South Korea halts its stock market for 20 minutes after the KOSPI falls 8%

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The Korea Exchange halted all trading on the KOSPI for 20 minutes on Thursday, October 15, after the benchmark fell 8% and stayed there for a minute. Yonhap, citing the exchange, put the index at 5,528.05 when the Level 1 circuit breaker tripped, down 480.76 points, or 8.00%, from the prior close of 6,008.81. That was about 12:38 PM KST (about 11:38 PM ET Wednesday), 15 minutes after the same breaker stopped the KOSDAQ at 12:23 PM KST (11:23 PM ET), when that index was down 8.01% at 757.88. After a halt, the exchange reopens with 10 minutes of single price auction trading. The day began badly. The KOSPI opened 5.59% lower at 5,673.01, and the exchange paused program selling for five minutes at 9:08 AM KST under its sell side sidecar rule. Both markets last tripped the breaker on the same day on July 29. The KOSPI closed Thursday at 5,554.22, down 454.59 points, or 7.57%, at the 3:30 PM KST bell (2:30 AM ET), according to Korea Exchange figures reported by Yonhap. The KOSDAQ ended at 760.82, down 63.06 points, or 7.65%.

Yonhap, The Korea Times and The Asia Business Daily tie the slide to two things. U.S. consumer prices rose 3.7% in the year to September, above the 3.6% economists expected, which revived talk of another Federal Reserve rate increase. And a Gartner estimate that AI infrastructure spending may far outrun the revenue it earns by 2030 deepened doubt about the AI trade. Chipmakers led the fall: CNBC reported SK hynix down more than 10% and Samsung Electronics down 7.1%. U.S. stock futures were already lower before the halt. At 8:20 PM ET Wednesday, Investing.com had S&P 500 futures down 0.3%, Nasdaq 100 futures down 0.8% and Dow futures flat. CNBC later described S&P 500 and Nasdaq 100 futures as only marginally lower and Dow futures up 6 points.

A circuit breaker is a pause that's built in on purpose, not a broken market. It doesn't say where prices go next. What stands out is the chain: one hot inflation number in Washington, and a few hours later Seoul's two main boards are stopped cold.