12.KOSPI Record Rebound: Samsung Electronics and SK hynix Lead a 17.9% Surge
The KOSPI posted its largest point and percentage gain on record as foreign investors bought more than KRW 7 trillion of main-board shares, led by Samsung Electronics (KRX: 005930) and SK hynix (KRX: 000660).
Official earnings and product disclosures support a stronger AI-memory cycle. The scale of the rebound, however, also reflected severe oversold conditions, program buying, position unwinds and likely short covering after three consecutive declines.
1. Market Close and Investor Flows
The KOSPI, Korea’s main board for larger listed companies, closed at 6,595.45, up 1,001.89 points or 17.91%. The index opened at 5,657.79 and reached an intraday high of 6,630.77. The KOSDAQ, Korea’s more growth-oriented market, gained 11.63% to 719.76.
Buy-side trading curbs known as sidecars were triggered shortly after the open in both markets. The mechanism temporarily pauses program buying when futures prices move sharply, giving the cash market time to absorb unusually large order flows.
| Market or Security | July 31 Close | Daily Change | Interpretation |
|---|---|---|---|
| KOSPI | 6,595.45 | +17.91% | Largest one-day point and percentage gain on record |
| KOSDAQ | 719.76 | +11.63% | Broad rebound led by semiconductor equipment and materials |
| Samsung Electronics KRX: 005930 | KRW 262,500 | +26.81% | Foreign buying and a sharp re-rating of memory earnings |
| SK hynix KRX: 000660 | KRW 1,718,000 | +29.95% | Closed at Korea’s 30% daily price limit |
| SK Square KRX: 402340 | KRW 1,038,000 | +29.91% | Direct exposure to the value of its SK hynix shareholding |
Market breadth was positive: 773 KOSPI stocks advanced, 127 declined and 15 were unchanged. Twelve stocks reached the upper daily price limit. The rally was therefore broader than the two largest chipmakers, although index performance remained heavily concentrated in semiconductor and electronics leaders.
| Investor Group | KOSPI Net Flow | Session Reading |
|---|---|---|
| Foreign investors | +KRW 7.2414tn | Exceptional cash-equity buying concentrated in large-cap exporters |
| Institutions | +KRW 1.0325tn | Added to the rebound through cash and program demand |
| Retail investors | -KRW 8.2739tn | Used the rally to reduce positions after an unusually volatile week |
Investor-flow totals are based on the Korea Exchange regular-session market tally. Figures may differ from statistics that include alternative-venue or after-hours transactions.
2. What Drove the Rebound
U.S. AI and semiconductor stocks moved first
The previous U.S. session provided the initial catalyst. The Nasdaq Composite rose about 2.8%, while the Philadelphia Semiconductor Index gained roughly 8.2%. Microsoft surged more than 15% after its cloud and cash-flow outlook eased some concerns that AI infrastructure spending was running too far ahead of revenue.
The move mattered disproportionately for Korea because Samsung Electronics and SK hynix are central suppliers to global data-center and memory markets. A renewed rise in U.S. chip shares quickly translated into demand for Korean large-cap semiconductor exposure.
The selloff had already become extreme
The KOSPI had fallen 10.84% on July 28, 5.98% on July 29 and another 1.23% on July 30. Samsung Electronics and SK hynix had each lost more than 14% on July 28 alone as investors reacted to Chinese memory expansion, progress in domestic Chinese chip equipment, high AI capital spending and the risk of leveraged-position liquidations.
Even after the July 31 rebound, the KOSPI remained down more than 22% for the month. The session may prove to be the beginning of a more durable recovery, but it was also a mechanical reversal from exceptionally oversold conditions.
Foreign buying, program flows and position unwinds amplified the move
Foreign investors bought more than KRW 7 trillion of KOSPI shares in one session. That demand met a market in which investors had already reduced leverage, increased hedges and sold heavily over the previous three days.
The precise contribution from short covering cannot be isolated from official end-of-day cash-flow data. Still, the speed of the advance, the early sidecar triggers and the concentration in recent losers indicate that positioning effects were material.
New leveraged-product rules were context, not the direct catalyst
Beginning July 31, investors making new or additional purchases of Korean single-stock leveraged exchange-traded products became subject to a KRW 30 million minimum cash deposit. Regulators also announced tighter product limits, investor education requirements and restrictions on new listings and promotion.
The rules were designed to reduce speculative leverage. There is no official evidence that money left leveraged products and automatically moved into Samsung Electronics or SK hynix ordinary shares. The regulation is better viewed as part of the broader positioning backdrop than as the primary cause of the rally.
