Exxon Mobil, the world's largest privately held oil and petrochemical company and a global leader in oil and gas, began in 1882 as Standard Oil Company, founded by John D. Rockefeller, and is headquartered in Avon, Texas. It is headquartered in Avon, Texas, USA. ExxonMobil is also the world's first company with a market capitalization of more than $400 billion, and was ranked first in the 2006 Top 500.