The Japanese owner of the British chip designer Arm is reportedly planning to float some of the company’s shares in London, in a sign the government’s efforts to lobby for a UK listing of the Cambridge-based company may have succeeded. SoftBank, which bought the chip company for $32bn in 2016, is said to be reconsidering earlier plans to only list shares on the US market. While the company is still likely to conduct its initial public offering in New York, the company may secure a secondary listing in London, according to Bloomberg, in a move that would be widely welcomed by officials who have been trying to lure more tech listings to the City. Bloomberg said the size and timing of the Arm share sale had not yet been finalised and that plans for the listing could still change, quoting sources familiar with SoftBank’s thinking. Analysts have estimated that Arm – which has more than 500 clients that use its chip designs, including Apple, Samsung and Google, in products ranging from iPads and mobile phones to cars and smart TVs – could be worth up to $40bn (£32.1bn) when it goes public. The news comes a month after it emerged that the UK prime minister, Boris Johnson, joined lobbying efforts already under way by London Stock Exchange executives, government departments and senior officials, to try to convince Arm to float its shares in London. It culminated in Johnson writing a letter to bosses at SoftBank as part of his last-ditch charm offensive. The chief executive of SoftBank, Masayoshi Son, had previously snubbed the UK for the Arm flotation, saying in February that “the Nasdaq stock exchange in the US, which is at the centre of global hi-tech, would be most suitable”. Son’s comments came after a potential $66bn sale of Arm to the US-based Nvidia collapsed earlier this year because of regulatory hurdles on both sides of the Atlantic. A New York-only listing of Arm would be a blow to Johnson and the chancellor, Rishi Sunak, who last year tried to make London more attractive to tech companies by controversially giving founders more control through dual-class share structures and slashing the number of shares required to be offered to the public to only 10%. SoftBank and Arm had not responded to requests for comment at the time of publication. A government spokesperson would not comment directly on the news but said: “We are committed to making the UK the most attractive place for innovative businesses to grow and raise capital. Following last year’s record number of tech IPOs in London, we continue to work hard to support and encourage all firms to list here.”