KOSPI falls 3.48% as US tech earnings fuel AI investment concerns

By Jun Ji-hye

• Published Oct 30, 2026 3:52 PM KST

KOSPI fell more than 3 percent Friday as losses in U.S. technology stocks and concerns over returns on artificial intelligence (AI) investments triggered selling in heavyweight chipmakers Samsung Electronics and SK hynix.

The benchmark index ended at 5,730.74, down 206.92 points, or 3.48 percent. It opened 2.99 percent lower at 5,760.35 and extended its losses during the session.

The sharp sell-off in KOSPI 200 futures triggered a sell-side sidecar at around 10:05 a.m., temporarily halting program sell orders. It was the first such activation in 11 trading sessions, following KOSPI’s 7.57 percent plunge on Oct. 15.

Samsung Electronics lost 3.02 percent, while SK hynix dropped 7.08 percent.

The declines followed earnings releases from U.S. technology giants that raised fresh doubts about the returns on their massive AI investments.

Google parent Alphabet reported weaker-than-expected results and a wider free cash flow deficit. Amazon’s earnings and guidance also fell short of forecasts, drawing attention to the costs of expanding AI infrastructure.

Wall Street’s three major indexes closed lower overnight. The Dow Jones Industrial Average slipped 0.25 percent, the S&P 500 shed 0.30 percent and the Nasdaq Composite declined 1.38 percent. Alphabet tumbled 12.64 percent, while Micron Technology fell 4.98 percent.

“Successive earnings disappointments from big tech companies and chipmakers sparked a sell-off across the AI value chain,” said Kang Jin-hyuk, a senior analyst at Shinhan Securities.

The tech-heavy Kosdaq index also extended its opening losses, finishing at 724.38, down 28.85 points, or 3.83 percent. It began the session 2.05 percent lower at 737.76.

In Seoul’s onshore foreign-exchange market, the won strengthened by 2.5 won against the dollar to close daytime trading at 1,334.3 won per dollar.