MILAN (MF-Dow Jones)--Atlantia SpA (ATL.MI) shareholders are looking at forming a pact to consolidate their respective stakes in Italy's biggest toll-road operator, a manager at one of the shareholders said Friday.

The shareholders, which together own more than 50% of the operator, have yet to start formal talks, however, the manager told MF-Dow Jones on condition of anonymity.

Atlantia shares were off 0.97% at EUR18.40 in Milan.

Atlantia's spokesman wasn't immediately available for comment.

Partly through its investment vehicle Sintonia SA, the Benetton family's Edizione Srl is the biggest shareholder in Atlantia, directly and indirectly owning a 38.06% stake.

Apart from Edizione, the shareholders that could join the pact include Spain's Abertis Infraestructuras SA (ABE.MC), Italian insurer Assicurazioni Generali SpA (G.MI). and Fondazione Cassa di Risparmio di Torino, a shareholder foundation in northern Italy.

A fifth shareholder is Aabar Investments PJSC (AABAR.AD) of Abu Dhabi.

Abertis tried to take over Atlantia four years ago but gave up on the idea when it faced fierce opposition from the Italian government. At the time, Atlantia was known as Autostrade SpA.

Many Italian companies have shareholder pacts, which are designed to keep control among a small group of investors and ward off any unwanted takeover attempts. The pacts also oblige its members to give the others the right of first refusal when they decide to sell their shares.

-By Gabriele La Monica, MF-Dow Jones and Gilles Castonguay, Dow Jones Newswires; +39 02 5821-9908; gilles.castonguay@dowjones.com