The Prediction Markets

OpenAI IPO Closing Market Cap

Closes
Jan 1, 2028, in 15 months
Traded
$537K
Venues
Polymarket
Prices updated
3 h ago
Share

What the markets expect

1.5T+ 47.7%

Next is No IPO by December 31, 2027 at 29.1%. Only Polymarket lists this market, so there is no second price to compare.

1.5T+ 47.7%No IPO by December 31, 2027 29.1%1.25T–1.5T 8.8%1T–1.25T 6.2%750B–1T 3.3%2 others 4.9%

Odds by venue

Fair chance strips out each venue’s built-in margin (its prices add up to more than 100%), then blends the venues by how much has traded there, so the outcomes add up to 100%. Best Yes price is the cheapest ask across venues, and the payout is what a winning $100 stake returns before fees. Open a row for each venue’s contract name, bid and ask, and how closely their rules match.

Prices come from our regular polls of each venue, the oldest 3 h ago. Ages are as of when this page was built.

  • Polymarket
1.5T+
47.7%
Polymarket 43.1%(47.7% fair)polled, 3 h agoBest Yes 44¢ on Polymarket, $100 pays $227 (2.27x)
Polymarket
Contract
1.5T+
Last price
43.1%
Fair, margin removed
47.7%
As of
Polled 3 h ago
Buy Yes
44¢
Sell Yes
42.2¢
$100 on Yes pays
$227 (2.27x)
Volume
$138K
Trade this on Polymarket
No IPO by December 31, 2027
29.1%
Polymarket 26.3%(29.1% fair)polled, 3 h agoBest Yes 26.5¢ on Polymarket, $100 pays $377 (3.77x)
Polymarket
Contract
No IPO by December 31, 2027
Last price
26.3%
Fair, margin removed
29.1%
As of
Polled 3 h ago
Buy Yes
26.5¢
Sell Yes
26.1¢
$100 on Yes pays
$377 (3.77x)
Volume
$94K
Trade this on Polymarket
1.25T–1.5T
8.8%
Polymarket 8%(8.8% fair)polled, 3 h agoBest Yes 9¢ on Polymarket, $100 pays $1,111 (11.1x)
Polymarket
Contract
1.25T–1.5T
Last price
8%
Fair, margin removed
8.8%
As of
Polled 3 h ago
Buy Yes
9¢
Sell Yes
7¢
$100 on Yes pays
$1,111 (11.1x)
Volume
$70K
Trade this on Polymarket
1T–1.25T
6.2%
Polymarket 5.7%(6.2% fair)polled, 3 h agoBest Yes 6.2¢ on Polymarket, $100 pays $1,613 (16.1x)
Polymarket
Contract
1T–1.25T
Last price
5.7%
Fair, margin removed
6.2%
As of
Polled 3 h ago
Buy Yes
6.2¢
Sell Yes
5.1¢
$100 on Yes pays
$1,613 (16.1x)
Volume
$89K
Trade this on Polymarket
750B–1T
3.3%
Polymarket 3%polled, 3 h agoBest Yes 3¢ on Polymarket, $100 pays $3,333 (33.3x)
Polymarket
Contract
750B–1T
Last price
3%
As of
Polled 3 h ago
Buy Yes
3¢
Sell Yes
2.9¢
$100 on Yes pays
$3,333 (33.3x)
Volume
$72K
Trade this on Polymarket
500B
2.5%
Polymarket 2.3%polled, 3 h agoBest Yes 2.8¢ on Polymarket, $100 pays $3,571 (35.7x)
Polymarket
Contract
500B
Last price
2.3%
As of
Polled 3 h ago
Buy Yes
2.8¢
Sell Yes
1.7¢
$100 on Yes pays
$3,571 (35.7x)
Volume
$44K
Trade this on Polymarket
500–750B
2.4%
Polymarket 2.2%polled, 3 h agoBest Yes 2.6¢ on Polymarket, $100 pays $3,846 (38.5x)
Polymarket
Contract
500–750B
Last price
2.2%
As of
Polled 3 h ago
Buy Yes
2.6¢
Sell Yes
1.8¢
$100 on Yes pays
$3,846 (38.5x)
Volume
$30K
Trade this on Polymarket

Who resolves this market

Polymarket
Polymarket resolves via:
UMA optimistic oracle

How the odds have moved

The top 3 outcomes on both venues, with the consensus between them. Hover for exact values.

  • 1.5T+
  • No IPO by December 31, 2027
  • 1.25T–1.5T

Order books

Each venue’s resting orders for the selected outcome’s Yes contract, side by side. Top of book streams live; depth refreshes every 15 seconds.

Polymarket

Open on Polymarket ↗

Top of book

Connecting
Best bid
—
Spread
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Best ask
—

Waiting for the first live quote…

Depth · top 8 levels

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Recent trades

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What your stake buys

Enter a stake to see where it buys the most after fees, using each venue’s live order book.

$
Buy

Loading both order books…

Buys at the asks resting now (taker orders), cheapest after fees first, from order-book snapshots up to 15 seconds old. Fees: Kalshi 0.07 × price × (1 − price) per share, rounded up to the cent; Polymarket 0.05 × price × (1 − price) per share (other / general rate). Fee calculator. Estimates only, not advice.

About this market

Live prediction market odds for "OpenAI IPO Closing Market Cap". 1.5T+ leads at 47.7%. Next is No IPO by December 31, 2027 at 29.1%. $537K has traded across 7 outcomes on Polymarket. The market is expected to resolve by Jan 1, 2028.

This market will resolve based on OpenAI's market capitalization at the closing price on its first day of trading. If no IPO occurs by December 31, 2027, 11:59 PM ET, the market will resolve to "No IPO by December 31, 2027". Market capitalization expresses the monetary value of a company’s outstanding shares, stated in its pricing currency. It is calculated as the number of shares outstanding multiplied by the closing share price on the first trading day. If the relevant value falls exactly between two brackets, then this market will resolve to the higher range bracket. Resolution will be based on the primary exchange’s official listing page. In the event that the relevant figure is not displayed, another reliable source will be used. In the event of an interruption in the course of the normal trading session on OpenAI’s first day of trading (e.g., a circuit breaker or half-day), the market will resolve according to the official closing price of the abbreviated session. If no such official closing price is published, the market will resolve according to the next trading day on which an official closing price is published, treating that as the first day of trading for purposes of this market.

Questions

What does the consensus price mean?

It is the price of a Yes contract that pays $1 if the outcome happens. A 14¢ price means traders put the chance near 14%. Where two venues list the same outcome, we blend their last prices, weighting the venue with more trading volume more heavily (neither counts for less than a quarter). When only one outcome can win, each venue’s prices add up to a little over 100% (its margin); the fair chance removes that margin so the outcomes add up to exactly 100%.

How is the payout worked out?

A Yes contract pays $1 if it wins, so at the best ask a $100 stake buys 100 ÷ ask contracts. At 18¢ that is about 555 contracts, paying $556 (5.56x) if Yes happens. Venue fees and price slippage on larger orders are not included.

Why do the venues show different prices?

Each venue has its own traders, fees and order book. Contracts can also settle on slightly different terms, which is why each row lists how closely the rules match.

Is a price gap an arbitrage?

Only when you can buy Yes on one venue below what someone pays for Yes on the other, after fees, and both contracts settle the same way. We show the executable bid and ask so you can check.

How fresh are these prices?

Venue prices refresh every few minutes, and the order book and live quotes stream continuously. Each venue’s card shows when we last observed it.

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