Financial service companies such as Citigroup are big players. Citigroup (2006 figures from Fortune 500) had revenues of over $131 billion, and a profit of $24.6 billion.

These companies make the oil majors look like pikers as far as profits are concerned.

Exxon Mobil- $340 billion. Profit- $36 billion, or 11 cents/dollar of revenue.
Citicorp- $131 billion. Profit $24.6 billion, or 19 cents/dollar revenue. (2007 revenue $159 billion)
Bank of America- $84 billion. Profit $16.6 billion, or c. 20 cents/dollar.
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Microsoft- $40 billion. Profit $12.2 billion, or over 30
cents/dollar revenue. - Hey, not bad for a mess of software! Or at least there are some out there who consider it a mess.

http://money.cnn.com/magazines/fortune500/full list/index.html