Strictly speaking, the Fortune 500 is a listing compiled by Fortune magazine raking the top 500 public corporations of the US as measured by their gross income. Although Silicon Valley is usually described as a boys' club where female CEOs are few and far between, the two largest Fortune 500 companies run by women are both in the tech industry: Hewlett-Packard, which ranked tenth on Fortune's listing and named Meg Whitman CEO final fall, and IBM, which ranked 19th and has been run by Ginni Rometty since January.
