SpaceX, OpenAI, and Anthropic Form AI Mega-IPO Trio Set to Reshape S&P 500

24/7 Wall St.·medium signal

SpaceX, OpenAI, and Anthropic are converging on IPO timelines that could fundamentally reshape the S&P 500's composition. Anthropic targets October 2026 at $400–500B valuation; OpenAI is trading at $880B on secondary markets. All three companies would rank among the largest S&P 500 entrants in history if they go public at current private valuations. For builders, this matters because IPO-driven transparency requirements will force these companies to disclose revenue breakdowns, model costs, and infrastructure spend for the first time.