Troubled Deutsche Bank has turned to one of its investors for advice on how to turn around fortunes at the loss-making lender. Chief executive Christian Sewing has hired New York-based private equity firm Cerberus as an adviser. The turnaround specialist has a roughly 3pc stake in Deutsche Bank and its other investments include fellow German lender Commerzbank. Mr Sewing, who took over from ousted Yorkshire-born boss John Cryan earlier this year, announced early in his tenure that he would push through more than 7,000 job losses, with the axe mainly falling in its under-performing investment bank.