A leaked document reveals that Microsoft is the biggest investor in OpenAI, with a stake worth over $228 billion. The initial $13 billion investment, followed by another $10 billion four years later, is now worth $228.3 billion. Microsoft, which has a 26.79 percent stake in the AI research and development company, is expected to make even more rich if OpenAI goes public. The biggest surprise is that CEO Sam Altman, who launched OpenAI as a nonprofit in 2015, has no equity in the company. The company's ongoing nonprofit entity, the OpenAI Foundation, also thrived.