"I Knew You Were Trouble" is a song by the American singer-songwriter Taylor Swift from her fourth studio album, Red (2012). She wrote it with its producers, Max Martin and Shellback. A dubstep and pop track, "I Knew You Were Trouble," has a production based around electric guitars and synthesizers, accentuated by a wobble bass and Swift's distorted vocals; critics found the dubstep production a radical departure from Swift's previous country-pop sounds. In the lyrics, the narrator blames herself for not recognizing the warning signs of a past toxic relationship.