South Korea halts KOSPI trading for 20 minutes as tech shares tumble

South Korea halted trading in KOSPI-listed shares for 20 minutes on Thursday, October 15, after the index fell more than 8% from its previous close. The circuit breaker took effect at 12:38 p.m. in Seoul, interrupting a broad sell-off led by technology stocks.

The halt came as investors sold semiconductor shares amid concern about persistent US inflation and whether spending on artificial intelligence infrastructure would generate enough income. Reuters reported that the KOSPI stood at 5,528.05, down 480.76 points, at 12:38 p.m. Seoul time, its lowest level since July 29.

Samsung and SK Hynix lead semiconductor losses

Samsung Electronics fell 9.70% and SK Hynix dropped 11.35%, according to Reuters. The losses followed a technology-led decline on Wall Street, where the Philadelphia Semiconductor Index had fallen 4.3% overnight. Reuters said US inflation data had raised expectations of further interest-rate increases.

The selling extended well beyond chipmakers: 855 of the 916 KOSPI issues traded were lower, while 52 rose. Foreign investors were net sellers of shares worth 2.9 trillion won, Reuters reported. The index was heading for a seventh consecutive losing session, which would be its longest losing streak since September 2024.

Why investors are questioning AI spending

Mixo Das, J.P. Morgan's Korea equity strategist, told Reuters that buyback programmes at Samsung and SK Hynix had run their course and the market was struggling to find a new buyer. Reuters said the KOSPI had risen 31% so far this year, although it remained 39% below its record peak reached in late June.

The market pressure also reached the won, which Reuters put at 1,348.2 per US dollar, down 0.44% from its previous close. Korean Treasury yields fell: the three-year yield was down 4.4 basis points at 3.841%, and the 10-year yield was down 5.7 basis points at 4.188%. Reuters described the circuit breaker as the first in two and a half months.