AI Cooling and Defense Sector Rise: Analysis of New US Stock Market Sector Rotation Pattern on September 23, 2026

After months of AI hype, the US stock market on September 23, 2026, showed a clear sector rotation pattern. As the AI sector cooled, defensive sectors began to rise, with significant changes in capital flows. This shift not only reflects the market's re-evaluation of economic prospects but also provides new layout opportunities for Asian investors. This article will deeply analyze the driving factors, market performance, and future trends of the current US stock sector rotation, providing professional references for investors.

1. AI Sector Cooling: From Valuation Bubble to Rational Regression

On September 23, 2026, the most significant change in the US stock market was the collective pullback of AI-related stocks. The Nasdaq index, dominated by tech stocks, performed relatively weakly that day, while traditional defensive sectors strengthened against the trend. This shift was not accidental but a rational correction of the market's overvaluation of the AI sector and overly optimistic profit expectations.

In the past few months, AI concept stocks experienced a wild surge, with some companies' stock prices doubling or even multiplying several times in a short period. However, as the market gradually realized that the commercialization process of AI technology is slower than expected, and the profitability of related companies has not yet met market expectations, investors began to re-evaluate the value of these stocks. Especially those companies that rely purely on the AI concept without actual profit support, performed particularly obviously in the market adjustment on September 23.

From a technical perspective, the cooling of the AI sector also reflects changes in market risk appetite. When investors feel uncertain about economic prospects, they tend to reduce allocations to high-risk, high-valuation tech stocks and instead seek more stable investment targets. This shift was fully reflected in the market performance on September 23.

2. Defense Sector Rise: Rising Market Risk-Aversion Sentiment

In sharp contrast to the cooling of the AI sector, defensive sectors performed strongly on September 23. Traditional defensive sectors such as utilities, consumer staples, and healthcare generally rose, becoming the highlights of the day's market. This phenomenon indicates that market risk-aversion sentiment is rising, and investors are beginning to seek assets that can withstand economic uncertainty.

The rise of the defense sector has several important reasons. First, as concerns about the slowdown in global economic growth intensify, investors are more inclined to hold stocks that perform relatively stably during economic downturns. Utility and consumer staple companies usually have stable cash flows and lower volatility, so they are more favored during market turmoil.

Second, changes in the Federal Reserve's monetary policy are also important factors driving the rise of defensive sectors. Although the market expects the Fed may cut rates in September, the uncertainty about the magnitude and timing of the rate cut has increased market volatility. In this case, the stability of defensive stocks is particularly important.

In addition, the increase in geopolitical risks also prompts investors to turn to defensive sectors. The global geopolitical situation in 2026 is complex and volatile, and investors seek industries that are not affected or less affected by geopolitical factors, a characteristic that defensive sectors usually possess.

3. Capital Flow Analysis: The Shift from Growth to Value

The market performance on September 23 clearly reflected changes in capital flows. According to market data, a large amount of capital flowed out of AI and tech stocks and into defensive sectors that day. This capital rotation was not only reflected in the day's trading but also in longer-term trends.

From the performance of industry ETFs, tech ETFs generally fell on September 23, while defensive ETFs such as utilities and consumer staples rose. This difference indicates that investors are reallocating assets, shifting from overvalued growth stocks to relatively reasonably valued defensive stocks.

It is worth noting that this change in capital flows does not mean the long-term investment value of AI and tech stocks has disappeared. On the contrary, this may be an adjustment process that allows the market to return to rationality and provides better investment opportunities for truly capable tech companies. For Asian investors, this shift means a need to focus more on company fundamentals and profitability rather than just chasing concepts.

4. Market Technical Analysis: Nasdaq's High-Level Consolidation Signal

From a technical analysis perspective, the market performance on September 23 also sent an important signal. The Nasdaq index showed consolidation at a high level, and technical indicators suggest the market may enter an adjustment phase. This signal is of great significance for investors to judge market trends.

Technical analysis shows that the Nasdaq faces resistance around 24,000 points, with support around 23,000 points. If the index can hold the support level, it may mean there is still room for the market to rise; but if it breaks below the support level, it may trigger a larger adjustment. Therefore, investors need to closely monitor the technical trend of the Nasdaq and adjust their investment strategies in a timely manner.

At the same time, changes in trading volume are also important technical indicators. On September 23, market trading volume increased compared to previous days, indicating higher investor participation and increased market volatility. In this case, investors need to be more cautious and avoid blindly chasing gains and selling at lows.

5. Asian Investor Layout Strategy: Balance and Diversification

Facing the new pattern of sector rotation presented by the market on September 23, Asian investors need to adjust their investment strategies to achieve balance and diversification. Here are some suggestions:

Maintain Balanced Allocation: Do not concentrate all funds in a single sector, but maintain balance between AI, defense, and traditional industries. This can provide relatively stable returns in different market environments.
Focus on Fundamentals: In the context of the AI sector cooling, investors should pay more attention to company fundamentals, choosing companies with actual profitability and competitive advantages rather than just chasing concepts.
Utilize Volatility Opportunities: Market volatility often brings investment opportunities. Asian investors can take advantage of the Nasdaq's adjustment to buy quality stocks at low prices, especially high-quality AI companies that have been unduly sold.
Diversify Investments: Not only diversify across different sectors but also across different regions and asset classes. This can reduce risks from a single market or asset class.
Long-Term Perspective: Although short-term market volatility is intense, investors should maintain a long-term perspective and not let short-term fluctuations affect investment decisions. The development trend of AI technology will not change due to short-term adjustments, and high-quality companies will eventually gain market recognition.

6. Future Outlook: Sector Rotation Will Continue

Looking ahead, the sector rotation in the US stock market may continue. As economic data changes and the Fed's policy adjusts, different sectors will show different performances. For Asian investors, understanding the logic behind this rotation and adjusting the investment portfolio in a timely manner is the key to long-term success.

In the long run, AI technology will still be an important force driving economic growth, but the market will pay more attention to its practical applications and profitability. At the same time, defensive sectors will continue to play a stabilizing role in the context of increasing economic uncertainty. Therefore, investors need to find a balance between growth and value to achieve long-term asset appreciation.

7. Conclusion

The performance of the US stock market on September 23, 2026, clearly reflected the new pattern of sector rotation: the AI sector cooled, and the defense sector rose. This change is a rational adjustment of the market to economic prospects and company valuations, providing new layout opportunities for Asian investors. By maintaining balanced allocation, focusing on fundamentals, utilizing volatility opportunities, diversifying investments, and maintaining a long-term perspective, investors can achieve asset preservation and appreciation in a changing market environment. As the market continues to develop, understanding the driving factors and trends of sector rotation will become the key for Asian investors to succeed in the US market.