Beyonce's surprise self-titled album is all but guaranteed a No. 1 debut on the Billboard 200 chart this week. Industry sources suggest its sales have grown to over 550,000 in the U.S. through Saturday night. The album may sell 600,000 by the end of the tracking week on Sunday, Dec. 15. 

The album bowed -- without any pre-release announcement -- in the iTunes Store at midnight EST on Friday morning, Dec. 13. None of its songs are available a la carte (which is likely helping encourage full album purchases). The 14-song set is selling for $15.99 and additionally comes with 18 music videos. 14 of those are for each of the album's songs.

Beyonce, which is exclusively available through the iTunes Store until Dec. 20, sold 430,000 through Friday night, and then another 120,000 or so on Saturday.

Read it at Billboard.