Chip stocks fell together. Why did Kioxia fall harder than the rest?
きょうの東京株式市場ではキオクシア株の急落が注目を集めました。
先週から株安が強まっていましたが、きょうはそこからさらにストップ安（制限値幅の下限）の10000円安（18%安）の44550円にまで下落し、売り注文を残したまま取引を終えました。
わずか1ヶ月前につけた最高値から60%あまり値下がりしました。
Kioxia shares hit their daily limit down again on July 28, sinking to 44,550 yen. That's an 18% drop from the previous close, and over 60% below the peak the stock hit just a month earlier. The same day, Samsung Electronics fell 13.4%, SK hynix fell 14.7%, and the Kospi dropped more than 11% intraday, triggering Korea's eighth circuit breaker this year.
Why did chip stocks fall together
The market points to two reasons. Doubts grew that the AI memory rally had run too hot, and reports that China's CXMT is accelerating DRAM capacity expansion revived worries about Samsung and SK hynix losing market share. South Korea's regulator is reportedly weighing tighter rules on retail investors piling into leveraged ETFs.
But why did Kioxia fall harder than the rest
That's the whole sector's story. But Kioxia's drop outpaced Samsung's and SK hynix's for a reason specific to the company. Kioxia is a NAND flash memory maker spun off from Toshiba. NAND is the chip that holds the photos on your phone and the files on your laptop, keeping them even with the power off.
On July 16, a jury at the US District Court for the Western District of Texas found Kioxia infringed a patent held by satellite communications company Viasat, and ordered it to pay about $228 million. The patent covered error-correction tech that cuts power use and extends NAND's lifespan and reliability. Kioxia called the verdict "completely unacceptable" and said it will appeal.
The day after the ruling, on the 17th, Kioxia shares fell 16.1%, already near a limit down at 52,110 yen. This is the same stock's second sharp fall within ten days.
But aren't the earnings supposed to be good
Here's the paradox: Kioxia reports earnings on the 30th, and the guidance doesn't look weak. Last quarter's revenue crossed 1 trillion yen for the first time, with a 66% gross margin and free cash flow above 241 billion yen. This quarter's guidance calls for revenue of 1.75 trillion yen, up 74.5% from the prior quarter, operating profit of 1.3 trillion yen, and net income of 870 billion yen.
Chip stocks across the board are correcting, and Kioxia is simply caught in it. Once earnings hold up, it should recover along with the rest.
Kioxia fell harder than peers in the same sector. A patent payout and an appeal fight, unrelated to its actual business, sit on this one company alone.
Both readings look at the same drop, differing only on whether it's sector weather or an extra weight unique to Kioxia.
So what settles it
The question comes down to one thing. Is this just a sector-wide correction, or has Kioxia's own lawsuit risk been added on top? If the 30th's earnings come in as guided and Samsung and SK hynix bounce back together, the sector read holds. If Kioxia lags the recovery, the patent risk is still weighing on it. Whichever comes first, an appeal ruling or a settlement, will be the first real signal of how heavy that patent burden is.
- Kioxia hit limit-down again on July 28, sinking to 44,550 yen, over 60% below its peak from a month earlier. Samsung fell 13.4%, SK hynix 14.7%, and the Kospi dropped over 11% intraday.
- The surface story is a sector-wide cooldown in AI memory stocks, compounded by fears over China's CXMT ramping up capacity.
- But Kioxia fell hardest of all, because on July 16 a US court alone ordered it to pay $228 million for patent infringement.
What happened next
Awaiting gradingTo be scored on whether Kioxia's July 30 earnings meet guidance (1.75 trillion yen revenue) and recover together with Samsung and SK hynix, and on when the Viasat patent appeal ruling or settlement lands.