Nearly half of all teenagers bought no compact discs in 2007, accelerating the music industry's painful transition from CDs to digital downloads, according to a report released Tuesday.

One big beneficiary: Apple. Its iTunes music store, which sells only digital downloads, jumped ahead of Best Buy to become the No. 2 U.S. music seller. Apple trailed only Wal-Mart Stores, which mostly sells CDs.

The music industry has grappled with how to replace its rapidly disappearing CD sales with digital downloads. The report by research firm NPD Group offered a window into how quickly the change was happening and who was leading it.