On 1 June 2026, SoftBank Group's market capitalisation crossed ¥46.5 trillion intraday — edging past Toyota Motor's ¥45.8 trillion — to make Masayoshi Son's conglomerate Japan's most valuable listed company. Shares rose 14% in that Tokyo session according to Yahoo Finance, with Seoul Economic Daily reporting a more conservative 9% figure; by the close SoftBank's cap had widened further, with some tallies putting it above ¥47 trillion. The last time SoftBank held the top position was briefly at the peak of Japan's internet bubble in 2000, meaning the gap spanned roughly a quarter-century of Toyota dominance.
How the Numbers Stacked Up
Toyota claimed the crown it has held since around 2003, when it overtook NTT DoCoMo, briefly touching ¥60 trillion in February 2026 before sliding on softer vehicle demand and higher fuel costs. SoftBank ran the other way: every month this year brought fresh gains as its AI-linked portfolio appreciated. Yahoo Finance data put SoftBank's year-to-date advance at more than 90% by the time the session closed on 1 June, while the company's annual net profit was reported to have quadrupled to over ¥5 trillion — a record for a Japanese company.
The AI Portfolio Doing the Heavy Lifting
Two holdings have driven the re-rating. SoftBank's stake in OpenAI, widely expected to list within the year with a bullish projection of a $1 trillion valuation, has become the single most-cited reason analysts give for the stock's premium. Arm Holdings, the UK chip designer in which SoftBank retains a majority stake, has seen its own shares surge on semiconductor demand tied to AI model training and inference. Together, the two positions have recast SoftBank — long viewed as an erratic venture vehicle — as a structural play on AI infrastructure. SoftBank is reportedly on track to hold approximately 13% of OpenAI by October through a commitment approaching $65 billion.
Masayoshi Son described the AI shift in a CNBC interview on 1 June as "probably 50x bigger than dot-com" — a characteristically outsized framing that nonetheless reflects where institutional money is moving. He acknowledged that market corrections are possible but said any such correction "will be the best investment opportunity to me," drawing parallels to how auto and electronics stocks recovered after the 1929 crash and internet stocks recovered after the dot-com bust.
The €75 Billion France Commitment
Days before the market cap milestone, Son announced that SoftBank would invest up to €75 billion (approximately $87 billion) in AI data centres across France — the company's largest commitment in Europe by a wide margin. Initial sites are planned in Dunkirk (Loon-Plage), Bosquel, and Bouchain, with a first phase delivering 3.1 gigawatts in Hauts-de-France by 2031, and up to 5 GW in total. French Economic Minister Roland Lescure described the pledge as evidence of President Macron's drive to position France as a leading destination along the full AI value chain.
What This Means for Japan's Capital Markets
The symbolic weight of the shift goes beyond a league-table line. Toyota built its supremacy on precision manufacturing and decades of export earnings — a model that defined how international investors read Japan Inc. SoftBank's ascent signals that AI infrastructure investment has overtaken automotive as the dominant value driver in Asia's second-largest capital market. For Japan's government, which has been pushing domestic AI adoption and chip investment since 2023, the change at the top of the Nikkei hierarchy functions as external validation. The Nikkei 225 itself broke through 67,000 intraday for the first time in the same session.
Memory chipmaker Kioxia Holdings also caught attention: the company climbed from 26th into the top three of Japan's market cap rankings (Seoul Economic Daily put it second, Yahoo Finance third), vaulting past Mitsubishi UFJ Financial Group. Portfolio managers who tracked Japan through the lens of quality manufacturing now need a second framework: AI-exposed conglomerates with global venture reach.
Risks Worth Watching
SoftBank's valuation is concentrated. If OpenAI's IPO disappoints or is delayed beyond 2026, or if Arm's growth trajectory slows as AI capex cycles peak, the premium the market is paying compresses fast. The company also carries significant debt from earlier Vision Fund-era investments, some of which remain impaired. A strong year-to-date rally in any single stock invites the question of how much upside has already been priced in.
Correction, 18 October 2026: An earlier version misquoted Masayoshi Son's "50x" remark, dated SoftBank's full 5 GW France plan to 2031 and attributed Kioxia's rise from 26th place to Yahoo Finance. These have been corrected, and an unsourced year-to-date figure for the Nikkei 225 has been removed.
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