Uber Technologies Inc. became one of the world’s most valuable startups by creating a new way to transport millions of people in more than 300 cities. Investors in Uber are enthusiastic about the potential, valuing the privately held company at $41 billion in its last funding round. Uber is in talks to raise a new funding round at a valuation of $50 billion or more, people familiar with the matter have said, roughly equal to FedEx Corp.’s stock-market value.