According to Charlie Bilello, OpenAI’s private valuation has reached about $500 billion (source: Charlie Bilello, X post on Oct 3, 2025). He adds that at this size, if OpenAI were public, it would be the 16th largest company in the S&P 500 by market capitalization (source: Charlie Bilello, X post on Oct 3, 2025). Bilello also notes the company’s valuation has expanded from roughly $28 billion to $500 billion in about two and a half years (source: Charlie Bilello, X post on Oct 3, 2025). For traders, these figures provide a high-profile benchmark for relative-value and sentiment checks across AI-exposed equities and AI-linked crypto narratives, grounded in the valuation numbers reported here (source for figures: Charlie Bilello, X post on Oct 3, 2025).