KOSPI plunges 3.5% overnight as memory-stock selloff extends into Asia; SK Hynix falls 4% (Oct 20)
What happened
South Korea's KOSPI plunged about 3.5% to ~5,563 at Tuesday's open, extending semiconductor losses and trimming its 2026 gains to around 31%, down sharply from nearly 116% at its record closing high in June. Memory chipmaker SK Hynix fell 4.07% and Samsung Electronics shed 1.03%. The Nikkei 225 declined ~1.2% (SoftBank -4.46%, Tokyo Electron -1.45%, Renesas -1.49%), the Hang Seng fell ~0.9%, and Euro Stoxx 50 futures pointed ~0.7% lower. U.S. futures were calm: S&P 500 futures up ~0.2% near 7,746, Nasdaq 100 futures flat near 29,730.
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Start your free 14-day trialWho’s affected
- Memory and semiconductor names: Micron (MU), Western Digital (WDC), SanDisk (SNDK), Samsung and SK Hynix (Nvidia's HBM suppliers); broader AI-infrastructure complex (Nvidia, Marvell, AMD)
- Asian-exposed Mag 7 supply chains.