Last year, Apple became the second-largest music retailer in the U.S. after Wal-Mart (based on music sold during 2007). At the time, many wondered how long it would be before Apple overtook Wal-Mart. It looks like it may have already happened.
Ars Technica has landed an internal Apple email that reveals that iTunes is now the number one U.S. music retailer. The email references an unpublished NPD MusicWatch survey for the month of January that shows Apple with a 19 percent marketshare compared to 15 percent for Wal-Mart. Best Buy is in third position with Amazon MP3 tied with Target for fourth and fifth.
If the data is correct (not that I have any reason to doubt it), it would be the first time that a digital-only music retailer has outsold all brick-and-mortar retailers.
Update: Apple has confirmed the story with a press release announcing that it was the largest music retailer in the US based on the amount of music sold during January and February 2008.
Source: The Unofficial Apple Weblog