Mark Vadon was born in United States. Mark Vadon is new to the Forbes Billionaires list but he has been at the online retailing game for a while. A Harvard alum with an MBA from Stanford, he spent six years with Bain & Company before founding online jewelry retailer Blue Nile in 1999. He took the company public in 2004, and by 2010 he had launched a new online retailer, Zulily. The Seattle-based company offers daily merchandise deals geared toward mothers and their children. Think lots of smiling toddlers and babies modeling colorful outfits at a deep discount. It turned out to be Vadon's billion-dollar idea. Zulily stock soared after its IPO in November 2013 and is now worth nearly $5 billion. The company made $700 million in sales in 2013, more than double sales for 2012.