SoftBank Group’s UK-based chip design subsidiary Arm filed for a listing in the US which market watchers expect to be one of the largest tech IPOs in history.

The long-awaited move comes after SoftBank acquired the remaining 25 per cent of Arm it does not directly control from the Japanese company’s Vision Fund 1 for $16 billion, a transaction valuing the chip unit at more than $64 billion.

SoftBank made no prediction on the expected share price in its IPO filing with the US Securities and Exchange Commission, but Bloomberg tipped the overall value at between $60 billion and $70 billion.

Bloomberg suggested Arm looked to raise $8 billion to $10 billion, but the target could be lower because SoftBank opted to list fewer shares after buying the Vision Fund stake.

Richard Windsor, founder of industry blog Radio Free Mobile, argued that to hit the $64 billion valuation “Arm needs to be seen to be like Nvidia and as an AI company”.

Windsor added “the AI story is so important to getting this IPO at the desired valuation” and explains why SoftBank has sought anchor investors from the technology industry.

Arm’s revenue in fiscal Q1 (ending 30 June) dropped 10.8 per cent to $641 million.

Talk of listing Arm started after a deal to sell the business to Nvidia fell apart in early 2022.

SoftBank acquired Arm in 2016 for $32 billion.