Warner Music Group has revealed that unit sales growth on the iTunes Store has decelerated since the move to a variable pricing scheme. AllThingsD reports that industry-wide, year-over-year “digital track equivalent album unit growth” was 5% in the December quarter, down from 10% in the September quarter and 11% in the June quarter. As iTunes makes up the majority of Warner’s digital revenue, growth is slowing in that metric, as…
