South Korea’s KOSPI index plunged 8.3% on June 8, closing at 7,484.41, as investors dumped semiconductor stocks on fears that a blistering rally had run too far, too fast. The decline was severe enough to trigger market-wide circuit breakers, halting trading for 20 minutes.

It was the largest single-day fall since March 4 and the third time circuit breakers have been activated in 2026.

The chip sell-off at the center of it all

Samsung Electronics dropped 10.2% on the day. SK Hynix fell 7.7%.

Those two names essentially are the KOSPI. They account for the bulk of the index’s gains over the past year and briefly pushed their combined market capitalization near the $1 trillion mark during the rally’s peak.

The catalyst wasn’t domestic. Broadcom issued disappointing forecasts that sent the Philadelphia Semiconductor Index tumbling more than 10%, creating a ripple effect across global chip stocks.

Adding fuel to the fire, strong US jobs data raised expectations for Federal Reserve rate hikes.

The KOSPI had closed at 8,801.49 on June 2, its recent peak. By June 8, the index sat roughly 15% below that level.

Foreign investors keep heading for the exits

Foreign investors recorded net selling of 355 billion won, approximately $231 million, on June 8 alone. That extended their selling streak to 21 consecutive sessions.

The KOSPI gained 76% in 2025, its best annual performance since 1999. Even after the June 8 sell-off, the index was still up 78% on a trailing twelve-month basis.

The Korean won dropped to a near 17-year low of 1,561.5 per dollar on June 5, prompting emergency meetings by South Korean financial authorities.