The group, which makes heavy trucks and buses along with turbo machinery and diesel engines, reported a net loss of €258 million, compared with a profit of €1.25 billion in 2008.
MAN's operating profit also plunged but remained in the black at €504 million, down from €1.729 billion a year earlier, on sales that shed nearly 20 percent to €12 billion from €14.9 billion in 2008, a statement said.
The group put the drop in sales down to a "massive decline in demand in the transportation sector in particular," as truck markets crashed owing to the global economic downturn.
MAN also took a write down of €382 million related to its stake in the Swedish truck company Scania, and paid a €150-million fine in December stemming from alleged corruption in foreign and domestic markets.
The last three months of the year were tough for MAN, with a quarterly net loss of €472 million and an operating profit that was one third that of the same period a year earlier, at €126 million.
The group did not give an overall outlook for this year but did say that "business at MAN (commercial vehicles) is expected to remain at the current level in 2010."
Part-time shifts would remain in effect at production plants, at least for the first six months of the year, MAN said.
Sales were expected to decline slightly at the turbine and engine divisions, which are to merge in the coming months, generating estimated savings of €60 million, the group said.
That would also leave the commercial vehicles division free for a mooted tie-up with Scania under the aegis of Volkswagen, which owns Scania outright and also holds a dominant stake in MAN.
MAN shares jumped by 1.24 percent to €50.69 in early trading on the Frankfurt stock exchange, while the DAX index of leading stocks was up by 0.63 percent overall.