Kospi falls 3.73% to lowest since April on AI chip doubts

South Korea's main share index, the Kospi, fell 3.73% on Tuesday, October 20, 2026, to close at about 5,553, its lowest close since April 7, according to Korean market reports. Chip makers led the fall: SK Hynix dropped about 4.2% and Samsung Electronics 2.98%, as investors questioned whether the huge sums being spent on artificial intelligence (AI) will pay off. Other Asian markets also fell, while Indian stock exchanges were closed for Dussehra.

The Kospi has become one of the clearest gauges of investor mood about AI. Samsung Electronics and SK Hynix make memory chips, the parts that store and move data inside AI servers, and together they carry a large weight in the index. When investors expect AI spending to keep rising, these shares climb; when doubts set in, they fall fast. On October 20 reports pointed to two worries: whether the money big technology companies are spending on AI data centres will earn an adequate return, and how that spending will be funded when borrowing costs are high.

The fall stands out because chip makers' own results have been strong. A Korean financial daily noted that strong earnings were not enough to hold the two shares up, which suggests the market is now worried less about this quarter's numbers than about how long the AI building boom can last.

The day also fits a pattern of sharp swings. The 7.57% fall on October 15 triggered a circuit breaker, and the index has struggled to recover since. Large one-day drops of this kind are unusual for a major market and show how concentrated the Kospi's gains had become in a few chip shares.

For Indian investors, the session matters even though Indian markets were closed. When Indian exchanges reopen, traders usually take their cue from how Asian and US markets moved during the holiday. India has fewer listed chip makers than South Korea or Taiwan, but Indian information technology companies and AI-linked stocks respond to the same global questions about technology spending. The Sensex had already fallen 876 points on October 19, weighed down by private banks and crude oil prices. Brent crude was near $110 a barrel on October 20, according to market reports, which adds to the pressure on oil-importing economies such as India.

Kospi and chip shares on October 20, 2026 Item | Close | Change Kospi | about 5,553 | down 3.73% Kosdaq | 781.97 | down 3.33% Samsung Electronics | 211,500 won | down 2.98% SK Hynix | 1,223,000 won | down about 4.2%

Short-term: Asian technology shares are likely to stay volatile as investors wait for results from large US technology companies, which will show whether AI spending plans are being kept or trimmed. Indian traders will watch Asian and US markets closely before Indian exchanges reopen.

Long-term: If doubts about returns on AI spending persist, companies that sell chips and equipment for AI data centres could see slower orders, which would hit export-led economies such as South Korea and Taiwan. If spending holds up, the sell-off may prove to be a pause rather than a turn.

Who is affected: Shareholders of Samsung Electronics, SK Hynix and other chip companies, including foreign funds; investors in Asian markets and in global technology funds; and Indian investors, whose markets reopen after the Dussehra holiday.

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