The memory chipmaker's stock has surged more than 3,500% since its IPO eighteen months ago, riding the AI infrastructure boom to a $281 billion valuation
A memory chip company that went public at a $5.2 billion valuation in December 2024 just briefly overtook Toyota Motor Corp. as Japan’s most valuable company. Kioxia Holdings Corp., the former Toshiba memory division, hit an intraday market cap above ¥45 trillion, roughly $281 billion, on June 3.
Kioxia’s shares have risen more than 3,500% since its IPO. Toyota, the automaker that dominated Japan’s corporate hierarchy for years, got leapfrogged twice in three days. SoftBank Group pulled ahead on June 1 with a market cap exceeding ¥48 trillion, and Kioxia followed on June 3.
The numbers behind the surge #
Kioxia’s stock climbed 7.2% on June 3, touching an intraday high of ¥83,140 per share before settling back to close at ¥78,080. That closing price put its market valuation at approximately ¥42.7 trillion, technically below Toyota’s ¥45.5 trillion at the end of the session.
Kioxia’s shares have gained more than 660% year-to-date through early June 2026. The company reported record quarterly earnings of ¥596.8 billion for the period ending March 2026. The next quarter looks even bigger, with an expected operating profit of ¥1.3 trillion, about $8.2 billion, for the June period.
Why NAND flash memory is suddenly worth more than cars #
Kioxia has been developing NAND flash memory since 1987. Toshiba Memory was sold to a Bain Capital-led consortium in 2018 to cover losses from its nuclear power business. The division was rebranded as Kioxia in 2019 and spent years as a privately held company before finally going public in December 2024. At that point, its initial valuation of ¥780 billion, about $5.2 billion, reflected a market that still viewed NAND flash as a commodity play.
What this means for investors #
Toyota is now the third most valuable company in Japan. The top two spots belong to SoftBank Group and Kioxia, both propelled by the AI trade.
An expected operating profit of $8.2 billion in a single quarter would place Kioxia among the most profitable chipmakers globally. Samsung and SK Hynix are both expanding capacity in the same NAND flash market. Bain Capital remains a dominant shareholder, and any large-scale share sales could create significant downward pressure on the stock.
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