Enel is preparing to take full control of fibre optic network operator Ufinet by exercising an option to buy the 79% owned by private equity firm Cinven, three sources with knowledge of the matter said. The sources cautioned a final decision on how the deal could be structured had not been taken. Enel, which already owns 21% of the South American broadband operator, could pay up to EUR 2.1 billion ($2.4 billion) for the majority stake it does not already own, the sources said. Enel and Cinven declined to comment.