South Korea’s two biggest chipmakers just had the kind of day traders dream about. SK Hynix surged nearly 13% and Samsung Electronics climbed approximately 8% during trading in Seoul on July 15, dragging the broader KOSPI index up 6.24% to close at 7,284.41. That’s a 427.58-point jump in a single session.
The catalyst? A renewed wave of optimism around high-bandwidth memory chips powering the AI infrastructure boom.
From sell-off to snapback
This rally came on the heels of a brutal sell-off earlier in July that saw SK Hynix suffer its steepest one-day drop on record, with shares cratering roughly 15%. That plunge was driven by profit-taking and growing anxiety over whether Big Tech’s AI capital expenditure spree was sustainable.
Positive analyst forecasts around AI memory demand, combined with softer US inflation data that lifted American semiconductor stocks, provided the confidence boost Seoul needed. Chip-equipment maker Hanmi Semiconductor rode the wave even harder, gaining about 25% in the session.











