Samsung, SK Hynix Shares Soar Nearly 30% in Record Single-Day Rally

Shares of Samsung Electronics and SK Hynix rocketed nearly 30% on Friday, marking the largest single-day percentage gains either stock has ever recorded and pulling the benchmark Kospi index to its own historic one-day advance. The surge effectively erased a brutal run of losses the two chipmakers had suffered just days earlier.

The turnaround traced back to Wall Street, where semiconductor and AI-linked shares jumped overnight after Alphabet, Microsoft and Meta Platforms all pointed to further increases in capital spending on data centers and AI infrastructure. The announcements reassured investors that demand for the high-bandwidth memory chips at the heart of AI servers is still climbing, not cooling, and Seoul-listed suppliers rode that wave almost as soon as trading opened.

The rebound came after a punishing few days for Korean chip stocks. Fears over China's fast-expanding domestic chip industry, combined with softer-than-expected quarterly results from SK Hynix, had triggered panic selling earlier in the week, dragging the Kospi down through back-to-back circuit breakers to its lowest level in roughly four months. SK Group Chairman Chey Tae-won stepped in personally on Thursday, purchasing about $3.3 million worth of SK Hynix shares on the open market in a bid to calm jittery investors.

Adding to the shift in mood, Samsung Electronics had told investors earlier in the week that it expects the global memory chip shortage to deepen through 2027 and persist into 2028, as hyperscalers' relentless AI buildout keeps demand running ahead of available supply. Sales of its next-generation HBM4 chips were already surging, the company said, a forecast that took on new weight once Wall Street's renewed enthusiasm for AI capital spending flowed through to Seoul.

Friday's rally underscored just how closely South Korea's two largest companies by market value are now tethered to the fortunes of the global AI investment cycle. With Samsung and SK Hynix supplying the bulk of the world's advanced memory chips for AI servers, their share prices have increasingly become a real-time gauge of investor confidence in the durability of the AI spending boom, for better or worse.