SK Hynix Shares Tumble as AI Leaders Call for Slower Development, Hot US Inflation Data Rattles Markets

Shares of SK Hynix tumbled more than 4% on Monday, one of the sharpest single-day declines for the chipmaker in months, as investors reassessed the outlook for artificial intelligence spending that has powered the company's record earnings over the past two years. The stock's slide helped drag South Korea's benchmark KOSPI index down more than 3% at the open, before paring some losses later in the session.

The trigger was an unusual joint statement from the chief executives of Anthropic, OpenAI and SpaceX calling for the pace of AI development to be deliberately slowed. Such a call from three of the industry's most influential leaders was enough to unsettle a market that has spent the past year pricing in ever-larger AI infrastructure budgets, and it raised fresh questions about how quickly data-center operators might keep expanding capacity.

For SK Hynix, the reaction was immediate and outsized. The company is the world's dominant supplier of High Bandwidth Memory, the specialized chips that sit at the heart of the graphics processors powering AI data centers, making it one of the stocks most directly tied to the health of the AI buildout. Any hint that spending on that infrastructure could slow tends to hit SK Hynix harder than most peers, and Monday's selloff extended to Samsung Electronics, the other major Korean producer racing to expand its own HBM business.

The AI-related jitters landed on top of an already nervous macro backdrop. A US core consumer price index reading that came in hotter than economists had expected fed worries that the Federal Reserve could strike a more hawkish tone at its September 15-16 policy meeting, encouraging traders to book profits after a strong AI-driven rally the previous week.

Broader forces compounded the selling in Seoul. Hopes for a diplomatic breakthrough over the Strait of Hormuz faded, sending oil prices sharply higher, while US Treasury yields climbed further, a combination that weighed on risk appetite across Asian equity markets and left few safe havens for Korean investors on the day.

Analysts note that the underlying demand case for HBM has not fundamentally changed overnight, and SK Hynix's order book from major AI chip customers remains largely intact for now. Even so, Monday's slump underscores how sensitive the stock has become to any signal, however preliminary, that the AI spending cycle underpinning its earnings could eventually cool.