On September 15, the US stock market experienced a broad decline, with all major indices closing lower. This downturn was primarily driven by mounting worries within the AI industry regarding the risks associated with developing advanced models, coupled with escalating tensions in the Middle East that propelled energy prices upward. The Philadelphia Semiconductor Index took a significant hit, plummeting nearly 6%, while the tech sector as a whole witnessed a 1.7% drop. Stocks related to the optical communication concept spearheaded the declines, and several prominent tech stocks were also impacted. However, the cybersecurity sector defied the general trend and registered an increase.

The CEO of Anthropic advocated for a deceleration in the development of cutting-edge AI models, a stance that garnered support from several industry leaders. This call for a slowdown raised market concerns about the potential repercussions on the commercialization process of AI and its impact on capital expenditures, thereby exerting downward pressure on related sectors.

Oil prices initially spiked following an attack on Saudi oil pipelines. However, they later relinquished most of their gains after comments from Trump. Ultimately, WTI crude closed up by approximately 1.7%. The surge in energy prices intensified inflation worries, with the market now factoring in a more than 90% likelihood of a 25 basis point interest rate hike by the Federal Reserve this week. Furthermore, the yield on the 10-year US Treasury briefly surpassed 5% before retreating, the US dollar index climbed to a near one-month peak, spot gold closed lower, while Bitcoin bucked the trend and rallied.