Son was forced to focus his attention on Yahoo! BB and BB Phone. So far, SoftBank has accumulated about $1.3 billion in debt. Yet, Yahoo! BB acquired Japan Telecom, the then third largest broadband and landline provider with 600,000 residential and 170,000 commercial subscribers. Yahoo! BB is now Japan's leading broadband provider. In June 2020, Son stepped down from the Alibaba board. Arm Holdings In July 2016, SoftBank announced plans to acquire Arm Holdings for £23.4 billion ($31.4 billion) which would be the largest ever purchase of a European technology company. In September 2016, SoftBank announced that the transaction was complete. The total acquisition price was approximately £24 billion ($34 billion). In 2020, SoftBank Group agreed to sell U.K. chip designer Arm Limited to U.S. chip-maker Nvidia in a cash and stock deal initially worth $40 billion. The buy price, initially set at $40bn (cash and Nvidia shares) when first announced in September 2020, had risen closer to an estimated $66bn by 2022 given the intervening hike in Nvidia's stock – that would make this deal the biggest deal in the semiconductor market. Announcing the deal, SoftBank said the combination of Arm and Nvidia would create a computing company "that will lead the era" of artificial intelligence. However, the deal with Nvidia failed as announced in February 2022. Sprint Corporation In the 2010s, through his holdings in SoftBank, Son bought a 76% share in Sprint. SoftBank has further accumulated shares in Sprint to about 84% ownership. Solar power In response to the Fukushima Daiichi nuclear disaster in 2011, Masayoshi Son criticized the nuclear industry for creating "the problem that worries Japanese the most today" and engaged in investing in a nationwide solar power network for Japan. In March 2018, it was announced that Son was investing in the biggest ever solar project, a 200GW development planned for Saudi Arabia as part of its Vision 2030. In July 2018, coverage indicated that Son "would underwrite most of 100 GW" of a planned 275 GW of new renewable provision in India by 2027. Vision Fund Established in 2017, SoftBank Group's investment vehicle, the $100 billion Vision Fund, was intended to invest in emerging technologies like artificial intelligence (AI), robotics and the internet of things. As of 2019, it aimed to nearly double its portfolio of AI companies from 70 to 125. However, it also invested in companies supposedly focused on revolutionizing real