South Korea's stock market experienced a short-lived trading interruption on Thursday after a steep early-morning advance in chipmaking stocks pushed the KOSPI higher by more than 5% at the opening bell.
The Korea Exchange applied a buy-side sidecar shortly after the market opened, temporarily suspending program trading in KOSPI-listed shares for a five-minute interval, according to a statement from the bourse operator. The mechanism is designed to curb automated selling or buying when rapid, large moves occur.
The index's jump was driven by sharp gains in major semiconductor names. Samsung Electronics Co Ltd (KS:005930) climbed 4.9% while SK Hynix Inc (KS:000660) surged 9.6%. The moves in Seoul followed sizable after-hours strength for Micron Technology Inc (NASDAQ:MU), which rose by more than 13% in U.S. aftermarket trade after reporting strong earnings and guidance overnight. Local chipmakers tracked Micron's upside into Thursday's session.
SK Hynix was among the top performers on the KOSPI, bolstered in part by the company's disclosure on Wednesday of plans to raise $29.4 billion through a U.S. stock market listing. The memory chip maker, noted as a supplier to Nvidia, said the proposed listing is aimed at further tapping demand for AI-linked equities.
Thursday's rally allowed the KOSPI to reclaim much of the ground lost earlier in the week. The benchmark had fallen roughly 10% on Tuesday amid heavy declines in local chip stocks, making Thursday's rebound a significant reversal in a short period.
Contextual notes
- The Korea Exchange enacted a buy-side sidecar - suspending program trading for five minutes.
- Samsung Electronics increased by 4.9% and SK Hynix rose 9.6% at the open.
- Micron's strong earnings and guidance drove a more than 13% rise in aftermarket trading in the U.S., which influenced gains in Seoul.
Market participants observed that the index's early surge and the brief suspension underlined the current sensitivity of South Korea's equity market to developments in the global semiconductor sector. The rapid movements also highlighted the role of automated trading controls in managing volatility during outsized sessions.