Wall Street started the week in the red on Monday as escalating military tensions between the US and Iran rippled through sector performance in opposite directions. Utilities took the hardest hit, while energy stocks were the lone bright spot, riding a wave of surging crude prices tied to fears of supply disruptions in the Strait of Hormuz.

The S&P 500 fell approximately 0.5%, the Dow Jones Industrial Average shed roughly 346 to 348 points (a decline of about 0.65% to 0.7%), and the Nasdaq Composite slipped around 0.3% to 0.5% in early trading.

Oil surges, utilities crater

Energy stocks climbed approximately 1% to 2%, making the group the only gainer on the day. The catalyst was straightforward: Brent crude surged more than 3% to above $90 to $91 per barrel, while West Texas Intermediate gained to around $86.

On the other end of the spectrum, utilities suffered the worst decline of any sector, falling around 1.2% to 1.6%.