South Korea's KOSPI sinks 8%; triggering circuit breaker

South Korea’s stock exchange temporarily halted programme trading on Thursday after the benchmark KOSPI index plunged more than 7%, as a technology-led sell-off on Wall Street and persistent US inflation concerns heightened fears of interest rates remaining elevated.

The exchange activated its sell-side “sidecar” mechanism following a sharp decline in index futures. The measure suspends programme sell orders for five minutes to curb excessive volatility during sudden market swings.

The trigger came as the KOSPI extended its losing streak to seven consecutive sessions, marking its longest run of losses since September 2024. The index was down 7.49%, or 450.02 points, at 5,558.79 as of 7:05 am.

Technology stocks led the decline, with Samsung Electronics tumbling 9.05% and SK Hynix plunging 11.06%. Heavy selling in chipmakers dragged the broader market lower as investors reacted to weakness on Wall Street and reassessed their exposure to technology stocks amid concerns over the global interest-rate outlook.

Japan's Nikkei was trading 4.53 per cent lower at 64,659.88. Hong Kong's Hang Seng was down 1 per cent at 24,071. China's mainland index Shanghai Composite declined 1.45 per cent while Taiwan's TAIEX also dropped 2.79 per cent.

In overnight trade, Tech-heavy Nasdaq Composite settled 1.88 per cent lower.

The US headline inflation accelerated to 3.7 per cent, above the 3.6 per cent estimate, while core inflation rose to 2.6 per cent. The data suggested that energy costs are beginning to reinforce underlying price pressures, increasing the possibility of another Federal Reserve rate increase or an extended period of restrictive policy, said Hariselvan Radhakrishnan, Founder & CEO of SEBI-registered HST Wealth.

He said the US 10-year treasury yield edged lower to 5.19 per cent, but the modest decline offered little reassurance given that yields remain near multi-decade highs.