SEOUL, March 18 (AJP) - South Korean stocks roared higher on Wednesday, powered by chip heavyweights, as easing oil prices and renewed momentum in AI-linked semiconductors lifted investor sentiment.
The benchmark KOSPI jumped 5.04 percent to close at 5,925.03, reclaiming the 5,900 level after opening at 5,767.10 and extending gains throughout the session.
A buy-side sidecar was triggered in afternoon trading as futures rose more than 5 percent, underscoring the strength of the rally.
Foreign and institutional investors led the advance, purchasing a combined 3.9 trillion won ($2.9 billion) worth of shares. Foreigners bought 880 billion won, while institutions added 3.1 trillion won. Retail investors, by contrast, were net sellers of 3.87 trillion won.
The divergence in flows pointed to a clear rotation into large-cap, AI-linked semiconductor stocks, with institutional and foreign capital moving aggressively into index heavyweights while retail investors took profits.
Technology shares led gains, supported by both near-term and structural drivers.
Samsung Electronics rose 7.5 percent to 208,500 won, while SK hynix surged 8.9 percent to 1,056,000 won. Optimism around Micron Technology’s upcoming earnings boosted sentiment across memory stocks, while continued momentum from Nvidia’s AI ecosystem reinforced demand for next-generation high-bandwidth memory (HBM).
Improved shareholder return expectations also lent support, with Samsung signaling stronger competitiveness and a commitment to enhancing shareholder value at its recent annual general meeting.
The rally pushed the combined market capitalization of Samsung Electronics and SK hynix to 1,986 trillion won ($1.4 trillion), accounting for 40.6 percent of the KOSPI — the first time their combined weight has exceeded the 40 percent threshold.
Samsung alone made up roughly a quarter of the market, with SK hynix contributing about 15 percent, highlighting the concentration of gains in semiconductor heavyweights.
Autos and industrials also advanced, with Hyundai Motor rising 4.4 percent to 545,000 won and Kia gaining 4.7 percent to 175,100 won, suggesting a modest broadening of the rally beyond chips.
The tech-heavy KOSDAQ rose 2.4 percent to 1,164.4. Foreign investors bought 491.7 billion won, while institutions and retail investors sold 27.5 billion won and 392.7 billion won, respectively.
Still, the contrasting flows underscored that buying interest remained concentrated in large-cap names rather than spreading evenly across smaller growth stocks.
Elsewhere in Asia, Japan’s Nikkei 225 climbed 2.9 percent, Hong Kong’s Hang Seng rose 0.5 percent and China’s Shanghai Composite gained 0.3 percent.
Oil prices eased, with Brent crude falling 1.5 percent to $101.85 per barrel and West Texas Intermediate declining 2.9 percent to $93.45.
In currency trading, the Korean won hovered around 1,488 per dollar ahead of the Federal Reserve’s policy decision.
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