SoftBank shares broke out of a prolonged trading range and surged this week, as investors began to view Masayoshi Son's company not as a mere investment firm but as an "AI holding company" combining OpenAI, Arm and data center power infrastructure.
SoftBank Soars Over Two Days as AI Optimism Sweeps In
SoftBank shares jumped more than 12% intraday on the Tokyo Stock Exchange on Saturday. The rally followed a 19.8% surge the previous day, the largest single-day gain since February 2000, marking two consecutive days of strong gains. SoftBank's market capitalization expanded by approximately $36 billion in a single day on Friday.
Behind the rally is a recovery in AI-related investor sentiment. Following Nvidia's earnings release, the perception that the AI infrastructure investment cycle remains strong has spread, putting SoftBank in the spotlight as a leading beneficiary given its holdings of multiple core assets across the AI ecosystem.
◇Arm = The surge was driven in particular by sharp gains in Arm Holdings, the U.K.-based chip designer in which SoftBank holds a controlling stake. Arm is regarded as a key player in chip design for data centers and AI servers. According to SoftBank's fiscal 2025 business report, the company holds approximately 90% of Arm.
Recently, Arm unveiled the "Arm AGI CPU," a CPU for AI data centers carrying its own brand for the first time in the company's 35-year history, marking a shift in its business structure. Until now, Arm has provided chip design intellectual property (IP) to companies such as Nvidia and Qualcomm and collected royalties, but it now plans to sell directly designed chips under the Arm brand. Meta is reportedly the first customer, while OpenAI, Cerebras and SK Telecom are also being mentioned as potential adopters. Analysts say Arm is moving beyond a pure design house and expanding its business toward directly capturing profitability amid soaring AI chip prices.
OpenAI, Arm, SB Energy: The Three Pieces of Son's AI Puzzle
◇OpenAI = An even stronger catalyst for SoftBank shares has been expectations for an OpenAI IPO. According to Reuters, OpenAI could file a confidential preliminary review request for a U.S. listing within weeks, with a listing possible as early as September. OpenAI's recent valuation has been assessed at around $852 billion, and a valuation of up to $1 trillion is being discussed at the time of listing.
SoftBank's investment in OpenAI is also massive. SoftBank Group officially announced in February that it would make an additional $30 billion investment in OpenAI, and once that investment is completed, cumulative investment is expected to reach $64.6 billion, with a stake of approximately 13%.
If OpenAI succeeds in its listing, SoftBank could realize massive valuation gains or use its holdings to raise additional capital. The Wall Street Journal reported that SoftBank has already invested $44 billion in OpenAI and plans to inject an additional $20 billion, adding that the IPO is fueling expectations of stake monetization.
◇SB Energy = News of SB Energy's push for a U.S. IPO also acted as a positive factor. SB Energy said on Thursday that it plans to submit a confidential draft registration statement to the U.S. Securities and Exchange Commission (SEC) for an initial public offering. The company is expanding its business of developing power and data center infrastructure to meet rising demand from AI data centers.
SB Energy, established in 2019, is a power infrastructure company pursuing large-scale power and data center infrastructure projects to meet rising AI workloads. It is also participating in energy infrastructure development related to the "Stargate" project in partnership with OpenAI.
Rolf Bulk, head of semiconductors and infrastructure at Futurum Group, said in an interview with CNBC that "SoftBank is a vehicle that allows simultaneous investment in the fastest-growing data center CPU market in AI chips and the OpenAI IPO."
'AI Bet Has Worked' vs. 'Holding-Company Discount Remains'
The latest surge is being read as a signal that Chairman Masayoshi Son's "all-in on AI" strategy, long dogged by claims of investment failure, is regaining momentum. The Vision Fund, which had been shaken by failed investments such as WeWork, is now fueling expectations of a comeback led by OpenAI and Arm.
However, optimism is not the only view. CNBC pointed out that even with SoftBank's many promising assets, a "holding-company discount" remains, in which the value of underlying assets is not fully reflected in the share price due to its holding-company structure.
Bay Sun Ling, chief equity advisor at UBP, also offered a cautious view, saying, "SoftBank's share price is reflecting the rising value of core assets such as Arm and OpenAI," while adding that "investors in holding companies often fail to fully enjoy the entire value of underlying assets."
The OpenAI IPO is also not yet a finalized process. Even if a confidential listing application is made, the actual timing of the listing and the corporate value could change depending on market conditions, regulations and earnings outlook. The SB Energy listing schedule could also shift depending on the SEC review and market conditions.
