40 under 40

Our 2013 edition of the list features young hotshots who are rocking businesses as diverse as air travel, natural gas, and genetic coding, as well as—if you can believe it— government.

1. Marissa Mayer

40u40 marissa mayer
  • Age: 38
  • Title: President and CEO
  • Company: Yahoo

"Get in over your head" is Mayer's guideline. It's this career philosophy that has fueled her turnaround effort at Yahoo since she joined the company as CEO last year, at age 37, after more than a decade at Google. Mayer has replaced key Yahoo executives, made a string of acquisitions (22 so far, including Tumblr—see No. 24—for $1.1 billion), and overhauled Yahoo's culture and HR rules (its logo too) in an effort to make the company innovative again. Revenue growth is her challenge, but investors like what our newly crowned No. 1 has done: The stock is up 86% since she came in.

  @FortuneMagazine - Last updated September 30 2013 03:41 PM ET
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