OpenAI leads trader sentiment at an 85% implied probability for the second-largest private company by valuation at end-August 2026, driven by its March 2026 $122 billion funding round at an $852 billion post-money valuation and sustained momentum in large language model development. SpaceX’s June IPO removed it from private rankings, leaving OpenAI and Anthropic—the latter at a $965 billion May valuation after its own $65 billion round—as the primary contenders. Anthropic’s confidential IPO filing and recent model releases create uncertainty around its private status, while OpenAI’s scale, Microsoft partnership, and revenue trajectory support market expectations it will hold or extend its positioning among remaining private AI firms. Key near-term catalysts include any additional funding announcements or regulatory signals before month-end.