River AI, a startup founded by xAI co-founder Igor Babuschkin, has closed a $1.1 billion funding round led by General Catalyst and AMP PBC, according to reporting on the round. Nvidia and Y Combinator participated as strategic investors.
Babuschkin left xAI in August 2025 and founded River AI in 2026. The startup is building what it describes as an open AI stack, positioning itself in a market where several companies are racing to offer alternatives to closed-model systems like OpenAI's GPT.
General Catalyst has invested in a range of AI infrastructure companies over the past two years, including Anthropic and Mistral. AMP PBC, the venture arm of the Andressen Horowitz portfolio, has backed AI projects across model development, inference optimization, and application layers. Nvidia's participation as an investor has not been accompanied by disclosure of the chip maker's stake or role.
Y Combinator's involvement as a secondary investor comes from an accelerator that has backed a cluster of open-source AI projects and model-focused startups in recent funding cycles. The firm does not typically lead rounds at this scale.
Babuschkin's departure from xAI came roughly 18 months before the round closed. He held the title of co-founder at xAI, which was established by Elon Musk in 2023. The reasons for his departure have not been publicly disclosed.
The $1.1 billion valuation and lead investor lineup place River AI among the larger AI infrastructure bets outside the dominant model labs. The round size is consistent with funding for companies addressing inference, optimization, or alternative model stacks, though River AI has not disclosed its technical approach or product roadmap in detail. Venture funding for AI infrastructure startups has continued through this period despite broader pullbacks in early-stage venture capital.
General Catalyst led the round, meaning the firm took the largest check and negotiated terms. If River AI reaches profitability or sells, General Catalyst's stake would be among the first to return capital. The investor group combines a traditional venture firm, a crypto-native fund, and hardware and accelerator participation.
