The index opened down 2.2% before extending its decline. The Korea Exchange halted trading on the main board for 20 minutes to curb volatility and imposed a separate five-minute halt on the smaller, technology-heavy Kosdaq market.

SK Hynix fell as much as 14% to 1,089,000 won, leading declines among semiconductor stocks. Samsung Electronics dropped up to 11% to 179,200 won. The two companies are the world’s largest memory-chip makers and suppliers of high-bandwidth memory to Nvidia, a major AI chipmaker. Together, they account for nearly half of the Kospi’s total market capitalization.

The Korean selloff followed a sharp decline among U.S. technology stocks on Thursday. The Nasdaq, which is heavily weighted toward technology companies, recorded its largest one-day drop in more than a year. The source linked the chipmakers’ losses to AI-related worries following the Democratic sweep in the U.S. midterm elections.