Factbox-From SpaceX to Saudi Aramco: World’s biggest IPOs as Anthropic’s blockbuster listing looms

Sept 28 (Reuters) – Anthropic’s hotly anticipated US IPO is expected to be one of the largest debuts ever ​attempted and a major test of public-market appetite for the rapidly growing artificial intelligence industry.

The listing, which could value the Claude maker at about $2 trillion, would represent one of the most consequential stock ​market debuts in years, potentially reshaping benchmark indexes, investor flows and the broader narrative driving US equities.

A GLANCE AT WORLD’S BIGGEST IPOs

The biggest IPOs globally, ranked by deal size:

Here is an overview of some of the mega IPOs:

ANTHROPIC

Anthropic revealed in June that it had confidentially filed for a US IPO, setting the stage for what could ​become a watershed moment for Wall Street’s AI frenzy.

The AI heavyweight is seeking to raise as much as $100 billion that could value the artificial intelligence startup at around $2 trillion, Reuters has reported.

Anthropic posted a net loss of $42 billion in 2025 and is planning to spend $518 billion on cloud, computing and infrastructure obligations in coming years, according to its IPO prospectus seen by Reuters.

The Claude maker could push its IPO to after the November US midterm elections, with ​the elections not expected to have a major impact on the offering, Reuters reported in September.

The IPO has already been pushed back from earlier plans, with Reuters previously reporting that marketing was expected to begin in mid-October at the ​earliest.

Anthropic raised $65 billion at a post-money valuation of $965 billion in late ​May, putting it ahead of rival OpenAI.

OPENAI

OpenAI, which operates AI chatbot ChatGPT, revealed in June that it had confidentially filed for a ​US initial public offering.

The AI lab will not go public in 2026, CEO Sam Altman said earlier this month, citing safety concerns over artificial intelligence that render “unacceptable” even a 10% risk that AI could cause human extinction by decade’s end.

In May, the Sam Altman-led company fended off an existential court challenge from Elon Musk, simplifying the path for OpenAI to proceed with a stock market listing.

“We have not decided on timing yet; it may be a while because there are things we want to do that are likely easier as a private company. But it’s a complicated set of tradeoffs and this gives us the option to go public sooner if that ends up being best,” OpenAI had said in June.

OpenAI was laying the groundwork to go public in an offering that could value it at up to $1 trillion, Reuters previously ​reported.

SPACEX

Elon Musk’s rocket and satellite maker SpaceX made its historic stock market debut on the Nasdaq in June, shattering records and eclipsing Saudi Aramco’s 2019 listing by a wide margin to become the largest initial public offering ever.

At $75 billion, the IPO’s proceeds were more than double those of Saudi Aramco’s record-setting 2019 IPO.

SpaceX shares ended their first day of trading at $160.95 per share to bring its value to $2.1 trillion. The stock has since lost some of its momentum and closed at $148.68 on September 25, well above the $135 IPO price.

(Compiled by Arasu Kannagi Basil and Manya Saini in Bengaluru; Editing by Arun Koyyur and Maju Samuel)