14. Marissa Mayer
CEO
Yahoo
2011 rank: 38
Age: 37
Yahoo
2011 rank: 38
Age: 37
Mayer was in her 13th year at Google (and somewhat marginalized) when she leaped to the top job at Yahoo in July. Despite the web company's woes, it boasts $5 billion in revenue, $18 billion in market cap, and 700 million users -- a significant platform for this engineer to build on. And though she has much to prove, Mayer has already shown she can wield power by securing the Yahoo job on her own terms. (Her first child is due Oct. 7.)
From the October 8, 2012 issue
Fortune's Most Powerful Women
For the latest on the most influential women in business, philanthropy, government, and the arts, like us on Facebook. How we pick the Power 50
The list is compiled by FORTUNE editors, who consider four criteria: the size and importance of the woman's business in the global economy, the health and direction of the business, the arc of the woman's career (resume and runway ahead), and societal and cultural influence.
