The Federal Trade Commission has sued to stop the takeover of Arm, which has ballooned in value from $40bn to $75bn since the offer was made last September due to a stock market surge in the chip sector, as seemingly almost insurmountable opposition now mounts after regulator action in Europe and the UK.
The US is the latest market to raise concerns about the merger as countries around the world increasingly focus on the ramifications of takeovers that threaten national security and infrastructure firms in the tech industry.
Arm, whose acquisition by Japanese group SoftBank for $32bn in 2016 raised no regulatory issues, has more than 500 clients who use its designs and compete globally including Apple, Samsung and Qualcomm.
Despite the mounting obstacles to the deal, Masayoshi Son, the chief executive of seller SoftBank, said last month that he expected the takeover to eventually be cleared.
