No. 50: ExxonMobil

Industry: Energy
Sales: $358.6 billion
Net Income: $40.6 billion

ExxonMobil broke its own profit record on Feb. 1 as it reported the highest quarterly and annual profits ever for a U.S. company. Exxon earned $40.6 billion in 2007. Meanwhile, the company bought back $28 billion in shares. Still, CEO Rex Tillerson faces major obstacles to oil and gas production, including the maturation of oil fields, rising resource nationalism in countries like Venezuela, and higher costs for rigs, drilling, and refining. Just to keep production flowing at current levels, Exxon will hike its capital spending by $5 billion this year. But with oil above $100 a barrel, 2008 will likely be another gusher.