The votes—or valuations—are in. Uber, the private-car smartphone platform, is the world's most valuable start-up as of this month, according to data from The Wall Street Journal/Dow Jones Venture Source. (Tweet This)
After the last round of funding, the company is now worth $50 billion. Uber is followed by Chinese smartphone vendor Xiaomi ($46 billion), which was the most valuable start-up last year, and Airbnb ($25.5 billion).