Stack L2
SK Hynix
HBM3E 12-high lead supplier to NVIDIA; first to complete HBM4 development, ramping for Rubin
HQ KR
Fit Score
avg of 4 segmentsRecent Business Signals
Strategic Position
What they do best
Volume-shipping the densest HBM stacks earliest — first to ship 12-high HBM3E to Nvidia in March 2025 (signal b67476b0) and first to complete HBM4 in September 2025 (signal fe64f30f).
Their bet
Lock the Nvidia Rubin socket via HBM4 on TSMC N3 base die (signal 910ed7ff) while the 20T won M15X fab (signal 9516af7d) absorbs the 2026-2027 capacity wave.
Top risk
Samsung clearing Nvidia HBM3E qualification in the next 6 months would crack the single-source pricing power that drove the 41% Q2 operating margin.
Compared to peers
Direct competitor
Samsung Electronics
Same HBM product roadmap but stuck on Nvidia HBM3E qualification delays; SK Hynix is the incumbent ~50% share leader.
Substitute
Micron Technology
US-strategic CHIPS Act hedge with HBM3E 12-Hi; one node behind on HBM4 (2026 roadmap vs SK Hynix mass-production-ready in 2025).
Why someone would join
- 1.Q3 2025 operating profit hit 11.4T won with HBM >40% of DRAM revenue (signal 6c2b52c8) — engineers join the highest-margin memory franchise in the industry, not a turnaround story.
- 2.Open reqs span the full HBM4 stack — principal DRAM design, TSV integration, hybrid bonding, signal integrity, KGSD test — meaning new hires touch the first product shipping into Nvidia Rubin in 2026.
Recent Hiring (60 days)
- DRAM circuit design1
- HBM41
- hybrid bonding1
- advanced packaging1
- memory test1
Reverse-Hype Watch
- !Q2 2025 41% operating margin is cyclical-peak behavior; same company posted operating losses across multiple 2023 quarters during the prior trough, so current growth rate is not durable through a 2026-2027 AI capex pause