Tech
David Silver Raised $1.1B on the Thesis He Wrote at DeepMind
Silver's April 2025 paper with Richard Sutton called the LLM era a ceiling. Sequoia and Lightspeed priced that argument at $5.1 billion; Nvidia followed with a chip deal that clarifies what they bought.
Ineffable Intelligence closed a $1.1 billion seed round on April 27, the largest in European history, valuing a company with no product and no revenue at $5.1 billion. Sequoia and Lightspeed co-led. Google, Nvidia, Index Ventures, and the British Business Bank participated.
The founder is David Silver, who ran Google DeepMind's reinforcement learning team for thirteen years and built AlphaGo, AlphaZero, AlphaStar, and AlphaProof. He left on sabbatical in late 2025 and was appointed director of Ineffable in January.
Nine months before he left, Silver published "Welcome to the Era of Experience" with Richard Sutton. The paper argued that LLMs cannot discover knowledge above the human corpus but RL from experience can.
A person with direct knowledge of his plans told Fortune he was leaving to return to "the awe and wonder of solving the hardest problems in AI."
Sutton won the Turing Award in 2025 for foundational RL work and publicly endorsed Ineffable in February. No public document lists him as an officer, investor, or advisor.
The Round
Google backed a company whose founder left its own AI division arguing that division's primary product class has fundamental limits. DeepMind and Ineffable now compete in the same market, funded by the same parent.
As of its April 27 disclosure, Silver was Ineffable's only named director. TechCrunch reported that several former DeepMind staffers are "reportedly set to join" the executive team, but none had been named. The contrast with Ilya Sutskever's SSI, which published a founding team of named ex-OpenAI researchers on day one, points to execution risk the valuation does not price in.
On May 13, Nvidia announced an engineering-level collaboration with Ineffable to build reinforcement learning training infrastructure, starting on Grace Blackwell chips and extending to the Vera Rubin platform. No financial terms were disclosed.
Where the Capability Lives
Ineffable's $5.1 billion valuation implies that the RL expertise Silver assembled at DeepMind is worth more outside the lab than inside it. His former employer agreed, then wrote a check.
The Nvidia deal reveals what the bet is actually on. With infrastructure delegated to Grace Blackwell, Ineffable's residual value lives in reward design at scale. No named hire has yet been shown to share that record with Silver.
If Ineffable publishes a working system before the $1.1 billion is spent, the valuation that looks exuberant today will look like OpenAI's Series A.