KOSPI Sinks 6% to 5,059.69 as AI Chip Rout Trips Circuit Breaker

South Korea's benchmark KOSPI fell 6.02% to 5,059.69 on Nov. 6, 2026, its second straight loss of more than 5%, as a sell-off in U.S. technology shares spread to Seoul. Investors feared that a Democratic Congress, after the party's landslide in the Nov. 3 U.S. midterm elections, could slow the construction of AI data centers. Those centers run on memory chips made by Samsung Electronics and SK hynix.

The index plunged more than 8% shortly after the opening bell, and the Korea Exchange suspended trading for 20 minutes. It fell as low as 4,911.28, its first drop below 5,000 since Feb. 2, 2026, before institutional buying helped it close back above that line, the Korea JoongAng Daily and News1 reported.

The KOSDAQ, home to smaller technology and biotech companies, lost 5.03% to 644.27. About ₩267 trillion ($197 billion) of KOSPI market value disappeared in the session, News1 reported. Won amounts in this article are converted at ₩1,356.6 per dollar, the Seoul closing rate at 3:30 p.m. on Nov. 6, 2026.

The drop came on top of a long slide. By Oct. 19, 2026, the KOSPI had already fallen more than 40% from "just below the 10,000 mark," Money Today reported.

Korea context: A circuit breaker stops all trading in KOSPI stocks for 20 minutes once the index has stayed 8% or more below the previous close for one minute, under Korea Exchange rules. Further stages apply at 15% and 20%, and the third ends trading for the day. The Nov. 6 halt was the 11th of 2026 and the 17th since the system began, the Asia Business Daily reported. Each stock also has a daily price limit of 30%, explained in our guide on how to buy Korean stocks from abroad.

What Drove the Drop

The trigger came from Wall Street. On Nov. 5, the tech-heavy Nasdaq fell 5.52%, and SOXL, a fund designed to return three times the daily move of U.S. chip stocks, plunged 38.71%, the Korea JoongAng Daily reported.

Data centers were at the center of the fear. Texas Governor-elect Gina Hinojosa said on Nov. 5 that "we need to stop what we are doing with data centers" until laws are introduced to protect residents, the Korea JoongAng Daily reported. Texas has become a major data center hub.

Korea's two largest companies took the heaviest hits. Samsung Electronics fell 6.35% to ₩188,700 ($139), and SK hynix dropped 10.44% to ₩1.13 million ($833), Yonhap reported. Over Nov. 5 and Nov. 6, Samsung lost 13% and SK hynix 19% based on closing prices, according to the Korea JoongAng Daily.

The selling was broad. Decliners outnumbered gainers 757 to 131, and carmaker Hyundai Motor fell 4.77%. Among the few winners were IT shares, with portal operator Naver up 2.87% and Samsung SDS up 6.34%.

"Concerns that the U.S. Congress could further tighten regulations on AI data centers were behind the market plunge," said Lee Kyoung-min, an analyst at Daishin Securities, as translated by Yonhap. He said the worry had spread to the entire AI value chain, including semiconductors.

Other Asian markets fell too, though less sharply in Taiwan. Japan's Nikkei 225 dropped 5.96% and Taiwan's Taiex slid 4.5% on Nov. 6, the Korea JoongAng Daily reported.

"Korea's market has suffered steeper losses given its heavy exposure to chipmakers, with semiconductor stocks emerging as among the biggest casualties of the midterm election fallout," said Hwang San-hae, a market strategy analyst at LS Securities, as translated by the Korea JoongAng Daily.

Who Was Buying

Foreign investors were net sellers of ₩2.8 trillion ($2.1 billion) of KOSPI shares on Nov. 6, Yonhap reported. Retail and institutional investors together bought a net ₩2.3 trillion ($1.7 billion), and turnover reached ₩27.5 trillion ($20.3 billion) on 297 million shares.

The foreign selling extended a weeklong run. Foreign investors sold a net ₩9.41 trillion ($6.9 billion) of main-board shares in the five sessions from Oct. 30 to Nov. 5, the Seoul Economic Daily reported. That included ₩3.44 trillion ($2.5 billion) on Nov. 5 alone, the most in a day since Oct. 15.

Domestic money pushed back. Pension funds bought a net ₩1.41 trillion ($1.0 billion) over the same five sessions, according to the Seoul Economic Daily.

Individual investors had been adding to the chip leaders through the slide. From Oct. 6 to Nov. 5, they made net purchases of ₩5.8 trillion ($4.3 billion) of Samsung Electronics and ₩3.4 trillion ($2.5 billion) of SK hynix, the Korea JoongAng Daily reported, citing data provider Check Expert+. Those were the two largest net purchases among all securities listed in Korea, exchange-traded funds included.

The Won and the Policy Response

The won weakened with stocks. The dollar rose 14.5 won to ₩1,356.6 at 3:30 p.m. in Seoul, its largest one-day gain against the won since May 12, 2026, and its highest afternoon level since Oct. 1, the Seoul Economic Daily reported. During the session it touched ₩1,362.2, according to News1.

"This surge in the exchange rate can be seen as a reaction largely to political issues rather than to the dollar's value, U.S. Treasury yields or oil prices," said Lee Min-hyuk, an economist at KB Kookmin Bank, as translated by the Seoul Economic Daily.

For investors abroad, the currency deepened the loss. The won lost about 1.1% against the dollar, so a dollar-based holder of Samsung Electronics was down about 7.4% on the day, compared with 6.35% in won.

The government acted during the session. At a 10:30 a.m. meeting chaired by Finance and Economy Minister Lee Hyoung-il, authorities waived for three months from Nov. 9 a rule requiring brokerages to hold collateral worth 140% of their margin loans, the Financial Services Commission said.

Analysts saw an overreaction but no quick recovery. "Considering the direction of AI data center investment, the current extent of the share price decline and the market's price reaction are somewhat excessive," said Lee Jin-woo, head of the research center at Meritz Securities, as translated by the Korea JoongAng Daily.

"But since market uncertainty has not been fully resolved, it will be difficult to expect a sharp rebound in the short term," Lee Jin-woo said.

What to Watch

The margin rule waiver takes effect on Nov. 9, 2026, when the market reopens after the weekend. It is aimed at the forced sales that can follow sharp drops in shares bought with borrowed money.

U.S. inflation data comes next. October consumer prices are due on Nov. 10, 2026, and producer prices on Nov. 13, ahead of the Federal Reserve's two-day policy meeting starting Dec. 8, the Korea JoongAng Daily reported.

The bigger question sits in Washington. Investors will watch what a Democratic Congress actually proposes on data centers, the concern that drove the Nov. 6 sell-off, and whether other U.S. states follow the Texas governor-elect's call to pause projects.

Taken together, Nov. 6 showed how closely the KOSPI now tracks the global AI-chip trade: a political shift in Washington erased ₩267 trillion ($197 billion) of Korean market value in one session, and the next test arrives with U.S. inflation data on Nov. 10, 2026.