Commerzbank said on Wednesday that Manfred Knof would step down as CEO of Germany's second-biggest lender earlier than planned, amid talk of a potential takeover by Italian rival UniCredit.

Knof, 59, will leave the Frankfurt-based bank at the end of September, according to a group statement. He will be replaced by Commerzbank's chief financial officer, Bettina Orlopp, who will become the first woman to lead the bank.

Commerzbank said this month that Knof had decided not to extend his contract beyond the end of 2025.

Immediately after Knof's announcement, Italian lender UniCredit surprised markets by saying it had taken a major stake in Commerzbank. UniCredit subsequently increased its holding to around 21%, becoming Commerzbank's biggest shareholder.

The Italian bank's moves have set off speculation that it could try to take over Commerzbank, leading consolidation in the European financial sector.

The announcement of Knof's early departure comes amid the speculation.

Now was the "right time" to hand over to Orlopp, Knof said in the statement.

Knof, who steered the German lender through a painful restructuring, had "brought Commerzbank back on the track of success through consistent and determined action," Jens Weidmann, supervisory board chair, said.

In a previous statement, Orlopp said that "significant tasks lie ahead" for Commerzbank.

"Together with all our key partners, we will navigate through the challenges ahead of us successfully," she said.

UniCredit not seeking seat on Commerzbank board

UniCredit CEO Andrea Orcel said Wednesday his group would not seek a seat on the Commerzbank's supervisory board.

"I think it's inappropriate for us to have a board seat, because we're also a competitor," Orcel told a conference organised by Bank of America in London.

UniCredit's approach has unsettled the Berlin government, which still has a 12% stake in Commerzbank following a 2008 bailout.

Chancellor Olaf Scholz on Monday warned that "unfriendly attacks, hostile takeovers are not a good thing for banks."

The German government, from whom UniCredit brought some of its recently acquired shares, has paused sales of its Commerzbank stake.

A German Finance Ministry official told Agence France Presse (AFP) that Berlin had "communicated" to UniCredit that "we do not support a takeover."

Italian Foreign Minister Antonio Tajani said that Europe had a free market with rules and that "it seems to me that Unicredit has respected them."

"Commerzbank, for us at the moment, is an investment, nothing else. There is no offer," UniCredit's Orcel said on Wednesday.

"We are indeed a large shareholder, a strategic shareholder now, but it is an investment," he added.