The Commerzbank building (second from right) in Frankfurt am Main, western Germany, on Sept. 25, 2023.Kirill Kudryavtsev | Afp | Getty ImagesUniCredit's move to take a stake in German lender Commerzbank is raising questions on whether a long awaited cross-border merger could spur more acquisitions and shake up the European banking sector.Last week, UniCredit announced it had taken a 9% stake in Commerzbank, confirming that half of this shareholding was acquired from the government. Berlin has been a major s ...