Diesel founder Renzo Rosso has bought a majority stake in design business Sophia Kokosalaki via his Staff International business. The acquisition is part of Rosso's strategy of focusing on emerging talent. The first joint venture between London-based designer Kokosalaki and Staff International will launch in March in Paris. Kokosalaki unveiled her first womenswear collection in 1999. Staff International also owns a controlling stake in Maison Martin Margiela.