ABERTIS INFRAESTRUCTURAS 
Atlantia was given the option to invest in Cellnex under an agreement clinched last week to acquire Spanish toll-road operator Abertis in a joint bid with Spanish builder ACS.
The Rome-based group will disclose whether it will purchase 29.9 percent or 34 percent of Cellnex only after the completion of the takeover offer on Abertis launched by ACS-controlled Hochtief
Under European rules, Atlantia would have to make a full takeover if it buys a stake of 30 percent or more in Cellnex.
Last week Atlantia's CEO said the company had no plans to buy all of Cellnex, suggesting the Italian group would buy only 29.9 percent of the masts company.
Atlantia also said Edizione, the holding company of Italy's Benetton family which controls it, granted the road and airport operator a put option to sell to Edizione 29.9 percent of Cellnex at a price of 21.50 euros per share, cum dividend, for a total of 1.49 billion euros (£1.3 billion).
That put option may be exercised by April 16.
Sources have told Reuters the Cellnex stake could end up in the hands of Edizione, whose boss Marco Patuano knows the towers sector well because of his past experience as CEO of Telecom Italia, Italy's biggest phone group.
If the sale goes ahead, Edizione will give Atlantia the right to co-invest in Cellnex by buying up to 6 percent of the masts company within two years of the execution of the deal.
Atlantia would also have a "right of first offer" and a "pre-emptive right" should Edizione decide to sell directly or indirectly part or all of the stake within seven years.
Cellnex is No. 1 European player in the sector with a portfolio of more than 27,000 towers across the region. Its total market value is 5 billion euros.
Atlantia sold its small towers unit TowerCo to Abertis in 2014. The Spanish firm then spun off its combined masts assets the following year and listed them under the Cellnex name.
(Reporting by Agnieszka Flak and Francesca Landini; Editing by Adrian Croft)
