I Knew You Were Trouble is a song recorded by American singer-songwriter Taylor Swift for her fourth studio album, Red (2012). It was released on October 9, 2012, in the United States by Big Machine Records as the third promotional single from the album. Later, "I Knew You Were Trouble" was released as the third single from Red on November 27, 2012, in the United States. The song was co-written by Swift, Max Martin and Shellback and produced by Martin and Shellback.
"I Knew You Were Trouble" received generally positive reviews from music critics, who commended its mainstream appeal yet noted Swift's experimentation with dubstep as relatively limited. Due to strong digital sales, the song debuted at number three on the Billboard Hot 100, selling more than 416,000 copies within its first week, making it Swift's 14th entry in the top ten; it later peaked at number two in January 2013, after Bruno Mars 's "Locked Out of Heaven". At the inaugural YouTube Music Awards in 2013, "I Knew You Were Trouble" won the award for YouTube phenomenon. The single has been certified Quintuple platinum by the Recording Industry Association of America (RIAA). The song is one of the best-selling singles worldwide, with worldwide sales of more than 6.6 millions of units (according to the IFPI).
Prior to its release as a promotional single on October 9, 2012, the song debuted at number three on Billboard Hot 100 and number one on Hot Digital Songs with 416,000 copies sold in its first week, Swift's second largest first week singles sales. It became Swift's 14th top ten hit and her 11th song to debut inside the top ten and also her second to chart at number one. After the song debuted in the top ten and became Swift's fourth top ten hit from the album, Swift became one of the few artists with 3 consecutive albums that all included 4 top ten hits. With sales of 416,000 from "I Knew You Were Trouble", Swift became the first artist in digital history to have two songs that debuted with sales of 400,000 or more copies. It also gave Swift two songs in the top five for the first time in her career when "We Are Never Ever Getting Back Together" held at number five on that week. On November 27, 2012, the song was released as the second pop single from Red. It is Swift's second album single not to be released on country, following "The Story of Us". The song bounced back at the top ten and during the chart week of December 30, 2012 and three weeks later, after the song sold 582,000 copies, it reached its new peak at number two, being blocked by Bruno Mars' "Locked Out of Heaven" from the top spot, and tying the song with her previous released singles, "You Belong with Me" (2009), and "Today Was a Fairytale" (2010) as her second highest charting song on the chart. This became the fourth best single-week digital sales of all time and second best for a track not in its debut frame. The song was certified 5x Platinum by the RIAA in December 2013; as of November 2014, it has sold 5 million copies in the United States.
"I Knew You Were Trouble" debuted at number 38 on the Billboard Pop Songs chart and went to number one in its ninth week, where it stayed for seven consecutive weeks. It is her longest running number-one on that chart. "I Knew You Were Trouble" also became her second number-one song there, following "Love Story," which reached number one for one week on the week ending February 28, 2009. It also became her first number-one on the Billboard Adult Pop Songs chart, where she'd risen as high as number two with "You Belong with Me" and her second number-one song in Billboard Hot 100 Airplay, where it peaked at number one for four weeks. "I Knew You Were Trouble" also became her seventh number-one song on the Billboard Hot Digital Songs chart, which tied her with Britney Spears as the artist with the third most number one hits on that chart. Thirty-three unsolicited plays from Los Angeles radio station KKGO enabled the song to debut at number 55 on the Billboard Country Airplay chart in April 2013; it spent only that week on the chart.
The song also attained commercial success worldwide, reaching top ten in ten countries. "I Knew You Were Trouble" became Swift's seventh top-five hit on Canada, reaching number two for two non-consecutive weeks, during its debut week and on January 12, 2013, when it was blocked from the top spot by "Scream & Shout" by Will.i.am featuring Britney Spears. The song is tied with "Love Story" and "Shake It Off" as her highest peaking song in United Kingdom after it reached number two on January 19, 2013. "I Knew You Were Trouble" became Swift's seventh top ten hit and second top five hit from Red in Australia after it reached number three. It became her best-charting single in Denmark, reaching number three, surpassing her previous best peak of number 16 with "Love Story". The track also peaked at number three in New Zealand, holding the position for three consecutive weeks. It became her fourth top five hit, and second from the Red album in that country.