The KOSPI tumbled more than 6 percent on Monday to the 5,400 level. The KOSDAQ also fell more than 5 percent to end the session lower.

The KOSPI ended down 375.45 points, or 6.49 percent, at 5,405.75 from the previous session. It opened down 201.05 points, or 3.48 percent, at 5,580.15 and fell as low as 5,397.94 during the session. A sell-side circuit breaker for program trading was triggered shortly after the open.

Retail investors posted net buying of 69.984 trillion won but failed to prevent the index from falling. Foreigners and institutions posted net selling of 36.754 trillion won and 38.127 trillion won, respectively.

All of the top market-cap stocks fell.

Samsung Electronics closed down 6.57 percent at 186,300 won, while SK Hynix fell 7.35 percent to 933,000 won.

Hyundai Motor fell 6.19 percent, LG Energy Solution slid 5.19 percent, SK Square dropped 8.39 percent, Samsung Biologics fell 4.87 percent, Hanwha Aerospace declined 3.18 percent, Doosan Enerbility sank 8.12 percent and Kia fell 4.04 percent.

The KOSDAQ ended down 64.63 points, or 5.56 percent, at 1,096.89 from the previous session.

In the Seoul foreign exchange market, the won-dollar exchange rate stood at 1,517.90 won, up 11.40 won, or 0.76 percent, from the previous session.