"$100 Oil, 5% Rate Shock"... KOSPI Slides for Fourth Straight Day

U.S. Treasury Yields Break Psychological Resistance Level of 5%
KOSPI Continues to Weaken Amid Concerns Over Rising Rates
Probability of U.S. Base Rate Hike Rises Ahead of September 17 Decision

On the 15th, the KOSPI index opened at 6659.25, down 25.12 points (0.38%) from the previous trading day. The current status of the domestic stock market was displayed on the electronic board in the dealing room of the Hana Bank headquarters in Jung-gu, Seoul. 2026.9.15 Photo by Hyunmin Kim

The KOSPI has remained weak for four consecutive days as a result of surging U.S. Treasury yields and international oil prices. There is growing speculation that the volatility in the market could intensify this week as the likelihood of a U.S. base rate hike increases.

KOSPI Weakens as U.S. Treasury Yields Break Psychological Resistance Level of 5%

As of 10:01 a.m. on September 15, the KOSPI was trading at 6,666.76, down 0.26% from the previous session. At the same time, the KOSDAQ was trading at 814.46, up 0.95%.

The surge in both interest rates and oil prices led to declines in all three major U.S. stock indices overnight, weighing on the Korean stock market as well. The Dow Jones Industrial Average and S&P 500 fell by 0.29% and 0.48%, respectively, and the Nasdaq Composite also declined by 0.56%.

The previous day, Saudi Arabia shut down its key 'East-West Pipeline,' sparking concerns about a disruption to oil supply and leading to a sharp rise in international crude prices. West Texas Intermediate (WTI) crude for October delivery closed at $101.39, up 1.34%. Continued unrest in the Middle East led the U.S. 10-year Treasury yield to surpass the psychological resistance level of 5%, further fueling declines in stock markets.

However, as the KOSPI had already declined for three consecutive sessions through the previous day, reflecting the impact of surging market rates, some bargain hunting flowed in today, resulting in fluctuation around modest losses.

As of 10:02 a.m., shares of Samsung Electronics were trading at 250,000 won, up 0.40% from the previous close, while SK hynix was trading at 174,000 won, up 0.41%. Among large-cap stocks, SK Square (up 1.30%), LG Energy Solution (up 1.42%), and Hyundai Motor (up 0.13%) were advancing, whereas KB Financial Group (down 2.75%), Samsung Life Insurance (down 2.85%), and Samsung C&T (down 1.81%) were declining.

Ji Yong Han, a researcher at Kiwoom Securities, analyzed, "Despite pressure from the U.S. 10-year yield breaking above 5.0% and a sharp drop in U.S. semiconductor stocks, the recognition that these factors were already reflected in the Korean market yesterday is expected to drive a recovery from the previous day’s steep declines."

Probability of U.S. Base Rate Hike Rises for September 17 Decision

The market is focusing on whether the U.S. Federal Reserve’s Federal Open Market Committee (FOMC) will decide on a base rate hike, with the decision expected to be announced in the early morning of September 17, Korea time. According to the CME FedWatch Tool, the likelihood that the Fed will raise rates by 0.25 percentage points at this meeting has risen from 87.3% the previous day to 90.1% today in the rate futures market.

Experts continue to warn that a sustained increase in interest rates will raise borrowing costs, eroding the relative appeal of risk assets such as stocks and increasing the funding burden for both corporations and households. In particular, if the pace of Fed rate hikes accelerates, there are concerns that a deeper market correction could occur.

Meanwhile, on the previous day, the Korea Exchange (KRX) launched its 'aftersession market,' allowing real-time trading of stocks between 4 p.m. and 8 p.m. On its first day, the trading volume of the KRX aftersession market reached 1.8177 trillion won, accounting for 6.6% of KRX's total trading volume of 27.6 trillion won. However, some confusion arose as a few brokerages experienced system glitches in the pre-market and the number of securities triggering the volatility interruption mechanism (VI) surged sharply.

This content was produced with the assistance of AI translation services.