Exxon Mobil (NYSE:XOM) is expected to announce its acquisition of U.S. rival Pioneer Natural Resources (NYSE:PXD) for approximately $60 billion, according to several media reports.

PXD shares rose 2.4% on the news, while Exxon stock fell 0.5%.

“We expect PXD to have a positive reaction vs. peers,” analysts at Roth MKM wrote in a note.

This strategic move would position Exxon as the dominant player in the largest U.S. oilfield and secure a decade of cost-effective production. The deal is set to be primarily a stock transaction with Exxon offering more than $250 per share for Pioneer, according to reports in Reuters and Bloomberg.

If realized, this acquisition would be the most significant corporate deal of the year and Exxon’s most substantial since its $81B acquisition of Mobil Oil in 1998.

The merger would leave four of the largest U.S. oil companies in control of a significant portion of the Permian Basin shale field and its extensive oilfield infrastructure.

“We maintain that Pioneer is a willing seller, given the imminent retirement of founder/CEO Scott Sheffield. This final transaction would be the last of many savvy deals for him since the advent of horizontal drilling in the Midland Basin in the early 2010s, which established Pioneer as one of the most core inventory-rich E&Ps in the most prolific U.S. shale oil basin,” analysts at KeyBanc wrote.

“We believe a price closer to $250 than $278/share may be better received by XOM shareholders,” the analysts added.