OpenAI IPO closing market cap above $1T?

What this market is about

The event is OpenAI’s first trading day after an IPO, if one happens before December 31, 2027. The market resolves “Yes” only if the company’s official closing market cap on that first day is above $1 trillion, using outstanding shares multiplied by the closing share price. If OpenAI does not IPO by the deadline, or if the official closing-price data is not available, the market follows the rules laid out on the page, including using the next trading day with an official close if needed.

Why the market exists

OpenAI is one of the most closely watched private companies in the market, so there is real uncertainty around what its public valuation would be on day one. The threshold is unusually high, which makes the question less about whether an IPO happens and more about whether the market assigns a trillion-dollar value immediately after listing. Readers are effectively watching whether public-market demand and the final share count produce a valuation above that line.

What can move the price

The biggest drivers are the implied valuation in any IPO filing, the number of shares offered, and how the stock trades once public. Any official disclosure about the offering size, pricing range, or expected share count could change expectations materially because the market cap formula depends on both price and shares outstanding. Trading conditions on the first day also matter: a strong opening, a weak close, or a suspended or shortened session can change the official closing value that determines resolution.

How to read the current probability