SK Hynix shares surge 25%, Samsung jumps 20% as AI rally roars back

South Korean semiconductor stocks surged on July 31, 2026, with SK Hynix climbing more than 25% and Samsung Electronics rising over 20%. The rally followed strong earnings from U.S. tech giants Amazon and Microsoft that renewed investor confidence in artificial intelligence spending.

The gains extended across the sector, with LG Innotek advancing 11.2% and Seoul Semiconductor adding 7.8%. Japanese chip stocks also jumped sharply: Advantest rose nearly 18%, Tokyo Electron gained almost 9%, Disco climbed over 13%, Lasertec advanced more than 12%, and Renesas Electronics increased over 10%. SoftBank Group, seen as an AI proxy due to its ownership of Arm, surged more than 9%.

The rally marked a sharp turnaround from a bruising sell-off earlier in the week, when semiconductor stocks were hit by worries over high AI valuations and growing competition from Chinese memory chipmakers. The iShares Semiconductor ETF (SOXX) had soared more than 8% overnight as investors returned to AI-linked chipmakers.

Amazon reported second-quarter revenue that exceeded analyst expectations, driven by continued cloud-computing strength, sending its shares up more than 9% in extended trading. Microsoft had already rallied 16% during Thursday's regular session after posting faster-than-expected Azure cloud growth, reinforcing the view that AI infrastructure investment remains solid.

Andrew Jackson, head of equity strategy at Ortus Advisors, said Microsoft's results "sparked a huge rebound for risk-on and AI," helping reverse the recent tech sell-off. In a note on Friday, he wrote that investors were reassured by Azure cloud revenue beating forecasts and management keeping capital spending "in check," noting that a "'spend at all costs' mentality has been punished by the market."