According to the latest data from The NPD Group, iTunes remained the largest U.S.-based music retailer through the first half of 2008. From January to June, iTunes was the number one retailer, followed by Wal-Mart, Best Buy, Amazon, and Target. “We expect Apple will consolidate its lead in the retail music market, as CD sales continue to slow,” said Russ Crupnick, entertainment industry analyst for The NPD Group. “Amazon’s CD buyers tend to be older, so they haven’t abandoned the CD format to the extent seen in the average music buyer. Plus Amazon’s successful introduction of its digital download store will help the company improve its position in the future.” NPD’s rankings are based on purchases of CDs and a-la-carte digital music downloads, using an equivalency of 12 single-track downloads per CD, for retailers who sell digital music as single tracks. In April, Apple announced that it had passed Wal-Mart to become the top music retailer in the U.S., based on sales information from January and February of 2008.