(Bloomberg) -- Exxon Mobil Corp. named Dan Ammann as head of its upstream oil and gas business, putting its low carbon president in charge of its most profitable division. Most Read from BloombergAs Wars Rage, Cities Face a Dark New Era of Urban DestructionRiyadh Metro Partially Opens in Bid to Ease City’s Traffic JamsAmmann will replace Liam Mallon, who on Feb. 1 retires after 34 years with Exxon, the Spring, Texas-based company said in a statement. Ammann joined Exxon in 2022, making him a rel