SK Hynix just pulled off one of the most impressive stock market debuts in recent memory. The South Korean memory chip giant’s American depositary receipts climbed roughly 13% on their first day of trading on the Nasdaq, riding a wave of enthusiasm for anything touching AI infrastructure.

The listing raised $26.5 billion, landing it as the second-largest share sale in US history, trailing only SpaceX.

The AI chip kingmaker goes public in the US

SK Hynix priced its ADRs at $149 each, with 10 ADRs representing one share traded on the Seoul exchange. The market’s response was immediate and emphatic, with shares jumping 12.8% to 13% on July 10, 2026.

The company controls approximately 60% of the global high-bandwidth memory market by revenue. It makes the specialized memory chips that companies like Nvidia need to power their AI processors.

The Nasdaq debut came shortly after two major catalysts. First, SK Hynix announced a multi-year partnership with Nvidia. Second, the company shipped HBM4E samples in June 2026, signaling that next-generation memory products are moving from lab to production.

From Samsung’s shadow to South Korea’s most valuable company

SK Hynix overtook Samsung as South Korea’s most valuable company around June 22-23, 2026. SK Hynix shares have increased over 340% year-to-date.

High-bandwidth memory, or HBM, is the fast-access memory that sits right next to AI processors, feeding them data at speeds that traditional memory can’t match. With a 60-61% share of this market, SK Hynix is one of the companies making the AI boom physically possible.

What this means for investors

Samsung, SK Hynix’s primary rival in HBM, now finds itself playing catch-up in a market segment that’s rapidly becoming the most important in the semiconductor industry. Micron, the US-based competitor, faces a similar challenge. SK Hynix’s Nvidia partnership and first-mover advantage in HBM4E technology create a moat that will be difficult to breach in the near term.

The risk to watch is cyclicality. Memory chip markets have historically been boom-and-bust, with oversupply crushing prices every few years. With shares already up 340% this year, any stumble in AI spending could trigger a sharp correction.