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Biggest Companies Run by Women

CEO: Marissa Mayer
Company value: $18.895 billion

Marissa Mayer made headlinesearlier this year when she jumped from Google to become president and CEO of Yahoo! at age 37, making her the youngest CEO of a Fortune 500 company. The same day, she announced that she was pregnant — another first for the Fortune 500. Mayer is the Internet corporation’s fourth CEO since 2007.