Nvidia will buy UK-based chip designer Arm from Japan's SoftBank Group for as much as $40 billion, the companies said today, in a deal set to reshape the global semiconductor sector. 

The sale puts a vital supplier to Apple and others across the industry under the control of a single player.

It also faces likely pushback from regulators and rivals to Nvidia, the biggest US chip company by market capitalisation. 

Within hours of the announcement, critics questioned how Arm would maintain its open approach under US ownership and at a time of friction with China. 

Nvidia CEO Jensen Huang emphasised that Arm would retain its neutral licensing model and expand it by licensing out Nvidia intellectual property for the first time. 

"We want to grow Arm and make it become even greater," he told analysts on a conference call. 

For Softbank, the sale marks an early exit from Arm, which it acquired for $32 billion. 

Chief executive Masayoshi Son has lionised the potential of Arm but is slashing his stakes in major assets to raise cash. 

The move comes as SoftBank executives, frustrated at the group's share performance, have held early stage talks about taking the Japanese technology group private, a source told Reuters.

Those talks could gain momentum following the Arm sale. SoftBank's shares soared 10% in Tokyo today. 

Nvidia will pay SoftBank $21.5 billion in shares and $12 billion in cash, including $2 billion on signing. The deal will see SoftBank and its $100 billion Vision Fund, which has a 25% stake in Arm, take a stake in Nvidia of between 6.7% and 8.1%. 

Nvidia will license its flagship graphical processor unit through Arm's network of silicon partners. It will build chips for devices like self-driving cars but also make its technology available for others. 

Taiwan-born Huang has promised to site a new artificial intelligence research centre - equipped with its own supercomputer - at Arm's base in the university city of Cambridge and said the company was ready to talk to the British government about expanding Arm's research efforts.

He stopped short of offering fresh job guarantees, however. 

Am does not make chips but has created an instruction set architecture - the most fundamental intellectual property that underpins computing chips - on which it bases designs for computing cores. 

It licenses its chip designs and technology to customers like Qualcomm, Apple and Samsung Electronics. Apple's forthcoming Mac computers will use Arm-based chips. 

Arm will not become subject to US export controls under the deal, said Huang. 

The purchase, which is subject to regulatory approvals including in Britain, the US and China, is likely to come under close scrutiny in China, where thousands of companies from Huawei to small startups use Arm technology. 

Nvidia will take control of the minority stake in joint venture Arm China. Arm is in dispute with the venture, which licenses chip architecture to local companies, over its management.

Co-founded by Huang, the firm began as a graphics chip designer but has expanded aggressively into products for areas including artificial intelligence and data centres. 

The Arm acquisition will put Nvidia into even more intense competition with rivals in the data centre chip market such as Intel and Advanced Micro Devices because Arm has been developing technology to compete with their chips. 

In what would amount to a direct challenge to those rivals, Huang said it is "possible" Nvidia will build its own server chips based on Arm designs. 

Nvidia is buying up technologies in parts of the booming data centre business where it does not currently play. 

In April it completed the purchase of Israel-based Mellanox, which makes high-speed networking technology that is used in data centres and supercomputers. 

The Arm deal is expected to close by March 2022. 

SoftBank could be paid an additional $5 billion in cash or shares depending on the chip designer's business performance, with Arm employees to be paid $1.5 billion in Nvidia shares.