Vodafone Group Plc has rejected an 11.25 billion-euro ($12.9 billion) offer for its Italian unit from a consortium backed by billionaire Xavier Niel’s Iliad SA.

The approach was “not in the best interests of shareholders,” Vodafone said in a statement Thursday, which confirmed an early Bloomberg News report it was leaning toward spurning the proposal. It also revealed that Iliad’s approach involved private equity firm Apax Partners LLP as a co-bidder.

Shares of Newbury, England-based Vodafone were down 1.4% at 4:26 p.m. in London, shedding earlier gains after Iliad’s statement and giving it a market value of about 37.2 billion pounds ($50.7 billion).

Read more: Bloomberg Quint