Kospi swings nearly 4 percentage points intraday, closes barely higher at 6,579

The Kospi closed marginally higher Thursday after a wild intraday swing of nearly 4 percentage points. The index surged more than 1.8 percent in the morning as international oil prices and US government bond yields stabilized, only to plunge suddenly around 2 p.m. and erase all of its gains. It then staged a rapid recovery to eke out a positive close.

According to Korea Exchange, the Kospi finished up 16.76 points, or 0.26 percent, at 6,579.48. The index opened 87.61 points, or 1.33 percent, higher at 6,650.33, briefly trimmed its advance, then extended gains to an intraday high of 6,682.97, up 1.83 percent. Around 2 p.m., however, the index abruptly reversed, tumbling to 6,439.49 — a loss of 1.88 percent — within roughly 10 minutes, a drop of nearly 4 percentage points from the day's peak.

All three major investor groups were net sellers of shares on the main board Thursday. Individuals net sold 955.2 billion won ($698 million), foreigners net sold 423.2 billion won, and institutions net sold 215.3 billion won. Other corporations — believed to represent buyback purchases by Samsung Electronics and SK hynix — were net buyers of 1.61 trillion won, providing underlying support for the index.

Large-cap semiconductor stocks, which had been strong throughout the morning, turned lower in the afternoon and weighed on the index. Samsung Electronics closed down 500 won, or 0.20 percent, at 250,000 won, while SK hynix fell 17,000 won, or 1.05 percent, to close at 1.6 million won.

Among other large-cap stocks, SK Square fell 0.10 percent, Samsung Electro-Mechanics dropped 3.71 percent, and Samsung Biologics declined 1.60 percent. On the upside, LG Energy Solution gained 5.18 percent, KB Financial Group rose 5.20 percent, Samsung Life Insurance added 3.06 percent, and Hyundai Motor advanced 1.46 percent.

The Kosdaq fell 13.77 points, or 1.71 percent, to close at 790.21. The index opened up 10.33 points, or 1.28 percent, at 814.31, but turned negative around 9:09 a.m. and oscillated between gains and losses for the remainder of the session.

On the Kosdaq, institutions and foreigners were net sellers of 184.6 billion won and 107.5 billion won, respectively. Individuals were net buyers of 295 billion won.

Among Kosdaq large-caps, Alteogen fell 5.19 percent, Ecopro slipped 0.37 percent, Jusung Engineering dropped 3.28 percent, Wonik IPS declined 4.28 percent, Leeno Industrial edged down 0.16 percent, Simtec fell 4.78 percent, and HLB lost 1.65 percent. EO Technics bucked the trend, rising 3.98 percent.

Lee Kyung-min, an analyst at Daishin Securities, said the domestic market suffered a sharp correction around 2 p.m. and recovered only part of its losses, even as external conditions were favorable with both oil prices and government bond yields falling. "With no clear negative catalyst in sight, the selling by financial investment firms and pension funds appears to have amplified intraday volatility," he said.

Lee added that the domestic market has recently become highly sensitive to external uncertainty, with volatility also rising in response to shifts in supply and demand — including futures selling by foreigners and spot selling by institutions. "We are in a phase where short-term supply-demand dynamics and investor sentiment are having an increasingly significant influence on the index's direction, beyond fundamentals," he said.