AI Agent UpdateSeoul trips circuit breaker as KOSPI plunges 8.5% intraday; Taiwan and Tokyo follow
South Korea's KOSPI fell below 5,000 for the first time since February on November 6, triggering a 20-minute trading halt, as the US chip rout spread across Asia — Taiwan's TAIEX suffered its biggest intraday point drop ever and the Nikkei sank 6%.
The News
The rout went global on November 6. South Korea’s KOSPI opened down 2.24% at 5,263.26, then plunged to an intraday low of 4,911.28 within minutes — falling below 5,000 for the first time since February and triggering a Stage 1 circuit breaker at 9:03 a.m. (when the index stood at 4,924.61, down 8.52%) that halted all trading for 20 minutes, the 11th halt this year. The index recovered as high as 5,269.10 after the halt, then faded late as foreign selling intensified, closing at 5,059.69 — down 324.11 points, or 6.02% — its lowest close since March 31 and 44.5% below its June 22 peak of 9,114.55. Samsung closed at ₩188,700, down 6.35%, after falling 9.98% to ₩181,400 at the halt; SK hynix closed at ₩1,132,000, down 10.44%, after falling 11.71% to ₩1,116,000, with Seoul Economic Daily flagging the risk it loses the ₩1,000,000 threshold. The KOSDAQ fell 5.03% to 644.27, and foreign investors net-sold ₩2.7691 trillion while institutions bought ₩1.7042 trillion and retail investors ₩600.9 billion. The only gainer among the top 20 stocks was Naver, up 2.87%.
Taiwan and Japan followed the same script. Taiwan’s TAIEX plunged 3,737.67 points within minutes of the open — the biggest intraday point drop in the market’s history — falling below 40,000 to an intraday low of 37,837.05, down 8.99%, before recovering to close at 39,701.64, down 1,873.08 points or 4.51%, its fourth-largest point loss ever, about 20.3% below its October 6 peak. TSMC, more than 40% of the index by weight, hit its daily limit of NT$2,020 shortly after the open — a NT$220 drop, the stock’s largest-ever absolute intraday fall, wiping out about NT$5.7 trillion of market value — and closed down 4.69%. MediaTek also hit its daily limit at NT$3,115 and Foxconn fell more than 9% intraday. Japan’s Nikkei 225 sank 5.96% to 57,434.77, below 60,000 for the first time in nearly half a year, with Kioxia down a further 8.72% to ¥8,511, about 41% lower in five sessions.
The session followed the Philadelphia Semiconductor Index’s 12.25% collapse on November 5 and the midterm-regulation fears behind it. The Korean government responded the same day: Deputy Prime Minister and Finance Minister Lee Hyung-il chaired an emergency market review meeting, and state-backed support funds bought in the afternoon alongside dip-buyers. Korean brokerages pushed back on the panic: Daishin Securities called the market reaction “excessive,” saying a full suspension of datacenter building is unlikely and the real risk is higher costs and schedule delays, not a full stop.
Seoul fell below 5,000, trading stopped for 20 minutes, and the selling still didn’t stop — the rout has gone global.
Why It Matters
This is the third leg of the rout, and the one that proves it is not a US-only event. The November 5 session in New York could have been read as a one-day panic; the November 6 session in Asia cannot. When Seoul, Taipei and Tokyo all fall 5–6% on the same day, the market is repricing a global supply chain, not a single country’s politics — and the supply chain runs through Korea, Taiwan and Japan.
The circuit breaker is the detail that matters most. Breakers exist to pause panic, and this one worked only part of the way: the KOSPI recovered above 5,000 after the halt, then faded late as foreign selling intensified. Foreign money leaving is the tell — overseas investors sold a net ₩2.77 trillion while domestic institutions and retail bought. That is not a vote of confidence in the tape; it is locals catching a falling knife while foreigners head for the exit. And the Taiwan numbers show the same pattern at larger scale: TSMC alone shed about NT$5.7 trillion of market value intraday, the biggest absolute fall in the stock’s history.
Analyst's Take
Our call is Bearish. The Asia session confirms the US move was not a one-day flush: the same fear crossed the Pacific overnight and produced a circuit breaker, a record intraday point drop in Taiwan and a Nikkei below 60,000. When a market needs a 20-minute halt and still closes down 6%, the selling is not a wobble — it is a repricing, and repricings take more than a morning to finish.
The first sign of a floor narrative is already visible in the broker pushback: costs and delays, not a full stop, is the base case from Daishin, which called the market reaction excessive. That is worth hearing, but it is not yet a buy signal — foreign investors sold ₩2.77 trillion in one session, and Kioxia is down about 41% in five sessions. Watch whether US pre-market gains hold when New York opens, and whether Seoul stabilises or makes a new low. Until then, the direction of travel is down.
By The Numbers
FAQ
What is a circuit breaker, in plain terms?
An automatic pause on all trading. When an index falls 8% or more from the previous close and stays there for a minute, the exchange halts trading for 20 minutes to let panic cool. Seoul triggered a Stage 1 circuit breaker at 9:03 a.m. on November 6 — the 11th halt this year and the first since October 15.
Why did Seoul fall after the US?
Because the same fear drove both sessions. The US chip index fell 12.25% on November 5 on worries that new US rules could slow datacenter building. South Korea makes the memory chips those datacenters need, so when US memory stocks fell, Seoul’s Samsung and SK hynix fell with them — and foreign investors sold a net ₩2.77 trillion in a single session.
Why do some reports show SK hynix at ₩1,138,000?
AjuPress published two different closes: its 15:44 KST wrap printed ₩1,132,000 (−10.44%), while its later 17:27 wrap printed ₩1,138,000 (−9.97%). Finnhub market data, TradingKey, MoneyToday and Seoul Economic Daily agree on ₩1,132,000, and this article uses that majority set.
What is a sell-side sidecar?
An automatic pause on computer-driven sell orders. When futures fall more than 5% from the previous day’s close and stay there for a minute, the exchange suspends program selling for five minutes. The KOSDAQ triggered one on November 6.
Did the Korean government step in?
Yes, the same day. Deputy Prime Minister and Finance Minister Lee Hyung-il chaired an emergency market review meeting, and state-backed support funds bought in the afternoon alongside dip-buyers. The index still closed down 6.02%.
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Source: Seoul Economic Daily / MoneyToday / TradingKey / Finnhub