[DigitalToday reporter Sangyeop Oh (오상엽)] South Korea's KOSPI broke below the 5,000 mark on Thursday after a shock originating in the United States. With investor sentiment in U.S. stocks weakening on concerns about artificial intelligence (AI), the local market also appeared to be affected.

The KOSPI opened at 5,013.15, down 2.91 percent, or 150.42 points, from the previous session's 5,163.57, but it soon gave up the 5,000 level as well.

As of 9:12 a.m., it was down 3.97 percent, or 203.87 points, at 4,958.82. At one point, KOSPI 200 futures plunged more than 5 percent, triggering a temporary halt of program sell orders, known as a sidecar, after the first selling sidecar of the year was triggered on Feb. 2 and again on Thursday.

In the market, foreign investors and institutions were selling 245.4 billion won and 20.5 billion won worth, respectively, while retail investors were buying 270.0 billion won worth.

SK Hynix fell 5.58 percent to 795,000 won, breaking below 800,000 won. Samsung Electronics fell 4.52 percent to 152,100 won, putting the 150,000 won level at risk.

Other large market-cap stocks were also in the red, including Hanwha Aerospace down 7.50 percent, Hyundai Motor down 6.86 percent, SK Square down 6.18 percent, Doosan Enerbility down 5.08 percent, Kia down 4.03 percent, LG Energy Solution down 3.80 percent and Samsung Biologics down 3.00 percent.

The KOSDAQ was also down 55.68 points, or 5.02 percent, at 1,052.73.