Heavy legal bills and restructuring costs pushed Deutsche Bank to a surprise pre-tax loss of €1.15 billion (£948 million) in the final quarter of 2013.
The lender also warned that 2014 would be another challenging year, piling more pressure on co-chief executives Anshu Jain and Juergen Fitschen to prove their turnaround plan is on track.
Although the German bank said it would its 2015 targets, it added: “We expect 2014 to be a year of further challenges and disciplined implementation.
Deutsche Bank said fourth-quarter litigation costs of €528m took the total bill for the year to €2.5bn.
Last month the group was fined $1.9bn (£1.2bn) by the US Federal Housing Finance Agency to settle claims it misled two government-controlled companies over the quality of mortgage-backed securities, while EU regulators fined it €725m for its part in the Libor-rigging scandal.