S.Korean shares log fifth weekly loss as AI spending worries hit chipmakers

South Korean shares tumbled nearly 6% on Friday, reversing gains for the week on concerns that heavy AI spending by major U.S. technology companies may not deliver returns fast enough to sustain demand for memory chips.

The KOSPI closed down 5.7% at 6,690.62 after a three-session winning run. It fell as much as 6.3% in intraday trading, triggering temporary trading curbs under the "sidecar" mechanism on the KOSPI and the junior Kosdaq index.

Oil's rise above $100 a barrel compounded the risk-off mood, raising concerns about inflation and economic headwinds for South Korea, which imports nearly all of its energy. New U.S. tariffs on goods from 60 countries, including South Korea, also weighed on sentiment.