Samsung Electronics and SK Hynix stocks sank on Monday as foreign and institutional selling hit Seoul after the Chuseok break, turning a volatile reopening into a fresh test of the memory-chip rally.
By 11:38 am in Seoul, Samsung was down 4.38% at 273,000 won and SK Hynix had fallen 4.78% to 1.773 million won.
The KOSPI was also back below 7,000. The selloff looks severe, but the bigger question is whether investors are abandoning the memory upcycle or cutting exposure before Micron Technology reports on September 30.
Foreign selling returns after the holiday
The market reopened with several overseas sessions to digest at once. During the three US trading days while Korea was shut, the Nasdaq fell 0.6% and the Philadelphia Semiconductor Index slipped 0.2%, according to MoneyToday.
At 9:30 am, foreigners had sold a net 156.2 billion won of KOSPI shares and institutions 23 billion won, while retail investors bought 165.2 billion won.
That matters because Samsung and SK Hynix had entered the holiday after a strong rebound. Samsung closed September 23 up 3.07% at 285,000 won, while SK Hynix gained 0.87% to 1.856 million won.
Kiwoom Securities analyst Han Ji-young told MoneyToday that US employment data, Korean exports and Micron earnings would create an “active tug-of-war” around the KOSPI’s 7,000 level this week.
Memory fundamentals are not falling as fast
A more contrarian signal is that analysts still describe DRAM supply as constrained.
Yuanta Securities Korea analyst Baek Gil-hyun recently raised his Samsung target to 630,000 won. In comments reported by Seoul Economic Daily, Baek said HBM production is absorbing conventional DRAM capacity while AI inference is lifting demand for higher-capacity memory.
“Supply constraints are likely to ease later than expected,” he said.
Yuanta expects memory bottlenecks to persist through 2028. That does not make Monday’s selloff irrelevant, as foreign investors have already shown a willingness to rotate away from Korea’s biggest semiconductor winners, and elevated expectations leave both stocks vulnerable to disappointment.
But there is an important distinction. Share-price positioning is weakening faster than the industry’s core supply and earnings assumptions.
If DRAM contract prices remain firm and HBM demand stays tight, the drop can still be interpreted as a reset. If those assumptions weaken, the repricing could deepen.
Micron now holds the next clue
Micron’s fiscal fourth-quarter report on September 30 is the clearest near-term test. The company has confirmed its earnings call for that date, and Wall Street expectations are already unusually high.
Investors will focus less on whether Micron beats quarterly estimates and more on what management says about 2027 DRAM supply, HBM demand, contract pricing and margins.
Stifel analyst Brian Chin has maintained a Buy rating and $1,500 target. He expects DRAM bit shipments to grow only around 15% to 20% in 2027 and argues that investors still underestimate the cycle’s durability.
“We believe the durability of this memory upcycle continues to be under-appreciated,” Chin said.
That makes Micron a direct read-through for Korea’s two memory leaders. Strong pricing and supply commentary would support the view that Monday’s selling is largely positioning and macro risk.
A weaker outlook would be more damaging because it would challenge the fundamental assumption behind the recent rebound.
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