SK Hynix stock plunges 14.5% as chip sector rout deepens over AI demand fears

SK Hynix fell 14.5% in a single session as the chip sector extended a rout tied to concerns that AI infrastructure spending — the primary driver of premium HBM3E memory demand — may be peaking or decelerating faster than the market priced in. The magnitude of the move is notable given SK Hynix has been the consensus best-in-class play on HBM, supplying a dominant share of NVIDIA's high-bandwidth memory stack.

The selloff touches the entire AI memory food chain: HBM suppliers, DRAM peers like Micron, and downstream AI chip names that depend on the same capex cycle. If hyperscaler AI capex is genuinely slowing, the ripple effect runs through the whole supply chain, not just Hynix.

The bull case rests on the idea that a 14.5% single-day flush is an overshoot on sentiment rather than fundamentals — HBM supply remains structurally tight, Hynix has multi-year supply agreements with key AI customers, and the long lead times in advanced packaging make a sudden demand collapse structurally difficult.

The bear case is more concerning: if AI demand fears reflect real capex guidance cuts from hyperscalers, memory is historically the first and most volatile sector to re-rate, and Hynix carries significant earnings sensitivity to both price and volume. Without enrichment data on analyst revisions or insider moves, the conviction level here is limited — the setup is genuinely two-sided and the news is still developing.