**OpenAI's dominant 88.5% market-implied probability reflects its position as one of the two highest-valued remaining U.S. private companies following SpaceX's June 12 IPO.** Anthropic's late-May $65 billion Series H round at a $965 billion post-money valuation established it as the clear leader among U.S. privates, while OpenAI's March close of the record $122 billion round at an $852 billion post-money valuation (supported by ~$25 billion annualized revenue) locks in second place with limited room for other U.S. names to overtake it by month-end. The wide gap to the next tier—Stripe at roughly $159 billion and Databricks near $134 billion—explains why secondary candidates such as Epic Games, Anduril, Neuralink, or Perplexity carry negligible odds. xAI's February absorption into SpaceX further narrows the field. With resolution only weeks away and no major new rounds or tender offers announced in the interim, trader capital has coalesced around OpenAI as the near-certain third-largest U.S. private company by end-of-June valuation. The low probabilities on all other listed names underscore how concentrated recent AI-driven capital formation has become at the top of the private-company hierarchy.