The KOSPI reclaimed the 5,700 level on the 21st, rising more than 3% as sentiment toward artificial intelligence investment recovered and semiconductor exports surged. Samsung Electronics and SK hynix each jumped more than 5%, while simultaneous buying by foreign and institutional investors lifted the index. A buy-side sidecar was triggered during the session for the first time in two months.
The KOSPI closed at 5,735.66, up 182.92 points, or 3.29%, from the previous trading day, according to the Korea Exchange. The index opened at 5,666.34, up 113.60 points, or 2.05%, and extended its gains through the session. The KOSDAQ ended at 792.76, up 10.79 points, or 1.38%.
Large-cap chip stocks led the advance. Samsung Electronics closed at 223,500 won, up 12,000 won, or 5.67%, from the previous session. SK hynix rose 71,000 won, or 5.81%, to 1,294,000 won. Samsung Electronics preferred shares gained 3.80%, SK Square 5.13% and Samsung Electro-Mechanics 1.13%. Samsung Electronics and SK hynix had risen as much as 7% and 8%, respectively, at one point in the morning before giving back part of those gains.
Among other large-cap stocks, Samsung Biologics rose 1.87% and Samsung Life Insurance gained 3.38%. LG Energy Solution fell 0.60%, Hyundai Motor slipped 0.16% and KB Financial Group declined 0.19%.
With buying concentrated in chip stocks, a buy-side sidecar was triggered on the main board at 10:51:56 a.m., the first since Aug. 20. At the time, KOSPI 200 futures were at 904.84, up 5.22% from the reference price. Because the futures price held more than 5% higher for one minute, program buy orders were suspended for five minutes.
On the KOSDAQ, Alteogen closed at 240,000 won, up 3.90%. EcoPro BM rose 3.33%, Jusung Engineering 3.48%, Samchundang Pharm 3.66%, EO Technics 2.14% and Wonik IPS 1.55%. EcoPro and Rainbow Robotics gained 0.12% and 0.67%, respectively, while HLB fell 1.51% and LEENO Industrial slipped 0.15%.
The rebound was attributed to improved investor sentiment following strong earnings from U.S. AI-related companies. Super Micro Computer guided for preliminary first-quarter fiscal 2027 revenue of $18.5 billion to $19.5 billion, far above the market consensus of $15.2 billion. Its gross margin forecast of 12.0% to 12.5% also topped the consensus of 10.15%, raising expectations that demand for AI data center servers remains solid.
SpaceX also beat market expectations with third-quarter revenue of $14.58 billion and operating profit of $2.79 billion. Alongside plans to expand AI computing capacity, the company projected that rising demand for computing power and supply shortages would persist, supporting expectations for AI infrastructure investment and chip demand.
Domestic export data added to optimism about the semiconductor cycle. Exports during the first 20 days of this month rose 105.4% from a year earlier to $61.6 billion. Average daily exports came to $4.74 billion, a record high. Semiconductor exports in particular surged 222.5% to $27.52 billion, driving the overall increase.
"Macroeconomic burdens remain, but improving sentiment toward AI investment has created upward pressure on the market," said Lee Kyoung-min, an analyst at Daishin Securities. "It is positive that foreign investors, who had recently added to downward pressure on the market, have turned net buyers."
