US stock futures declined on Wednesday as Brent crude surged above $100 per barrel, extending losses from Tuesday's session. The Dow Jones Industrial Average futures fell 331 points, or 0.6%, while S&P 500 futures dropped 0.4% and NASDAQ-100 futures slipped 0.5%. The sell-off followed Tuesday's losses, with the Dow sliding 1.2% and the S&P 500 declining 0.6%.

Oil prices rallied over 2% amid heightened tensions between the United States and Iran, raising concerns about Middle East energy supplies and shipping through the Strait of Hormuz. Kara Murphy of Kestra Investment Management called the move "a little bit of a speed bump," noting investors are focusing on market risks amid fewer earnings reports. Treasury yields rose, with the 10-year US Treasury yield briefly exceeding 4.8%, as higher oil prices renewed inflation worries.

Markets await two key inflation reports this week—the US Producer Price Index on Thursday and the Consumer Price Index on Friday—before the Federal Reserve’s September policy meeting. Traders currently see about a 60% probability of a 25-basis-point rate hike. European and Asian markets also weakened, with the Stoxx 600 dropping 0.7% and Japan's Nikkei 225 falling 0.19%.

Volatility remains low ahead of November midterm elections and further US-Iran developments.