Fidelity Investments is competing to lead Uber Technologies Inc.’s new financing in a round that could value the ride-sharing service at about $17 billion, according to people familiar with the situation. Uber’s new financing, if completed at a $17 billion valuation, would mean the company is more valuable than public technology companies including car-rental service Hertz Global Holdings Inc. and retailer Best Buy Co. Other closely held technology startups such as Dropbox Inc. and Airbnb Inc. have raised money at a $10 billion valuation in recent months.