OpenAI is close to finalizing a $40 billion funding round led by SoftBank Group Corp. — with investors including Magnetar Capital, Coatue Management, Founders Fund and Altimeter Capital Management in talks to participate, according to people familiar with the matter.

Magnetar Capital — an Evanston, Illinois-based hedge fund — could contribute up to $1 billion, according to multiple people, all of whom asked not to be identified because the information is private.

Representatives for OpenAI, Magnetar and Founders Fund declined to comment on the funding round. Coatue and Altimeter did not immediately respond to requests for comment.

The artificial intelligence developer’s funding round would be the largest of all time, according to data compiled by research firm PitchBook. The deal is set to value the company at $300 billion including dollars raised — almost double the ChatGPT maker’s previous valuation of $157 billion from when it raised money in October.

Two years ago, OpenAI’s ChatGPT became the tech industry’s biggest product. Yet increasingly, AI developers find their models aren’t improving as fast as they used to and profitability remains elusive.

As part of the deal, SoftBank will invest an initial $7.5 billion in the company, along with $2.5 billion from an investor syndicate, said one of the people familiar with the discussions. There will be a second tranche of $30 billion later this year that will include $22.5 billion from SoftBank, and $7.5 billion from a syndicate, this person said.

SoftBank declined to comment. The Japanese conglomerate has separately committed billions to the Stargate Project, the Abilene, Texas-based joint venture with partners including OpenAI, Oracle Corp. and MGX.