South Korean stocks dropped nearly 10 percent on Tuesday on big tech sell-offs, triggering a circuit breaker and sidecars to cool down panic-selling.

People work at the dealing room of Hana Bank in Seoul, South Korea, March 4, 2026. (Photo: Xinhua)

The benchmark KOSPI dived 910.71 points, or 9.99 percent, to close at 8,203.84, while the smaller KOSDAQ tumbled 76.88 points, or 7.94 percent, to finish at 891.52.

After opening slightly lower, the KOSPI extended losses throughout the session amid growing concerns over artificial intelligence (AI) infrastructure costs in the United States, SpaceX's plan to issue corporate bonds and a drop in big tech shares in New York.

Foreign investors dumped semiconductor leaders, including Samsung Electronics and SK hynix.

Institutional investors were net sellers, but retail investors snapped up stocks amid a resurgence in bargain-hunting sentiment.

Sell-sidecars were issued both in the KOSDAQ and KOSPI markets in the morning session as futures prices tanked.

The sidecar is activated when the benchmark futures index fluctuates for at least one minute by 5 percent for KOSPI and 6 percent for KOSDAQ, which also requires a 3 percent spot index move, leading to a temporary halt of program trading for five minutes.

A level 1 circuit breaker was triggered in the KOSPI after the index sustained a loss of over 8 percent for more than one minute.

The circuit breaker is issued in stages when the KOSPI or KOSDAQ dives by 8 percent, 15 percent and 20 percent.

The first two stages halt trading for 20 minutes, followed by a 10-minute single price auction, while the final stage instantly shuts down the market for the day.

The South Korean won versus U.S. dollar exchange rate finished its daytime session at 1,539.1 won per dollar as of 3:30 p.m. local time (0630 GMT), up 2.1 won from the previous session's daytime close.

Market bellwether Samsung Electronics and memory chip giant SK hynix plunged 12.31 percent and 12.47 percent.

The country's top automaker Hyundai Motor dipped 12.05 percent, and the largest battery maker LG Energy Solution retreated 6.10 percent.

The No. 1 biopharmaceutical contract manufacturer Samsung Biologics fell 1.70 percent, and the leading aerospace and defense company Hanwha Aerospace decreased 4.62 percent.

The biggest shipbuilder HD Hyundai Heavy Industries plummeted 7.55 percent, and the energy infrastructure leader Doosan Enerbility was down 5.31 percent.