Martin Blessing, the only chief executive of a German state-rescued bank to remain in power, had recently skirted questions on his future, but said on Sunday he would leave the bank after his contract expires in October next year as it was time for someone else to take over the running of the bank.

Blessing, who took the helm in May 2008, has spent most of his time restructuring the lender after its near-collapse following the Dresdner Bank takeover in the midst of the financial crisis.

The state had to rescue Commerzbank with the infusion of more than €18 billion, much of which has now been repaid.

Under Blessing's direction, the bank, which finances more than a third of the country's exports, has cut costs and shrunk its balance sheet by exiting shipping and commercial property loans, among others.

Instead he has focused Germany's second-biggest bank on corporate and retail banking.

"Today, Commerzbank has a robust business model, excellent employees and managers, as well as a culture that is the envy of many companies," Blessing said in a statement on Sunday.

It is not clear who will succeed Blessing. Commerzbank does not have a deputy chief executive on its board.

Markus Beumer, who heads the Mittelstandsbank unit, which serves Germany's raft of medium-sized companies, is seen as a candidate to take the helm but the bank is also expected to scout for outside candidates.

In the third quarter Commerzbank beat analysts' expectations for pre-tax profit as the lender's retail bank thrived, provisions for bad loans decreased and its run-down portfolio of unwanted assets broke even.

The lender posted a pre-tax profit of €401 million in the July to September period, compared with €349 million expected by analysts in a poll.

Commerzbank's Mittelstandsbank unit, which caters to medium-sized companies, saw operating profit decline, partly due to a write-down on a loan to failed construction company Imtech.