Relieved investors sent shares in French low-cost telecom operator Iliad (ILD.PA) up 11 percent on Tuesday after it abandoned an effort to buy the fourth-largest U.S. Backed by billionaire founder Xavier Niel, Iliad made an initial bid worth $15 billion and then raised it further, but was rebuffed by T-Mobile US’ (TMUS.N) parent company, Deutsche Telekom (DTEGn.DE). Sources told Reuters Deutsche Telekom was unconvinced by the price and by Niel’s ability to run the business better than its own managers could. “Now that Iliad has abandoned the U.S.