BASF, the world's biggest chemicals group, surprised markets with a fourth quarter net profit of €455 million ($612 million), compared with a loss of €313 million in the same period of 2008.
Analysts polled by Dow Jones Newswires had forecast an average quarterly net profit of 274 million euros.
A group statement said: "The fourth quarter of 2009 was encouraging and gives us grounds for confidence," with chairman Jürgen Hambrecht forecasting sales growth this year.
Investors were cheered by the comments, and BASF shares shot up by 3.90 percent to €42.24 to lead morning gains on the Frankfurt stock exchange, which was 0.38 percent lower overall.
BASF reported an overall 2009 net profit of €1.41 billion, down by 51.6 percent from the figure in 2008. Sales fell by 19 percent to €50.7 billion, a statement added, while core earnings were off by more than 43 percent at €3.6 billion.
The group suffered in almost all markets owing to the global economic crisis, but said "the worst is behind us, even though dark clouds remain.
"2010 will be a transitional year with uneven development from region to region," the statement added.
Generalised chemical production suffered losses in 2009, while specialty and agro-chemicals fared better, the group said.
It planned to trim its 2009 dividend by 25 cents to €1.70 per share after "earnings were negatively impacted by expenses for the acquisition and integration of Ciba," a Swiss specialty chemicals company, BASF said.