South Korea’s benchmark KOSPI drops sharply in one session and then rebounds the next, driven primarily by heavy losses in semiconductor stocks. On Monday, the index falls nearly 9% to close at 6,806.93, dropping below 7,000 in a “Black Monday” sell-off. SK hynix and Samsung Electronics, which together account for more than 60% of KOSPI’s market capitalization, lead the decline, falling about 15.4% and 10.7% respectively. The rout comes despite the blockbuster U.S. debut of SK hynix’s American depositary receipts (ADRs). SK hynix ADRs trade under the ticker SKHY and close at $168 on Friday, up from the $149 offering price. The Monday sell-off triggers market risk controls, including the 35th sell-side program-trading curb and the seventh circuit breaker of the year.

On Tuesday, KOSPI reverses course after an intraday plunge of nearly 5%, briefly slipping below 6,500 before bargain buying lifts it. It finishes slightly higher at 6,856.83. Foreign and institutional investors purchase shares, while retail investors sell a net 4.15 trillion won. Kosdaq, by contrast, closes at its lowest level of the year.