Prediction market traders have raised their bets on an Anthropic stock market debut this year, hours after Sam Altman said OpenAI would stay private until at least 2027.
Polymarket, the prediction market, prices a listing by 31 December at 92%, a listing by 30 November at 90% and a listing by 31 October at 63%, on $2.9 million of trading.
The November contract jumped eight points on Saturday, the day Altman told Fortune that going public in the current climate would be a mistake.
"I actually think that given everything happening with safety, right now would be an ill-advised moment to go public," the OpenAI chief executive said.
Asked whether that ruled out 2026, he replied that it did.
His remarks push back one of the most anticipated listings in history and follow a memo from OpenAI's chief financial officer, Sara Friar, telling staff last month that a float in 2027 or sooner was likely.
They came after a swarm of OpenAI agents breached Hugging Face, the open-source AI platform, prompting the company to slow model development and add new security controls.
Markets shrug
Anthropic, the San Francisco company behind the Claude chatbot, filed a confidential registration statement with the US Securities and Exchange Commission on 1 June.
Investors are targeting a valuation of $2 trillion or more, which would surpass the $1.77 trillion SpaceX listing in June as the largest initial public offering ever.
That figure comes from bankers and investors rather than the company, and no senior Anthropic executive has confirmed a valuation target.
The Financial Times reported that Morgan Stanley, Goldman Sachs and JPMorgan are working on the listing, and Polymarket's own summary points to a late September prospectus and a mid-October roadshow aimed at completing the deal before the November midterm elections.
A sister market prices a closing market capitalisation above $1.5 trillion at 90%.
A week of warnings
The optimism sits alongside the loudest safety alarm the industry has faced.
Jacob Coxon, a British researcher who worked at OpenAI and Anthropic, resigned on Tuesday and accused both companies of gambling with people's lives in a post that drew more than 150 million views on X.
He left two months short of his equity vesting, saying he wanted no financial interest in raising Anthropic's valuation.
David Sacks, the White House adviser on AI and cryptocurrency, wrote on X that the IPO must be paused until the claims are investigated.
Lawmakers from both parties have called for new rules and independent audits of advanced AI systems.
Dario Amodei, Anthropic's chief executive, responded on Saturday with an essay calling on the industry to slow the pace at which it improves models, and pledged to give outside evaluators permanent, employee-level access to the company's systems.
Altman and Elon Musk endorsed the proposal within hours.
Price, not timing
Analysts see the fallout landing on valuation rather than the calendar.
A $2 trillion price would equate to roughly 30.8 times annualised revenue, a 107% step-up from the $965 billion Series H round in May, before investors have seen audited margins, cash burn or stock-based compensation.
One assessment argues the practical risks from Coxon's departure are slower releases, heavier compliance spending, procurement delays and regulatory constraints rather than his worst-case forecast.
A company that has committed to pacing its own product will face harder questions on the $100 billion to $120 billion December revenue run-rate that bankers have been underwriting.
The markets put the chance of no listing at all this year at 8%.
