KOSPI Plunges 8.5%, Breaks 5,000 as Circuit Breaker Triggers

As of the close on November 6, 2026, South Korea’s benchmark index delivered one of its sharpest intraday breaks on record. The KOSPI was down 460.33 points, or 8.55%, at 4,923.47 by 09:08 KST, having surrendered the 5,000 level within minutes of the open, and the Korea Exchange triggered a stage-1 circuit breaker at 09:03:33 KST that halted trading for 20 minutes. The index opened at 5,263.26, slid further, then recovered part of the damage to close at 5,059.69, down 6.02%.

How fast did the 5,000 level give way?

The break was measured in minutes. Yonhap put the KOSPI at 4,923.47 by 09:08 KST, and Maeil Business News reported that the 5,000 level gave way three minutes after the open. A sell sidecar followed at 09:34 KST once losses exceeded 6%.

Outlets disagree on the interval: Yonhap dated the prior intraday break to February 6, while News1 reported the last sub-5,000 reading as January. Neither is treated here as established fact. At the close the index stood at 5,059.69, down 324.11 points, or 6.02%.

What connected a US election result to Seoul’s chip tape?

News1 reported that concerns spread after Democrats took both chambers of Congress, on the view that stronger data-center regulation could slow AI investment. Yonhap recorded the Nasdaq Composite down 5.52% and the Philadelphia Semiconductor Index down 12.25%, its worst session since 2020. Financial News recorded Broadcom down 10.43% and Nvidia down 9.26%, with SK Hynix’s US depositary receipts down 13.40%. News1 reported UBS estimating that about 30% of expected 2028 US new data-center capacity could be at risk from construction halts.

How hard did Samsung and SK Hynix fall?

At 09:20 KST, Financial News reported Samsung Electronics down 9.98% at 181,400 won and SK Hynix down 11.71% at 1,116,000 won. News1’s snapshot taken minutes later showed SK Hynix down 11.79% at 1,115,000 won; the observations are timestamped separately and not averaged.

By the close, News1 reported Samsung Electronics finished down 6.35% at 188,700 won, its first close below 200,000 won in about seven months, after trading as low as 179,200 won. SK Hynix closed down 10.44% at 1,132,000 won.

Who was selling into the decline?

News1 reported foreign net sales of about 2.05 trillion won across the two names against retail net buying. Maeil Business News, citing Koscom CHECK, reported retail bought a net 5.8323 trillion won of Samsung Electronics and 3.3601 trillion won of SK Hynix between October 6 and November 5, 2026, the two largest domestic net-buy totals among listed Korean stocks. On the preceding session, when the KOSPI fell 5.28%, retail still net-bought 1.2277 trillion won of Samsung Electronics and 890.2 billion won of SK Hynix.

Why the rout may be about investment paths, not demand

News1 reported that Meritz Securities checked US sales channels at Samsung Electronics, SK Hynix and Micron and found no abnormal signs of demand change, framing the issue as investment-path uncertainty rather than a demand decline. Mirae Asset Securities’ Suh Sang-young said HBM and server memory demand remains firm and that repricing the pace of investment growth need not be read as current earnings deterioration.

Electronic Times reported Micron has effectively halted work on its new Fab 11E plant in Taoyuan, Taiwan, over a labour dispute on performance bonuses, which the paper said could push customers toward long-term contracts with Korean suppliers. Counterpoint Research put third-quarter global DRAM revenue share at 38% for Samsung Electronics, 29% for SK Hynix and 21% for Micron. By the November 6 pre-market session Edaily reported Nvidia up 3.6% and Micron, AMD, Intel and Broadcom up 5% to 8.3%.

한국거래소에 따르면 이날 오전 9시 8분 현재 코스피는 전 거래일 대비 460.33포인트(8.55%) 하락한 4,923.47이다.

According to the Korea Exchange, the KOSPI stood at 4,923.47 as of 09:08 that morning, down 460.33 points, or 8.55%, from the previous session.

Frequently Asked Questions

What is a stage-1 circuit breaker on the KOSPI?

A market-wide halt the Korea Exchange imposes when the KOSPI falls sharply. This one came at 09:03:33 KST, according to the Yonhap report.

Did the KOSPI close below 5,000?

No. It closed at 5,059.69, down 6.02%, after trading as low as 4,923.47, according to Edaily and Yonhap.

What do analysts say about memory demand?

Meritz Securities found no immediate signs of a demand change, and Mirae Asset Securities said demand remains firm, both as reported by News1.