Cambridge-based computer chip designer ARM Holdings has been sold to American company Nvidia in a deal worth £31.2 billion, the US firm said.
ARM, whose products appear in most smartphones, was bought by Japanese conglomerate SoftBank four years ago for £24.3bn.
But the new owners have pledged that the firm will stay in the UK and have promised that more staff will be recruited. Similar hopes were expressed when it was initially sold to Softbank in 2016.
ARM will remain headquartered in Cambridge. We will expand on this great site and build a world-class AI research facility, supporting developments in healthcare, life sciences, robotics, self-driving cars and other fields.
Nvidia chief executive Jensen Huang said ARM makes computer chip designs that are customised by clients including technology giants Samsung, Apple and Huawei.
Last week, the Labour Party's Ed Miliband urged the Government to obtain "legally binding assurances" ARM would remain in the UK "rather than see jobs and decision-making moved across the ocean".
Nvidia said in its statement that ARM would "continue to operate its open-licensing model, while maintaining its global customer neutrality", but there are still likely to be questions about the takeover.
Two of ARM's co-founders, Tudor Brown and Hermann Hauser, have suggested the firm should stay neutral and not be owned by a company like Nvidia which produces its own processors.