Exxon and Mobil merged to create ExxonMobil in 1999.
The merger reunited two companies whose histories traced back to Standard Oil, the oil trust broken up by the United States Supreme Court in 1911. One successor became Standard Oil of New Jersey, later known as Exxon, while another became Standard Oil of New York, later known as Mobil.
Exxon and Mobil announced their agreement in 1998, and the transaction was completed in November 1999. The combined company became one of the world’s largest publicly traded energy businesses, operating across oil exploration, production, refining, chemicals, and fuel marketing.
The merger year is sometimes confused with the year ExxonMobil adopted later corporate branding or with Standard Oil’s 1911 breakup. Those are different milestones. ExxonMobil’s formation specifically refers to the completed combination of Exxon Corporation and Mobil Corporation in 1999.