Session conclusion: The rebound combined three distinct forces: stronger global AI sentiment, verified Korean memory earnings and an unusually powerful reversal of defensive and leveraged positions. Treating the full 17.9% index gain as a permanent increase in fundamental value would overstate what one trading day can establish.
3. What the Earnings Say About the Memory Cycle
The case for a stronger semiconductor cycle is more substantial than the one-day price move. Both Korean memory leaders have reported exceptional second-quarter results and confirmed that next-generation high-bandwidth memory is moving from qualification into commercial shipments.
| Company | Q2 2026 Revenue | Operating Profit | Key Evidence |
|---|---|---|---|
| Samsung Electronics Consolidated, final results | KRW 171.5tn | KRW 89.5tn | Device Solutions generated KRW 127.5tn of revenue and KRW 89.2tn of operating profit |
| SK hynix Consolidated, preliminary results | KRW 79.3187tn | KRW 60.5426tn | Operating margin reached 76%, supported by HBM and server-memory pricing |
SK hynix: HBM4 is already shipping
SK hynix reported that HBM4 mass-production shipments began during the second quarter and that production would expand in the second half. The company also completed initial HBM4E sample shipments during the first half and said it had concluded long-term supply discussions with roughly ten customers.
The balance sheet has strengthened alongside earnings. SK hynix reported KRW 88 trillion of cash and cash equivalents, KRW 18.6 trillion of borrowings and a net-cash position of about KRW 69.4 trillion.
That supports further fabrication and advanced-packaging investment, but capital deployment still matters. The company’s approximately USD 26.5 billion Nasdaq ADR offering provides significant funding while increasing the number of shares represented in the market. Investors should monitor dilution, capital intensity, production yields and free cash flow rather than treating the fund-raising as unambiguously positive.
SK Group Chairman Chey Tae-won’s purchase of 3,620 SK hynix shares, worth approximately KRW 4.8 billion at the July 30 close, was a constructive signal of confidence. It was not large enough relative to the company’s market value to explain the following day’s limit-up move.
Samsung Electronics: memory strength is offset by weaker non-memory businesses
Samsung Electronics’ final second-quarter results confirmed a powerful recovery in memory. Device Solutions generated KRW 127.5 trillion of revenue and KRW 89.2 trillion of operating profit, with HBM4, server DRAM and enterprise SSD demand supporting the result.
The recovery was not uniform across the company. Mobile Experience and Networks reported an operating loss, while television and appliance profitability also remained under pressure from component costs. Samsung’s earnings are therefore highly dependent on the semiconductor division at this stage of the cycle.
Samsung stated that HBM4 supply was expanding and that HBM4E samples had been shipped to major customers. The company separately announced commercial HBM4 shipments and performance of up to 3.3 terabytes per second, about 2.7 times the throughput of the prior generation.
Foundry conditions also improved as utilization increased and demand strengthened for advanced nodes, HBM base dies and products for U.S. customers. Samsung cited additional design wins, including 2-nanometer high-performance-computing projects, and planned second-generation 2-nanometer mobile production during the second half.
Specific customers, volumes and profitability remain less transparent. Claims that any particular global technology company has definitively driven the foundry recovery should be treated cautiously unless supported by a filing or customer announcement.
Does this qualify as a semiconductor supercycle?
The cycle has broadened beyond HBM. Conventional server DRAM and enterprise SSD demand and pricing are also improving, suggesting that the earnings recovery is not dependent on one product category alone.
The World Semiconductor Trade Statistics organization’s spring 2026 forecast projected a global semiconductor market of approximately USD 1.51 trillion, up about 90%, with memory revenue exceeding USD 800 billion and rising roughly 250%.
Those figures are forecasts, not realized sales. The thesis would weaken if hyperscale companies reduce AI capital spending, memory pricing peaks sooner than expected, Chinese suppliers expand competitive capacity faster than anticipated or new fabrication investment produces weaker returns.
4. Why It Matters for Global Investors
Korea provides concentrated AI-memory exposure
Samsung Electronics and SK hynix have an unusually large influence on the KOSPI. When global memory expectations change, the Korean benchmark can move far more sharply than its number of listed companies would suggest.
Foreign flows are a major transmission channel
Large Korean exporters are sensitive to global risk appetite, semiconductor benchmarks, U.S. interest rates and the Korean won. A single day of foreign buying can move the index substantially, but it does not guarantee that the capital will remain.
