The S&P 500 closed lower on Monday as renewed selling pressure in chip stocks outweighed the positive impact from falling oil prices. NVIDIA fell for a seventh consecutive session, marking its longest losing streak since 2022. While the company's upcoming earnings report this week is expected to reaffirm its dominant industry position, reports that servers equipped with NVIDIA's AI chips could see price increases of more than 15% have intensified concerns within the semiconductor sector.

The ETF tracking memory chip stocks tumbled roughly 6% on the day. Meanwhile, US Treasury Secretary Bessent announced on Monday the launch of an "unprecedented" campaign aimed at isolating Iran, warning that any nation continuing to conduct business with Tehran could face US economic penalties. Additionally, there are reports suggesting the Treasury Department may utilize a portion of its cash reserves to buy back higher-yielding, older debt. Bessent did not signal any further shifts in the government's debt management approach on Monday.

Investors are also awaiting remarks from Federal Reserve Chair Warsh, scheduled for Friday at the central bank's annual symposium in Jackson Hole, Wyoming, hoping for greater clarity on how the Fed intends to tackle persistent inflation. Chris Larkin of Morgan Stanley's E*Trade noted that the details of US economic sanctions on Iran, the Treasury's efforts to push down long-term yields, and upcoming economic data could significantly influence market sentiment, but earnings from tech giants like NVIDIA are likely to have a major impact on market momentum.

The S&P 500 closed down 0.28% at 7,652.86 points, while the Dow Jones Industrial Average rose 0.26% to 53,417.16 points. The Nasdaq Composite fell 0.76% to 25,980.19 points, and the Nasdaq 100 slipped 0.97% to 29,023.18 points. The Russell 2000 index declined 0.76% to 2,995.08 points.