An obvious question swirled around Commerzbank’s tortured takeover of Dresdner Bank on Thursday – why go ahead with a deal that has become so much more troubled in the four months since it was announced?

Reeling under the weight of the financial crisis and its consequences for both banks, Commerzbank has been forced to take a hugely expensive slug of capital from the German government. When it returns to profit, the enlarged bank is in line to pay 9 per cent annually on a total of €16.4bn of so-called “silent participations”, while a further €1.8bn ($2.5bn) gives the state a 25 per cent stake plus one share, diluting private investors who had already been told to endure two years without dividends.