Shares in Commerzbank, the German banking group, have risen nearly 10% in the past ten days on mounting speculation that HSBC or one of the leading Spanish banks is preparing a takeover bid.

Commerzbank closed last night at €20.03 on the Frankfurt Stock Exchange, up 1.78% on the day and its highest close since early 2002. The closing price values Commerzbank at €12bn ($14.9bn).