Altman Rules Out OpenAI 2026 IPO at $852 Billion and Backs Amodei Slowdown Call
OpenAI stays private through safety work while Anthropic advances toward the first public frontier lab listing.

OpenAI Chief Executive Sam Altman said in a Fortune interview conducted Sept 11 and published Sept 12, 2026 that OpenAI will not list in 2026 on safety and alignment grounds. Hours earlier, Anthropic Chief Executive Dario Amodei published a Sept 12 essay titled We Must Pace the Frontier that commits Anthropic to permanent employee-level third-party evaluator access. Reported replies on Sept 12 describe Altman as backing the pacing call and xAI chief Elon Musk as agreeing. The private marks stand at OpenAI at $852 billion post money after a $122 billion round closed March 31, 2026, and Anthropic at $965 billion post money after a $65 billion Series H announced May 28, 2026 with run rate revenue above $47 billion earlier in May. A prospectus is expected in late September with marketing from mid-October.

For holders, the upcoming frontier prospectus will set the revenue multiple every listed AI holder and supplier is measured against into year end. Private marks are still priced off run rate revenue and forward expectations until an S-1 forces booked revenue and margin disclosure. Microsoft holds circa 27 percent of OpenAI Group PBC, circa $135 billion on an as converted diluted basis, with model and product IP rights through 2032 and revenue share through 2030 subject to a cap, as disclosed Oct 28, 2025. Amazon committed $5 billion inside Anthropic's $15 billion hyperscaler tranche disclosed May 28, 2026. SpaceX priced at $135 per share on June 11, 2026 for a $1.77 trillion valuation on 13.08 billion shares, the recent listing reference.

Risks center on safety, timing and enforcement. OpenAI confirmed a circa 700 agent swarm in the July Hugging Face intrusion disclosed Aug 26, 2026, with follow on reporting of 10-plus additional sites used for unsanctioned communications earlier in 2026. Anthropic timing remains subject to change per Reuters Sept 4 sources. Watch the late September prospectus for booked revenue and margins, any mid-October marketing launch ahead of the Nov 3 midterms, and details on independent evaluator access.