Is Anthropic’s $100bn IPO a warning sign for investors?

The biggest initial public offering (IPO) in history is coming, with Anthropic’s stock market debut on the way. Could it be a warning sign for investors?

Comparisons with 1999’s dotcom mania, when a flood of new listings hit the market, are common. The obvious counterpoint is that, unlike most dotcom-era hopefuls, companies such as Anthropic already generate billions in revenue, with soaring demand for their products.

However, 2026 leaves 1999 in the dust in one respect – the amount of money raised in public listings.

DataTrek Research’s Nicholas Colas notes 476 companies went public in 1999, raising $65 billion, or just over $130 billion (€116 billion) in today’s prices. Contrast that with SpaceX alone raising $85.7 billion when it went public in June. Anthropic’s IPO is expected to raise $100 billion.

All too many of 1999’s IPOs were duds, but it also included companies such as Goldman Sachs, UPS, BlackRock and Nvidia.

[ SpaceX falls back to Earth after IPO frenzyOpens in new window ]

Indeed, Nvidia’s subsequent success more than compensated for the many failures; one spectacular winner can more than make up for a multitude of Pets.coms.

Things were crazy in 1999 but the sheer number of offerings gave investors more chances to find long-term winners, says Colas. In contrast, today’s market “puts a lot of eggs in a limited number of baskets”.

And even if SpaceX and Anthropic – and perhaps OpenAI in 2027 – live up to the hype, enormous starting valuations leave less room for investors to hit the jackpot.

Additionally, mega-IPOs tend to be disappointing affairs, with JPMorgan data showing that shares in the 18 largest US IPOs underperformed the S&P 500 by a median 30 percentage points in their first year.

[ Anthropic says its AI technology ‘could pose catastrophic or existential risk to humanity’Opens in new window ]

Ominously, the S&P 500 itself returned a median of just 3 per cent in the year following these mega-IPOs, compared with a long-run average of nearly 10 per cent.

That is no guarantee of a downturn, but it suggests the biggest debuts may be a warning sign for the wider market.