Investing.com-- OpenAI is close to finalizing a $40 billion funding round led by Japan’s Softbank (OTC: SFTBY ) Group along with a slew of other private equity groups, Bloomberg reported on Thursday.

Other participants in the round include Magnetar Capital, Coatue Management, and Alitmeter Capital, the Bloomberg report said, citing people familiar with the matter.

An earlier report from Bloomberg said Softbank could invest as much as $25 billion in OpenAI, making it the biggest backer of the ChatGPT maker after Microsoft (NASDAQ: MSFT ).

The Softbank funding comes after  the Japanese technology giant and OpenAI committed to a $500 billion project to build artificial intelligence infrastructure in the U.S.

The project- called Project Stargate- is aimed largely at building more data centers to increase OpenAI’s access to computing power.

Greater computing power entails better performance for OpenAI’s flagship AI models. The company had earlier this week updated its GPT-4o model to add image generation to its features.

Softbank has vowed to aggressively increase its investment in AI, with CEO Masayoshi Son flagging great potential in the fast-growing technology.

But Thursday’s report also comes amid some doubts over increased investment in AI infrastructure, especially as companies focus on developing leaner, more efficient models and as the industry shifts to inference from training.

TD Cowen said Microsoft had canceled several data center leases in the U.S. and Europe in the last six months, amid concerns of oversupply in data center capacity.

Alibaba (NYSE: BABA ) Chair Joe Tsai also warned that there was a growing AI data center bubble in the U.S.