SoftBank stock jumped 5% on Wednesday, extending its September rally even as the yen strengthened towards its highest level in nearly seven months.
The stock traded at ¥6,884 around 10:15 JST, up from ¥5,001 on September 3, a gain of almost 38%.
The move 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 carry trades that have supported high-beta technology exposure.
SoftBank’s AI rerating is overpowering the yen
A sharp repricing of SoftBank’s AI exposure has driven the rally.
OpenAI’s launch of GPT-6 Astra helped reignite enthusiasm across Asian technology stocks, while gains in Arm added another tailwind.
SoftBank rose 11.8% on September 4, 11.2% on September 7 and 5.5% on September 8 before Wednesday’s advance.
SoftBank behaves like an investment holding company rather than an operating business.
Its 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.
If dollar-denominated assets rise less quickly than the yen strengthens, their value can fall when translated back into Japan’s currency.
Currently, investors are looking through that drag because they believe Astra and Arm are increasing SoftBank’s AI value faster than the yen is reducing it.
The yen rally is serious, but not a risk-off shock
The yen traded near ¥153.3 per dollar on Wednesday after strengthening over the past week.
Expectations for another Bank of Japan rate increase have accelerated. As per market data, the probability of a September increase had climbed from about 65% to 98%, with another move by December nearly priced in.
But the reason the yen is strengthening matters.
MUFG strategist Michael Wan wrote on Wednesday that the move so far has been driven by domestic Japanese factors. He added that emerging markets and carry trades had remained “very resilient”.
That distinction helps explain why SoftBank can rally alongside the currency.
If investors are buying yen because they expect higher Japanese rates or more domestic capital repatriation, they do not automatically need to sell equities.
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.
The danger begins if carry trades start breaking
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.
That matters for SoftBank because its valuation is tied to the same AI ecosystem that could be vulnerable during a deleveraging shock.
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