ToplineConocoPhillips plans to buy fellow American energy giant Marathon Oil in an all-stock deal worth a total of $22.5 billion, the companies announced Wednesday, marking the latest in a string of multibillion-dollar mergers and acquisitions deals in the energy industry. A ConocoPhillips oil field in Alaska in 2019.The Washington Post via Getty Images Key FactsThe all-stock deal values Marathon Oil at $17.1 billion, knocking off the $5.4 billion in debt included in the total transaction value for the Hous ...