[U.S. stocks before the market] Tariff uncertainty is heating up, and the risk of fluctuations in September increases after continuing to rise in August (2025.09.01)

Tariff ruling raises policy risks, and September starts to be volatile

The U.S. Court of Appeals for the Federal Circuit ruled that most Trump-era tariffs were illegal and maintained the arrangement pending appeal until October 14, putting companies under pressure to keep policies on and off. After the overall U.S. stock market closed red in August, the market was intertwined with the historic off-season effect in September and tariff uncertainty. The pre-market sentiment was on the guidance of inflation and employment data on the path of the economy.

The results of tariff rulings are complex, and the market is highly sensitive to the appeal schedule and content

The court ruled that Trump's tariffs in the name of "reciprocity" and tariffs related to China, Canada and Mexico and based on fentanyl constituted ultra vires, but allowed the current tariffs to remain until mid-October so that the government could appeal to the Supreme Court. For companies, tariffs may be opened and closed as decisions progress, strategic planning costs will rise in the short term, and the stock market will become more sensitive to fluctuations in any legal progress and communication with the White House.

The visibility of corporate operations has declined, and pressure on import, export and manufacturing chains has increased

The discontinuity of tariff policies increases the difficulty of making quotations, procurement and inventory decisions, and has a greater impact on industries with a high proportion of exports and deep cross-border supply chains, including industry, automobiles and electronic hardware. If the pricing transmission time frame is lengthened and the company's gross profit elasticity is limited, investors will pay attention to the extent to which management will adjust the guidance in the upcoming legal and financial updates.

Core inflation rebounds, interest rate expectations rely more on data

The core item of the U.S. personal consumption expenditure price index increased by 2.9% year-on-year in July, in line with expectations but hitting a new high since February, indicating that inflation fell unevenly. The interest rate path has become more sensitive to subsequent data. The market pays attention to the linkage between wage growth, service inflationary stickiness and real consumption strength as clues to judge whether the economy is soft landing or growth is cooling.

The employment report ranks C this week, and data and policy responses are equally concerned.

The August employment report became key after July's poor employment performance triggered government personnel changes. Indicators such as non-agricultural new employment, unemployment rate and average hourly wage were released at 20:30 on Friday in Taiwan time. The data itself and the White House's response both affected risk appetite and interest rate expectations. If the labor market shows a cooling and wage pressure easing, detailed fine-tuning may occur in the inflation trajectory assessment.

August's index closed red, with seasonality and policy noise affecting September

In August, Dow Jones rose more than 3% monthly, the S & P 500 rose nearly 2% monthly, and the Nasdaq rose 1.6% monthly, but September has historically been a challenge for U.S. stocks. The intersecting signals of tariffs and macro data may amplify short-term fluctuations, and investors focus on changes in volume and energy and the relative strength of defensive and cyclical stocks.

China's manufacturing expansion unexpectedly warms up, regional signals support risk appetite

China's manufacturing purchasing managers 'index reported 50.5 in August, higher than the market estimate of 49.7 and hitting a high since March, indicating a moderate expansion of the manufacturing boom and helping alleviate some global demand concerns. China's leaders released a message at the security conference to reject the Cold War mentality and emphasize cooperation, providing limited emotional support against the background of trade tensions, but the implementation of substantive policies remains to be seen.

European stocks weakened last week, with cross-market funds biased towards conservative allocation

The pan-European Stoxx 600 closed down 0.64% last week, with most regional stock markets falling, reflecting investors 'reservations about global trading frictions and growth prospects. With cross-market linkage, U.S. stocks are affected by external risk appetite before the market, and their reactions to unexpected policies and data may be amplified.

News about China and electric vehicles diverge, and U.S. stocks attract attention

Hong Kong stocks Alibaba strengthened due to better-than-expected profits, driving US-listed Alibaba Group Holding(Alibaba, BABA) to increase pre-market attention; BYD weakened due to the decline in profit in the second quarter. The market observed the spillover impact of demand and price competition for electric vehicles on the gross profit of global car manufacturers. The trend of China's ADR is pulled between tariffs and China's domestic demand signals, and the volatility may increase.

Geography and policy signals are intertwined, and cross-border supply chain evaluation is rebalanced

China-India interaction has released the coexistence of cooperation tone and the uncertainty of the US-China game, allowing the logic of supply chain spillover and regional diversification to continue to ferment. If companies strengthen capacity allocation in India and Southeast Asia, short-term transfer costs will increase, and medium-and long-term gross profit margins and delivery stability will affect valuation and repricing.

Federal Reserve governance discussions heat up, central bank independence and policy predictability are under review

President Trump's intention to replace Federal Reserve Board member Lisa Cook has attracted market attention. If the voting structure of the board of directors changes, the impact on the policy framework, financial supervision and market infrastructure cannot be ignored. At this stage, the realization conditions and probability are still uncertain, but the impact of relevant news on the interest rate curve and the sentiment of financial stocks cannot be underestimated.

Pre-market trading is on the sidelines, and futures indices are highly sensitive to unexpected headlines and data

Ahead of the progress of tariff laws and this week's heavy data, the trading sentiment of the three major futures indices is relatively cautious, and the volume, energy and fluctuations may be concentrated on policy news and individual news from large equity stocks. If there is a rapid switch in emotions in the external market, pre-market quotes are prone to amplification.

Focus on three main lines that day to assess short-term risks and rhythm

First, the tariff litigation schedule and the White House's statement that any progress from the legal level to administrative communication may affect risk appetite. Second, forward signs of inflation and employment, including corporate salary and hiring reviews, have an immediate impact on interest rate pricing. Third, the response of Asian and European markets to China manufacturing data and corporate financial reports can serve as a reference for intraday stock rotation in U.S. stocks.

In summary, policy and data uncertainty prevailed at the start of September, with August gains providing a cushion but also raising evaluation pressures. Investors tend to stay on the sidelines until tariff rulings and employment reports are settled, and market volatility can amplify reactions to unexpected news.