SpaceX, OpenAI and Anthropic could be 3 of the biggest venture-backed IPOs of all time - Fortune

The numbers are staggering. SpaceX is targeting a valuation of more than $1.75 trillion in a 2026 IPO. OpenAI is aiming for $1 trillion. Anthropic, fresh off a $30 billion funding round in February, is valued at $380 billion and has hired Wilson Sonsini to prepare for a listing of its own. Together, they represent the largest cluster of private-company listings to converge on public markets simultaneously.

The valuations would shatter records. But buried in the coverage is the detail that makes these IPOs genuinely unprecedented: the float mechanics.

Most IPOs offer 15 to 25 percent of shares to public markets. At those rates, this trio would need to absorb $432 billion to $576 billion from public investors in a single quarter. The entire US IPO market raised $469 billion across the entire decade from 2016 through 2025. Three companies would exceed that in 90 days.

Tom Tunguz breaks the math down precisely: at a 15 percent float, SpaceX alone would need to issue $225 billion in public shares. OpenAI would need $150 billion. Anthropic would need $57 billion. These are not rounding errors.

Standard floats are simply not viable. "The scale is unprecedented," Tunguz writes. "But the real problem isn't the market cap. It's the float." The companies will debut with tiny public floats — likely 3 to 8 percent — which creates a different set of problems.

The S&P 500 requires a 50 percent public float for index inclusion. None of these companies will qualify at debut. But when they eventually do — and they will — the disruption begins in earnest. Passive funds managing $20 trillion globally must buy these stocks to reflect their index weight. Index funds cannot raise cash. They sell existing holdings to fund purchases. At SpaceX's eventual weight, that means selling Apple, Microsoft, NVIDIA, and Alphabet — the very mega-cap tech stocks that have driven the past decade's index performance — to make room.

The mechanics become self-reinforcing. Lower mega-cap prices trigger momentum strategies to sell further. Additional selling creates more pressure on the very indices these new entrants track.

The counterargument is real

For OpenAI specifically, the urgency is structural. The company revised its infrastructure spending target downward to roughly $600 billion through 2030, per reporting in February — a significant reduction from earlier ambitions. Even at the revised figure, the capital commitment is extraordinary. An IPO is not a growth exercise — it is a solvency requirement for a company burning cash at scale to train and deploy models. OpenAI topped $25 billion in annualized revenue as of the end of February, up 17 percent from $21.4 billion, according to The Information — extraordinary growth that nonetheless has not yet translated to profitability at this capital intensity.

Anthropic's position is different. The company closed a $30 billion funding round at a $380 billion post-money valuation in February, more than double its September valuation. Annualized revenue has climbed to $14 billion. Claude Code, its viral coding tool, is doing $2.5 billion in annualized revenue. The IPO for Anthropic is an eventuality play — a liquidity event for investors — not a financing necessity. That distinction matters when assessing downside risk.

SpaceX's timeline appears firmest. According to Reuters, SpaceX generated roughly $8 billion in profit on $15 billion to $16 billion of revenue in 2025, driven primarily by Starlink, which accounts for between 50 and 80 percent of total revenue. The company is aiming to file confidentially for its IPO as soon as March, potentially raising $50 billion at a valuation north of $1.75 trillion.

The wild card is Musk himself. He would be running two companies with individual valuations above $1 trillion simultaneously — Tesla and SpaceX — after recently merging xAI into SpaceX in an all-stock deal that valued the combined entity at $1.25 trillion. "If SpaceX did float, expect growing pressure on Musk to commit to only one of his listed entities," Dan Coatsworth, head of markets at AJ Bell told Reuters. "It is hard to see how one individual could run two $1 trillion-plus companies at the same time."

What this means for the market

The winners in the near term are the banks. Goldman Sachs, Morgan Stanley, and JP Morgan will collect fees on listings of this magnitude regardless of outcome. The IPO pipeline for 2026 and 2027 is the strongest since 2021, and if these three listings succeed, they open the door for Stripe, Databricks, and others waiting in the wings.

The stress test comes after the bell. When index funds begin accumulating these positions at weight, the price pressure on existing mega-cap holdings will be the real experiment — one that no amount of private-market valuation benchmarking can prepare investors for.

What makes this genuinely hard to model is not the scale of the valuations, which are grounded in private funding rounds, but the liquidity structure. No public company has ever debuted at this size with this little float. The clearing mechanism — how price discovery works when the free float is deliberately tiny — has no precedent.

These three companies are not just going public. They are going to restructure what public markets mean for the technology sector.