(Telecompaper) Australian infrastructure fund Macquarie is set to make a binding offer to acquire all or part of Enel's 50 percent stake in Italian wholesale-only operator Open Fiber, according to an unnamed source cited by Reuters. The offer for a stake of between 35 percent and 50 percent will be sent to Enel before the utility giant's board meeting on 17 September, said the source. In June, Enel confirmed that Macquarie had tabled a non-binding offer for all or part of its stake in a bid that according to various sources valued the company at EUR 7.7 billion.