Amazon revealed Friday that it is investing another $4 billion in AI startup Anthropic, which named AWS as its primary training partner.

"Amazon and Anthropic are deepening their collaboration," Amazon announced. "Anthropic is now naming AWS its primary training partner, in addition to continuing to be its primary cloud provider, and will use AWS Trainium and Inferentia chips to train and deploy its future foundation models. Both companies will continue to work closely to keep advancing Trainium's hardware and software capabilities."

Amazon announced a $4 billion investment in Anthropic in September 23, and it finalized that investment the following March. At the time, Anthropic chose AWS as its primary cloud provider, but with this new development, Amazon has doubled its investment in the firm and the two have deepened their ties. Among the changes, AWS customers will gain early access to new Anthropic Claude models before they're made available elsewhere.

According to the firm's Anthropic's Claude models have consistently outperformed other AI models all year. Its recently released Claude 3.5 Sonnet model offers advanced agentic capabilities including computer use, and it outperforms all publicly available models on agentic coding tasks. (Microsoft recently announced that it would make this and other third-party models available to GitHub Copilot customers.)