Shares of SK Hynix fell 15.37 percent in Seoul on Monday, the steepest single-day decline since the company’s listing, wiping out more than $100 billion in market value and pushing the benchmark Kospi index down as much as 9 percent. The sell-off triggered a 20-minute trading halt and dragged both SK Hynix and Samsung Electronics below a $1 trillion market capitalisation, removing them from the ranks of the world’s most valuable companies. The Kospi has now lost over 20 percent from its June peak, entering a bear market.

The rout followed the company’s record $26.5 billion American Depositary Receipt offering on the Nasdaq, which priced at $149 per ADR and surged 12.8 percent on its first trading day. Investors in Seoul moved to lock in profits after a rally that had multiplied the stock more than 25-fold since late 2022, while some capital rotated into the newly listed US instruments, which by Monday’s close traded at a roughly 37 percent premium to the domestic shares. Analysts in Seoul also cited caution ahead of second-quarter earnings, noting that shipments of the next-generation HBM4 memory chips had not yet scaled up as anticipated, and that SK Hynix’s heavy exposure to high-bandwidth memory meant it would benefit less from a recent uptick in conventional DRAM prices than rival Samsung.

The shockwaves extended beyond Korea. Japan’s Nikkei 225 briefly shed over 1,300 points, with memory-related stocks such as Kioxia Holdings and Taiyo Yuden under heavy selling pressure, as traders tracked the Seoul decline. In Hong Kong, a leveraged single-stock ETF tracking SK Hynix lost more than a third of its value. From Singapore, market strategists noted that the persistent US premium reflects broader investor access and stronger valuation support, though conversion hurdles limit arbitrage. In Moscow, some fund managers described the stock as oversold and a potential buying opportunity, while others pointed to longer-term concerns that AI customers are improving efficiency to reduce memory consumption, potentially softening future demand.

The company’s chief executive, Kwak No-jung, maintained that the global chip shortage is not over and that demand for advanced memory still exceeds supply. The immediate focus now turns to SK Hynix’s quarterly results, due in the coming weeks, which will provide the first concrete test of whether the AI-driven memory boom can sustain the elevated valuations that have made the stock one of the world’s most volatile large-cap names.