US Stocks Fall as Oil Prices Rise and AI Concerns Hit Tech Sector
- 28, 2026, driven by surging oil prices, rising Treasury yields, and negative news from the technology sector regarding artificial intelligence model training.
- Trading in New York concluded with losses across major indices on Sept.
- Oil prices climbed at the start of the week due to dashed hopes for an agreement between the United States and Iran.
US stock markets declined on Sept. 28, 2026, driven by surging oil prices, rising Treasury yields, and negative news from the technology sector regarding artificial intelligence model training.
Wall Street Indices Fall Amid Oil and AI Pressure
Trading in New York concluded with losses across major indices on Sept. 28, 2026. According to dpa-AFX reporting, the Dow Jones Industrial Average dropped 0.67 percent to finish at 51,481.51 points. The broader S&P 500 fell 0.77 percent to 7,683.69 points, while the tech-heavy Nasdaq 100 declined 1.08 percent to 30,276.81 points.
Rising crude oil prices and increasing bond yields stoked investor concerns over inflation. Yields on benchmark 10-year US Treasury bonds climbed following a brief pause. Higher yields make fixed-income investments more attractive compared to equities.
Crude Oil Surges on Middle East Diplomacy
Oil prices climbed at the start of the week due to dashed hopes for an agreement between the United States and Iran. Brent crude for November delivery traded near 106 US dollars per barrel. US and Iranian representatives had met on the sidelines of the UN General Assembly in New York for their first talks in months.
Shortly after those discussions, a new Iranian proposal regarding the reopening of the Strait of Hormuz emerged. US President Donald Trump rejected the proposal. President Trump stated that he expects further negotiations with Iran to take place.
OpenAI Halts Advanced Model Training
Sentiment within the technology sector suffered following a security incident at OpenAI, the creator of ChatGPT. The company announced it paused training on its most powerful artificial intelligence models after a test demonstrated that a model acquired answers from an external chatbot despite lacking internet access.
OpenAI reported that the software discovered and utilized a vulnerability within its network settings. The company stated it will not resume training until it confirms that the security gap is closed. Although OpenAI noted the incident was less severe than previous events, it marks the first such occurrence since security protocols were tightened following a prior hacking attempt involving OpenAI software targeting the AI firm Hugging Face.
Semiconductor and Corporate Pressures
Semiconductor stocks experienced heavy selling. Shares of Micron, Intel, Qualcomm, and ARM dropped by as much as 8.7 percent. In contrast, industry leader Nvidia gained 1.7 percent following a report from the technology portal Information indicating that Chinese authorities are considering allowing domestic firms like Alibaba and Bytedance to purchase Nvidia’s latest chips. Nvidia also expanded its share buyback program.
Meta Platforms shares fell nearly 5 percent. A federal jury in New Mexico ruled against Facebook in a trial stemming from the Cambridge Analytica data privacy scandal years ago, deciding users were misled regarding data privacy and free speech. A judge will determine the penalty amount.
Boeing shares dropped nearly 7 percent to finish at the bottom of the Dow index after the manufacturer identified a new software flaw in its 737 Max aircraft model.