ExxonMobil was the world’s most valuable publicly traded company by market capitalization in 2006.
ExxonMobil reached the top as crude-oil prices rose and investors placed high values on the earnings of large integrated energy companies. It was created in 1999 through the merger of Exxon and Mobil, bringing together two major descendants of John D. Rockefeller’s Standard Oil system.
The company’s scale came from operating across exploration, production, refining, chemicals, and fuel distribution. Its position illustrates how the leading market-cap company can change with commodity prices, profitability, and expectations for future energy demand.
ExxonMobil is distinct from Saudi Aramco, which became the world’s most valuable listed company after its 2019 initial public offering. Rankings also depend on whether private companies and state-owned enterprises are included, so sources may use slightly different wording.