(Reuters] – Europe’s third-largest insurance company Assicurazioni Generali (MI:), said Thursday that Francesco Caltagirone had resigned as director amid a dispute between investors about Philippe Donnet, Generali CEO.

Caltagirone (a construction and newspaper magnate) is Generali’s 2nd-largest investor, holding an 8.4% share. Caltagirone has stood against Donnet’s reappointment. Donnet is supported by Mediobanca, Generali’s largest investor (OTC:), and the majority of board members.

Generali stated in a statement that Caltagirone was frustrated by the board’s work methods. This included its treatment of confidential information, handling of strategic plans, and relationships with shareholders and the media.

Gabriele Galateri di Genola, Generali Group Chairman, has rejected Caltagirone’s reasons and stated that Generali Group always operated with transparency and fairness.

Caltagirone’s offensive began in April after he decided to skip a General Meeting to accept Generali’s results. He reached an agreement with Leonardo Del Vecchio (the eyewear billionaire and third largest investor in Generali), to help him make decisions regarding the company.

CRT, a smaller Generali investor joined the consultation agreement. This represents an aggregate stake of over 16%.

Mediobanca borrowed shares from them to increase its 17% vote share. Both sides will meet at the April general meeting in order to elect a new board.

According to people familiar with the matter, Caltagirone & Del Vecchio would be open to supporting a different CEO candidate as well as presenting their own candidates to the board.