River AI, a startup founded by former xAI co-founder Igor Babuschkin, secured $1.1 billion in combined seed and Series A funding led by General Catalyst and AMP PBC, with participation from Nvidia, AMD Ventures, Y Combinator and Temasek. The company, which came out of stealth in June, aims to rebuild the AI stack end to end — training, models, the product layer, and hardware — to turn AI agents into personally trainable assistants rather than generic chatbots. River already offers an API priced per million tokens that lets developers apply reinforcement learning and LoRA fine-tuning to open models as an alternative to prompt engineering.
