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Kospi Plunges 7.6% as AI Chip Selloff Deepens
Why is the Kospi down today?
Kospi (KS11) plunged 7.57% to 5,554.22 on Thursday, its seventh straight loss, after an AI chip selloff hit Samsung and SK Hynix as hot US inflation raised Fed rate-hike fears.
Key numbers
| Kospi close | 5,554.22-7.57% on the day |
|---|---|
| Samsung Electronics | 210,000 won-9.48% |
| SK Hynix | 1.26M won-11.06% |
| Foreign net selling | $2.7B8th straight session of selling |
| US inflation (Sept) | 3.7%above 3.6% expected |
What happened
Kospi (KS11) plunged 7.57% to 5,554.22 on Thursday, its seventh straight loss, after an AI chip selloff hit Samsung and SK Hynix as hot US inflation raised Fed rate-hike fears. Trading was paused twice: first for automated sell orders (a "sidecar"), then for all trading for 20 minutes (a "circuit breaker"). Samsung Electronics fell 9.48% and SK Hynix 11.06%, while foreign investors sold about $2.7 billion of shares. US prices rose 3.7% in September from a year earlier, more than expected, fueling bets the US central bank (the Fed) will raise interest rates.
Why it matters
The Kospi's slide shows how closely South Korea's stock market is tied to Samsung and SK Hynix, two memory chip makers (chips that store data) that supply AI data centers. Investors are worried that huge AI spending may not earn enough money back, and that higher interest rates make that borrowing costlier. The index is now at its lowest level in six months.
Who this affects
- MarketbearishHigh impact
- Korean and global chip-linked shares fell sharply; bad for holders.
- CompanybearishHigh impact
- Samsung and SK Hynix shareholders took steep one-day losses.
- CompetitorsbearishMedium impact
- Japanese and Taiwanese chip firms fell too; bad for rivals.
- IndustrybearishHigh impact
- AI chip makers face doubts over funding and profits.
Kospi vs Nikkei 225, Taiex
| Kospi (South Korea)KS11 | 5,554.22 | -7.57% |
|---|---|---|
| Nikkei 225 (Japan)N225 | 64,425.90 | -4.90% |
| Taiex (Taiwan)TWII | — | -3.4% |
As of 2026-10-15
How we got here
Wall Street falls after hot US inflation: S&P 500 down 1.1%, Nasdaq down 1.9%, Nvidia down 3.2%.
Sell-side sidecar triggers at 9:07 a.m. Seoul time after Kospi opens 5.59% lower.
All trading halts for 20 minutes at 12:38 p.m. after Kospi falls more than 8%.
Kospi closes at 5,554.22, down 7.57%, its lowest level in six months.
What to watch
- Whether foreign investors keep selling after eight straight sessions of net selling2026-10-16
- TSMC earnings, a key read on AI chip demandOctober 2026
- Federal Reserve's October and December rate decisions after hotter inflation dataQ4 2026
Educational content only. Not investment advice.
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