Investors are pricing SoftBank Group's Arm and OpenAI stakes as rising faster than a strengthening yen erodes their translated value, letting the stock climb nearly 38 percent in a week despite a currency headwind that usually pressures the holding company.
SoftBank Group shares climbed 5 percent to ¥6,884 on Wednesday, extending a near-38 percent rally since September 3 even as the yen strengthened toward its highest level in almost seven months.
"The move so far has been driven by domestic Japanese factors," said Michael Wan, a strategist at MUFG, adding that emerging markets and carry trades had remained "very resilient." That distinction helps explain why SoftBank can rally alongside the currency.
The stock has risen 11.8 percent on September 4, 11.2 percent on September 7 and 5.5 percent on September 8, driven by a repricing of SoftBank's AI exposure. OpenAI's launch of GPT-6 Astra reignited enthusiasm across Asian technology stocks, while gains in Arm added another tailwind. SoftBank's official figures showed a net asset value of ¥72.3 trillion as of June 30, with Arm accounting for ¥49.91 trillion of adjusted equity value. SoftBank has also become one of OpenAI's most important backers.
The rally is unusual because SoftBank's valuation is tied to overseas technology assets such as Arm and OpenAI. A stronger yen reduces the yen-equivalent value of those holdings and raises questions about the carry trades that have supported high-beta technology exposure. The yen traded near ¥153.3 per dollar on Wednesday, with expectations for another Bank of Japan rate increase accelerating — the probability of a September move had climbed from about 65 percent to 98 percent, with another hike by December nearly priced in.
Why the yen rally hasn't hurt SoftBank
If dollar-denominated assets rise less quickly than the yen strengthens, their value can fall when translated back into Japan's currency. Investors are currently looking through that drag because they believe Astra and Arm are increasing SoftBank's AI value faster than the yen is reducing it. Because the yen's strength is driven by domestic Japanese factors — expectations of higher rates and capital repatriation — investors do not automatically need to sell equities to fund the currency move.
SoftBank behaves like an investment holding company rather than an operating business, so its share price tracks the mark-to-market of its portfolio. That structure makes the current divergence a test of whether the AI rerating is durable enough to outweigh a currency that is climbing on its own policy logic. For the Nikkei, where SoftBank carries heavy index weight, the stock's persistence matters beyond the single name.
The carry-trade unwind risk
The yen has long been used as a cheap funding currency. Investors borrow yen and deploy the money into higher-returning assets elsewhere, including US technology stocks. When the yen rises and Japanese rates climb, that trade becomes less attractive. A disorderly unwind can force investors to sell dollar-denominated assets and buy yen to repay borrowing, reinforcing both moves. LPL Financial's Adam Turnquist told the Wall Street Journal that a break below ¥152 per dollar could accelerate the yen rally and force more short covering.
That matters for SoftBank because its valuation is tied to the same AI ecosystem that could be vulnerable during a deleveraging shock. If dollar assets rise more slowly than the yen appreciates, their translated value falls — the exact pressure investors are now betting the AI repricing can outrun.
This article is for informational purposes only and does not constitute investment advice.
