Anthropic vs OpenAI IPO Odds on Polymarket

As of 18 September 2026, Polymarket traders priced an Anthropic IPO before 2027 at about 88 percent, while an OpenAI listing by the end of 2026 was priced at an implied 4 percent (a market titled "Will OpenAI not IPO by December 31, 2026?" traded at 0.96). Those figures come from Allium's polygon.predictions dataset, which reads the USDC-denominated "Yes" token prices on Polymarket, a crypto-based prediction market where users buy and sell contracts that pay out based on real-world events. On Kalshi, a US event-contract exchange regulated by the Commodity Futures Trading Commission (CFTC), the same class of question can trade, but no comparable price figure is included here, so the numbers below are Polymarket only.

Two companies often grouped together as "frontier AI" labs are priced on very different timelines. A prediction-market price is not a verdict on which lab is better. It is a bet on timing, and sometimes on a very specific number attached to that timing.

One thing to state plainly before any of the numbers: neither Anthropic nor OpenAI has announced or filed for an IPO. Everything below is third-party market pricing, not company guidance.

Key takeaways

• As of 18 September 2026, Polymarket implied roughly 88 percent for an Anthropic IPO before 2027, up from about 71 percent 120 days earlier.
• An OpenAI listing by end-2026 implied only about 4 percent; a listing by 30 June 2027 sat closer to 53 percent.
• The line "Will OpenAI raise at least $100B in its IPO?" collapsed from 0.90 to 0.37 over 120 days, which is consistent with a repricing of deal size rather than timing.
• A Polymarket "Yes" token price approximates an implied probability but is not an exact one: fees, spread, and the cost of tying up capital all sit inside the number.
• These prices measure crowd belief. They do not predict outcomes, and nothing here is investment advice.

What a prediction-market price is saying

Buying a "Yes" contract works like a $1 bet settled by a public market. If a "Yes" contract trades at 88 cents, the crowd is pricing the event at 88 cents, an implied 88 percent. A contract that pays $1 on success is worth 88 cents to a buyer who thinks the event is about 88 percent likely: at that price, repeated over many identical bets, the buyer roughly breaks even before fees. When Anthropic's "IPO before 2027" contract sits at 0.88, traders are not saying Anthropic is a good company. They are saying they expect the event, an initial public offering, to happen inside a specific window.

That distinction explains the Anthropic-OpenAI gap. The Anthropic questions cluster tightly by date, and the price steps down as the deadline gets tighter:

The ladder steps down as the deadline tightens, which is what you would expect: a shorter window leaves less time for the event to happen. Two rows repay a closer look, though. “Anthropic IPO before 2027?” and “Will Anthropic IPO by December 31, 2026?” describe the same deadline and trade two cents apart, which is a spread between two separate markets rather than a difference in view. Traders are paying 79 to 88 cents across the ladder; they are haggling over exactly when.

Why OpenAI is priced as a distant event

OpenAI's ladder tells a different story. A listing by end-2026 read as roughly 4 percent, but a listing by 30 June 2027 traded at 0.53 (up from 0.38 about 120 days earlier). Put those together and the market is not saying OpenAI will never go public. It is saying the crowd does not expect it soon, and pushes most of the probability into 2027 and beyond.

Quoting that 4 percent without its end-2026 deadline is technically true and badly misleading. Timing is the entire story. Anthropic is priced as an imminent event; OpenAI is priced as a later and much less certain one.

The $100B line that collapsed, and why it is a different question

The largest move among the markets we looked at was not a timing bet at all. The market "Will OpenAI raise at least $100B in its IPO?" fell from 0.90 to 0.37. Over the same window, "Will OpenAI's IPO valuation be between $1.75T and $2.0T?" rose from 0.06 to 0.24.

Those two moves belong together. A timing market asks "does the event happen by date X?" A size or valuation market asks "if or when it happens, how big is it?" The $100B line collapsing does not mean traders think OpenAI is failing. It is consistent with the crowd repricing the structure of the deal rather than the fact of it: less confidence in a single, record-breaking $100B raise, and more probability spreading into specific valuation bands. Reading that fall as a sign the company is in trouble confuses the size of the bet with the fact of it.

