Unocal Corporation
As the pipeline's flow has diminished, its ownership has fluctuated. In 2000, as Exxon and Mobil merged, Mobil sold its 3.1% stake in the pipeline to Williams Companies as a condition of the merger. Three years later, Williams sold that share to Koch Alaska Pipeline Company, a subsidiary of Koch Industries. Nine years later, Koch announced it would sell its share to the other pipeline owners, as did Unocal Corporation, which had held a small ownership share since 1970. In 2019, BP announced plans to sell its Alaska operations to Hilcorp Energy Company. The deal, which closed in 2020, included BP's 49.1% ownership share of the Trans-Alaska Pipeline System.