Exxonmobil and shale oil giant Pioneer Natural Resources issued a joint statement on October 11, announcing a definitive agreement to merge.

The acquisition is an all-stock transaction valued at $59.5 billion, or $253 per share, based on ExxonMobil's Oct. 5 closing price, according to the statement. Under the terms of the agreement, Vanguard shareholders will receive 2.3234 shares of Exxon Mobil for each Pioneer share they own at the time of closing. Including net debt, the transaction has an implied total enterprise value of approximately $64.5 billion.