South Korean stocks weakened sharply on Oct. 22 as concerns that heavy investment across the artificial-intelligence value chain may not generate sufficient returns drove selling in major chipmakers. The KOSPI fell 129.12 points, or 2.25%, to 5,605.54 at 11:20 a.m. after opening 1.14% lower, while a later report put the index down 3% at 5,561.22. The Nikkei 225, which was down 0.4% at around 64,350 earlier, was later reported 2% lower, signaling broader weakness across major Asian equity markets. Samsung Electronics and SK hynix declined 3.36% and 3.63%, respectively, while Samsung Electro-Mechanics fell 0.98% after initially rising on news of cooperation with Nvidia. The KOSDAQ later fell 1.78% to 778.66. U.S. stocks closed higher overnight, but the gains offered limited support as investors reassessed whether debt-backed AI spending would produce sufficient returns. The won traded at 1,324 per dollar, up 2 won from the previous session, while Brent crude rose 1.1% to $110.03 a barrel amid Gulf tensions and the Bank of Korea held its benchmark rate at 3.00%.