Ex-DeepMind researcher raises $1.1B seed round for London AI startup Ineffable Intelligence

The round, led by Sequoia and Lightspeed, values the months-old startup at $5.1 billion — the largest seed round ever in Europe

JUSTIN TALLIS / Getty Images

David Silver, a former head of reinforcement learning at Google $GOOGL DeepMind and a professor at University College London, has closed a $1.1 billion seed round for Ineffable Intelligence, his London-based AI startup, at a valuation of $5.1 billion.

Sequoia Capital and Lightspeed Venture Partners co-led the round, with participation from Nvidia $NVDA, Google, Index Ventures, DST Global, and the U.K. government's Sovereign AI Fund, the company said. According to The Next Web, Nvidia's venture arm contributed at least $250 million. The round is the largest seed round ever raised in Europe, according to the company.

Founded in November 2025, Ineffable Intelligence has yet to release a product, generate any revenue, or publish a roadmap for what it intends to build. The company's stated mission is to build a "superlearner" — an AI system that discovers knowledge through its own experience rather than from human-generated data, applying reinforcement learning at a scale Silver believes can reach superintelligence.

"Our mission is to make first contact with superintelligence," Silver said in a statement. "We are creating a superlearner that discovers all knowledge from its own experience, from elementary motor skills through to profound intellectual breakthroughs."

Silver spent more than a decade at Google DeepMind, where he led development of AlphaGo, AlphaZero, and AlphaStar. AlphaGo, upon its release in 2016, demonstrated for the first time that an AI could beat a professional Go player on equal terms; the follow-up system AlphaZero then taught itself to play Go, Chess, and Shogi at superhuman levels using only self-generated experience.

Rounding out the leadership team are Wojciech Czarnecki, Lasse Espeholt, and Junhyuk Oh, all of whom previously worked at DeepMind, Bloomberg reported.

On the government side, backing comes from Sovereign AI — a £500 million ($678 million) publicly funded vehicle established to take equity stakes in AI companies — alongside the British Business Bank. The government said the Ineffable investment is Sovereign AI's second direct equity deal since the fund launched.

Joséphine Kant, who leads venture activity at the Sovereign AI Unit, offered a pointed endorsement in a statement: "Very few founders in the world could credibly set out to build a superlearner. David is one of them."

Science and Technology Secretary Liz Kendall described the investment as evidence that "the U.K. isn't just an AI taker but an AI maker," in a statement.

Ineffable Intelligence is among a broader wave of AI labs founded by researchers departing major technology companies. CNBC noted that AMI Labs, the startup launched by Yann LeCun after he stepped down as Meta $META's chief AI scientist, closed a $1 billion raise in March, while Recursive Superintelligence — a separate venture from former DeepMind engineer Tim Rocktäschel — has been reported to be in the market for as much as $1 billion.

📬 Sign up for the Daily Brief

Our free, fast and fun briefing on the global economy, delivered every weekday morning.

© Quartz