Exxon Mobil is buying Pioneer Natural Resources in an all-stock deal valued at $59.5 billion, its largest buyout since acquiring Mobil two decades ago, creating a colossal fracking operator in West Texas.

The transaction’s value, including debt, is about $64.5 billion.

Pioneer shareholders will receive 2.3234 shares of Exxon Mobil for each Pioneer share they own.

Exxon purchased XTO Energy in 2009 for approximately $36 billion. In the late 1990s, the merger between Exxon and Mobil totaled more than $80 billion.

Exxon has been flush with cash. The company posted record annual profits in 2022, bringing in $55.7 billion in annual profits, exceeding its previous record of $45.22 billion in 2008.

Exxon has been using some of that cash on acquisitions. In July the company announced that it was buying pipeline operator Denbury in an all-stock deal valued at $4.9 billion.

Pioneer Natural has been making similar moves. In 2020 the company said it was buying Parsley Energy in an all-stock deal valued at approximately $4.5 billion. It then purchased DoublePoint Energy in a cash-and-stock deal worth about $6.4 billion in 2021.

Both companies’ boards have approved the transaction, which is expected to close in the first half of next year. It still needs approval from Pioneer shareholders.