Zurich Insurance on Tuesday said Chief Executive Martin Senn was stepping down, with Chairman Tom de Swaan immediately taking temporary charge of the Swiss insurer.
Senn's departure, which Zurich said was by mutual agreement, comes after a difficult third-quarter in which it abandoned a takeover of Britain's RSA and searched for a plan to turn around its flagship general insurance business.
"There have been some setbacks in recent months, but I am convinced that we have put in place the right measures for Zurich to reach its targets," Senn, who was CEO for six years, said in a statement.
The process to appoint Senn's successor is underway, Zurich said.
Shares in Zurich are down 13.1 percent in 2015, making it the second worst performer on the European insurance sector index, which is up 18.6 percent this year.
Zurich said Senn's departure would have no impact on its strategic focus or financial targets and that it was confident of achieving or exceeding its three financial aims for 2014-2016.
Its targets are for net cash remittances of more than $9 billion over the three-year cycle, a business operating profit after-tax return on equity of 12-14 percent and a Zurich-Economic Capital Model ratio of 100-120 percent.
Zurich added that it will provide information on the deployment of $3 billion in excess capital in February when it publishes its results for 2015, as previously announced.