Anthropic, OpenAI’s close rival, has raised an additional $4 billion from Amazon, and has agreed to make Amazon Web Services, Amazon’s cloud computing division, the primary place it’ll train its flagship generative AI models.

Anthropic also says it’s working with Annapurna Labs, AWS’ chipmaking division, to develop future generations of Trainium accelerators, AWS’ custom-built chips for training AI models.

“Our engineers work closely with Annapurna’s chip design team to extract maximum computational efficiency from the hardware, which we plan to leverage to train our most advanced foundation models,” Anthropic wrote in a blog post. “Together with AWS, we’re laying the technological foundation — from silicon to software — that will power the next generation of AI research and development.”

The new infusion from Amazon brings the company’s total investment in Anthropic to $8 billion, but maintains Amazon’s position as a minority investor, Anthropic says. To date, Anthropic has raised $13.7 billion in venture capital, according to Crunchbase data.

The Information reported earlier this month that Amazon was in talks to invest multiple billions in Anthropic, its first financial pledge in the company since a deal struck last year. The new investment is reportedly structured similar to the last one — but with a twist. Amazon insisted that Anthropic use Amazon-developed silicon hosted on Amazon Web Services to train its AI.

Anthropic is said to prefer Nvidia chips. But the money may have been too good to pass up. Around the start of the year, Anthropic reportedly projected it would burn through over $2.7 billion in 2024 as it trained and scaled up its AI products. Anthropic has for several months been discussing new funding at a $40 billion valuation, per The Information, and no doubt the pressure was on to clinch something soon.

Anthropic notes that its work with Amazon Web Services has expanded over the years.