MILAN, Jan 10 (Reuters) - A bid by motorway group Atlantia for Gemina, the holding company that controls Rome airport operator ADR, would only be on about 64 percent of share capital, according to a source close to the situation.
The two companies, both controlled by the Benetton family's holding Sintonia, said on Wednesday they were in talks to merge.
One idea would be for Atlantia to launch a cash takeover offer for Gemina, although a share deal could not be ruled out at this stage, a source said.
"If there is a takeover bid, Sintonia will not tender its shares," the source told Reuters on Thursday.
The 64 percent of Gemina that Sintonia does not already own is worth about 1 billion euros ($1.3 billion) at current market prices . Atlantia has a market value of 9.1 billion euros.
Shares in Atlantia fell to their lowest since Dec. 18 on Thursday. ($1 = 0.7667 euros) (Reporting By Paola Arosio; writing by Danilo Masoni; editing by Stephen Jewkes)