Energy stocks slumped Thursday afternoon with the NYSE Energy Sector Index dropping 5.4% and the Energy Select Sector SPDR Fund (XLE) down 6.8%.

The Philadelphia Oil Service Sector Index tumbled 11%, and the Dow Jones US Utilities Index rose 0.2%.

West Texas Intermediate crude oil plunged 7.1% to $66.63 a barrel, and global benchmark Brent dropped 6.4% to $70.12 a barrel.

US natural gas stocks rose by 29 billion cubic feet in the week ended Friday, topping the 27 billion increase expected in a survey compiled by Bloomberg and following a gain of 37 billion in the previous week.

Henry Hub natural gas futures rose 2.1% to $4.14 per 1 million BTU.

In corporate news, Exxon Mobil (XOM) shares fell 4% after Mizuho cut its price target to $129 from $131 while keeping its neutral rating.

Venture Global (VG) received approval from the Federal Energy Regulatory Commission to start service on the remaining facilities at the Calcasieu Pass LNG Terminal in Louisiana, Reuters reported. Venture shares 7.8%.

Alliant Energy (LNT) kept its quarterly dividend at $0.5075 a share, payable May 15 to investors of record April 30. The stock rose 1%.