US Market Plunges and Korea Daily Briefing
Yesterday, US stocks closed sharply lower as the Dow plummeted over 700 points due to Fed rate hike fears and inflation concerns. Combined with regulatory and safety worries in the AI sector, the South Korean market is also expected to see increased volatility, particularly among semiconductor and AI infrastructure-related stocks.
US Market Plunges and Korea Daily Briefing — 2026-09-16
Yesterday's US Stock Market Summary
Yesterday (Tuesday, September 15), the US stock market dropped significantly due to news of a rate hike by the Federal Reserve (Fed) and warnings of inflation risks from Chair Jerome Powell.
- Dow Plunges Over 700 Points: Investor anxiety over the possibility of an additional Fed rate hike cycle pushed the Dow Jones Industrial Average down by more than 700 points.
- 10-Year Treasury Yield Exceeds 5%: Driven by rising oil prices and mounting inflation concerns, the US 10-year Treasury yield hit 5%, adding valuation pressure to the stock market.
- Weakness in Semiconductor and AI Sectors: Major AI companies warned that slowing down is necessary for human safety, causing semiconductor and other AI-related stocks to decline across the board.

Key Themes and Issues in the Korean Stock Market
Today's Korean market is expected to be directly impacted by yesterday's sharp decline in US stocks and rate hike issues. Careful approach is especially needed for semiconductor and AI-related themes.
- Semiconductor and AI Sector Correction: US semiconductor ETFs fell 4.6%, and the weakness in tech stocks continued. This was a major factor pulling the KOSPI down by over 3%, and domestic large-cap semiconductor stocks may see continued short-term weakness.
- Strength in Cybersecurity and Optical Communication Themes: Following NVIDIA CEO Jensen Huang's remarks on "the necessity of cybersecurity in the physical AI era," domestic cybersecurity and optical communication themes showed counter-trend strength.
- Rising Energy Prices and Middle East Geopolitical Risks: Instability in the Middle East, such as the Iran-Israel conflict surrounding the Strait of Hormuz, is pushing up international oil prices. This is positive for energy-related stocks but acts as a negative factor for the broader market.
Featured Stocks to Watch Today
Considering the themes derived above and yesterday's US market trends, the following stocks are likely to experience high short-term volatility:
- SK hynix: Dropped about 5.19% yesterday, with foreign net selling concentrated around 643.4 billion won. While long-term positives like increased HBM demand remain intact, a conservative short-term approach is required due to the sympathetic weakness in the US semiconductor sector.
- Dream Security & Sands Lab: Domestic security stocks are undergoing a valuation re-rating, boosted by Jensen Huang's emphasis on cybersecurity infrastructure. These stocks are showing relative strength amidst semiconductor weakness.
- Optoelectronics-Related Stocks: Recording an intraday upper limit (+30%), funds continue to flow in, forming individual themes despite the semiconductor downturn. This reflects expectations of benefits from AI infrastructure expansion.

- Important: This briefing is for reference purposes only, and investors bear full responsibility for their investment decisions.
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