[DigitalToday reporter Sangyeob Oh (오상엽)] The KOSPI index plunged more than 5 percent early in the session and at one point sank to the 5,400 level, triggering a sell sidecar.

As of 9:20 a.m. on Tuesday, the KOSPI was down 142.99 points, or 2.47 percent, from the previous session at 5,648.92.

The index opened sharply lower at 5,592.59 and later slid to as low as 5,438.97, but it has pared some losses.

With the index tumbling, the Korea Exchange activated a temporary halt on program sell orders, known as a sidecar, on the main board at 9:05 a.m.

The trigger came after KOSPI200 futures plunged 6.04 percent from the previous session and stayed there for 1 minute. Program sell orders were halted for 5 minutes to ease market volatility. The KOSPI sell sidecar has been activated for a second straight day, following Monday.

By investor type, institutions were net buyers of 396.3 billion won, acting alone to support the index, while individuals and foreigners posted net sales of 398.4 billion won and 2.2 billion won, respectively, adding downward pressure.

Most top market-cap stocks were in the red. Index heavyweight Samsung Electronics was down 2,650 won, or 1.36 percent, at 192,450 won. SK Hynix, meanwhile, rose 0.43 percent to 943,000 won, with the two chip leaders moving in opposite directions.

Other major market-cap shares were also falling, including Hyundai Motor, down 2.69 percent, LG Energy Solution, down 1.40 percent, SK Square, down 0.52 percent, Samsung Biologics, down 4.52 percent, Hanwha Aerospace, down 6.01 percent, Kia, down 3.46 percent, Doosan Enerbility, down 4.44 percent.

In Seoul's foreign exchange market, the won was trading at 1,476.60 per dollar, up 3.40 won, or 0.23 percent, from the previous session.

The exchange rate ended at 1,485.7 per dollar, up 19.6 won from the Seoul FX market's daytime closing price at 2 a.m. local time.

In overnight trading, it sharply extended gains and topped 1,500 per dollar at around 12:05 a.m. local time on Tuesday, about 30 minutes after the New York stock market opened.