KOSPI Plunges 5.8% Amid Semiconductor Sell-Off and Geopolitical Tension

The Korea Composite Stock Price Index (KOSPI) fell 5.8 percent to close at 6,471.17 on August 19, 2026, driven by a steep sell-off in semiconductor stocks. The rout was triggered by overnight losses on Wall Street, rising global bond yields, and climbing oil prices linked to stalled peace talks between the United States and Iran. The geopolitical instability intensified as Iran fired two ballistic missiles toward the United Arab Emirates, though both fell into the sea.

Market bellwethers Samsung Electronics and SK Hynix bore the brunt of the decline, plunging 7.82 percent and 9.75 percent respectively. The volatility prompted the bourse operator to activate a five-minute sell-side sidecar suspension of program trading at 9:06 a.m. to curb the slide. The tech-heavy KOSDAQ also closed down 1.17 percent, while SK Square, the parent firm of SK Hynix, saw shares sink 11.54 percent.

Despite the broader downturn, some sectors saw gains. Hanwha Aerospace shares rose 2.71 percent after its U.S. unit secured a contract to provide K9 self-propelled howitzer prototypes to the U.S. Army. In a separate regional trend, Unitree Robotics shares surged 629 percent during its Shanghai trading debut. Amid the market turmoil, the South Korean won strengthened to 1,397.7 per U.S. dollar, its lowest reading since September 2025.