10 of 40
10. Marc Andreessen
Founder, Netscape, Opsware, Ning, Andreessen Horowitz
Age: 38
Marital status: Married
Highest Education: Bachelor's degree

The Wisconsin native majored in engineering because he had read engineers had the highest starting income among college graduates. The bet paid off: Five years out of the University of Illinois, Andreessen sold his first startup, Netscape Communications, to AOL for $4.2 billion.

Since then he's started two companies: software firm OpsWare (sold to HP in 2007 for $1.6 billion) and social-networking platform Ning. In July the eBay, Facebook, and HP board member launched a $300 million venture capital fund.

Stress reliever: "Hard alcohol."

NEXT: Lorenzo Simonelli

Last updated March 26 2010: 10:26 AM ET
Email | Print | Share  |  RSS
google my aol my msn my yahoo! netvibes
Paste this link into your favorite RSS desktop reader
See all CNNMoney.com RSS FEEDS (close)
Note: To be eligible for Fortune's 40 under 40, candidates had to be 39 or younger on Nov. 1, 2009.
List compiled by Alyssa Abkowitz, Maha Atal, Katie Benner, Scott Cendrowski, Lawrence Delevigne, Telis Demos, Jessi Hempel, Suzanne Kapner, Mina Kimes, Beth Kowitt, Jessica Shambora, Richard Siklos, Kim Thai, Christopher Tkaczyk and Jia Lynn Yang. Research by Marilyn Adamo and Doris Burke.
20 highest paid Which young executives at public companies raked it in - and how much did they earn? More
They're hiring! These stars on our list have great jobs to fill. What are they looking for and how can you impress them? More
'My biggest mistake' The folks on our list may be remarkable, but they're not perfect. Here are the decisions they most regret in their careers. More