Deutsche Bank, Germany's biggest bank, announced the surprise resignation Sunday of co-CEOs Anshu Jain and Juergen Fitschen, to be replaced by former UBS banker John Cryan.

Jain and Fitschen have led the banking giant since May 2012. Jain will step down at the end of this month, making way for Cryan, while Fitschen will leave in May next year, the bank said.