Headquarters: San Antonio
Revenue: $138.3 billion
Profit: $2.1 billion
2012 rank: 12
Valero has 16 petroleum refineries and employs some 22,000 people in the US and abroad. It is the largest independent oil refiner in the US, and last month a plan was approved to spin off its retail business, CST Brands, into a separate company. The news sent Valero’s share price climbing.