Ineffable Intelligence, a London artificial intelligence lab founded by former Google DeepMind researcher David Silver, came out of stealth on April 27, 2026 with a $1.1bn (about £810m) seed round at a $5.1bn valuation.
Sequoia Capital and Lightspeed Venture Partners co-led the round. The company said it was the largest seed round ever raised in Europe.
Nvidia, Google, Index Ventures, DST Global, BOND, EQT Ventures, Evantic Capital, Flying Fish Ventures and the Wellcome Trust also invested, along with two UK government vehicles: the British Business Bank, which put in $20m according to The Telegraph, and the Sovereign AI fund, which invested an undisclosed sum.
“The world needs a place where the full ambition of the reinforcement learning paradigm can flourish.”David Silver, Founder, Ineffable Intelligence
What Ineffable Intelligence does
Ineffable says its mission is to "make first contact with superintelligence". It is building what it calls a superlearner: a system that uses reinforcement learning, in which software learns by trial and error, to discover knowledge and skills from its own experience instead of from human-generated data.
The company has not released a product. According to Quartz, it was founded in November 2025 and has no revenue or published roadmap yet. In a statement on its website, the company compared the possible impact of its work to Darwin's.
Silver led the reinforcement learning team at DeepMind for more than a decade and worked on systems including AlphaGo, AlphaZero and AlphaStar. He is also a professor at University College London. Quartz, citing Bloomberg, reported that Wojciech Czarnecki, Lasse Espeholt and Junhyuk Oh, all formerly of DeepMind, are among the company's leaders.
Silver set out his reasons for starting the company in a note on its website dated January 15, 2026. In a statement quoted by Tech.eu, he said he had a unique opportunity to build such a lab, drawing on his leadership, track record and the strength of his team.
Who invested
At Sequoia, partners Alfred Lin and Sonya Huang led the investment; at Lightspeed, Ravi Mhatre and Raviraj Jain did, according to Tech.eu. Quartz, citing The Next Web, reported that Nvidia's venture arm contributed at least $250m.
The Telegraph reported that the British Business Bank's $20m came from taxpayer funds, and that the Sovereign AI fund is part of a £500m government programme. Science and Technology Secretary Liz Kendall said the government was backing the UK's entrepreneurs "to seize the benefits of AI for the UK". Joséphine Kant of the Sovereign AI Unit said very few founders could credibly set out to build a superlearner and that Silver was one of them.
Tech.eu reported that Silver has committed to give away all of the money he makes from his Ineffable shares through Founders Pledge.
A busy market for AI labs
Quartz noted that AMI Labs, the start-up founded by Yann LeCun, closed a $1bn raise in March.
Quartz also pointed to an earlier Telegraph report on a $1bn raise for Silver's then three-month-old company. The company did not say how it would spend the new money, how many people it employs or whether it had raised money before this round.
Company website: ineffable.ai