Will OpenAI’s market cap be less than $500B at market close on IPO day?

Prediction markets put the probability at 5%: Will OpenAI’s market cap be less than $500B at market close on IPO day. Currently, markets see this as unlikely (5% YES).

What’s Happening

Anthropic filed a confidential S-1 prospectus with the U.S. Securities and Exchange Commission on Monday, June 1, 2026, formally entering the IPO pipeline days after closing a $65 billion Series H at a $965 billion post-money valuation. The Claude maker's listing announcement positioned it ahead of rival OpenAI in the race to public markets, with Anthropic's valuation now eclipsing OpenAI's most recent $122 billion funding round, which itself accounted for nearly 46% of U.S. venture capital deployment in its quarter. Annualized revenue at Anthropic crossed $47 billion in May 2026, up from $30 billion earlier in the year and $10 billion twelve months prior — a trajectory underwriters are referencing when modeling OpenAI's own debut. [Forbes, Jun 1]

The question of whether OpenAI's market cap be less than $500B at market close on IPO day sits against a private-market benchmark that already exceeds that floor by a wide margin. OpenAI's last primary round priced the company at levels well above the $500 billion threshold, and underwriters have signaled a listing range consistent with — or above — that mark. Historical precedent from mega-cap tech debuts including Meta (2012), Alibaba (2014), and Saudi Aramco (2019) shows first-day closes typically print at or above the upper end of the indicative range when demand is oversubscribed. Bloomberg reported that SpaceX's planned June 2026 listing may absorb institutional allocation ahead of the AI debuts, though analysts note the AI cohort's revenue growth profile is distinct. [Bloomberg, Jun 1]

PitchBook characterized the upcoming SpaceX-OpenAI-Anthropic trifecta as the most consequential venture liquidity event in recent memory, noting that "in a normal year, three listings would not determine the fate of the entire venture asset class, but in 2026, they might." Whether OpenAI's market cap be less than $500B at market close on IPO day hinges on final pricing decisions from lead underwriters, allocation absorption following SpaceX's debut, and macro conditions including the 10-year Treasury yield and equity-risk-premium dynamics at listing. Adweek noted Anthropic's filing "tests investor appetite" for the AI cohort, framing OpenAI's subsequent debut as a referendum on the sustainability of private-market AI valuations now exceeding $900 billion on the secondary tape. [Investordaily, Jun 1]

Traded on Polymarket — $276K Volume

Polymarket prices this at 5c YES with $276K in volume. Moderate liquidity — use limit orders for positions above $1K to avoid moving the price.