The Prediction Markets

OpenAI IPO closing market cap above ___ ?

Closes
Jan 1, 2028, in 15 months
Traded
$1.6M
Venues
Polymarket
Prices updated
just now
Share

What the markets expect

800B 72.2%

Next is 1T at 66.5%. Only Polymarket lists this market, so there is no second price to compare.

Odds by venue

Consensus blends each venue’s last price, weighted by how much has traded there. 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. Ages are as of when this page was built.

  • Polymarket
800B
72.2%
Polymarket 72.2%polled, 43s agoBest Yes 72.4¢ on Polymarket, $100 pays $138 (1.38x)
Polymarket
Contract
800B
Last price
72.2%
As of
Polled just now
Buy Yes
72.4¢
Sell Yes
72¢
$100 on Yes pays
$138 (1.38x)
Volume
$128K
Trade this on Polymarket
1T
66.5%
Polymarket 66.5%polled, 43s agoBest Yes 68¢ on Polymarket, $100 pays $147 (1.47x)
Polymarket
Contract
1T
Last price
66.5%
As of
Polled just now
Buy Yes
68¢
Sell Yes
65¢
$100 on Yes pays
$147 (1.47x)
Volume
$1.1M
Trade this on Polymarket
1.2T
59%
Polymarket 59%polled, 43s agoBest Yes 71¢ on Polymarket, $100 pays $141 (1.41x)
Polymarket
Contract
1.2T
Last price
59%
As of
Polled just now
Buy Yes
71¢
Sell Yes
47¢
$100 on Yes pays
$141 (1.41x)
Volume
$251K
Trade this on Polymarket
1.4T
47%
Polymarket 47%polled, 43s agoBest Yes 52¢ on Polymarket, $100 pays $192 (1.92x)
Polymarket
Contract
1.4T
Last price
47%
As of
Polled just now
Buy Yes
52¢
Sell Yes
42¢
$100 on Yes pays
$192 (1.92x)
Volume
$74K
Trade this on Polymarket
1.6T
32%
Polymarket 32%polled, 43s agoBest Yes 33¢ on Polymarket, $100 pays $303 (3.03x)
Polymarket
Contract
1.6T
Last price
32%
As of
Polled just now
Buy Yes
33¢
Sell Yes
31¢
$100 on Yes pays
$303 (3.03x)
Volume
$56K
Trade this on Polymarket
2T
30%
Polymarket 30%polled, 43s agoBest Yes 56¢ on Polymarket, $100 pays $179 (1.79x)
Polymarket
Contract
2T
Last price
30%
As of
Polled just now
Buy Yes
56¢
Sell Yes
4¢
$100 on Yes pays
$179 (1.79x)
Trade this on Polymarket
1.8T
22%
Polymarket 22%polled, 43s agoBest Yes 40¢ on Polymarket, $100 pays $250 (2.50x)
Polymarket
Contract
1.8T
Last price
22%
As of
Polled just now
Buy Yes
40¢
Sell Yes
4¢
$100 on Yes pays
$250 (2.50x)
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.

  • 800B
  • 1T
  • 1.2T

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
—
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

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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 (economics rate). Fee calculator. Estimates only, not advice.

About this market

Live prediction market odds for "OpenAI IPO closing market cap above ___ ?". 800B leads at 72.2%. Next is 1T at 66.5%. $1.6M has traded across 7 outcomes on Polymarket. The market is expected to resolve by Jan 1, 2028.

This market will resolve to “Yes” if the official closing price for OpenAI's market capitalization on its first trading day is above the listed value. Otherwise, it will resolve to “No”. If no IPO occurs by December 31, 2027, 11:59 PM ET, this market will resolve to “No”. Market capitalization is defined as the total number of outstanding shares multiplied by the closing share price on the first trading day. 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.

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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