Don't Sell Semiconductors in May — The Buy Case After HBM4 Mass Production Begins
Foreign investors dumped a combined ₩63 trillion in Samsung and SK Hynix from January through March — yet KOSPI broke 6,900. The consensus is 'Sell in May and take profits,' but the zero-loss-in-May stat after an April surge above 5%, combined with HBM4 mass production kicking off, makes a strong buy case.
On May 6, 2026, Samsung Electronics closed at ₩266,000 (+14.41%) and SK Hynix at ₩1,601,000 (+10.64%). Both hit 52-week highs. Two stocks already up +84% and +98% YTD each added 10%+ in a single day.
Calling “Sell in May” here is easy. On May 2, foreign investors dumped ₩1.4 trillion in a single session. Individual investors who piled into 2x inverse ETNs were forced out by early delisting. The sentiment is clearly skewed toward “the drop is coming.”
The buy case sits on the other side of that consensus.
Why Now
IBK Securities analyst Byun Joon-ho’s observation is the crux: Since 2000, in every year where April KOSPI gained more than 5%, May has never recorded a decline. April 2026 KOSPI was up +30.61%. Statistically, the Sell in May baseline is broken.
The fundamental layer delivers the same verdict. On February 12, 2026, Samsung Electronics announced industry-first mass production and commercial shipment of HBM4. From the Samsung Global Newsroom verbatim: “Samsung Electronics today announced that it has begun mass production of its industry-leading HBM4 and has shipped commercial products to customers. This achievement marks a first in the industry.” Transfer speed: 11.7Gbps steady-state, 46% above the JEDEC 8Gbps standard. For NVIDIA’s Vera Rubin platform, UBS estimates SK Hynix at ~70% HBM4 market share.
The combined ₩63T foreign net selling from January through March (Samsung ₩42T + SK Hynix ₩22T) is already priced in and known. Since April, foreigners flipped to net buying — ₩5T+ combined in April alone. Stocks printing 52-week highs while foreigners sold ₩63T means domestic and institutional buyers absorbed every share. That is a fundamental strength signal, not a weakness.
The Buy Case
Market consensus: “Take profits after a +56.59% four-month rally.” Buy thesis: “HBM4 mass production is the beginning of the supercycle, not the end.”
Shinhan Investment fair value: Samsung ₩338,000 (current ₩266,000, +27% upside), SK Hynix ₩1,893,000 (current ₩1,601,000, +18% upside). KB Securities targets Samsung at ₩360,000; SK Securities targets SK Hynix at ₩2,000,000.
SK Hynix ROE: -15.61% in 2023 → 92.7% estimated for 2026. Forward PER at 4.5x (2026E) is a historic trough.
The right execution is not “buy now at 52-week highs.” RSI overextension makes chasing dangerous. The right play: wait for KOSPI to pull back to the 6,100–6,300 first support or 5,800 bedrock, then accumulate in tranches. That’s the entry — while the crowd panics on “Sell in May.”
Risks
Conditions under which this thesis fails:
- NVIDIA earnings miss on May 27 — Data center demand concerns could drag the entire semiconductor sector -10–15%.
- EM fund rebalancing resumes — Foreigners hold stocks with a -52% price correlation to their position size; sudden EM rebalancing can create a panic leg down.
- HBM4 shipment volume cut — ZDNet reported SK Hynix cutting NVIDIA-bound HBM4 shipments 20–30%; if this hits earnings consensus EPS materially, the thesis weakens.
- Kevin Warsh Fed Chair hawkish debut — Rate expectation reversal can cool global risk-on sentiment.
References
- Sell in May KOSPI Outlook 2026 — 21st Century Issue
- KOSPI April Surge, May Strategy — 21st Century Issue
- Samsung Ships Industry-First Commercial HBM4 — Samsung Newsroom
- Naver Sector Overview — Naver Finance