Revenues of three biggest Korean pop record labels nearly doubled over the past three years, as their young clients took to the global popularity of K-pop, business reports showed Tuesday. Leading management agency and record label S.M. Entertainment Co.'s sales reached 164.3 billion won (US$155.7 million) last year, up 90.2 percent from 86.4 billion won three years ago. The agency represents Girls' Generation, Super Junior and TVXQ