This is the practical skill for reading any of these markets: separate the three questions a headline can blur. Does it happen? By when? How big? Each is a distinct contract with a distinct price, and they can move in opposite directions on the same day.

Reading the price without over-reading it

A "Yes" token trading at 0.88 does not mean the true probability is exactly 88 percent. The price also absorbs trading fees, the bid-ask spread, and the cost of locking up capital until the market resolves. A trader who has to tie up a dollar for a year to win a few cents needs compensation for that, and it shows up as a small drag in the price. Treat these numbers as a well-informed crowd estimate with friction baked in, not a laboratory-clean probability.

For contrast, the same dataset showed several other large private names priced in the 0.03 to 0.06 range for a listing before 2027 (as of 18 September 2026). Against that backdrop, Anthropic’s 0.88 is the highest-priced near-term listing among the pre-IPO markets we queried.

How these numbers get pulled off-chain and made comparable

Polymarket runs on Polygon, a blockchain that records every trade publicly, and each market is identified on-chain by a condition_id and its outcome by a token_id. To turn that raw ledger into a clean price history, the "Yes" token price for each market has to be matched to the correct market on both identifiers, filtered to remove resolved contracts (whose prices pin at 0 or 1) and non-IPO noise, and joined to a daily price series so you can see where a line was 120 days ago rather than only today. Get any of those joins wrong and you either double-count a market or read a resolved contract as a live signal.

Allium is a data infrastructure provider that normalizes on-chain Polymarket records into consistent fields (market, condition, token, outcome, USDC price, date) so a price history is comparable across hundreds of markets. Bloomberg has cited Allium data on SpaceX pre-IPO tokenized stock volume, a case where the raw onchain record needed careful reading before it meant anything. Allium is not a venue, exchange, or broker, and none of this is investment advice. Allium has or may seek commercial relationships with companies named here, including Polymarket, and Allium personnel may hold positions in the markets discussed.

For the mechanics of how the two markets differ structurally, see Kalshi vs Polymarket: two roads to the same bet, and for the wider pre-IPO pricing question, can you price an IPO before the IPO?

Frequently asked questions

What are the current Polymarket odds on an Anthropic IPO?

As of 18 September 2026, Polymarket's "Anthropic IPO before 2027?" market traded at 0.88, an implied chance of roughly 88 percent, up from about 71 percent 120 days earlier. Tighter deadlines priced lower: end-2026 at 0.86, mid-December 2026 at 0.83, and end-November 2026 at 0.79. Prices move, so treat these as a snapshot.

Why are OpenAI's IPO odds so much lower than Anthropic's?

The gap is about timing, not quality. As of 18 September 2026, an OpenAI listing by end-2026 implied only about 4 percent, but a listing by 30 June 2027 sat near 53 percent. The crowd expects OpenAI to go public later than Anthropic, so most of the probability lands in 2027 rather than 2026.

Why did the OpenAI $100B IPO market crash from 0.90 to 0.37?

That market asks whether OpenAI raises at least $100B in its IPO, a bet on deal size rather than on whether or when a listing happens. Over the 120-day window it fell from 0.90 to 0.37, while a specific $1.75T to $2.0T valuation band rose from 0.06 to 0.24. That is consistent with the crowd repricing the structure of the deal rather than the fact of it.

Do Kalshi and Polymarket show the same odds on these IPOs?

They can list similar questions, but the figures here are Polymarket only. Kalshi is a CFTC-regulated US event-contract exchange with its own market structure, fees, and participant base, so its prices can differ from Polymarket's for the same event. No Kalshi price figure is provided in this piece.

Does a Polymarket price equal the true probability of an IPO?

Not exactly. A "Yes" token price approximates an implied probability, but it also absorbs trading fees, bid-ask spread, and the cost of tying up capital until the market resolves. Read it as an informed crowd estimate with friction baked in, and remember these markets measure belief, not outcomes.

Where does this prediction-market data come from?

The figures come from Allium's polygon.predictions dataset, which reads Polymarket's on-chain records on Polygon. Each market is matched on its condition_id and token_id, filtered to remove resolved and non-IPO markets, and joined to a daily price series so you can compare today's price with where it sat 120 days earlier.

Interested in learning more about Allium’s prediction market data? Speak to someone on the team.