iTunes now the No. 2 music retailer in the US

The Cupertino-based company also said that there are now over 50 million iTunes Store customers who've combined to purchase over four billion songs, with an astounding 20 million songs sold on Christmas Day 2007 alone.

"We'd like to thank the over 50 million music lovers who have helped the iTunes Store reach this incredible milestone," said Eddy Cue, Apple's vice president of iTunes. "We continue to add great new features like iTunes Movie Rentals to give our customers even more reason to love iTunes."

iTunes had held the title of the No. 3 US music retail since last June, when it cruised by online retailer Amazon.com, snagging over 10 percent of the nation's overall music sales.

Apple's rank as a US music retail has been rising steadily ever since November 2005 when it passed Tower Records, Sam Goody and Borders to crack the Top-10 for the first time.