Investors dumped shares of Commerzbank on Monday, a day after the lender sealed an agreement to acquire Dresdner Bank, on concern that it had overpaid.

Under the terms of the deal, Commerzbank will initially acquire 60.2 percent of Dresdner, one of the oldest German banks, and will buy the remainder by the end of next year.

With the planned sale of Dresdner Bank to Commerzbank, Allianz is set to abandon the biggest experiment in German finance of the last decade in favor of a global trend: focusing on core competencies.