Used smartphones are continuing to become a greater part of new smartphone sales. By 2018 they’ll account for 8% of new phone sales. This is only a problem because companies like Apple and Samsung who rely on selling phones to users who need upgrades, but re-commerce doesn’t seem to be going anywhere. The website Gazelle started the trend of selling your old devices, then other stores like Walmart and Best Buy jumped on board with their own trade-in services. iPhone’s actually make up about half of all traded-in phones. Most of these used smartphones end up in emerging markets like China. But there is a silver lining: users are selling their old devices to make money so they can upgrade more often.