Also, some locations are bogus. Accenture is incorporated in Bermuda for tax purposes, but the actual work is done in many major cities. IBM, though the headquarters are in NY, has major offices in Silicon Valley.
IBM has major offices of comparable size in Austin, Raleigh, and several international locations, as well. I would say the proportion of their Silicon Valley presence is insignificant. They're probably to big and historic to localize, in any case.
