OpenAI sells shares at $500 billion and converts to a PBC

A secondary share sale of up to $10 billion completed on 2 October 2025 valued OpenAI at $500 billion, the highest of any private company at the time. On 28 October, with approval from the California and Delaware attorneys general, it became OpenAI Group PBC.

Why it mattered The restructuring ended years of argument over the hybrid nonprofit arrangement and left Microsoft with about 27 percent of the company and the OpenAI Foundation with 26 percent.