Foreign selling sends benchmark down 8%, triggering circuit breaker A financial data screen at Hana Bank’s dealing room in central Seoul displays the Kospi at 8,375.31, while shares of SK hynix and Samsung Electronics trade at 2.582 million won and 322,500 won, respectively. (Yoon Chang-bin/The Korea Herald) The South Korean benchmark Kospi plunged during intraday trading Tuesday, amid heavy profit-taking after SK hynix became the market's most valuable listed company in the previous session.The Kospi opened 0.34 percent down at 9,083.54. The index traded flat in early dealings before turning sharply lower around noon.A sell-side sidecar, a five-minute halt on program trading, was triggered at 11:40 a.m., and a marketwide circuit breaker followed at 2:33 p.m. after the Kospi tumbled 8.11 percent to 8,375.31, prompting the stock exchange to suspend trading for 20 minutes.It marked the 13th sell-side sidecar and fourth circuit breaker triggered on the Kospi this year alone.Foreign investors were net sellers of 4.67 trillion won ($3.03 billion) in shares, while institutional investors also offloaded a net 2.56 trillion won. Retail investors were the sole net buyers, snapping up a net 7.17 trillion won worth of stocks on the main board.Shortly before the circuit breaker was activated, SK hynix shares plunged 11.55 percent to 2,582,000 won, a day after overtaking Samsung Electronics in market capitalization for the first time. Samsung Electronics shed 8.77 percent to 322,500 won.Following the sharp declines, Samsung Electronics reclaimed its position as the most valuable company on the Kospi. Its market capitalization stood at 1,882.5 trillion won, narrowly ahead of SK hynix at 1,856.5 trillion won.Other large-cap stocks also declined. SK Square fell 3.1 percent to 1,899,000 won, while Samsung Electro-Mechanics tumbled 9.87 percent to 2,013,000 won.The junior Kosdaq market also came under heavy selling pressure. A sell-side sidecar was triggered at 11:37 a.m. The index stood at 903.29 as of 2:54 p.m., down 6.72 percent.