Gucci, Kering SA's biggest brand, saw sales tumble in the first quarter. Sales dropped 25% on a comparable basis, a slightly bigger fall than analysts were expecting. Kering has lost about half its market value in the past year, a worse performance than rivals LVMH Moët Hennessy Louis Vuitton, SE Hermes International SCA and Richemont. Bloomberg's Angelina Rascouet reports. -------- More on Bloomberg Television and Markets Like this video? Subscribe and turn on notifications so you don't miss