President Donald Trump instructed the Department of Justice to investigate major oil companies for potential price gouging.
The probe follows a significant decline in global crude prices driven by progress in U.S.-Iran peace talks.
Trump alleged on social media that oil companies are failing to lower retail prices in line with crude benchmarks.
Brent crude prices recently dropped toward the $75 to $76 per barrel range.
U.S. retail gasoline prices currently remain above the five-year seasonal average.
The announcement introduces regulatory uncertainty for energy sector investors in ETFs like VDE and XLE.