Amazon.com Inc. is investing $50 billion in the financing round, OpenAI said Friday, by far the largest amount the e-commerce giant has put into any company. SoftBank Group Corp. and Nvidia Corp. each invested $30 billion, the company said. The firm’s new $730 billion valuation doesn’t include the money raised. Post-money, it’s now valued at $840 billion.

OpenAI and rival Anthropic PBC have ramped up their fundraising this year to support costly bets on chips and data centers to support their artificial intelligence software. Increasingly, the two AI startups have tapped an overlapping group of venture funds and Big Tech investors.

The large investment from Amazon, a longtime Anthropic backer, also tightens its relationship with OpenAI. As part of the agreement, OpenAI will use Amazon’s line of in-house AI chips, called Trainium, and jointly develop customized models for Amazon’s own engineering teams. OpenAI will also spend an additional $100 billion on Amazon Web Services over the next eight years. The two companies in November announced a deal under which the model builder would use some $38 billion in AWS services over seven years.

“Amazon can deliver so much to us in terms of new demand and opportunities in the market,” OpenAI Chief Executive Officer Sam Altman said in an interview with CNBC on Friday. Andy Jassy, Amazon’s CEO, said the deal “will yield a good return for Amazon over a long period of time.”

Microsoft Corp., one of OpenAI’s largest previous backers and formerly an exclusive infrastructure partner, said its relationship with the developer remains strong. “Nothing about today’s announcements in any way changes the terms of the Microsoft and OpenAI relationship,” the companies said in a joint statement Friday.

Anthropic raised $30 billion in a funding round earlier this month from investors, including Nvidia and Microsoft. The financing valued Anthropic at $380 billion, including the money raised.

The funding commitments mark the latest example of circular financing deals between leading AI startups and suppliers of chips and cloud computing. These tie-ups are intended to ensure the AI sector can meet its immense infrastructure needs, but the risk is such deals can magnify losses if demand for AI fails to match today’s lofty expectations.

Altman downplayed the risk of such arrangements in the CNBC interview.

“I get where the concern comes from,” Altman said. “This only makes sense if new revenue flows into the whole AI ecosystem.” He said much of his effort goes into trying to get more computing capacity to serve demand for ChatGPT and OpenAI’s other products.

This is a developing story. More to come.