4. Uber

Cars on call

Travis Kalanick, co-founder and CEO of Uber Technologies
David Paul Morris | Bloomberg | Getty Images
Travis Kalanick, co-founder and CEO of Uber Technologies

Founders: Travis Kalanick, Garrett Camp
Date launched: 2009
Funding: $4.9 billion
Industries disrupted: Public transportation, taxi and limousine services

Life isn't always so kind in the sharing economy. Just ask the folks at Uber. For all the press this San Francisco-based company gets for its mobile app that lets users hail a car with a few taps on the screen, there seems to be just as much news detailing the battles the company has with regulators, taxi and limousine commissions and sometimes even its own drivers and customers.

Read MoreFULL LIST: 2015 DISRUPTOR 50

Even so, the company, launched by serial entrepreneurs Travis Kalanick—also CEO—and Garrett Camp is growing quickly. Before starting Uber, Kalanick had just sold his content-delivery company—Red Swoosh—to Akamai Technologies. Camp had sold StumbleUpon, his Web discovery engine, to eBay. Since its founding, Uber has expanded to 300 cities across nearly 60 countries. In the past six years, the company—currently valued at $50 billion—has raised a whopping $4.9 billion in equity financing from such venture heavyweights as Google Ventures and Kleiner Perkins Caufield & Byers.

Now the company is expanding its UberPool service, a ride-sharing initiative that lets multiple passengers heading to the same place—say, the airport—get together and split the cost. It also wants to further expand its European operations in the year ahead in Spain and France, a goal that will likely cost some serious marketing money as the company looks to overcome strong opposition from taxi and limousine services throughout the European Union.

Of course, the question on the minds of most investors is when the company will go public. Uber isn't saying, but given how much money it's been able to raise so far, perhaps the more important question is, Does it have to?

"Folks want to sit in the backseat ... and if you can make the economics work so that it's actually more economical to push a button and get a ride than it is to own a car, then a lot of people are gonna do it." -Travis Kalanick, Uber CEO

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