Chicago investor Eric Lefkofsky, cofounder and 30% owner of the fastest-growing company ever, Web phenom Groupon, has made the Forbes 400 Billionaires List. Groupon, which sends out daily coupons to its users about deep discounts on products and services, was launched in 2008 and employs more than 300 people at its Chicago headquarters. His venture fund cofounded with Brad Keywell, named

, has stakes in 11 companies, including two now public ones: Innerworkings (NASDAQ:

) and Echo Global Logistics (Nasdaq:

). As for being outed as an almost-billionaire: "It's a good thing and a bad thing." says Lefkofsky. Andrew Mason, the founder of Groupon, and also

, has managed one of the largest venture capital deals in the city of Chicago, and as of the August 2010 issue of

, Groupon is valued at $1.35 billion. Eric Lefkofsky is worth an estimated $750 million, according to

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