Pioneer Natural Resources Company, headquartered in Irving, Texas, is engaged in hydrocarbon exploration. It operates in the Cline Shale, which is part of the Spraberry Trend of the Permian Basin, where the company is the largest acreage holder. Pioneer is presently undergoing an acquisition by ExxonMobil, which in October 2023 agreed to acquire the company in the largest merger in the energy industry in 20 years; closing is expected in the first half of 2024.