MADRID (Reuters) -Spanish infrastructure group ACS confirmed on Friday it had made an offer for Atlantia’s 88% stake in motorway unit Autostrade per l’Italia, which values the business at 9 billion-10 billion euros ($10.7 billion-$11.9 billion). ACS said in a statement it had sent a letter to the Italian group’s board of directors on Thursday declaring its interest in the stake, confirming information released by Atlantia on Thursday. Atlantia has been under pressure to sell its stake in Autostrade, which manages half of Italy’s motorway network, since the collapse of a motorway bridge run by the group in the town of Genoa caused the death of 43 people in 2018. Italian state lender Cassa Depositi e Prestiti (CDP) is already heading a team of investors, including Macquarie and Blackstone, which presented a binding bid for the unit last week. The ACS statement fuelled investors’ appetite for the Italian infrastructure group, with Atlantia shares rising more than 3% on Friday, adding to a 3.1% gain posted on Thursday. Investment firms UBS, Alantra and Mirabaud welcomed the prospect of the acquisition, although some noted likely political opposition from Italy, as well as possible strain on ACS. “It would have to raise around 5 billion euros in debt... (putting) too much pressure on ACS’s balance sheet,” Mirabaud analysts said in a note, recommending that the company pair up with other investors such as CDP. ACS declined to comment on who it might partner with or how it would structure the deal. CDP and its partners’ bid is based on a valuation of 9.1 billion euros for the whole of Autostrade. It has asked Atlantia to cover 870 million euros in potential legal risks linked to the 2018 bridge disaster, sources had said. Atlantia said its board on Thursday began looking at a revised offer sent last week by the CDP-led consortium, while acknowledging the ACS group’s interest. ACS has been Atlantia’s partner in Spanish toll road operator Abertis since the two groups’ joint acquisition of the company in 2017. Asked whether the ultimate goal would be to merge Abertis and Atlantia, and further down the line sell all or part of its stake in subsidiaries Hochtief and CIMIC, ACS declined to comment. Florentino Perez, chairman of ACS and Real Madrid soccer club, said on Tuesday he hoped to create a pan-European group of road operators with his Italian partner. ($1 = 0.8411 euros)