Ineffable Intelligence, the London-based AI startup founded by former Google DeepMind researcher David Silver, has recruited six cofounders after raising $1.1 billion in a seed round that valued the pre-revenue company at $5.1 billion. The financing, announced when the startup emerged from stealth on April 27, 2026, is the largest seed round in European startup history. Four of the hires—Chris Apps, Wojciech Czarnecki, Junhyuk Oh and Lasse Espeholt—previously worked at DeepMind. Apps, Czarnecki and Oh worked with Silver on AlphaStar, the 2019 system that reached grandmaster-level performance in StarCraft II, while Espeholt helped develop Google’s MetNet weather-prediction models. Alexandre Laterre was head of research at InstaDeep before BioNTech acquired the company in 2023, and Heather Gorham came from venture firm Flying Fish. Ineffable is pursuing a departure from internet-scale pretraining, aiming instead to develop a system it calls a superlearner through large-scale reinforcement learning in simulated environments. Silver incorporated the company in November 2025, left DeepMind in January 2026 and is leading it full-time. Sequoia Capital and Lightspeed Venture Partners co-led the funding, which also included Nvidia, Google, Index Ventures, the Sovereign AI Fund and British Business Bank. Silver has pledged to donate all proceeds from his Ineffable equity to high-impact charities.