KOSPI loses 7,000 in 24 hours as oil and yields hammer Korean stocks

South Korean stocks fell sharply on Thursday as Brent crude held above $100 a barrel, pushing the KOSPI back below the 7,000 mark just a day after it reclaimed the level for the first time in more than a month.

The benchmark was down 1.28% at 6,961.23 by late morning in Seoul. Samsung Electronics fell 1.3%, SK Hynix slipped 0.59%, Hyundai Motor lost 1.55% and LG Energy Solution dropped 2.83%.

Foreign investors sold a net 496.4 billion won of shares, while institutions unloaded just over 1 trillion won. Retail investors were net buyers.

Oil shock hits an import-dependent market

The KOSPI is especially exposed to the latest energy shock because South Korea relies heavily on imported crude and gas.

Brent traded above $101 after another escalation in Middle East fighting, reinforcing fears that higher fuel costs will feed through to transport, manufacturing and consumer prices.

Brent had settled Wednesday at $101.21, while WTI reached $96.05.

That pressure is showing up across the market rather than only in energy-sensitive sectors.

Even Seoul’s heavyweight technology names weakened, despite the strong AI and memory-chip narrative that helped the KOSPI close at 7,051.64 on Wednesday.

Seoul Economic Daily cited Kiwoom Securities analyst Han Ji-young as expecting Korean equities to surrender part of Wednesday’s gains as higher oil prices and US yields weighed on sentiment.

He nevertheless sees support coming from Samsung and SK Hynix share buybacks and the return of foreign investors as net buyers this month.

Quadruple witching adds another layer of volatility

Thursday is also a quadruple-witching session in South Korea, with index futures, index options, single-stock futures and single-stock options expiring together.

That has amplified swings in programme trading and foreign futures flows. The KOSPI briefly turned positive after opening 0.18% lower before selling accelerated later in the morning.

The timing is awkward because the index had only just broken back above 7,000.

As per market data, retail investors sold 16.84 trillion won over the five sessions through Wednesday, while institutions, foreign investors and corporate treasury-share purchases absorbed most of that supply.

The next question is whether 7,000 becomes resistance again or whether strong semiconductor earnings expectations bring buyers back quickly.

Wider Asia weakens as yields stay elevated

The pressure was regional. The broader MSCI Asia-Pacific gauge fell about 0.4%, while Japan’s Nikkei 225 dropped 0.6% to 64,759.80.

Australian equities also retreated as higher energy costs weakened risk appetite.

Bond yields added another headwind. The US 10-year Treasury yield remained near 4.84%, close to its highest since 2023, after a $6 billion Treasury buyback of longer-dated debt disappointed investors hoping for a larger intervention.

Raymond James strategist Tracey Manzi told The Wall Street Journal that expectations had been centred closer to a $7 billion-$8 billion buyback, leaving the announced amount short of what many bond investors wanted.

US producer-price data are due Thursday, followed by CPI on Friday.