Richemont Chairman Johann Rupert invited LVMH Moet Hennessy Louis Vuitton SE and Gucci owner Kering SA to join in an attempt to build a luxury retail website that can compete with the world’s largest online vendors. The South African billionaire, who controls the Swiss company and its 20 brands, said he’s spoken to LVMH Chairman Bernard Arnault and Kering about them joining the Yoox Net-a-Porter platform. “We’re not big enough,” Rupert said in a speech at the Financial Times Business of Luxury Summit in Monaco Monday.