The chief scientist is leaving after 27 years, taking Sanjay Ghemawat, a Gemini co-lead and a Google Brain founding member with him. Demis Hassabis steps back from running DeepMind on the same day. Alphabet shares fell.
Summary
Jeff Dean is leaving Google after 27 years to found Discovery Loop, a public benefit corporation applying AI to scientific and engineering discovery. Three senior colleagues are joining him. Demis Hassabis becomes Alphabet’s chief scientist and chairman of Google DeepMind, stepping back from day-to-day leadership, with Koray Kavukcuoglu taking over. Alphabet shares fell around 4 to 5% on the announcement.
Key Takeaways
- Jeff Dean is leaving Google after 27 years to found Discovery Loop
- Three senior Google AI researchers are joining him, including a Gemini co-lead
- Discovery Loop is a public benefit corporation applying AI to scientific discovery
- Google is a founding investor and Cloud partner
- Demis Hassabis becomes Alphabet chief scientist and chairman of Google DeepMind
- Koray Kavukcuoglu takes over day-to-day DeepMind leadership, reporting to Pichai
- Alphabet shares fell around 4 to 5% on the news
- Google Cloud revenue grew 82% year over year in the second quarter
What Was Announced
CEO Sundar Pichai set out the changes in a memo posted to Google’s blog. Three moves at once:
| Person | Change |
| Jeff Dean | Leaves Google after 27 years to found Discovery Loop |
| Demis Hassabis | Becomes Alphabet chief scientist and chairman of Google DeepMind |
| Koray Kavukcuoglu | Becomes SVP of Google DeepMind, taking day-to-day leadership |
Hassabis retains his position as CEO of AI drug discovery subsidiary Isomorphic Labs and says he will focus on developing artificial general intelligence.
Kavukcuoglu reports directly to Pichai, overseeing Gemini model development, frontier AI research, the Gemini app and Google’s AI developer platforms. He remains Google’s chief AI architect.
The Detail Most Coverage Buries
Dean is not leaving alone. Discovery Loop’s founding team is four senior Google AI people.
- Jeff Dean — chief scientist across Google DeepMind and Google Research
- Sanjay Ghemawat — Google Senior Fellow, instrumental to TensorFlow, Bigtable and Spanner
- Oriol Vinyals — VP of research and deep learning lead at Google DeepMind, and a Gemini co-lead
- Quoc Le — Google DeepMind fellow and a founding member of Google Brain
Vinyals is the one to notice. A co-lead of Gemini departing while Google is preparing Gemini 4 is a materially different event from a distinguished veteran retiring into a startup.
Between them, these four span Google’s distributed computing foundations, its machine learning framework, the Brain project and its current frontier model programme.
What Discovery Loop Is
A public benefit corporation focused on using AI to automate experimental workflows across science and engineering.
The stated aim is a system that can propose, execute and analyse thousands of experiments in parallel — compressing research cycles that have historically depended on sequential human work.
The company says its approach could help address nearly all 14 Grand Challenges identified by the US National Academy of Engineering.
Google is a founding investor and Cloud partner. Pichai confirmed the arrangement publicly and said it had been “a privilege to work with Jeff and Sanjay.”
That structure matters. This is not a competitive defection — Google keeps equity and the compute contract.
Who Jeff Dean Is
Dean joined Google in 1999, among the company’s earliest employees, when it had roughly 25 staff.
His contributions run underneath most of what Google became: the distributed computing architecture that made web-scale search possible, the Google Brain project, and co-invention of TensorFlow — one of the foundational platforms of modern deep learning.
In his farewell message he recalled a childhood ambition of building software used by millions, noting Google now operates 13 products with more than a billion active users each.
His posted message to colleagues: “It has been an absolute pleasure to work with you and to help build some of the most widely used and impactful products of all time.”
A discrepancy worth noting: at least one outlet observed that Dean’s initial post on X did not thank Google or mention his 27 years, calling the omission unusual — while another reported him expressing gratitude for those 27 years. He appears to have posted more than once. Anyone citing the tone of his farewell should check the original posts rather than secondhand characterisations.
The Market Reaction
Alphabet shares fell around 4 to 5% on the announcement.
That is a substantial move for a leadership change at a company posting the numbers Google currently is. Google Cloud revenue rose 82% in the second quarter to $24.8 billion — against 37% growth at AWS and 43% at Azure. Pichai attributed it to AI infrastructure demand, helped by the company’s own tensor processing units.
The drop suggests investors read the announcement as something other than a routine succession.
