown sufficiently large to absorb them. If the IPO wave does not overwhelm markets at launch, the greater risks may instead turn in what follows.
Lock-up expirations and liquidity dynamics
Liquidity dynamics after AI mega-IPOs will be crucial to monitor, particularly lock-up periods, which temporarily prevent insiders and early investors from selling their shares for 180 days after a listing. Historically, stocks often face pressure ahead of the expirations of these lock-ups, as markets anticipate an increase in tradable shares, before stabilizing once the additional supply is absorbed. This effect could be amplified for AI leaders given their concentrated insider ownership and large latent shareholdings. Companies such as SpaceX are trying to mitigate the impact through phased share releases.
A familiar pattern: strong starts, weaker follow-through
Another important consideration is post-listing performance. While IPOs often generate strong initial trading momentum, historical outcomes are less encouraging over the medium term.
Across multiple market cycles, IPOs have tended to deliver negative or underwhelming returns in the three years following their debut. One reason is that companies deliberately choose to go public when private-market enthusiasm is at its strongest and growth expectations are highly optimistic. Once public discipline forces more transparency, valuations often compress.
According to a study by Goldman Sachs, the companies that do succeed after listing share a consistent set of characteristics:
- sustained and credible revenue growth,
- a clear path to profitability, typically within two years,
- and valuation discipline at entry, with more moderate multiples supporting better long-term outcomes.
In the context of AI mega-IPOs, this raises an important red flag. While the growth story is compelling, valuations are already stretched, leaving little room for disappointment. The SpaceX debut may be exemplifying this. While the offering’s two-times oversubscription and post-listing peak showed that market appetite for structural growth and AI remains fierce, the stock has now retreated from its initial highs.
IPO waves as sentiment indicators
Perhaps the most important insight lies not in the mechanics of IPO supply, but in what IPO waves tend to signal about the broader market environment. Historically, periods marked by large, high-profile IPOs have often coincided with peaks in market optimism.
From the late stages of the dot-com boom to the SPAC-driven surge of 2020-21, strong issuance cycles have frequently preceded periods of weaker equity performance. This does not mean IPO activity causes market downturns. Instead, heavy issuance tends to emerge when investor optimism and liquidity are abundant, conditions that have historically preceded periods of weaker market performance.
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When capital is abundant and confidence is high, companies rush to list at ambitious valuations, and investors are willing to absorb them. Over time, however, this can lead to excesses as expectations outpace fundamentals. Artificial intelligence adds another layer of complexity to the current IPO cycle. Like previous waves of transformative technologies, AI has become a powerful investment narrative. Its perceived long-term potential has reinforced investor enthusiasm and could lead to an even greater concentration of capital in a small number of high-profile companies.
The common thread: Financial conditions
The question, therefore, is whether these IPOs represent the beginning of a new growth era or the culmination of an exceptionally favorable market environment. The common thread of these past equity downturns were not the large IPOs themselves but a subsequent tightening in financial conditions.
Whether through higher interest rates, tighter credit, or reduced liquidity, markets typically turned when the environment that had supported elevated valuations began to change.
As a result, investors should pay close attention not only to IPO activity, but also to the path of interest rates, liquidity conditions, and economic growth.
Summary: What it means for investors
The upcoming wave of AI mega-IPOs is unlikely to disrupt markets through sheer size alone. Supply, while large in absolute terms, remains manageable relative to the overall equity universe.
Instead, the implications are more subtle and potentially more important:
First, investors should expect episodic volatility, particularly around lock-up expirations and secondary share releases.
Second, dispersion will increase. Not all AI companies will deliver on expectations, and the gap between winners and underperformers is likely to widen. The key challenge will be distinguishing between:
- companies that can translate AI leadership into sustainable economic value,
- versus those that primarily benefit from narrative-driven valuation expansion.
Third, investors should closely monitor the evolution of financial conditions. History suggests that major IPO waves often coincide with periods of abundant liquidity and strong risk appetite, while many of the subsequent market downturns were triggered by tighter monetary policy, rising interest rates, or weakening growth. As a result, the path of financial conditions may ultimately matter more than the IPO activity itself.
