Energy stocks were lower Monday afternoon, with the NYSE Energy Sector Index falling 1.2% and the State Street Energy Select Sector SPDR ETF (XLE) shedding 1.1%.

The Philadelphia Oil Service Sector Index was down 1.1%, and the Dow Jones US Utilities Index was fractionally lower.

Crude oil prices fell after US President Donald Trump said talks with Iran were set to begin Monday after he called off a planned military strike against the Gulf nation. Over the weekend, Trump said negotiations with Iran would begin Monday, without revealing the venue or participants, news outlets reported. In a social media post, Trump said he had called off a planned attack against Iran after being asked by Tehran and other Middle Eastern countries because the "perimeters of a deal has been agreed to."

Front-month West Texas Intermediate crude oil fell 5.6% to $79.97 a barrel, and the global benchmark Brent crude contract dropped 4.6% to $83.85 a barrel. Henry Hub natural gas futures rose 0.5% to $2.76 per 1 million BTU.

In corporate news, Shell (SHEL) said Monday it has agreed to sell its European onshore renewables portfolio to Total Energies (TTE). Shell was down 0.8%, and Total Energies eased 0.4%.