KOSPI tumbles back below 7,000 in 'Black Thursday' rout

The KOSPI tumbled back below 7,000, Thursday, just one session after a sharp rebound, as concerns over slowing artificial intelligence (AI) infrastructure investment and intensifying competition in memory chips battered semiconductor shares.

The benchmark closed at 6,820.60, down 6.37 percent from the previous session.

It opened 4.45 percent lower and extended its losses, falling as much as 7.6 percent to 6,730.87 intraday.

A sell-side sidecar was activated at 9:10 a.m., marking the 19th such activation on the KOSPI this year.

Foreign investors sold a net 1.44 trillion won ($973.9 million) of shares, while institutional investors offloaded 1.39 trillion won.

Retail investors, however, bought a net 2.78 trillion won.

Chipmakers led the retreat.

SK hynix sank 11.53 percent to 1,842,000 won, while Samsung Electronics dropped 8.77 percent to 255,000 won.

The declines followed weakness in U.S. semiconductor shares overnight.

Morgan Stanley said cancellations and delays of data-center projects were becoming more widespread, citing postponement of a data-center development in Wyoming and a one-y ...