Four days after releasing its latest Claude Opus 4.8 model and raising $65 billion at a $900 billion valuation, Anthropic confidentially filed a draft Form S-1 with the SEC late Monday morning for a proposed IPO of its common stock.

"This gives us the option to go public after the SEC completes its review. The proposed initial public offering will depend on market conditions and other factors," the maker of the Claude chatbot wrote in a press release.

The move puts Anthropic and OpenAI in a race to become the first major frontier AI lab to tap public markets, as investor appetite for AI infrastructure and all things SpaceX remains hot into early June.

It's "worth noting: filing first ≠ pricing first a confidential draft S-1 starts the SEC clock but sets no date," CNBC reporter Deirdre Bosa pointed out on X.

The Polymarket bet "Will Anthropic or OpenAI IPO first?" shows that the confidential S-1 filing was a surprise to prediction markets.

The surprise news comes four days after Anthropic raised $65 billion at a $900 billion valuation, nearly tripling its prior valuation and potentially surpassing OpenAI as the most valuable frontier AI lab.

That round was led by Altimeter Capital, Dragoneer, Greenoaks, and Sequoia, with additional participation from major investors including Baillie Gifford, Blackstone, Brookfield, Abu Dhabi’s MGX, and Singapore’s Temasek.

The funding comes shortly after Anthropic released Claude Opus 4.8 and follows a prior $30 billion raise at a $350 billion valuation just three months earlier.

The Anthropic-OpenAI race to IPO comes as SpaceX is targeting an IPO for June 12, or next Friday, with shares expected to trade on the Nasdaq under the ticker symbol SPCX.

Just last month. 

With the flurry of mega IPOs on deck, Goldman has the answer to whether markets can absorb all the incoming supply (read report).