Anthropic IPO by September 30, 2026? Market Prices 99.8% No After Missed Deadlines

What is happening now

Polymarket’s “Anthropic IPO by __?” event is a date ladder: a cluster of individual deadline markets under one umbrella, each asking whether Anthropic shares will be listed on a public exchange by a specific date. Three earlier deadlines have already closed and resolved No with 100% certainty — June 30, July 31, and September 15. As of September 19, the September 30 deadline market is effectively settled as No at a 99.8% No price, meaning traders overwhelmingly expect no listing before the end of this month.

What makes this event notable is how the probability curve behaves across the remaining open deadlines. Rather than a flat distribution, the market shows a steep ramp: near-term No prices above 94%, but Yes prices climbing steadily as the deadline extends further into late 2026.

How the market is structured

This is a date ladder — multiple binary Yes/No markets grouped under one event, each with its own resolution date. The active markets and their leading outcomes are:

• September 30, 2026: No at 99.8% (Yes 0.2%) — effectively settled against
• October 15, 2026: No at 99.6% (Yes 0.5%)
• October 31, 2026: No at 94.6% (Yes 5.4%)
• November 15, 2026: No at 71.5% (Yes 28.5%)
• November 30, 2026: Yes at 50.5% (No 49.5%) — the crossover point
• December 15, 2026: Yes at 60% (No 40%)
• December 31, 2026: Yes at 76.5% (No 23.5%)

Each market resolves Yes only if Anthropic shares are listed and trading on a public securities exchange by 11:59 PM ET on that date. Official SEC filings (e.g., Form S-1, Form 8-A), exchange listing confirmations, or official press releases serve as primary resolution sources. A critical override: if Anthropic is acquired by an already-public company, every market in the ladder resolves No immediately regardless of listing status.

Path to the leading outcome

The near-term markets (September 30 through October 31) are dominated by No, with implied probabilities ranging from 94.6% to 99.8%. For a trader buying No on these dates, the path is straightforward: no S-1 filing, no exchange listing, and no official announcement of an IPO opening before the deadline. Three prior deadlines already closed No, establishing a consistent pattern.

The leading outcome shifts at the November 30 mark, where Yes edges ahead at 50.5%. The December 31 market carries the highest Yes probability at 76.5%. For the Yes side to win on these later dates, Anthropic would need to complete the full IPO process — SEC filing, roadshow, pricing, and first day of trading — within roughly the next 12 to 15 months. The market is effectively pricing a late-2026 or year-end window as the plausible timeframe if an IPO happens at all.

What could change the pricing

Several concrete events could shift these numbers:

• An SEC S-1 filing: The single most market-moving signal. A public filing would likely send October and November No prices collapsing toward zero as the listing timeline becomes concrete.
• Acquisition news: Any confirmed deal where Anthropic is bought by an already-public company would instantly resolve every market in the ladder to No, wiping out all Yes positions.
• Official IPO delay or cancellation statements: A credible announcement that Anthropic is postponing or abandoning public listing plans would push all remaining Yes prices lower.
• Exchange listing confirmations or press releases: Even without an S-1, a credible report of a target listing date could move specific deadline markets.
• Liquidity shocks: Current liquidity on the December 31 market sits at roughly $16,800, and November 15 at roughly $1,700. Large orders on these thinner books could move prices significantly independent of new information.

Editorial read

The date ladder structure here tells a clearer story than any single binary market could. Three consecutive No resolutions (June, July, mid-September) have already eliminated the first three quarters of 2026. The September 30 market at 99.8% No is a formality. What matters is the shape of the ramp from October through December: the market is not pricing an IPO as imminent, but it is pricing one as plausible in the November–December window if the process accelerates sharply.

Volume concentration reinforces this. The October 31 market has the highest 24-hour volume at roughly $93,500, and the September 30 market leads total volume at over $1.05 million — traders are actively repositioning around the near-term No settlements. By contrast, the December 31 market, despite carrying the highest Yes probability at 76.5%, has only about $16,800 in liquidity, meaning execution risk on that side of the trade is non-trivial. The crossover at November 30 (50.5% Yes) is the market’s central statement: if an Anthropic IPO happens, it likely lands in the final two months of 2026. But the market has not yet committed to that outcome with high conviction, and the acquisition override remains a binary risk that no amount of IPO momentum can survive.

All prices reflect Polymarket data as of September 19, 2026, 18:32 UTC. Prediction market prices are not guarantees of objective probability. Verify resolution rules before trading.