OpenAI and Anthropic have both filed confidential S-1 registration statements with the SEC, setting up what could be the two largest AI IPOs in history. OpenAI's last private valuation was approximately $852 billion; Anthropic's was roughly $965 billion. When both companies list -- expected in the second half of 2026 -- all six members of the MANGOS index (Meta, Anthropic, Nvidia, Google, OpenAI, SpaceX) will be publicly traded for the first time.
The Fable 5 government shutdown throws a massive wrench into Anthropic's roadshow narrative. How do you pitch institutional investors on a $965 billion valuation when the federal government just demonstrated it can pull your flagship product in 72 hours? Anthropic's S-1 will need to include extensive risk factor disclosures around regulatory intervention, model recalls, and revenue concentration -- disclosures that didn't exist in any tech S-1 before June 2026. OpenAI faces similar scrutiny, though its model hasn't been subject to a government shutdown (yet). Both companies will be pitching growth in an environment where the regulatory ceiling is visibly lower than it was a month ago.
“The Fable 5 government shutdown throws a massive wrench into Anthropic's roadshow narrative.”
The scale of these potential IPOs is staggering in historical context. Two $800B+ companies going public in the same year would represent the largest tech liquidity event since the late 1990s. For comparison, the entire US IPO market raised $142 billion in 2021 -- the biggest year on record. OpenAI and Anthropic alone could match or exceed that in a single quarter. The downstream effects include massive secondary market activity, LP distribution events that could reshape fund recycling across the venture ecosystem, and potentially enough new public-market AI supply to satisfy institutional demand that's currently concentrated in Nvidia and Microsoft.
The timing chess game is critical. Neither company wants to go second -- the first mover captures the surge of institutional AI allocation, while the second mover faces potential allocation fatigue. Expect both companies to watch SpaceX's post-IPO trading closely as a demand signal, with the first to price likely targeting Q3 2026.