ExxonMobil’s pursuit of Pioneer Natural Resources heralds an era of potential megadeals in the US shale oil industry, analysts say, in which the long-fragmented sector is controlled by a handful of larger operators.

The top western oil supermajor was in talks with Pioneer over a potential acquisition, people familiar with the matter said this week. A takeover of Pioneer, which has an enterprise value of $56bn, would be Exxon’s biggest since its landmark merger with Mobil in 1999.

A combined company would also be the undisputed leader in the Permian Basin, the vast field in western Texas and New Mexico that has powered America’s rise to become the world’s largest oil and gas producer. Analysts say a transaction could turbocharge merger and acquisition activity in the US shale patch as other companies seek to match Exxon’s unrivalled scale.