ExxonMobil and Pioneer Natural Resources logos are seen in this illustration taken, October 8, 2023. Pioneer shares closed at $237.41 on Tuesday, having risen 11% since the first reports of a deal surfaced last Thursday. Exxon declined to comment on "market speculation," while Pioneer did not immediately respond to a request for comment. It is the third-largest oil producer in the Permian basin, after Chevron Corp (CVX.N) and ConocoPhillips (COP.N), with rock-bottom production costs averaging about $10.50 per barrel of oil and gas. Under CEO Scott Sheffield, the oil producer grew through rapid-fire purchases, including multi-billion dollar deals in 2021 for DoublePoint Energy and Parsley Energy.

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Persons: Dado Ruvic, Darren Woods, Scott Sheffield, Exxon's, Shubhendu, Anirban Sen, Sabrina Valle, Gary McWilliams, Rashmi Aich, Jamie Freed Organizations: ExxonMobil, Pioneer, REUTERS, Exxon Mobil, Natural Resources, Exxon, Mobil Oil, Antitrust, Reuters, Exxon socked, Chevron Corp, ConocoPhillips, DoublePoint Energy, Parsley Energy, BG Group, Bloomberg News, Denbury Inc, Denbury, Shubhendu Deshmukh, Thomson Locations: HOUSTON, Ukraine, U.S, Bengaluru, New York, Houston