Caltagirone, Generali's second largest investor, in April snubbed the company's AGM in a sign that he was unhappy with the balance of power among shareholders, sources told Reuters.
This week he added to his previous 5.96% stake by buying more than 1 million shares, or 0.07% of the insurer's total capital, through vehicle VM 2006, a filing with market regulator Consob showed.
Caltagirone, whose businesses span construction to publishing, also has a stake in Mediobanca, Generali's top investor with a 12.9% stake.
Trieste-based Generali is due to appoint a new board next spring and speculation has mounted over the future of CEO Philippe Donnet due to tensions among top shareholders.
(Reporting by Francesca Landini, writing by Giuia Segreti; editing by Jason Neely)