Denmark's A.P. Moller-Maersk tumbled to a loss of $2.5 billion in the last three months of 2015 after the shipping and energy group wrote down the value of its oil assets by the same amount.
Maersk warned investors on Wednesday that it expects its underlying net result in 2016 to be significantly below 2015's $3.1 billion as it struggles with plummeting oil prices and low rates for container freight. Its shares fell as much as 9 percent in early trading and were down 4.4 percent by 0855 GMT.
Chief Executive Nils Smedegaard Andersen said the oil price was the biggest short-term challenge for the company.
"Given our expectation that the oil price will remain at a low level for a longer period, we have impaired the value of a number of Maersk Oil's assets by $2.5 billion after tax," Andersen said.
The result for 2015 fell short of previously lowered guidance for a profit before special items of $3.1 billion.
"The downgrade of 2015 guidance in October warned everybody of a tough fourth quarter, but it turned out a lot harder than expected," said analyst Ricky Rasmussen from Nykredit Markets.
Shares in A.P. Moller-Maersk have dropped 50 percent since April last year.