South Korean Stocks Slide 5% as SK Hynix Extends Drop to 7%

South Korea’s Kospi plunged 5% on Oct. 13 as semiconductor shares extended their losses, adding to pressure across chip and artificial-intelligence-linked markets.

SK Hynix fell as much as 7% intraday, while Samsung Electronics dropped 5.89%. Both companies were on track for a fifth consecutive decline, extending a recent selloff in South Korean semiconductor stocks.

The move followed a 3.9% overnight decline in Micron Technology, a U.S. memory-chip manufacturer. Investors are weighing competition from China’s ChangXin Storage (CXMT), which has made progress on a newer memory architecture also being developed by Samsung and SK Hynix.

Concerns about stretched AI-stock valuations also intensified after Broadcom’s chief executive compared AI-stock investing with gambling. Ha SeokKeun, chief investment officer at Eugene Asset Management, said uncertainty over whether the current upcycle can last through 2028 and beyond is weighing on Korean chipmakers’ valuations and share prices.