Ineffable Intelligence, the AI startup founded by David Silver, the creator of AlphaGo, AlphaZero, and AlphaStar at Google DeepMind, has achieved a $5.1 billion valuation shortly after its incorporation in November 2025. This valuation stems from a substantial seed funding round of $1.1 billion, which closed in April 2026. The company, based in London, was incorporated in November 2025, and Silver was appointed director in January 2026. This makes it one of the most valuable pre-product AI startups in Europe, despite having no public product, revenue, or roadmap.
The $1.1 billion seed round was co-led by Sequoia Capital and Lightspeed Venture Partners. Other significant investors included Nvidia, Google, Index Ventures, DST Global, and the UK's Sovereign AI Fund. Nvidia's venture arm alone contributed at least $250 million. Google also established a compute partnership with Ineffable Intelligence in July 2026, leveraging Google Cloud infrastructure. The initial investment came from Flying Fish, a venture fund where one of the later-appointed co-founders, Heather Gorham, previously served as a venture partner.
The valuation context for Ineffable Intelligence is noteworthy. For comparison, Ilya Sutskever's Safe Superintelligence, also founded with no product, raised $3 billion and reached a $32 billion valuation by April 2025. Similarly, Mira Murati's Thinking Machines Lab secured a multi-billion-dollar cloud infrastructure agreement with Google and later achieved a $2 billion seed round at a $12 billion valuation. Ineffable Intelligence stands out as the only one of these high-value, pre-product AI startups based outside the US, with a sovereign fund as part of its cap table.
In September 2026, Ineffable Intelligence retroactively elevated six senior hires to co-founder status, four of whom were former Google DeepMind colleagues of Silver's. This group includes Chris Apps (mission acceleration), Wojciech Czarnecki (science team lead), Lasse Espeholt (compute and infrastructure strategy), Junhyuk Oh (reinforcement learning operations), Alexandre Laterre (research engineering), and Heather Gorham (compute procurement, fundraising, operations). This move is seen as a strategic compensation and control decision, aimed at retaining top talent from DeepMind and other leading AI organizations, and highlights the ongoing talent drain from established AI labs.
