OpenAI IPO Closing Market Cap: 750B–1T

30-day trend

Analysis

This contract asks whether OpenAI will conduct an IPO with a closing market capitalization between $750 billion and $1 trillion. At 22%, the market assigns roughly a one-in-five probability to this outcome. The low probability reflects two competing uncertainties: whether OpenAI will go public by December 31, 2026 (market-priced at 27%, based on the inverse of the 73¢ "no IPO" contract), and—conditional on an IPO occurring—whether the valuation will land in this specific band rather than higher or lower. The primary driver is timing: OpenAI has not announced IPO plans or a regulatory filing as of May 2026. If the company signals intent to pursue public markets before year-end, probabilities across all valuation tiers would shift materially. The secondary driver is valuation expectations. Current pricing suggests markets view outcomes above $1.5 trillion as more likely (11¢) or outcomes below $750 billion as plausible. A narrowing of this range through management guidance or market comps would clarify which strike is most likely. The $750B–$1T band sits in a middle zone with limited current conviction.

• ›OpenAI has made no public IPO announcement or SEC filing as of May 2026; any confirmation of IPO intent before Q4 2026 would be the primary probability mover
• ›Comparable AI company valuations (e.g., recent funding rounds, public comps like Nvidia) will anchor investor expectations for a closing price; current $1.5T+ pricing suggests skepticism about the midpoint band
• ›The 73¢ price on 'no IPO by December 31, 2026' implies only ~27% near-term IPO probability, making the $750B–$1T outcome dependent on an already-unlikely near-term listing at a specific valuation
• ›Recent market volatility and interest-rate expectations affect IPO appetite and valuation multiples across AI infrastructure; this band's specificity makes it sensitive to market-wide repricing
• ›Contractual settlement will require verified IPO closing documents; ambiguity around what "closing market cap" means (first-day close vs. prospectus valuation) could affect dispute resolution

What moved the line

• Jun 1750B–1T↑8pp14→22¢ · Polymarket
• May 31750B–1T↓7pp21→14¢ · Polymarket
• Jun 2750B–1T↓6pp22→16¢ · Polymarket
• May 30750B–1T↓5pp26→21¢ · Polymarket

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These markets stopped trading. Last odds and any captured outcome are shown above — full settlement detail lives at the venue.

How we compute these odds