The Context Behind It
Google’s position in AI is strong commercially and contested technically.
Reporting indicates Google’s best models have fallen behind OpenAI and Anthropic in coding, a category that has become central to how frontier models are judged and monetised. The company is counting on Gemini 4, described as a “much larger” foundation model currently in training. No release date has been announced.
The announcement also came a day after Google unveiled three new Gemini models.
Against that backdrop, losing a Gemini co-lead while restructuring AI leadership is timing worth noting rather than a coincidence to be assumed.
Who Is Koray Kavukcuoglu
The person actually running Google DeepMind day to day now.
He has been at DeepMind for 13 years, since its early days. He started the deep learning team and led work on WaveNet and DQN — respectively a breakthrough in speech synthesis and one of the foundational results in deep reinforcement learning.
Pichai’s framing: “Koray has been at DeepMind since its early days, and over his 13 years there, he has started our deep learning team and led the way on breakthroughs like WaveNet and DQN. I look forward to seeing him lead GDM into this next chapter.”
He was previously DeepMind’s CTO and remains Google’s chief AI architect.
Expert Analysis
Read as a single event rather than three, this looks different.
Google announced the departure of its chief scientist, the step-back of its DeepMind CEO from operational leadership, and the exit of a Gemini co-lead plus two other senior researchers — simultaneously. Any one of those is a normal corporate development. Together they represent a substantial change in who is making technical decisions at Google’s AI operation.
The reassuring reading is that this is orderly succession. Hassabis moves up rather than out and takes the chief scientist title. Kavukcuoglu is a 13-year internal veteran, not an external hire. Google is investing in Discovery Loop and serving as its cloud provider, which is not how companies treat departures they resent.
The less reassuring reading is what the share price did. A 4 to 5% fall at a company whose cloud division just grew 82% suggests investors are weighing the loss of technical leadership against strong financial performance and the technical loss won.
The specific concern is Vinyals. Gemini co-leads do not leave in the middle of training the model expected to close a competitive gap unless something has changed. Nothing in the public record explains it, and it may be entirely benign.
On Dean himself: twenty-seven years at one company is a full career, and Discovery Loop’s premise AI systems proposing and running experiments in parallel is exactly the problem someone with his background would find more interesting than another model release. The founding team is unusually strong for a new venture. That is worth watching independently of what it means for Google.
Frequently Asked Questions
Why is Jeff Dean leaving Google?
To found Discovery Loop, a public benefit corporation using AI to automate experimental workflows across science and engineering. Google says the departure is on friendly terms and is investing in the venture as a founding investor and Cloud partner.
Who is going with him?
Sanjay Ghemawat, a Google Senior Fellow central to TensorFlow, Bigtable and Spanner; Oriol Vinyals, a Google DeepMind VP and Gemini co-lead; and Quoc Le, a Google DeepMind fellow and founding member of Google Brain.
Who replaces him as chief scientist?
Demis Hassabis, who becomes Alphabet’s chief scientist while also serving as chairman of Google DeepMind. He steps back from day-to-day leadership of DeepMind but remains CEO of Isomorphic Labs.
Who now runs Google DeepMind?
Koray Kavukcuoglu, previously DeepMind’s chief technology officer and Google’s chief AI architect. He becomes senior vice president of Google DeepMind and reports directly to Sundar Pichai.
What did Jeff Dean actually build?
The distributed computing architecture underpinning Google Search, the Google Brain project, and co-invention of TensorFlow. He joined in 1999 when Google had roughly 25 employees.
How did the market react?
Alphabet shares fell around 4 to 5% following the announcement, despite the company reporting 82% year-over-year growth in cloud revenue to $24.8 billion in the second quarter.
What is Discovery Loop trying to do?
Build systems that can propose, execute and analyse thousands of experiments in parallel, shortening research cycles that have depended on sequential human work. It says its approach could address nearly all 14 Grand Challenges identified by the National Academy of Engineering.
Does this affect Gemini?
Google has not said so. Gemini 4, described as a much larger foundation model, is in training with no announced release date. Kavukcuoglu now oversees Gemini model development directly.
Conclusion
The headline is that Google lost the engineer who helped build modern search. The more consequential fact is that it lost four senior AI researchers in a single announcement, one of them a Gemini co-lead, on the same day its DeepMind chief stepped back from running the place.
Google’s own framing is orderly succession, and the structure supports it Hassabis moves up, an internal veteran takes over, and Google is funding the startup.
The share price disagreed. That gap between the announcement and the market’s reading of it is the thing to watch over the coming quarter.
