KOSPI and Nikkei Slide as Samsung, SK Hynix and Kioxia Lead Chip Sell-Off

Key Takeaways

• South Korea’s KOSPI opened 3.29% lower and fell below 6,900, while Japan’s Nikkei 225 declined by nearly 3% in early trading.
• Samsung Electronics, SK Hynix, Kioxia, SoftBank and Advantest dropped as rising Treasury yields weighed on technology-sector valuations.
• Oil prices above $100 and persistent US producer inflation intensified concerns about interest rates, imported inflation and corporate costs.

KOSPI Falls Below 6,900 as Asian Stocks Extend Global Sell-Off

source: tradingview

Japanese and South Korean stocks fell sharply on September 11 as investors reacted to higher oil prices, persistent US inflation and a renewed rise in government bond yields.

South Korea’s KOSPI opened at 6,802.50, down 231.42 points or 3.29% from the previous close. The index subsequently recovered part of the decline but remained below 6,900 during early trading. The technology-heavy market came under pressure after semiconductor stocks declined in the United States overnight.

The Nikkei 225 also fell by almost 3% after the Tokyo open, trading near 63,400. The simultaneous declines placed both markets among the weakest performers in the Asia-Pacific region and reflected broader risk aversion rather than a company-specific development.

The sell-off followed a fourth consecutive decline for major US stock indices. The S&P 500 lost 0.6%, while the Dow Jones Industrial Average fell 0.6% and the Nasdaq Composite dropped 0.7%. Weakness was particularly visible among technology and semiconductor companies, which tend to be more sensitive to changes in interest-rate expectations.

Samsung Electronics and SK Hynix Lead Korean Chip Losses

Samsung Electronics fell approximately 3.7% to 259,000 won in early Seoul trading, losing the 260,000-won level. SK Hynix declined by just over 4% to around 1.78 million won.

Other Korean large-cap stocks also moved lower. SK Square lost almost 5%, while LG Energy Solution, Hyundai Motor and Samsung Biologics recorded more moderate declines.

The downturn in Samsung Electronics and SK Hynix followed losses among US-listed semiconductor and memory companies. Micron Technology dropped almost 5%, while Nvidia declined more than 2%. The Philadelphia Semiconductor Index fell by approximately 2.7%, reinforcing negative sentiment toward Asian chip manufacturers at the start of Friday’s session.

Rising bond yields present a valuation challenge for technology stocks because a larger proportion of their expected value is tied to future earnings. When the discount rate applied to those earnings increases, investors may become less willing to pay elevated valuation multiples.

This effect can be particularly strong for semiconductor stocks after an extended rally. Even when underlying demand for artificial intelligence chips, high-bandwidth memory and data-centre infrastructure remains firm, higher yields can trigger profit-taking and reduce investors’ tolerance for execution or cyclical risks.

Kioxia, SoftBank and Advantest Drop in Tokyo

Japan’s semiconductor and technology shares experienced similar pressure. Kioxia Holdings fell approximately 5.7%, SoftBank Group declined about 4.7%, and semiconductor-testing equipment producer Advantest dropped around 6%.

These companies carry significant weight in Japanese technology sentiment. SoftBank is closely associated with global artificial intelligence investment, while Kioxia is exposed to NAND flash-memory pricing and Advantest supplies testing equipment used across the advanced semiconductor industry.

The declines therefore extended beyond direct memory-chip producers and affected companies across the AI and semiconductor supply chain.

Currency movements provided little relief. The dollar strengthened to around 154.38 yen, compared with 153.53 yen at the previous Tokyo stock-market close. Although a weaker yen can support the overseas earnings of Japanese exporters, it also raises the local-currency cost of imported oil and other commodities.

With energy prices already elevated, investors appeared more focused on inflation and input costs than on the potential earnings benefit for exporters.

US Producer Inflation Raises Fed Rate-Hike Expectations

The latest US Producer Price Index added to concerns that inflation could remain persistent. Final-demand producer prices increased 0.4% month over month in August and 5.4% from a year earlier.

The monthly increase was broadly in line with market expectations but represented an acceleration from the revised 0.1% rise recorded in July. Prices for final-demand goods increased 1.1%, while the energy component rose 4.2%.

Diesel prices jumped 24.1% during the month, accounting for more than one-third of the rise in the final-demand goods index. Core producer prices excluding food and energy increased 0.2% month over month and 4.6% year over year.

The combination of persistent inflation and rising energy costs led interest-rate futures to price a roughly 70% probability of a 25-basis-point Federal Reserve rate increase at the September meeting. Expectations for an additional move later in the year also increased.

US Treasury yields moved higher in response. The 10-year yield reached approximately 4.95%, increasing the relative attraction of government bonds and placing additional pressure on equity valuations.

What Could Determine the Next Move in Asian Stocks?

The next major catalyst is the US Consumer Price Index. A stronger-than-expected CPI reading could reinforce expectations for a September Fed rate increase and push Treasury yields higher, extending pressure on growth and technology shares.

A softer reading could reduce immediate rate concerns and allow markets to stabilise, although oil prices would remain an independent inflation risk.

Developments in the Middle East will also be important. Any further disruption to crude production or shipping routes could keep oil prices elevated. Conversely, signs of de-escalation or improving energy flows could reduce some of the inflation premium embedded in oil and bond markets.

For Samsung Electronics, SK Hynix and Kioxia, investors will continue to balance strong structural demand for AI-related memory against a more difficult macroeconomic environment. High-bandwidth memory demand and constrained inventories may support the sector’s earnings outlook, but rising yields and broad risk aversion could continue to drive near-term volatility.

The September 11 decline shows that Asian semiconductor stocks remain highly sensitive to global interest rates, US technology sentiment and energy markets. Until Treasury yields and oil prices stabilise, movements in the KOSPI and Nikkei 225 may remain driven as much by macroeconomic conditions as by company fundamentals.