SK hynix shares closed Friday at 2,333,000 won, up 1.92% and near all-time highs, capping a week that saw the memory chipmaker reach a $1 trillion market capitalization for the first time. The milestone places SK hynix alongside Samsung Electronics and Micron Technology in the trillion-dollar club, underscoring the outsized role of artificial intelligence-driven demand for high-bandwidth memory (HBM).
The Korea Composite Stock Price Index (KOSPI) ended the week at a record 8,476.15, up 3.55%. However, the rally was narrow. Data from the Korea Exchange cited by Seoul Economic Daily showed that 82.34% of 2,764 stocks listed on the KOSPI and KOSDAQ declined over the past month, even as the main index hit new highs. Money continues to concentrate in a handful of semiconductor names, with Samsung Electronics and SK hynix absorbing the bulk of inflows.
SK hynix's ascent defies its historical characterization as a cyclical memory stock. Analysts point to structural changes in the market. Kim Young-gun of Mirae Asset Securities said, "memory chip demand to continue exceeding supply by 2028." Kang Jin-hyuk at Shinhan Securities attributed recent buying to leveraged ETF flows, which use derivatives or borrowed money to amplify gains. The stock's weekly trajectory tells the story: it closed at 2,052,000 won on Tuesday, 2,243,000 won on Wednesday, 2,289,000 won on Thursday, and 2,333,000 won on Friday, after ending the prior week at 1,941,000 won.
Competition in the HBM space is heating up. Samsung Electronics has begun shipping samples of its 12-layer HBM4E chip to global customers, a move that could reshape the market. HBM, a stacked memory crucial for AI server data movement, has been a key profit driver for SK hynix. According to Counterpoint Research, SK hynix held a 57% share of the global HBM market at the end of the fourth quarter of 2025, compared to Samsung's 22% and Micron's 21%. Jeff Kim, head of research at KB Securities-Jefferies, noted that early movers typically secure most HBM orders, and Samsung's progress in qualifying its chip could shift the vendor mix "toward SK Hynix and Samsung."
South Korean policy is providing additional tailwinds. The National Pension Service has raised its target for domestic equity allocation to 20.8% by end-2026, up from 14.9%. Barclays analyst Bum Ki Son wrote in a note that "booming" semiconductor demand could persist for "two to three more years," and the fund may maintain its equity exposure to capture upside rather than sell into the rally.
The narrowing of the KOSPI rally poses risks for traders. If AI demand slows, memory prices plateau, or Samsung accelerates its HBM product rollout, SK hynix's premium could come under pressure quickly. Investors are also watching whether Friday's record close will attract fresh domestic money after the weekend, and whether Samsung's HBM4E ramp is a near-term threat or a longer-term story.
Korean markets will be closed on Wednesday, June 3, for local elections, the Korea Exchange confirmed. The closure includes KOSPI, KOSDAQ, ETFs, derivatives, and commodities. Traders will have less time to assess the implications of the week's events.
For now, SK hynix retains its leadership in AI memory, but the next few sessions will test whether that story can sustain earnings momentum or whether the market's narrow breadth forces investors to look elsewhere.
