The maker of Aspirin lost 2.86 percent to €47.97 in early trading on the Frankfurt stock exchange, while the DAX index of leading stocks was 0.71 percent higher overall, as investors were unimpressed by the group's outlook for 2010.
Bayer posted a net profit of €153 million ($208 million) in the last three months of the year, up by 44 percent from the same period a year earlier, but just half an analyst forecast of €303 million compiled by Dow Jones Newswires.
For all of 2009, net profit fell by 20 percent to €1.35 billion, on sales that slipped by 5.3 percent to €31.168 million, a statement said.
"We were successful in a difficult environment, and we are optimistic for the future," a statement nonetheless quoted Bayer chief executive Werner Wenning as saying.
The group reduced its net debt by €4.5 billion to €9.7 billion, it said. This year Bayer forecast a five percent gain in sales and is aiming for core profit before exceptional items "to increase toward €7 billion." That figure amounted to €6.47 billion in 2009, a decrease of 6.6 percent from 2008.
UniCredit analysts said the outlook would not fuel Bayer's share price, however.
Last year, Bayer suffered above all in its chemical activities, those most exposed to the global economic downturn.
Its MaterialScience division saw a 22.8 percent drop in sales to €7.5 billion, though "business recovered markedly as the year progressed," Wenning said.
The group's HealthCare pharmaceutical unit posted increased sales of €15.98 billion meanwhile and made a core profit of €2.64 billion, for an increase of 21 percent.
"This growth was driven by positive business trends in both the pharmaceuticals and the consumer health segments, particularly in the emerging markets," with sales of Bayer's cancer drug Nexavar a main driver of growth, the statement said.
The board will recommend a 2009 dividend of €1.40 per share, the same level as in 2008, the statement said. More than €460 million would also be paid to Bayer's 108,400 workers in variable one-time payments.
Finally, "to safeguard our long-term growth, we are planning capital expenditures of €1.4 billion," Wenning said. "A budget of €2.9 billion has again been set aside for research and development."