MILAN, May 27 (Reuters) - The second biggest investor in Generali, Francesco Gaetano Caltagirone, has stepped down from the board, the group said on Friday, signaling that a protracted boardroom clash at Italy's leading insurer is not over.

Caltagirone's bid to replace Generali Chief Executive Philippe Donnet with his own CEO candidate was defeated in a shareholder vote last month. Caltagirone secured three seats on the new board at the shareholder meeting. (Reporting by Valentina Za, editing by Giulia Segreti)