Atlantia said it would offer Abertis investors the option of €16.5 for each of their shares or a ratio of 0.697 share of the Italian manufacturing group. The deal would value Abertis at €16.34 billion, just ahead of its closing market value from Friday.
"Over the past weeks we have worked to design an offer that is friendly and attractive for all shareholders, stakeholders and the management of both companies," Atlantia CEO Giovanni Castellucci said in a statement. "We believe we have achieved this goal. Should the offer be successful, the combined Group will result in a very strong cash flow generation capacity and ability to invest, which together with our unique geographic presence, will allow us to be the most suitable partner to address the needs of the relevant institutions and customers in our countries of operation."
"The transaction will create the global leader in transport infrastructure," Castellucci said. "I am confident that the strong and integrated management team, which results from the combination of Atlantia and Abertis' unique capabilities, will allow us to benefit from the substantial opportunities created by this transaction."
Atlantia said the deal would create the world's biggest toll road operator, with just over 14,000 kilometres (8,700 miles) of assets under management in 19 countries. The combined group, Atlantia said, would have operating earnings of €6.6 billion, based on pro-forma figures from 2016.
Abertis shares were marked 0.2% higher at from their Friday close at €16.48 each in early trading in Madrid, extending their year-to-date gain to just under 24%. Atlantia shares gained 2.7% in early trading in Milan to change hands at a year-to-date high of €24.87.