Seeking information on possible price fixing in the digital music marketplace, the U.S. Department of Justice contacted the legal departments of the major record labels as part of an initial inquiry into Apple, sources have told "Billboard" (http://news.yahoo.com/s/nm/20100529/media_nm/us_apple), a music industry trade publication. The DOJ also spoke with a number of digital music services, the article adds.

Earlier this month, the DOJ reportedly reached out to the major music lablels to learn whether Apple was affecting pricing in the market. Since the featured album in Amazon's Daily Deal usually sells for the low prices of $3.99-$5.99, as opposed to the almost standard $9.99 for digital albums, any attempt to discourage labels from participating in the Amazon promotion might be construed as price fixing. And some sources said Apple had pushed music labels to not participate in the deal.

While iTunes has significant market share, it's not a monopoly, says "Billboard." Overall, iTunes had 26.7% U.S. market share last year, which translates into 65.5% of digital market share, "Billboard" estimates. However, for a la carte download sales, its U.S. presence is overwhelming, with an estimated 93% market share, per "Billboard."