SpaceX vs Anthropic: The $2.1 Trillion Bar for 2026's Biggest IPO
There is a number I keep coming back to this week, and it is not the one in the headlines. On Polymarket's "Largest IPO by market cap in 2026" market, the price on SpaceX climbed to 66.5% in the past week, up about 12 points, while Anthropic fell to 29.2%, down about 11 points. The trigger was not a filing or a roadshow date. It was a valuation whisper: a mid-October report that investors were now talking about roughly $1.5 trillion for Anthropic, down from the roughly $2 trillion figure that had framed the deal for most of the year.
The two deals make the comparison almost unfair, which is exactly why it is interesting. SpaceX went public on June 12, pricing at $135 a share, opening at $150 and closing its first session at $160.95 — a first-day market value of roughly $2.1 trillion, on a raise of about $85.7 billion including the underwriters' overallotment, the largest IPO on record. Anthropic, the maker of Claude, filed its S-1 confidentially in June, published it on October 26, and plans to list Class A shares on Nasdaq under the ticker ANT, with Goldman Sachs as lead-left bookrunner and Morgan Stanley alongside. Reports put the raise at up to $100 billion, the roadshow starting in the week of November 9, and pricing the week after. The business behind the pitch is genuinely large: third-quarter revenue of $16.8 billion, up 45% from $11.6 billion in the second quarter, against a last private valuation of $965 billion post-money in May.
Here is the detail that changes the arithmetic, and the one most coverage skips: the market resolves on market capitalisation at the official closing price on the first trading day, not on the valuation at pricing. SpaceX's bar is therefore not the $1.77 trillion figure quoted at its offer price. It is the roughly $2.1 trillion it was worth at the closing bell.
| The bar Anthropic must clear | Valuation | First-day pop needed to beat SpaceX |
|---|---|---|
| SpaceX, June debut | About $1.77 trillion at pricing | About $2.1 trillion at the first-day close — its own bar |
| Anthropic at $1.5 trillion | $1.5 trillion | About 40% |
| Anthropic at $2 trillion | $2 trillion | About 5% |
At $1.5 trillion, Anthropic would need a spectacular first day. At $2 trillion, it would need merely a good one. The whole contest, in other words, will be decided not by the roadshow's asking price but by what happens in the six and a half hours after the opening bell.
That is also why traders moved when they did. The $1.5 trillion talk landed alongside Anthropic's investor day in mid-October, just as the market was turning tougher on AI valuations — and just as SpaceX's own history supplied a warning. SpaceX has fallen as much as 54% from the high it hit days after its debut, and an analysis of the 30 most popular tech IPOs since 2012 found an average peak-to-trough drawdown of 55% in their first year. Hot debuts fade; the question is only how high the first-day close gets before the fade starts. There is also a quieter tail risk for Anthropic: one analysis has raised the possibility of a slip into December, and a slip past New Year's Eve would hand the title to SpaceX by default, since only IPOs completed in 2026 count.
My own reading sides with the market, narrowly. I put SpaceX at 65% to keep the crown — close to its 66.5% market price, because the arithmetic above is the market's arithmetic too. The roadshow in the week of November 9 is the genuine test: if institutions bid the deal back toward $2 trillion, a first-day pop of the kind SpaceX itself enjoyed would clear the bar, and I would revise quickly. Until then, the burden of proof sits with the challenger. SpaceX does not need to do anything at all to win this race. It only needs Anthropic's first day to be ordinary.