French media giant Vivendi's logo is pictured at the main entrance of the entertainment-to-telecoms conglomerate headquarters in Paris, France, August 12, 2020. REUTERS/Charles Platiau/File Photo June 14 (Reuters) - Billionaire hedge fund manager Daniel Loeb's Third Point owns a substantial stake in Vivendi SE (VIV.PA) and is "evaluating" the French media giant's plan to sell a stake in its Universal Music Group to rival billionaire investor William Ackman, a source familiar with the firm's holdings said on Monday.