A buy-side sidecar was triggered on South Korea's main stock market on the 21st as Samsung Electronics (005930.KS) and SK hynix (000660.KS) surged 7% and 8%, respectively. Korean stocks rebounded sharply after strong earnings from U.S. AI server maker Super Micro Computer revived sentiment toward semiconductor shares.
The Korea Exchange said it halted program buy orders on the main board for five minutes at 10:51:56 a.m. The measure was the first buy-side sidecar on the KOSPI since Aug. 20.
KOSPI 200 futures stood at 904.84 at the time, up 44.94 points, or 5.22%, from the previous session's reference price of 859.90. A buy-side sidecar is triggered when KOSPI 200 futures rise more than 5% above the reference price and hold that level for one minute. The mechanism suspends program buy orders for five minutes to limit the impact of sharp futures swings on the spot market.
As of 10:58 a.m., Samsung Electronics traded at 228,000 won, up 16,500 won or 7.80% from the previous session. SK hynix was at 1.324 million won, up 101,000 won or 8.26%.
Other chip-related shares also advanced. Samsung Electronics preferred shares rose 5.79%, SK Square (402340.KS) gained 7.69% and Samsung Electro-Mechanics (009150.KS) added 4.85%. Other large caps also climbed, including LG Energy Solution (373220.KS), up 0.60%, Samsung Biologics (207940.KS), up 1.22%, Hyundai Motor (005380.KS), up 0.32%, and KB Financial Group (105560.KS), up 0.62%.
The rebound followed Super Micro Computer's earnings, released after the close of regular U.S. trading. Preliminary first-quarter revenue of $19 billion exceeded market expectations of $15 billion, easing some concerns about demand for AI infrastructure. Super Micro shares jumped more than 13% in after-hours trading, while Micron Technology and SanDisk each rose more than 2%.