Amazon Inc (AMZN) is investing an additional $4 billion in AI startup Anthropic, a direct rival of AI powerhouse OpenAI. According to a Friday announcement, the two companies are continuing their partnership through funding after a previous $4B investment earlier this year by Amazon.

Anthropic uses Amazon Web Services data centers for some of its computing needs, as well as AWS-designed AI chips. According to a press release Friday by Anthropic, the latest investment “establishes AWS as our primary cloud and training partner.” Additionally, the startup plans to use Amazon’s AI chips to develop its most advanced models. Amazon’s initial additional investment will be $1.3 billion, with the rest to follow in the form of convertible notes. Amazon’s total investment in Anthropic sits at $8 billion, making them a minority investor.

What is Anthropic, Amazon’s Latest AI Venture?

Anthropic was founded in 2021 by former employees of OpenAI, quickly becoming one of the ChatGPT developer’s biggest rivals. The company also has close ties with Alphabet Inc.’s Google. It is not a coincidence that the business rivalry between Anthropic and OpenAI also follows Amazon and Google’s rivalry with Apple Inc. (AAPL). Apple has also made strides in AI investments, putting billions into OpenAI to advance its own Apple AI development. Now, Amazon is continuing to do the same.

According to an Anthropic press release, the company is working closely with Annapurna Labs at AWS on the development and optimization of future generations of Trainium accelerators. These accelerators will boost the capabilities of specialized machine-learning hardware. Through deep technical collaboration, Anthropic is writing low-level kernels that allow them to directly interface with the Trainium silicon, and contributing to the AWS Neuron software stack to strengthen Trainium.

Anthropic Chief Executive Officer Dario Amodei has said he expects the costs of developing larger AI models could eventually grow to $100 billion, up from $100 million this year.

“Together with AWS, we’re laying the technological foundation—from silicon to software—that will power the next generation of AI research and development,” Athropic added. “By combining Anthropic’s expertise in frontier AI systems with AWS’s world-class infrastructure, we’re building a secure, enterprise-ready platform that gives organizations of all sizes access to the forefront of AI technology.