AI chip stocks in South Korea and Japan tumble after US semiconductor selloff

Wall Street’s chip stocks had a bad day. On October 13, 2026, Asia inherited the hangover. AI-related shares in South Korea and Japan slid sharply after US semiconductor names sold off in the prior session. South Korea’s Kospi fell as much as 7% intraday before closing down approximately 5.5%. Seoul takes the heaviest hit The damage in Korea was concentrated in exactly the place you would expect: memory chips. Samsung Electronics and SK Hynix both fell by around 7-10% during the session. The two companies account for nearly half of the Kospi’s market capitalization. The selloff pushed the Kospi to its lowest level since late July 2026. The index had peaked earlier in the year, so this was a fall from a considerable height. Foreign investors sold more than $6.3 billion worth of Kospi shares in October 2026. Tokyo follows the same script Japan did not escape. The Nikkei 225 lost more than 2-3%, dragged lower by chip-related names. Kioxia led the decline, with its shares falling about 12-13%. Why Wall Street’s chip slump traveled east The trigger came from the US. The Philadelphia Semiconductor Index, known by its ticker .SOX, posted its sixth straight decline, with an approximate 1.5...