When you upgraded to your most recent phone, what did you do with the old one? Based on market research group OnePoll’s latest “Mobile Mountain Study,” it’s very likely that you stored it away for a rainy day. In fact, almost 40% of the participants in the study said that keep their old phones for themselves, while just 20% gave them to family members or friends and 9% actually dumped them in the garbage. Whether or not you fall into any of these categories, if you’re holding on to an old iPhone, you’re contributing to a $13 billion hole in the resale economy, reports MarketWatch.

That’s right, all of the dormant iPhones combined are worth approximately $13.4 billion, or about 35% of the total resale value of every old gadget that a site like SellCell or Gazelle would be willing to take off of your hands. As the number of first-time smartphone owners shrinks and upgrades become more common, consumers might become more inclined to trade in their old devices. Of course, considering how saturated the market will be by then, there’s no telling if your iPhone 5 will still be worth the shipping and handling fees.

Jacob started covering video games and technology in college as a hobby, but it quickly became clear to him that this was what he wanted to do for a living. He currently resides in New York writing for BGR. His previously published work can be found on TechHive, VentureBeat and Game Rant.