The digital music distribution industry continues to grow week-by-week, with official US sales tracking agency Nielsen SoundScan revealing that over two million tracks sold online in the US last week.

Last week emerged as a "music shopping frenzy", USA Today reports: Total album sales in all formats exceeded 17 million units – the biggest in a non-Christmas period since 1991. Year-to-date sales are also up 13 per cent.

It's a great sign for operators in the space, but market maturity remains some way off – it's a creative, competitive space.

Parks Associates research analyst John Barrett told Digital Music News last week: "The digital-music market is quickly growing and everyone is jumping into the space. Margins are razor thin, however, and substantial volumes are needed to make a profit. I expect, therefore, that the less successful players will begin to quit the market within a year or two, and we'll see just the best of the best survive."

At Macworld Expo Apple announced it had sold 30 million tracks through iTunes Music Store so far.