Alphabet NASDAQ:GOOGL fell 3.45% intraday after Jeff Dean, who joined Google 27 years ago and built much of its AI research operation, left to co-found a startup. Sanjay Ghemawat, Oriol Vinyals and Quoc Le went with him to Discovery Loop, a public benefit corporation working on machine learning and scientific research, Reuters reported. Google invested in it, and its cloud division agreed to supply computing capacity.

Alphabet also announced that Demis Hassabis is moving out of the DeepMind CEO seat. He becomes Alphabet's chief scientist, a newly created title, and DeepMind's chairman, with few direct reports and a focus on artificial general intelligence. Koray Kavukcuoglu, the unit's chief technology officer, takes over day to day as senior vice president rather than CEO. Alphabet gave no explanation for the departures or why they landed together.

The timing is awkward. The flagship version of Google's latest Gemini model still hasn't shipped after a planned June launch, feeding concern that the company is falling behind Anthropic and OpenAI. Noam Shazeer left for OpenAI in June, and Nobel laureate John Jumper joined Anthropic the same week.