Will OpenAI’s market cap be between $500B and $750B at market close on IPO day?

Prediction markets put the probability at 12%: Will OpenAI’s market cap be between $500B and $750B at market close on IPO day. Currently, markets see this as unlikely (12% YES). Initial Public Offerings (IPOs) - Latest News and Updates - WSJ.com.

What’s Happening

OpenAI is preparing to confidentially file for a U.S. initial public offering "in the coming weeks," according to a source familiar with the matter, with reports indicating a filing could land as soon as Friday, May 22, 2026. The ChatGPT maker was last valued at $852 billion in its most recent private round, a level that already sits above the upper bound of the $500B-$750B band tracked by this market. The filing follows OpenAI's successful defense against Elon Musk's court challenge two days earlier, removing a key legal overhang that had previously deterred underwriters. [HuffPost, May 20]

The question of whether openai's market cap be between $500b and $750b at market close on ipo day hinges on the pricing gap between last-round private valuation and first-day public demand. Recent AI listings show aggressive upward repricing on debut: Cerebras Systems priced its IPO at $185 on May 14, 2026, and closed at $311 — a 68% pop — finishing day one at a standard market cap of $67 billion, the largest IPO of 2026 to date. Applied to OpenAI's $852B last mark, a comparable first-day move would push the close well above $1 trillion, structurally outside the $500B-$750B range. [Motley Fool, May 15]

Comparable late-stage private peers reinforce the upside skew: SpaceX is targeting a June 12 listing at a valuation north of $1.5 trillion following its February xAI merger at a $1.25 trillion combined mark, while Anthropic is raising another $30 billion at a $380 billion level ahead of its own expected float. For openai's market cap be between $500b and $750b at market close on ipo day to resolve YES, underwriters would need to price roughly 12-41% below the last private round and avoid any first-day pop — a setup inconsistent with the demand seen across AI chip and platform listings this cycle. Confidential S-1 filing details and the indicative price range remain the next catalysts. [CNBC, May 20]

Traded on Polymarket — $151K Volume

Polymarket prices this at 8c YES with $151K in volume. Moderate liquidity — use limit orders for positions above $1K to avoid moving the price.