SK Hynix (000660.KS) Tops ₩1,000T Market Cap, KOSPI's 2nd Ever

TL;DR - SK hynix shares jumped 10.42% intraday on May 4 to a record ₩1.42 million ($1,036), pushing market cap above ₩1,000 trillion ($730 billion) — a level only Samsung Electronics had previously reached on KOSPI. - Foreign investors net-bought roughly ₩800 billion ($584 million) on the main board within the first 40 minutes of trade, helping the KOSPI open at 6,782.93 (+2.79%) and surpass 6,830 intraday for an all-time high. - Watch whether the close holds the ₩1,000 trillion threshold, the cadence of HBM long-term agreements, and whether SK Square clears ₩1 million per share to join the "emperor stock" club.

Lead. SK hynix (000660.KS), Korea's leading high-bandwidth memory (HBM) supplier, became the second stock ever to surpass ₩1,000 trillion (about $730 billion) in market capitalization on KOSPI — Korea's main equity benchmark — during intraday trading on May 4, joining only Samsung Electronics (005930.KS), the country's largest listed company. The chipmaker's shares climbed 10.42% to a record ₩1.42 million ($1,036), helping push the index past 6,800 for the first time.

What Happened

Per Maeil Business (a Seoul business daily), as of 11:00 a.m. KST SK hynix traded at ₩1.40 million ($1,022), up ₩114,000 ($83.20), or 8.86%. Forty minutes later, per Chosun Biz (the business arm of Chosun Ilbo), the stock had climbed further to ₩1.42 million, up ₩134,000 ($97.80), or 10.42%, with market capitalization crossing ₩1,000 trillion — second on KOSPI behind Samsung Electronics.

The broader market followed. KOSPI opened at 6,782.93, up 184.06 points (2.79%), per Chosun Biz, and intraday surpassed 6,830, per Hankyung (Korea Economic Daily).

Foreign investors led the charge. By 9:40 a.m. KST, per Chosun Biz, foreigners had net-bought nearly ₩800 billion ($584 million) on the KOSPI main board, with institutions adding ₩236.1 billion ($172 million); retail investors net-sold ₩871 billion ($636 million).

SK Group affiliates rallied in tandem. SK Square (402340.KS), SK hynix's largest shareholder, jumped over 13% to ₩959,000 ($700) — also an all-time high, per Chosun Biz — placing it within ₩41,000 of "emperor stock" status (the local term for shares trading above ₩1 million). SK Inc. (034730.KS), the SK Group holding company, climbed 8.94%. Samsung Electronics added 2.3%, per Yonhap News (Korea's main wire service).

Why It Matters

The breach is the first concrete signal that Korea's AI-memory super-cycle has produced a second mega-cap on KOSPI within a single session. For roughly two decades, ₩1,000 trillion was a line only Samsung Electronics had crossed. SK hynix joining marks a structural shift: a single-product franchise tied to HBM now commands valuation comparable to Samsung's diversified electronics empire. The milestone caps a year-to-date rally widely reported above 30%, fueled by hyperscaler AI capex and tightening HBM supply.

Business Impact

Eugene Investment & Securities (a Seoul brokerage) on May 4 newly issued a ₩2.3 million ($1,679) target price on SK hynix, per Chosun Biz. Analyst Son In-jun forecast Q2 2026 revenue of ₩82.3 trillion ($60.1 billion) and operating profit of ₩63.7 trillion ($46.5 billion), writing that "current projected server-demand growth alone will deepen supply tightness by 2027," and that any recovery in smartphone and PC unit demand "will further intensify the shortfall." Son added that memory makers are negotiating long-term agreements (LTAs) with select customers under "fairly favorable conditions backed by a minimum-price-guarantee mechanism."

For context, SK hynix reported Q1 2026 revenue of ₩52.58 trillion ($38.4 billion) and operating profit of ₩37.61 trillion ($27.5 billion) — a 72% operating margin — per the company's earnings disclosure. Q1 already represented a record quarterly result.

Industry & Historical Context

Today's surge reflects spillover from a strong U.S. session while Korea was closed for the May 1 holiday. The Philadelphia Semiconductor Index rose 2.26% on April 30 and 0.87% on May 1, per Chosun Biz. The S&P 500 closed up 21.11 points (0.29%) at 7,230.12 on May 1, an all-time high driven by Apple's earnings beat, per Chosun Biz.

Samsung Electronics remains the only other KOSPI-listed company to have ever held a ₩1,000 trillion market cap. The parallel rally in SK Group affiliates illustrates how the holding-company structure is amplifying gains as foreign investors rotate into Korea's AI-semiconductor names.

What to Watch

• Whether SK hynix sustains its ₩1,000 trillion footprint at the closing print; intraday touches do not always hold.
• Q2 2026 earnings, the next test of Eugene Investment's bullish thesis given the gap between the Q1 reported revenue (₩52.58 trillion) and the Q2 projected revenue (₩82.3 trillion).
• Pace and pricing of HBM long-term agreements that Eugene's Son cites as the cycle's structural anchor.
• Foreign flows: the near-₩800 billion ($584 million) main-board inflow in the first 40 minutes is the swing factor most likely to determine whether the rally extends.
• Whether SK Square clears ₩1 million per share to formally join Korea's "emperor stock" cohort.

Sources: - Yonhap News — https://www.yna.co.kr/view/AKR20260504034600008 - Yonhap News (KOSPI 6,800) — https://www.yna.co.kr/view/AKR20260504060900008 - Chosun Biz (SK hynix ₩1.42M) — https://biz.chosun.com/stock/stock_general/2026/05/04/ATOIJIHA6JFUFCLQI7FWOZCX7Y/ - Chosun Biz (KOSPI open) — https://biz.chosun.com/stock/stock_general/2026/05/04/WT4ITEEPWJET7FMESSDOV6IGGQ/ - Hankyung — https://www.hankyung.com/article/202605044205i - Maeil Business — https://www.mk.co.kr/news/stock/12034965 - SK hynix Q1 2026 results — https://news.skhynix.com/q1-2026-business-results/ - Seoul Economic Daily — https://en.sedaily.com/markets/2026/05/04/top-10-korean-conglomerates-add-1500-trillion-won-in-market

By LineVest Markets Desk — May 4, 2026 This article is for informational purposes only and does not constitute investment advice.