Shares in Japanese tech behemoth SoftBank Group soared more than eight per cent on Wednesday after US President Donald Trump announced a major investment to build AI infrastructure.

Trump said that ChatGPT's creator OpenAI, SoftBank and Oracle are planning a joint venture called Stargate, which he said would build data centres and create more than 100,000 jobs in the United States.

These companies, along with other equity backers of Stargate, have committed US$100 billion for immediate deployment, with the remaining investment expected to occur over the next four years.

SoftBank CEO Masayoshi Son, OpenAI CEO Sam Altman and Oracle Chairman Larry Ellison joined Trump at the White House for the launch.

The first of the project's data centres are already under construction in Texas, Ellison said at the press conference.

Twenty will be built, half-a-million square feet each, he said. The project could power AI that analyses electronic health records and helps doctors care for their patients, Ellison said.

It was not immediately clear whether the announcement was an update to a previously reported venture.

In March 2024, The Information, a technology news website, reported OpenAI and Microsoft were working on plans for a US$100 billion data centre project that would include an artificial intelligence supercomputer, also called "Stargate", set to launch in 2028.

The announcement on Trump's second day in office follows the rolling back of former President Joe Biden's executive order on AI, that was intended to reduce the risks that AI poses to consumers, workers and national security.

Oracle shares were up seven per cent on an initial report of the project earlier in the day. Nvidia, Arm Holdings and Dell shares also rose. (Agencies)