Spencer Rascoff
40u40 spencer rascoff
Age: 36
Company: Zillow

Zillow CEO Spencer Rascoff has built a career digitizing businesses. He co-founded online travel site Howire.com in 1999, then continued working for Expedia when it bought Hotwire in 2003. In 2005, he switched to real estate, becoming one of the founding employees of Zillow. He was CEO by 2010.

The most attractive part of Zillow (Z), which is an online home and real estate marketplace, is probably its mobile app, which allows its 37 million active users to access information on about 110 million homes while on the go.

Following the company's IPO last year, the firm has hired about 275 people to keep up with its growth.

  @FortuneMagazine - Last updated October 11 2012 09:26 AM ET
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