ExxonMobil (XOM) agreed to buy shale driller Pioneer Natural Resources (PXD) in an all-stock deal for $59.5 billion or $253 per share, the companies jointly announced on Wednesday.

At that price, it’s the biggest deal for the oil giant since Exxon bought Mobil for $81 billion in the late 1990s and is ✃expected to be finalized in 🍸the first half of 2024. Pioneer shareholders will receive 2.3 shares of ExxonMobil for every Pioneer share.

Pioneer is the third-largest producer of oil in the Permian Basin, which stretches across parts of Texas and New Mexico, and the move could help ExxonMobil cement its position as the dominant producer in the region, with ExxonMobi's production volume expected to more than double to 1.3 million barrels per day once the deal is finalized.

The companies also claimed that by combining forces, they co꧅uld generate double-digit returns and a lower environmental impact.

ExxonMobil shares were♛ down 4% in early trading as of 11 a.m. Eastern Time Wednesday following the news, while shares of Pioneer were up less than 1%.