Amazon on Friday announced it would invest an additional $4 billion in Anthropic, the artificial intelligence startup founded by ex-OpenAI research executives.

The new funding brings the tech giant’s total investment to $8 billion, though Amazon will retain its position as a minority investor, according to Anthropic, the San Francisco-based company behind the Claude chatbot and AI model.

Amazon Web Services will also become Anthropic’s “primary cloud and training partner,” according to a blog post. From now on, Anthropic will use AWS Trainium and Inferentia chips to train and deploy its largest AI models.

Anthropic is the company behind Claude — one of the chatbots that, like OpenAI’s ChatGPT and Google’s Gemini, has exploded in popularity. Startups like Anthropic and OpenAI, alongside tech giants such as Google, Amazon, Microsoft and Meta, are all part of a generative AI arms race to ensure they don’t fall behind in a market predicted to top $1 trillion in revenue within a decade.

Some, like Microsoft and Amazon, are backing generative AI startups with hefty investments as well as working on in-house generative AI.

The partnership announced Friday will also allow AWS customers “early access” to an Anthropic feature: the ability for an AWS customer to do fine-tuning with their own data on Anthropic’s Claude. It’s a unique benefit for AWS customers, according to a company blog post.

In March, Amazon’s $2.75 billion investment in Anthropic was the company’s largest outside investment in its three-decade history. The companies announced an initial $1.25 billion investment in September 2023.

Amazon does not have a seat on Anthropic’s board.

News of Amazon’s additional investment comes one month after Anthropic announced a significant milestone for the company: AI agents that can use a computer to complete complex tasks like a human would.

Anthropic’s new Computer Use capability, part of its two newest AI models, allows its tech to interpret what’s on a computer screen, select buttons, enter text, navigate websites, and execute tasks through any software and real-time internet browsing.

The tool can “use computers in basically the same way that we do,” Jared Kaplan, Anthropic’s chief science officer, told CNBC in an interview last month, adding it can do tasks with “tens or even hundreds of steps.”

Amazon had early access to the tool, Anthropic told CNBC at the time, and early customers and beta testers included Asana, Canva and Notion. The company had been working on the tool since early this year, according to Kaplan.

In September, Anthropic rolled out Claude Enterprise, its biggest new product since its chatbot’s debut, designed for businesses looking to integrate Anthropic’s AI. In June, the company debuted its more powerful AI model, Claude 3.5 Sonnet, and in May, it rolled out its “Team” plan for smaller businesses.

Last year, Google committed to invest $2 billion in Anthropic, after previously confirming it had taken a 10% stake in the startup alongside a large cloud contract between the two companies.