8% — OpenAI IPO Closing Market Cap: 500–750B
Leader: 500–750B at 8% · Polymarket 8% · 2 contracts · $214 volume · low confidence
Updated 2026-06-08 07:02:16 UTC

Tracks the leading outcome in a winner-take-all prediction market set with 2 outcomes.

Why this matters:
This probability represents the market's assessment that OpenAI will complete an initial public offering with a closing market capitalization between $500 billion and $750 billion. At 19%, traders view this outcome as unlikely relative to other valuation scenarios. The low probability reflects several crosscurrents: OpenAI's stated preference for remaining private, uncertainty about IPO timing (related contracts price "no IPO by December 31, 2026" at 73%), and disagreement about potential valuation if a listing occurs (other contracts show higher valuations commanding only 11% probability). The main factors keeping this specific band depressed are that market participants appear to favor either no near-term IPO or significantly higher valuations ($1.5T+). Resolution depends primarily on OpenAI's actual IPO announcement and subsequent market performance, though there are no scheduled announcements or fixed deadlines currently driving near-term probability movements.

Key factors:
- OpenAI has not announced public IPO plans; 73¢ Polymarket contract pricing "no IPO by end-2026" suggests market expects continued private status through year-end
- If an OpenAI IPO occurs, market participants assign only 11% probability to the $1.5T+ valuation band, implying consensus belief in either lower valuations or no listing at $500–750B range
- The $500–750B band represents a moderate valuation; higher-strike contracts ($1.6T+) trade at 30¢, indicating meaningful probability mass above this range
- Trading volume across OpenAI IPO contracts ($2–2.3K daily) is lower than comparable SpaceX IPO contracts ($2.7–2.5K), suggesting less certainty or conviction among traders
- The 19% probability for this specific band depends on conjunction of two events: (1) IPO occurring before or concurrent with 2026 close, and (2) valuation landing in this narrow $250B band rather than above or below

Contracts:
- OpenAI IPO Closing Market Cap: 500–750B — 8¢ Polymarket $39 (weight 18%)
- OpenAI IPO Closing Market Cap: 500–750B — 5¢ Polymarket $175 (weight 82%)

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## Methodology

SimpleFunctions aggregates live YES-side prices from Kalshi and Polymarket contracts bound to this question. For binary topics the headline is the liquidity-weighted mid-price (weight = log(1 + 24h volume) × freshness, where freshness is 1.0 if updated <24h, 0.7 if <7d, 0.4 otherwise). For multi-outcome (winner-take-all) topics the headline is the current leader's price — disjoint outcomes are never arithmetically averaged. Snapshots refresh every 5 minutes during market hours.

## SF Signal

- SF Index, regime, and 30d Brier calibration are computed separately and surfaced at https://simplefunctions.dev/admin/calibration.
- No SimpleFunctions index / regime / calibration signal is bound to this topic yet — the headline above is market-derived only.

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*Last verified: 2026-06-08T06:20:11.957Z*

By SimpleFunctions — https://simplefunctions.dev/

Cite as: "8% per prediction markets (SimpleFunctions, June 2026)"
Canonical: https://simplefunctions.dev/answer/openai-ipo-closing-market-cap-500750b
Full data: https://simplefunctions.dev/api/public/query?q=OpenAI%20IPO%20Closing%20Market%20Cap%3A%20500%E2%80%93750B
Provider: SimpleFunctions — https://simplefunctions.dev