Jay Z's Tidal music streaming service is bleeding money, and more than doubled its losses last year

Jay Z's music streaming service, Tidal, lost $28 million last year, according to a legal filing reviewed by The Wall Street Journal.

That's twice as much as it lost in the year before Jay Z took control of Aspiro, Tidal's Swedish holding company. In 2015 it lost 239 million Swedish kronor, while in 2014, it lost 88.9 million. Tidal has also reportedly failed to pay over 100 outstanding bills.

There is a slight silver lining, however. As Tidal's losses accelerated, so did revenue, which rose 30%.

And Tidal is far from the only music streaming service that isn't profitable. Market leader Spotify had an operating loss of 184.5 million euros in 2015, compared with 165.1 million in 2014, Reuters reports. Spotify's revenue rose 80% in 2015.

Tidal said that, as of June, it had 4.2 million paid subscribers. That is well behind Spotify's 39 million (August) and Apple Music's 17 million (September).

Tidal's strategy for getting new customers seems to rely heavily on high-profile exclusives from the likes of Kanye West, Rihanna, and Beyoncé. But while those exclusives seem to have been effective in signing people up, they don't seem to have been as good at retaining them as loyal customers.