Igor Babuschkin, co-founder of xAI, has raised approximately 1.1 billion dollars for his new startup River AI in an early funding round led by General Catalyst and AMP PBC, with participation from investors including NVIDIA, AMD Ventures, Y Combinator, and Temasek. River AI, a two-month-old company, emerged publicly in June 2026 after being founded by Babuschkin, who previously co-founded xAI and worked in AI research and development. The round included funding from both Seed and Series A stages. River AI focuses on enabling companies to build custom AI models based on their own data, providing a software interface for fine-tuning and reinforcement learning training on open-weight models, supporting model sizes ranging from 35 billion to one trillion parameters. The company aims to reduce the time and resources required for model customization by offering the technical infrastructure for training and reinforcement learning without companies needing to build and manage such systems internally. The deal reflects investor bets on a new layer of the AI market focused on customizing open models, amid dominance by major companies developing closed models. The strategic investments from chip companies NVIDIA and AMD Ventures add significance to the round, given advanced model training's reliance on massive computing capabilities. The funding demonstrates investor readiness to inject large sums into AI companies even before their commercial product development cycle is fully complete.