One Direction's debut album Up All Night has sold 2.95 million units -- presented as track-equivalent albums -- through March 22nd, according to Nielsen Music. (Track sales have been converted to album sales at the standard 10 tracks-to-1 album ratio.) Sales slip 12.2 percent for the band's second album, decline a further 20.7 percent for the third and plummet another 44.4 percent for the fourth and latest. One Direction's last album has sold only 38.7 percent as many TEA units as its first.
*NSYNC didn't even get to a fourth album. But its third album is a 61.5 percent decline from its second, which is 31.7 percent higher than its debut.
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Backstreet Boys also hit their peak on the second album. The group's third album represents a 57 percent decline (13.8 million to 5.9 million) and the fourth album represents a 70.2 percent decline (5.9 million to 1.8 million). The fifth and six albums have sold 229,000 and 130,000 TEA units, respectively.