Ineffable Raises $1.1B Seed, Europe's Largest Round

London-based AI startup Ineffable Intelligence, founded by former Google DeepMind researcher David Silver, has raised $1.1 billion in seed funding, the largest such round in European history, at a valuation of $5.1 billion. The company, incorporated in November 2025, announced the investment on Monday from a group of prominent venture firms and strategic backers.

The round was co-led by Sequoia Capital, with managing partner Alfred Lin and partner Sonya Huang involved, and Lightspeed Venture Partners. Participants included Nvidia, which contributed at least $250 million, Google, Index Ventures, DST Global, EQT Ventures, Evantic Capital, Flying Fish Ventures, BOND Capital, the UK government's Sovereign AI Fund, and the British Business Bank, which invested $15 million. Silver, a professor at University College London who led DeepMind's reinforcement learning team for over a decade, left the company in late 2025 to launch Ineffable.

The startup aims to develop superintelligence through reinforcement learning, creating "superlearners" that discover knowledge independently from experience and self-play, rather than relying on human-generated data. "Our mission is to make first...