PARIS, Aug 10 (Reuters) - Billionaire hedge fund manager William Ackman on Tuesday bought 7.1% of Universal Music Group from French conglomerate Vivendi (VIV.PA) and pledged to keep buying after his original plan to acquire a 10% stake in the record label for his blank-check company collapsed. Vivendi said the transaction was valued at $2.8 billion, based on an enterprise value of 35 billion euros ($41.01 billion) for 100% of UMG"s share capital. Ackman still has the right to buy up to 2.9% more in UMG by Sept. 9, Vivendi said. For Ackman, this marks the first part of a promise to make good on his pledge to buy a sizable stake in UMG after the complex SPAC deal he put together crumbled last month amid scrutiny from U.S. regulators. Ackman has told his own clients that music is the cheapest form of entertainment in the world and a savvy investment because it pays royalties. His public and private hedge funds run by his firm Pershing Square Capital Management made this investment. Ackman is currently raising fresh capital from investors to potentially buy more of UMG, according to people familiar with his plans. "Vivendi is very satisfied with the arrival at UMG of Mr. Ackman, a major American investor, providing once again evidence of the music company"s global success and attractiveness," Vivendi said. UMG"s enterprise value is worth more than the market value of its own parent company. The company, which represents artists like Justin Bieber and Taylor Swift, is thriving on a music industry rebound, underpinned by booming streaming revenues but also a recent surge in sales of vinyl records and CDs. Ackman"s investment in UMG comes before a plan to list and spin off 60% of Universal to Vivendi shareholders. ($1 = 0.8535 euros)