djuggler/Flickr One of last week's biggest losers was Pandora Media (P), shedding nearly 10 percent of its value after disruptive peer-to-peer taxi service Uber struck a deal with Spotify and media reports suggested that Apple (AAPL) was intensifying its digital music efforts. Consumer appetite for streaming music is growing, and Pandora is still the top dog. This would seem to make it a natural beneficiary of the trend, but some things aren't working out so swimmingly for Pandora investors. The stock has shed more than half of its value since its springtime peak, and the marketplace is starting to get a lot more competitive. The Uber Challenge Uber has been making waves as the new way for car-less folks to get around. Instead of hailing a cab or dealing with the lengthy delays of mass transit, people who need to get somewhere can fire up the Uber app and have a registered driver come over and take them there for less than the conventional cab fare. Uber announced earlier this month that it's teaming up with Pandora rival Spotify to allow that music service's premium subscribers to play the tunes they want to hear through their driver's stereo. All they need is an iPhone or Android smartphone with Bluetooth functionality. The offering rolled out in 10 Uber markets. Pandora has tried to get its integration in cars, but it could never let folks pick out the actual tracks they want to hear on a drive as a passenger. Unlike Spotify, where users single out the exact songs they want to hear, Pandora is a music discovery engine that plays similar tunes based on the user's input. In theory, the Uber deal with Spotify is a small deal. Just a quarter of Spotify's 40 million users are premium subscribers, and some would argue that many of those folks already have cars. However, it's just one more way that a Pandora rival is standing out in this heated climate. Growth at Pandora, after all, is slowing. Its active user base has only increased 5 percent to 76.5 million over the past year, and is practically unchanged from the 76.4 million active listeners it had on its rolls just three months earlier. Pandora users are listening more, and it's commanding higher ad rates. However, the future is going to get more cutthroat than the past. An Apple a Day London's Financial Times reported last week that Apple will bundle its fledgling Beats Music service into its iOS operating system, according to people familiar with the situation. Apple was the original leader of the digital music revolution with its iTunes app and storefront. However, as the way we consume music has changed -- we prefer to stream a wide catalog of music instead of owning a handful of tunes -- the consumer tech giant has been trying to catch up. The first step came last year when Apple introduced the Pandora-like iTunes Radio. Earlier this year it acquired premium headphones maker Beats Electronics, and with that came the Spotify-like Beats Music platform that rolled out earlier this year. In other words, Apple is about to throw some muscle behind music discovery and on-demand streaming. Pandora is still cool. It's still popular. However, its inability to turn its users into paying customers -- there were just 2.5 million of those as of early last year -- has cast it as an ad-supported platform for freeloaders. With user growth slowing and the competition getting smarter, one has to wonder if Pandora is peaking in popularity, just months after its stock appears to have done the same.