Apple may have a bigger business problem than displeasing Taylor Swift with its new Apple Music service; According to Reuters, U.S. regulators are said (by anonymous sources) to be looking into Apple's treatment of music-streaming rivals, now that the company has gone from selling only downloadable music to competing directly with alternatives like Spotify and Pandora. A slice: While $9.99 has emerged as the going monthly rate for music subscriptions, including Apple's, some streaming companies complain that Apple's cut forces them to either charge more in the App Store than they do on other platforms or erode their profit margins. The Federal Trade Commission is looking at the issue but has not begun a formal investigation, said the three industry sources, who requested anonymity. The agency has had meetings with multiple concerned parties, one source said. The agency meets with companies routinely, and a formal investigation may not materialize.