US stock indexes fell Monday as higher oil prices intensified inflation concerns and reinforced expectations of an incoming Federal Reserve rate hike. The S&P 500 and Nasdaq 100 each declined 0.3%, while the Dow dropped more than 0.5%. Oil wholesale prices and related products gained after the US and Iran exchanged fresh strikes, following signals from both sides that tankers and vessels could face blockades in the Persian Gulf. The developments prolonged the suspension of exports from the region, pushed yields higher across the curve and pressured credit-sensitive sectors. Microsoft, Alphabet and Amazon each fell more than 1%, while Citi, Morgan Stanley and Amex each lost 1%. Nvidia was flat after announcing a $3.5 billion stake in MediaTek, increasing its net exposure to global chip production and AI infrastructure. Broadcom was also flat ahead of earnings this week.