SK Hynix at a Crossroads: Record Earnings, Supplier Probe, and Next-Gen HBM Competition Collide

South Korean raiders target three SK Hynix suppliers for price-fixing; stock surges 245% YTD on AI HBM demand, but index concentration and Samsung's faster HBM4E samples pose risks.

The announcement landed just as SK Hynix’s stock touched a fresh peak. On May 28, South Korean investigators raided three key suppliers — MK Electron, LT Metal, and Duksan Hi-Metal — on suspicion of price-fixing and manipulating delivery volumes for semiconductor materials. SK Hynix itself faces no accusations, but the probe strikes at the fragile supply chain underpinning its most critical product: High Bandwidth Memory for AI data centers. Any disruption to materials, pricing, or partner relationships could squeeze margins and delay deliveries, adding an unwelcome layer of regulatory uncertainty to a company riding an unprecedented wave.

The wave itself is hard to argue with. SK Hynix’s market capitalization has breached $1.10 trillion, a milestone few non-US tech companies achieve. On Friday, the stock hit 2,333,000 won, a 1.92% gain that marked a new 52-week high. Year to date, the shares have surged 244.61%, with 80.43% of that advance coming in the last 30 days alone. The driver is singular: AI server demand for HBM memory, which remains scarce and strategically vital.

That scarcity is reflected in the numbers. For the first quarter of 2026, SK Hynix reported an operating profit of 37.6 trillion won, a 400% leap from the same period last year. Revenue soared to 52.6 trillion won, up 200%, and the operating margin hit a staggering 72%. According to Counterpoint Research, SK Hynix controlled 57% of the global HBM market in the fourth quarter of 2025, far ahead of Samsung’s 22% and Micron’s 21%. Long-term supply contracts with AI hyperscalers have given the business unusual visibility for a cyclical memory maker.

But that very success has created a structural headache. SK Hynix’s ballooning weight in the KOSPI index means many institutional investors are bumping against internal concentration limits — typically around 10% of a fund’s assets. Goldman Sachs estimates that this mechanism has triggered selling of roughly $69 billion since October. Net outflows from Korean equities reached $63.6 billion in the latest monthly period, the highest print since 1999. RBC warns that SK Hynix and Samsung together now represent about 50% of the entire KOSPI market value, leaving the broader market dangerously top-heavy. Some portfolio managers are forced to cut their SK Hynix holdings even if they remain bullish on the stock.

Competition is also stirring. On the very day SK Hynix set a new 52-week high, Samsung announced it had shipped samples of its 12-layer HBM4E chips to major customers. Samsung’s HBM4E delivers 16 gigabits per second per pin and a memory bandwidth of 3.6 terabytes per second per stack — more than 20% faster than its HBM4 predecessor. Mass production will follow once customer qualification wraps up. By contrast, SK Hynix has guided that its own HBM4E samples will not ship until the second half of 2026, with volume production slated for 2027. Samsung appears ahead on the calendar, though sample delivery is a long way from securing volume orders or pricing power.

SK Hynix enters that race with deep momentum. The current HBM cycle is still delivering explosive earnings, and its dominant market share gives it a strong negotiating position. Yet the premium already baked into the stock — the 244% YTD rally — assumes that the company can retain its pricing lead into the next generation. Samsung’s earlier sample timing creates a visible benchmark. The real test will come in the second half of 2026, when SK Hynix presents its own HBM4E samples and the industry begins to judge whose architecture meets the demanding bandwidth, thermal, and efficiency requirements of the next wave of AI accelerators.

For now, three forces are pulling the stock in different directions: record-breaking profitability, rule-driven selling by large funds, and the regulatory spotlight on the supply chain. The KOSPI itself closed at 8,476.15 on May 29, up 3.55% on the day and nearly doubling year to date. But that headline masks a market increasingly dependent on two semiconductor giants. SK Hynix has never been stronger operationally, yet the mix of forced divestments, a looming technology transition, and an antitrust investigation means the path ahead is anything but smooth.