EQT Corp. agreed Thursday to acquire Alta Resources Development LLC in a $2.9 billion deal that would add another 300,000 net Marcellus Shale acres and give it entry into Northeast Pennsylvania. 

The nation’s largest natural gas producer said the acquisition would push its volumes to 5.6 Bcfe/d from 4.6 Bcfe/d. Once completed, the company would hold 1.6 million net Marcellus acres. Management also said the assets would boost free cash flow (FCF), accelerate deleveraging targets and ultimately return the company to investment grade metrics. 

“This Alta asset is really unique,” said CEO Toby Rice. “It’s derisked. There’s thousands of wells drilled in the area. It’s high margin with the midstream asset and the mineral structure.”

EQT primarily operates in...