Williams closed on its acquisition of MountainWest Pipelines Holding Co., previously announced on Dec. 15, according to a press release on Feb. 14.

The company purchased the interstate natural gas pipeline systems from Southwest Gas Holdings Inc. for a total enterprise value of $1.5 billion - $1.07 billion cash, along with $0.43 billion of assumed debt.

"This acquisition enhances our position in the western U.S. and is complementary to our current footprint, providing us with infrastructure for natural gas deliveries across key demand markets," Williams president and CEO Alan Armstrong commented in the release.

Through the acquisition, Williams adds to its "infrastructure network and increases its business mix of FERC-regulated natural gas transmission and storage" with the addition of 2,000 miles of pipeline systems holding approximately 8 Bcf/d of transmission capacity spanning Utah, Wyoming and Colorado.

TD Securities and J.P. Morgan served as Williams' co-financial advisers, while Moelis & Co. and Lazard Freres & Co. LLC served as Southwest Gas Holdings' co-financial advisers. Davis Polk & Wardwell LLP provided representation to Williams, while Morrison & Foerster LLP represented Southwest.

"With the acquisition now complete, we look forward to welcoming MountainWest employees to Williams and bringing value to our shareholders by delivering safe and reliable services to both Williams and MountainWest customers as we increase the utilization of our existing large scale platforms," Armstrong continued.