Chip rout deepens as KOSPI slides 6% for a second steep loss

Seoul’s stock market suffered a second heavy loss in two sessions on Nov 6, 2026, as a rout in chip shares spread from New York to Asia. The KOSPI, South Korea’s main share index, ended the day at 5,059.69. That was 324.11 points, or 6.02%, below its previous close, and it left the index only a little above the 5,000 level.

The fall came after the KOSPI had already dropped 5.28% in the session before, The Korea Times reported. The newspaper tied the panic selling in chip stocks to fears that the United States will tighten its regulation of AI data centers. Those are the large server sites where artificial intelligence models are trained and run, and where much of the newest memory and processor hardware ends up.

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US chip index lost 12.25% in a day

The pressure built first on Wall Street. The PHLX Semiconductor Index, or SOX, a gauge of US-listed chip stocks, fell 12.25% on Nov 5 in New York. It closed at 9,011.14.

While US trading was still under way, Bloomberg reported that the slide in chip shares was getting worse. According to Bloomberg, doubts about the AI trade, meaning the run of investment into companies seen as gaining from artificial intelligence, were weighing on the market.

The losses then carried into Seoul. In pre-market trading on Nov 6, before the regular session opened, Korean chip stocks were down 10%, Bloomberg reported. Because US and Asian markets trade at different hours, a sharp move in New York often shows up in Seoul, Taipei and Tokyo the next morning; Pacific Tape explains how the four closes line up.

Tokyo fell almost as far as Seoul

Japan’s market was hit nearly as hard. The Nikkei 225, Tokyo’s best-known index, dropped 5.96% on Nov 6 to close at 57,434.77.

In Taipei, the TAIEX had already lost 3.2% on Nov 5, finishing that day at 41,574.72. Taiwan’s market is home to TSMC, the world’s largest contract chipmaker.

The Korea Times account of fears about US data center rules was given for the selling in chip shares. No cause has been given for the declines in Tokyo and Taipei, and it is not established that the same concern drove them.

Rules on data centers put AI demand in question

For investors in Asian chipmakers, the reason The Korea Times cited goes to the heart of the recent rally. Demand for chips used in AI has been the main support for the gains in Asia’s chip stocks. A move by Washington to tighten rules on the data centers that house AI hardware would bear on where that demand comes from, which is why the fear reached chip shares so quickly.

The two-day slide in Seoul follows a steep fall on Nov 5 that already weighed on the country’s chipmakers. The size of the moves stands out. A 6.02% drop in a single session is large for a broad national index, and it came directly after a 5.28% fall rather than after a pause or rebound.

It is not clear what tighter US rules on AI data centers would cover, or when any would be put in place. Until there is more detail, the link between that concern and chip stocks rests on The Korea Times account of why traders were selling.

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Information only, not investment advice.