Altman’s departure came as a surprise to people outside and inside the company. According to Bloomberg, Altman was still sending regular emails to employees as of late Friday morning. He had not shown any signs of trouble and had recently met with world leaders to discuss the responsible use of generative AI.

In October, reports indicated that OpenAI was in discussions to sell shares that would value the company at $86 billion. As for Altman, a Y-Combinator alum and a prominent figure in AI development, he has not yet issued a statement regarding his departure from OpenAI and his future plans. This is not the first turbulent chapter in OpenAI’s history. Founded with support from Elon Musk, the billionaire Tesla owner departed soon after. Rumors suggest Musk’s attempt to acquire the company was rejected, while he claims he disagreed with the company’s shift away from its non-profit focus.

In addition to his involvement with OpenAI, Altman is also an investor in other high-profile companies, including Humane, co-founded by former Apple executives, which recently launched its first AI-infused wearable product. He is also an investor in Neuralink, Reddit, Patreon, Asana, CodeAcademy, and InstaCart, among others. Neuralink is known for its development of human brain interface chip implants and has received FDA approval for human testing.