(Reuters) - Two investors are preparing a takeover bid for German sportswear maker Puma, Manager Magazin reported on Wednesday, pushing its share price up more than 11%. Authentic Brands CEO Jamie Salter and private equity firm CVC's German head Alex Dibelius have both expressed their interest in the 29% stake held by the Pinault family, paving the way for a potential bidding war, the German magazine reported. A person close to the French family's holding company Artemis said there was no active sales pr ...