SoftBank Group Corp is in talks to acquire the 25 per cent stake in Arm Ltd it does not directly own from Vision Fund 1 (VF1), a $100-billion investment fund it raised in 2017, according to people familiar with the matter, potentially delivering a win for investors who have waited years for strong returns. The discussions come as SoftBank is preparing to list the chip designer on Nasdaq next month at a valuation of $60-billion to $70-billion. If the negotiations lead to a deal, the Japanese tech investor would be delivering a major, immediate windfall to VF1 investors, including Saudi…