Around half of U.S. consumers are hoarding their old iPhones in cupboards and sock drawers — representing an inventory worth around $13.4 billion in total.

Guilty as charged. I’ve got three.

According to the annual “Mobile Mountain Study” conducted by research group OnePoll for resale site SellCell.com, this figure is down from the 55% of people who admitted to holding onto their old smartphones last year — although the total amount of money being left on the table is up from last year’s sum of $9 billion, thanks to the growing smartphone market.