(Telecompaper) UK-based investment fund Zegona has offered over EUR 500 million for the 77 percent stake in Spanish mobile operator Yoigo owned by TeliaSonera, according to unnamed sources cited by business daily Expansion. The bid is some EUR 60-65 million higher than that offered by Spanish operator MasMovil, added the sources, after both companies responded to an invitation from TeliaSonera to bid for its controlling stake in Spain's fourth largest mobile operator.