As has been speculated for months, ExxonMobil on Wednesday agreed to buy Permian Basin pure-play Pioneer Natural Resources Co. in a mega all-stock transaction valued at $59.5 billion. The implied total enterprise value, including net debt, is estimated at $64.5 billion.

“Pioneer is a clear leader in the Permian, with a unique asset base and people with deep industry knowledge,” ExxonMobil CEO Darren Woods said. “The combined capabilities of our two companies will provide long-term value creation well in excess of what either company is capable of doing on a standalone basis. Their tier-one acreage is highly contiguous, allowing for greater opportunities to deploy our technologies, delivering operating and capital efficiency as well as significantly increasing...