Stock Market Today, Oct. 28: SK Hynix Surges on Record Q3 Results and AI-Memory Demand

SK Hynix (SKHY) surged 13.30% on October 28, 2026, after reporting record Q3 results that included a sevenfold jump in operating profit and an 80% operating margin. The move stands out as one of the sharpest single-day gains tied to AI-memory demand.

The stated driver is robust AI-memory demand. DRAM and HBM production at SKHY is effectively sold out through 2029, a supply-visibility claim that stretches years beyond the current quarter.

The rally spilled into peers. Micron Technology (MU) and SanDisk (SNDK) both rose as sentiment around AI-memory demand improved. The source does not quantify their gains, so SKHY's 13.30% jump remains the benchmark for the group.

Interpretation: an 80% operating margin paired with sold-out capacity through 2029 suggests the market is pricing sustained pricing power rather than a one-quarter spike. The sector-wide response to a single company's report also shows how tightly MU and SNDK are being traded as a basket against SKHY's results.