KOSPI suffers worst day since August as China's chip advance routs Samsung and SK Hynix

South Korea's KOSPI closed Tuesday at 6,035.35, down 348.89 points or 5.46 per cent — its biggest single-day drop since Aug. 19 — after falling as low as 5,911.11 intraday, briefly breaching the 6,000 level for the first time since July 31, according to Korea Exchange figures reported by Aju Press.

Samsung Electronics fell 7.39 per cent and SK Hynix 10.09 per cent. The exchange triggered a "sidecar" program-trading halt, the first since August. Foreign investors net-sold roughly 5.2 trillion won; market capitalization fell below 5,000 trillion won for the first time since July 30.

The trigger remains China's CXMT and its 4F² DRAM architecture plans — the company's own claims, which analysts interpret as potentially beating the Korean incumbents to market — layered onto fading buyback support and fresh AI-bubble anxiety. In an irony worth noting, the IMF raised Korea's 2026 growth forecast to 3.3 per cent from 2.6 per cent on the same day.

For Canadians: pension funds and retail investors carry heavy chip exposure through global index funds; sustained memory-sector repricing also feeds into consumer device costs heading into the holidays.