US equity markets closed mostly lower on Thursday, 8 October, pressured by rising oil prices and escalating tensions in the Middle East. Semiconductor stocks recorded significant losses after a downward revision to revenue estimates for OpenAI.

The S&P 500 fell 0.47% to 7,765.36 points, while the Nasdaq Composite dropped 1.25% to 27,193.34 points. The Dow Jones Industrial Average bucked the trend, advancing 0.10% to 51,231.64 points.

Among the steepest decliners, Intel shed 5.34%, Marvell fell 3.52%, and Nvidia lost 2.94%, as investors grew increasingly concerned about the revenue outlook for OpenAI, the creator of ChatGPT.

According to information published by Bloomberg and the Financial Times, OpenAI may generate annualised revenues of approximately US$50 billion, well below the nearly US$70 billion figure previously cited by some media outlets. The revision deepened doubts about the scale and sustainability of investment in artificial intelligence (AI).

In energy markets, oil prices rose more than 5% at their session peak amid growing Middle East tensions. A statement by US President Donald Trump, indicating that the United States would not strike Iran again before the 3 November midterm elections, helped moderate the advance in crude prices.

Investors continue to assess the sustainability of elevated AI spending, at a time when rising financing costs are placing pressure on corporate investment plans. Matt Maley of Miller Tabak said the market is beginning to show scepticism about the longevity of the current capital expenditure cycle.

On the other side of the debate, Ulrike Hoffmann-Burchardi, Chief Investment Officer at UBS, reiterated confidence in the growth potential of artificial intelligence, arguing that technology-related investments remain a significant driver for equity markets.