Michael Rubin started his business career at age 13, running a ski-tuning shop out of his parents' basement. He went on to open several retail ski shops in New York and Pennsylvania by the time he graduated from high school.

Now 34, Rubin is chief executive of GSI Commerce, a King of Prussia (Pa.)-based e-commerce company with $524.6 million in revenue in the 12 months ended Sept. 30.

Meet the new boss, younger than the old boss. Rubin is one of approximately 140 executives age 40 or younger who are chief executive officers of publicly traded companies around the world, according to data compiled by Capital IQ. Of these, nearly 100 are located within the U.S., while another 40 or so lead companies headquartered in other countries. The youngest, Harry Vafias, CEO of StealthGas in Athens, Greece, is only 28.

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For generations, the corner office has been the domain of experience, occupied in literature and film by crusty old-timers like Ebenezer Scrooge or It's a Wonderful Life's Mr. Potter. In more recent decades, investors grew accustomed to fresher faces, as such young visionaries as Microsoft's Bill Gates and Apple's Steve Jobs helped lead the 1980s personal-computing revolution.

Now, a new generation of 40-and-under CEOs offers proof that today's young entrepreneurs can scale the corporate ladder, too.

Tech Ladder

The tech sector may still be the quickest road to the top. More public-company CEOs age 40 and under lead organizations involved in technology products or services than work in any other industry. These companies range from online travel publisher Travelzoo to semiconductor materials provider Cree and software maker Borland.

A tech background can also help executives in related businesses, such as retail. Michael Soenen, 36-year-old chief of flower seller FTD, recalls becoming CEO of his company's Web division in 1999. "Internet CEOs were young by nature, and the success we were having made me a logical choice," Soenen explains.

"Having run that business successfully, becoming CEO of FTD Inc. was a natural extension for me."

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Many of the youngest CEOs achieved their position by launching their own companies from scratch. "If you really want to be a CEO at a young age, start a company and call yourself a CEO," says David Liu, who recently turned 41 but has been CEO of wedding information Web site The Knot since age 30.

Experience Can't Hurt

Sometimes the hardest part may just be getting started. "You can't wait until you know all the answers," says 36-year-old Taser International CEO Rick Smith, who started his stun-gun operation in a garage at age 23. "You never will. When your gut tells you there's an opportunity there, you have to take it."

Others suggest seeking out a broad range of experiences en route to the corner office. Jonathan Huberman, now 41, became CEO of Zip-disk storage device maker Iomega earlier this year at age 40, following stints in tech, management consulting, venture capital, and hedge funds. "Look for diversity of experiences, because to be a CEO you need to be able to understand and set strategy for every facet of the business," Huberman says.

While it's never easy to be a CEO, for those 40 and under it can be even more challenging. "It changes your life top to bottom," says Jordan Greenhall, 35-year-old chief of digital video compression software maker DivX. "Not as much as having children, but in that same zone."

Ready for Risk

And like having children, CEOs typically say the job is worth any sleepless nights. "I have to say I really love it," says Michael Chasen, 35-year-old head of school software developer Blackboard. "I thrive on the fast pace and excitement in running a fast-growth, successful company."

The people who become CEO at a young age are increasingly unafraid to take risks, notes Peter Cappelli, a management professor at the University of Pennsylvania's Wharton School. "They're willing to look for opportunities to stand out," Cappelli explains. Still, he cautions that bigger appetites for risk may have unwanted consequences, citing the Enron scandal.

Today's young CEOs are likely to have a better understanding of technology and globalization than did the bright up-and-comers of decades past, adds Michael Feiner, a management professor at Columbia University Graduate School of Business and author of The Feiner Points of Leadership. "The biggest challenge is the leading-people piece," Feiner says. "It takes a while for even really smart CEOs to understand it's people first, strategy second. That comes from experience and mistakes, and I don't think there's a shortcut."

Passion Projects

Meanwhile, new CEOs are taking on the mantle at a time of unprecedented turnover. Corner-office job changes this year are on pace to top last year's record 1,322 departures, according to Chicago consulting firm Challenger, Gray & Christmas.

Such big-name companies as Bristol-Myers Squibb, Ford and Viacom were among those making CEO switches in 2006.

Ultimately, a CEO of any age needs to have a passion for the job. "You can have all the products and packaging and scale that you need to perform, but really none of that takes you any place if you don't have the right attitude about the business," says Mariner Kemper, 34-year-old head of Kansas City (Mo.)-based financial services company UMB Financial.

The best CEOs grow into the position because they followed what excited them, not because they set out to become CEOs, adds Mark Vadon, 36-year-old chief of online jewelry retailer Blue Nile.

"Do something that you really love doing," Vadon advises. "If you're not doing something that you really like, you're not going to be that successful at it."

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