Alphabet shares fell as much as 5% on Wednesday after four of Google's most-cited researchers quit on the same day. The stock closed at $360.71, down 3.9% from Tuesday's close of $375.35, wiping out roughly $190 billion in market value. At its lowest point, the stock hit $355.16, erasing as much as $260 billion from the company's $4.61 trillion market cap.
Who left and where they're going
Jeff Dean, Google's chief scientist and a 27-year veteran, is leaving to co-found Discovery Loop, a public benefit corporation focused on automating machine learning, science, and engineering. Dean joined Google in 1999 as its 30th employee and co-created MapReduce and Bigtable. He is joined by three other researchers: Sanjay Ghemawat, Oriol Vinyals, and Quoc Le. Discovery Loop says it has three of the most-cited AI researchers and two of the most-cited in distributed systems.
Demis Hassabis is stepping away from daily control of Google DeepMind. He becomes chairman of DeepMind and chief scientist of Alphabet, while continuing to lead Isomorphic Labs. Koray Kavukcuoglu takes over as senior vice president of DeepMind, responsible for Gemini model development, frontier research, and the Gemini app.
Why the market reacted
Investors saw the departures as a blow to Google's AI leadership. The stock remains about 11% below its 52-week high of $404.47. A similar event happened on June 22, when Alphabet closed 5.1% lower after two researchers left: Noam Shazeer (to OpenAI) and John Jumper (to Anthropic). Shazeer was the second of eight authors on the 2017 transformer paper; Jumper shared the 2024 Nobel Prize in Chemistry with Hassabis.
Google CEO Sundar Pichai thanked Dean and said Google will support Discovery Loop. The company merged DeepMind and Google Brain in April 2023, with Dean becoming chief scientist in that merger.
The Gemini app has over 950 million monthly users. Hassabis told staff that Gemini 4 is coming. It will be the first flagship model shipped without Jeff Dean, who shaped Google's AI since 2011. Alphabet reported Q2 revenue of $119.8 billion, up 24%, with Google Cloud growing 82% to $24.8 billion. Operating margin was 34%.
Kavukcuoglu now leads the team that will deliver Gemini 4. The question hanging over the stock is whether the brain drain will slow down that release.
