Uber is best known for allowing people to book a taxi through its smartphone application. But the fast-growing company has far broader ambitions.

Fitbit Inc., a pioneer in wearable fitness tracking, on Thursday filed for an initial public offering to help fend against a mounting assault from a range of corporate giants eager for a piece of the burgeoning market.

Yelp Inc., the consumer-review website, is working with Goldman Sachs Group Inc. to find a buyer, a person with knowledge of the matter said. The $3.5 billion company, based in San Francisco, may draw interest from potential suitors including Priceline Group Inc., Yahoo! Inc., Amazon.com Inc. and Rakuten Inc., said the person, who asked not to be identified because the process is private.

Online music streaming service Spotify's revenues leapt 45 percent to top 1 billion euros ($1.1 billion) last year, though its operating loss widened due to product development and expansion costs, its holding company said. Stockholm-based Spotify, which provides free on-demand music or ad-free tunes for paying customers, posted an operating loss of 165 million euros, compared with a loss of 91 million euros in 2013.