SK hynix now has a Nasdaq ADR
SK hynix ADRs trade on Nasdaq under the ticker SKHY. The listing gives U.S.-market investors another access route, but the ADR may trade at a premium or discount to the Korean ordinary shares, particularly when conversion and arbitrage capacity are constrained.
Currency risk remains material
Returns on Korean-listed shares depend on both the local share price and USD/KRW movements. A stronger won can add to a dollar-based investor’s return, while won depreciation can offset gains in the underlying stock.
Directly exposed Korean securities
- Samsung Electronics (KRX: 005930): diversified electronics group with direct exposure to memory, foundry, advanced packaging, displays and consumer devices.
- SK hynix (KRX: 000660; Nasdaq ADR: SKHY): more concentrated memory exposure, with a leading position in HBM and server DRAM.
- SK Square (KRX: 402340): an investment holding company whose asset value is strongly influenced by its SK hynix shareholding.
The three securities do not provide identical exposure. Samsung offers broader diversification but also carries weaker consumer-device and foundry businesses. SK hynix offers more direct memory-cycle sensitivity, while SK Square adds holding-company discount and governance considerations.
5. Bull, Base and Bear Scenarios
| Scenario | What Would Support It | Likely Market Effect | What Would Disconfirm It |
|---|---|---|---|
| Bull | Foreign cash buying continues, HBM4 revenue scales quickly, U.S. AI earnings remain strong and market breadth expands | Semiconductor leadership broadens to equipment, packaging, substrates and data-center infrastructure | Foreign selling returns or company shipment guidance fails to rise |
| Base | Memory earnings remain strong, but investors take profits after the record rebound | High volatility and consolidation rather than another straight-line advance | A sustained increase in foreign demand or a renewed global technology selloff |
| Bear | AI capital-spending concerns return, U.S. yields stay high, Chinese competition intensifies or financing risks dominate | Another rapid de-rating in the index’s largest semiconductor stocks | Stronger long-term contracts, improving free cash flow and resilient memory pricing |
6. What to Watch Next
- Foreign cash demand: Determine whether buying continues in ordinary shares rather than appearing mainly through futures and program trades.
- Market breadth: A healthier recovery would extend beyond Samsung Electronics and SK hynix into companies with verified orders and earnings exposure.
- SK hynix HBM4 execution: Watch production growth, revenue recognition under long-term agreements, packaging yields and free cash flow after expansion spending.
- Samsung HBM and foundry execution: Monitor customer qualification, shipment volumes, 2-nanometer yields, utilization and whether foundry profitability improves.
- SKHY ADR pricing: Compare the Nasdaq ADR with the Korean ordinary shares and account for currency, conversion and liquidity differences.
- U.S. macro conditions: June PCE inflation of 3.7% and core inflation of 3.3%, together with the Federal Reserve’s decision to hold rates at 3.50%–3.75%, leave global growth stocks sensitive to bond yields.
- Leveraged-product activity: Observe whether the new deposit and product rules reduce speculative turnover or merely shift it to other instruments.
Bottom line: Official earnings, HBM4 shipments and long-term supply arrangements support the argument that Korea’s memory industry is in a structurally stronger phase. The July 31 market move, however, also contained a large reversal of oversold and leveraged positioning. The next confirmation must come from sustained foreign demand, broader earnings participation and cash-flow delivery—not another one-day price surge.
7. Frequently Asked Questions
Why did the KOSPI rise 17.9% on July 31?
The rally combined a rebound in U.S. AI and semiconductor stocks, strong Korean memory earnings, more than KRW 7 trillion of foreign KOSPI buying and a sharp reversal of positions built during the previous three-day selloff.
Was the rally entirely driven by better fundamentals?
No. Semiconductor earnings and HBM demand supported the direction of the move, but the scale also reflected oversold conditions, program buying, reduced hedges and likely short covering.
Are Samsung Electronics and SK hynix already shipping HBM4?
Yes. Both companies have publicly announced commercial or mass-production HBM4 shipments. They have also begun customer sampling or development work for HBM4E.
Can U.S. investors access SK hynix through an ADR?
SK hynix ADRs trade on Nasdaq under SKHY. Investors should compare the ADR with the Korean ordinary shares because premiums, discounts, currency movements, liquidity and conversion constraints can affect relative performance.
What would weaken the semiconductor recovery thesis?
Key risks include lower hyperscale AI spending, an early peak in memory prices, faster Chinese capacity growth, weak manufacturing yields, aggressive capital spending, shareholder dilution and a reversal in foreign investor flows.
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