Kioxia shares closed 15.8% lower in Tokyo on Monday, 2 November, in the first trading session after the memory maker guided its October-to-December operating profit to about ยฅ2 trillion, level with the quarter before, Trading Economics reported in a market wrap carried by TradingView. Business Insider put the close at 16% lower and said the shares fell as much as 17% during the day.
SK hynix moved the other way. Its shares closed 3.8% higher in Seoul the same day, and Samsung Electronics closed 1.8% higher, by our arithmetic from Yahoo Finance daily closes. That is a gap of about 19.6 percentage points between Kioxia and SK hynix on one day, by our arithmetic.
The key insight: Kioxia closed 15.8% lower on Monday in its first session after guiding October-to-December operating profit level with the quarter before, while SK hynix closed 3.8% higher the same day, by our arithmetic from Yahoo Finance closes, a gap of about 19.6 percentage points.
Kioxia closed at 11,345 yen against 13,470 yen on Friday, 30 October, according to Yahoo Finance data, and touched an intraday low of 11,135 yen, 17.3% below Friday’s close by our arithmetic. TradingKey reported that the stock hit its lowest level since May.
The close is 41.2% below Kioxia’s 19,300 yen close on 2 October, by our arithmetic. Kioxia was among the biggest stock-market winners of the AI infrastructure boom, with its shares surging more than 750% in the first half of the year, Business Insider reported.
The Nikkei 225 fell 0.33% to close at 63,082, Trading Economics reported, and Business Insider said the index had been down as much as 1% before recovering. Screen Holdings fell 19% after keeping its full-year guidance unchanged, and Ibiden fell 3.8%, Trading Economics reported.
Kioxia Holdings daily closing price in yen, 2 October to 2 November 2026, from Yahoo Finance data. Kioxia closed at 11,345 yen on 2 November, 15.8% below its 30 October close of 13,470 yen and 41.2% below its 2 October close of 19,300 yen, by our arithmetic.Animated: Kioxia Holdings daily closing price in yen, 2 October to 2 November 2026. The 15.8% fall on 2 November is our arithmetic from Yahoo Finance closes.
What Investors Were Reacting To
Kioxia’s results filing of 30 October guided October-to-December operating profit to 1,995.0 billion yen, against 1,994.7 billion yen in July to September, and revenue to 2,500.0 billion yen, up 0.8% on the quarter. The company said that while data-centre demand should stay strong, factors such as the negative impact of exchange rates would leave revenue and profit broadly in line with the second quarter.
Bernstein analysts led by Mark Li called the forecast for essentially flat quarterly revenue and profit “a massive miss” in a 30 October note, Business Insider reported. Kioxia said its weaker outlook partly reflected delays in shipping data-centre storage products, pushing some expected sales into the following quarter, according to Business Insider, which added that a greater share of lower-priced smartphone and PC products is expected to weigh on average selling pricegrowth.
An evergreen Business Engineer explainer on the memory wall. It teaches the general idea only and does not discuss Kioxia or these results.
Sold Out for 2027, Flat for the Quarter
Kioxia still expects memory supplies to remain tight in 2027, with its planned capacity for that year already sold out, and long-term agreements cover more than half of its expected shipment volume in 2028, Business Insider reported.
SK hynix gave investors similar visibility, with long-term customer agreements covering more than half of its production capacity for 2027 and 2028, and its shares rallied after its earnings report, Business Insider said. Sandisk, Kioxia’s manufacturing joint-venture partner, closed 13.5% lower on Friday, 30 October, by our arithmetic from Yahoo Finance data.
Update, 2 November: October benchmark prices split the same way: the 8-gigabit DDR4 DRAM average hit a record $27.50 while 128-gigabit MLC NAND held at $30.61, according to DRAMeXchange data reported by TheElec. Read: DRAM prices hit a record as NAND’s 21-month rally stalls.
As we read the sources together, Monday’s split tracked guidance rather than demand: Kioxia’s filing says data-centre demand stays strong, yet its October-to-December profit guide was flat, while Business Insider says SK hynix’s long-term agreements gave investors more visibility.
As we read Business Insider’s account, Kioxia’s own explanation mixes timing and mix: delayed data-centre storage shipments pushing sales into the next quarter, and more lower-priced smartphone and PC products weighing on average selling prices, alongside the exchange-rate effect its filing cites.
Bernstein analysts led by Mark Li, in an October 30 note, on Kioxia’s forecast for essentially flat quarterly revenue and profit, as reported by Business Insider
“a massive miss”
Three Implications
FOR MEMORY INVESTORS Kioxia closed 15.8% lower while SK hynix closed 3.8% higher and Samsung Electronics 1.8% higher on the same day, by our arithmetic from Yahoo Finance closes.
FOR KIOXIA The company guided October-to-December operating profit to 1,995.0 billion yen against 1,994.7 billion yen in July to September, citing the negative impact of exchange rates, according to its filing.
FOR FLASH MEMORY BUYERS Kioxia expects supplies to stay tight in 2027, with its planned capacity for that year already sold out and long-term agreements covering more than half its expected 2028 shipments, Business Insider reported.
The framework opens: “While attention remains fixed on GPU shortages and frontier model capabilities, the binding constraint on AI scaling has quietly shifted to High Bandwidth Memory (HBM).”
As we read it, Monday’s gap between SK hynix and Kioxia, a flash maker, is a reminder that memory is several markets with different contract books, not one. The framework is the owner’s argument and does not discuss Kioxia.
We could not read Bloomberg’s report on the selloff, which sits behind a paywall, so this piece relies on Trading Economics, Business Insider and TradingKey for the market reaction and on Yahoo Finance for prices. The sources give slightly different closing declines: 15.8% from Trading Economics and our arithmetic, 16% from Business Insider.
The sources do not say how much of Monday’s fall reflects the guide itself, the shipping delays Kioxia cited, or the selloff in US chip stocks the week before. Kioxia’s comments on 2027 and 2028 reach us through Business Insider; we did not find them in the results filing we hold.
This Week In The AI Supercycle
Anthropic’s Reality Check, The Capital Squeeze, & The New World Order
This week’s issue: for two years the AI build-out was priced as a growthstory. This week it started being priced as a credit story.
Kioxia closed 15.8% lower on Monday in its first session after guiding October-to-December operating profit level with the quarter before, while SK hynix closed 3.8% higher. Kioxia also says its 2027 capacity is already sold out, according to Business Insider.
A note on sourcing. This follow-up relies on a Trading Economics market wrap carried by TradingView, Business Insider and TradingKey for the market reaction, Kioxia’s 30 October results filing for the guidance, and Yahoo Finance daily closes for prices. The 41.2%, 17.3%, 3.8%, 1.8% and 13.5% moves are our arithmetic from those closes.
Gennaro Cuofano is a CRO and tech executive who has worked in AI since late 2015, starting with bringing NLP, natural-language generation, voice and chatbot products to the marketing industry. His background is in law and finance: he holds a Master's degree in Law and an International MBA with an emphasis on corporate finance (LUISS Business School and the University of San Diego, 2012), and worked as a financial analyst at a real-estate investment firm in San Diego and as an assistant controller. His work focuses on business model strategy, business engineering and, more broadly, structural analysis: how companies make money, read from their own filings. He created FourWeekMBA and leads research there and at The Business Engineer, his newsletter on AI and business strategy, with over 95,000 subscribers and more than 1,000 published analyses. His writing has also appeared on Entrepreneur (for example, How to Digitize a Family Business in Europe) and HackerNoon. Find him on LinkedIn and Substack. See how we source.
