River AI Raises $1.1 Billion to Develop Open AI Training Tools

River AI, a startup founded by a former xAI cofounder, has raised $1.1 billion in a funding round to develop tools for training and owning artificial intelligence models, challenging the dominant industry practice of relying on large, centralized labs. The round, which closed ahead of its target, was led by General Catalyst and AMP PBC, with strategic investments from chipmakers NVIDIA and AMD Ventures. Additional funding came from Y Combinator and Temasek.

The company was incorporated in Nevada on April 20, 2026, and is based in Palo Alto. It was founded by Igor Babuschkin, who previously worked at Google DeepMind, OpenAI, and was a cofounder of Elon Musk's xAI before departing in August 2025. River AI's platform provides an application programming interface for LoRA finetuning and reinforcement learning on open-weight models, managing the underlying infrastructure tasks like weight transfers and compute allocation. According to the company, this allows a complex reinforcement learning run to be completed in 15 to 20 minutes without an internal infrastructure team, claiming cost savings of two to four times compared to closed-source alternatives.