CRT and GIC own 4.5% and 8.3%, respectively, in the infrastructure group. Benettons' holding company Edizione controls Atlantia with a 33% stake.

As of Friday, Italian bourse data showed the take-up had increased to 19.8% of the shares targeted by the offer, or around 13.2% of the group's capital.

Earlier this year Fondazione CRT said it would tender its stake and then reinvest the proceedings from the sale of shares representing a 3% in the vehicle set up by the Benettons and the U.S. fund to launch the buyout offer.

Atlantia's second biggest shareholder GIC made no public statement about its intentions.

Atlantia's takeover bid will end on Nov. 11.

(Reporting by Elisa Anzolin; editing by Agnieszka Flak)