Il Giornale newspaper had reported in its Friday edition that carmaker Fiat could swap its 1.8% Mediobanca stake for the bank's 11.7% holding in Ferrari.
"Fiat and Mediobanca are in 360-degree discussions to reach an accord over the bank's shareholding in Ferrari. At the moment, no decision has been finalised," the spokesman said.
Fiat Chief Executive Officer Sergio Marchionne said last month that the company could buy back the stake, which it sold to pay down debt when it was in crisis in 2002.
Marchionne has presided over a massive restructuring which has pulled Fiat out of debt and turned its key auto division round to profit.
Mediobanca has been looking to dispose of its stake in Ferrari and has said a number of private investors have expressed interest.
Fiat sold 34% of Ferrari to Mediobanca and a group of banks in 2002 for €775.2m and since then, the merchant bank has gradually reduced it through sales to a number of parties.