(Bloomberg) -- Kering SA shares tumbled after the luxury group warned that profit will plunge in the first half of the year on slumping sales at Gucci, its biggest brand. Most Read from BloombergTaylor Swift Is Proof That How We Critique Music Is BrokenBiden’s New Chopper Is Demoted After Scorching White House LawnTech Giants Roar as Tesla Spikes in Late Hours: Markets WrapBillionaire Pinaults Fight to Pull Gucci Off the Discount RackRay Dalio’s Famous Trade Is Sputtering, Investors BailingThe s