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Kospi Falls 3.7% as AI Spending Doubts Hit Samsung, SK Hynix
Why is the Kospi down today?
South Korea's Kospi (^KS11) fell 3.7% to 5,552.74 on Tuesday after AI spending doubts and high US Treasury yields hit Samsung Electronics (005930.KS) and SK Hynix, as foreign investors sold.
Key numbers
| Kospi close | 5,552.74-3.73% (-215.27 pts) |
|---|---|
| Samsung Electronics | 211,500 won-2.98% |
| SK Hynix | 1,223,000 won-4.23%, lowest close since April |
| Foreign net selling (main board) | 530.3B won (~$400M)vs $480M in first two hours (per Bloomberg) |
| US 10-year Treasury yield | 5.14%up from 5.09% Friday |
| Kospi vs June 19 record high (9,385) | ~41% belowwas -40.4% on Oct 15 |
What happened
South Korea's Kospi (^KS11) fell 3.7% to 5,552.74 on Tuesday after AI spending doubts and high US Treasury yields hit Samsung Electronics (005930.KS) and SK Hynix, as foreign investors sold. Samsung closed down 2.98% and SK Hynix fell 4.23%, its lowest finish since April. Foreign investors sold a net 530 billion won of shares (about $400 million) by the close, while Korean individual investors bought. Bloomberg counted $480 million of foreign selling in the first two hours alone (per). The slide follows a roughly 7% one-day plunge last Thursday.
Why it matters
Samsung Electronics and SK Hynix, South Korea's two biggest chipmakers, supply memory chips for AI data centers, so their slide drags the whole Kospi down. Investors worry that the huge sums being spent on AI may not pay off. Higher interest rates on US government debt (Treasury yields) also make that spending costlier to fund. Because these two companies carry so much weight, their swings can move the whole market.
Who this affects
- MarketbearishHigh impact
- Korean stock investors lose as foreign sellers dominate trading.
- CompanybearishMedium impact
- Samsung and SK Hynix shareholders face further paper losses.
- CompetitorsbearishLow impact
- Other Asian stocks also slipped, though far less than Korea.
- IndustrybearishMedium impact
- AI chip suppliers face tougher funding and demand questions.
Kospi vs Nikkei 225, Hang Seng, Shanghai Composite
| Kospi (South Korea)^KS11 | 5,552.74 | -3.73% |
|---|---|---|
| Nikkei 225 (Japan)^N225 | 64,075.42 | -1.3% |
| Hang Seng (Hong Kong)^HSI | 23,927.47 | -1.1% |
| Shanghai Composite (China)000001.SS | 3,726.38 | -0.1% |
As of 2026-10-20
How we got here
Kospi hits its record high of 9,385 points.
Kospi plunges roughly 7% on hot US inflation data and AI funding fears.
Kospi rebounds 1.8% as AI stocks recover on Wall Street.
Kospi closes down 3.73% at 5,552.74 as foreign investors sell a net 530 billion won.
What to watch
- Whether foreign investors keep selling Samsung and SK Hynix shares in coming sessions.2026-10-21
- US 10-year Treasury yield, near 5.14%, and its effect on AI funding costs.2026-10-21
Educational content only. Not investment advice.
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