On the 4th, the day after the June 3 local elections, the KOSPI index slipped into the 8,600 range, down 1%. Overnight weakness on Wall Street, rising international oil prices amid heightened Middle East tensions, and the announcement of additional U.S. tariffs appear to have dampened investor sentiment.

The KOSPI closed at 8,639.41, down 162.08 points (1.84%) from the previous session. It was the first negative close since the 28th of last month.

The KOSPI opened at 8,623.82, down 177.67 points (2.02%) from the previous session, briefly recovered the 8,700 level early on, then fell again, sliding as low as 8,577.30.

The semiconductor sector's ‘two-top’, which accounts for half of market capitalization, also paused. Samsung Electronics closed at 351,500 won, down 2.50% from the previous session, while SK hynix closed at 2,298,000 won, down 2.63%.

Stocks that had surged on expectations of cooperation ahead of NVIDIA CEO Jensen Huang's visit to Korea also fell. LG Electronics dropped 16.43% to 323,000 won, while Naver (-4.63%), Hyundai Motor (-3.98%), and Doosan Robotics (-5.28%) also declined.

On the main board that day, foreign investors were net sellers of 6.988 trillion won, extending a 19-session selling streak. The day's foreign net selling was the second largest on record. By contrast, retail investors and institutions were net buyers of 5.0125 trillion won and 1.8124 trillion won, respectively, helping support the lower end of the index.

The KOSDAQ index turned higher for the first time in six sessions. The KOSDAQ closed at 1,049.73, up 23.70 points (2.31%) from the previous session.

Lee Kyung-min, a researcher at Daishin Securities, said the KOSPI weakened as profit-taking emerged amid overheating from recent cumulative gains. However, he added that sector rotation narrowed the decline and tested support at the 8,700 level.