Apple's iTunes Store surpassed WalMart as the No. 1 music retailer in the U.S. this January 2008, according to the NPD MusicWatch Survey via ArsTechnica. While this is an astounding feat, Apple has already announced that they were the number 2 retailer in February 2008 so it was a temporary rise. Still a very quick rise to number 2 (or number 1) for iTunes which only started selling online music back in April 2003.
From the ArsTechinca article:
"The fact that a digital-only retailer has ascended to the top of the sales charts is not unexpected, but it does demonstrate just how much the music landscape has changed since the beginning of the decade. The NPD Group has been tracking a "sharp increase" in digital downloads over the past several months as physical sales dry up. According to NPD's research, 48 percent of US teens didn't buy a single CD in 2007, compared to 38 percent in 2006."
While iTunes may have passed the competition in the past month, its likely that this is a temporary thing related to Christmas sales and such. Its only a matter of time though as the trend for online, digital music sales is a sharp arrow in the upward direction.
UPDATE:
Apple put out a press release later today saying the following:
"*Based on data from market research firm the NPD Group’s MusicWatch survey that captures consumer reported past week unit purchases and counts one CD representing 12 tracks, excluding wireless transactions. The iTunes Store became the largest music retailer in the US based on the amount of music sold during January and February 2008."
I think this means that iTunes was #1 in the months of January and February, but their earlier statement of being #2 in February was based on a full years data.