 A CD single was released through Swift's official website on December 13, 2012; the same day also saw the release of an "I Knew You Were Trouble" single package collection, consisting of a black t-shirt, a red drawstring bag, a spiral notebook, and the CD single, which was individually numbered.In the United Kingdom, "I Knew You Were Trouble" was the second single from the album and was released on December 10, 2012.In December 2015, media reported that Swift's recording of "I Knew You Were Trouble" had been delivered to the streaming website Spotify, but that its credit and copyright was mistakenly given to Welsh band Lostprophets and lead singer Ian Watkins.