River AI raised $1.1bn to let companies train and keep their own models

TL;DR River AI raised $1.1bn led by General Catalyst and AMP PBC. Sells fine-tuning and reinforcement learning on open weight models. River AI has raised $1.1bn, roughly four months after the company was incorporated. River sells an API for LoRA fine-tuning and reinforcement learning on frontier open weight models, taking on the infrastructure underneath, including weight transfers, sampling-training consistency and elastic compute. River AI was incorporated in Nevada on April 20.