Apple overtakes Amazon in sales

Apple Inc.'s digital music store iTunes became the third-largest U.S. music retailer with 10% of the market in the fourth quarter, overtaking Amazon .com, according to a survey by NPD Group.

The report highlights the growing strength of digital music as physical sales of compact discs continue to slide.

Wal-Mart Stores Inc. was the market leader with a 15.8% share, followed by Best Buy Co. with 13.8%, according to the survey of 40,000 people. Amazon fell to No. 4 with 6.7%.