Will OpenAI’s market cap be between $750B and $1T at market close on IPO day?

Prediction markets put the probability at 9%: Will OpenAI’s market cap be between $750B and $1T at market close on IPO day. Currently, markets see this as unlikely (9% YES). Switch between CA and NY editions here.

What’s Happening

OpenAI is preparing to confidentially file a draft of its IPO prospectus with the U.S. Securities and Exchange Commission as soon as Friday, May 22, 2026, according to people familiar with the matter, in what could rank among the largest public-markets debuts on record. The ChatGPT maker is working with bankers at Goldman Sachs and Morgan Stanley on the paperwork, with a filing window of days to weeks. The company was most recently valued at $852 billion in secondary markets, according to data cited on May 14, 2026, placing it just below the lower bound of the question on openai's market cap be between $750b and $1t at market close on IPO day. [CNBC, May 20]

The $750B–$1T band sits between OpenAI's last private mark of $852B and the trillion-dollar threshold that mega-cap tech debuts have historically cleared on day one. By comparison, SpaceX is tipped to go public at a valuation above $1.5 trillion as soon as June 2026 following its February merger with xAI at a combined $1.25 trillion, while Anthropic is reportedly in talks to match OpenAI's valuation in a new fundraise at $380 billion. IPO pricing typically settles 10–30% below the latest private round to leave room for a first-day pop, though high-demand AI listings have repeatedly cleared their reference price by double-digit percentages at the open. The S&P 500 closed at 7,405.33 on May 20, up 0.70%, with risk appetite intact heading into the filing window. [WSJ, May 20]

Confidential SEC filings typically precede a public S-1 by 4–8 weeks, with a roadshow and pricing following 2–3 weeks thereafter, placing a plausible market debut in the July–September 2026 window. The probability that openai's market cap be between $750b and $1t at market close on IPO day will depend on three variables: the final reference price set by underwriters, first-day demand absorption across institutional allocations, and aggregate AI-sector sentiment at pricing. With CEO Sam Altman targeting one of the largest debuts in history and secondary-market marks already at $852B, the narrow $250B band — requiring closing cap between openai's market cap be between $750b and $1t at market close on IPO day thresholds — represents roughly the bottom third of plausible day-one outcomes given comparable AI-sector first-day premiums. [NY Post, May 20]

Traded on Polymarket — $148K Volume

Polymarket prices this at 11c YES with $148K in volume. Moderate liquidity — use limit orders for positions above $1K to avoid moving the price.