Shares in Scandi Standard tumbled as the Nordic region's top poultry group warned of the hit to trade from Europe's spreading bird flu outbreak.
Cases of bird flu in Denmark have led to a number of countries banning the import of Danish poultry products.
And Sweden is likely to be similarly affected after cases were detected there, Scandi said.
"On November 23, bird flu was detected in Sweden, and Sweden is therefore likely to be subject to similar trade restrictions," the group said.
"Such temporary trade restrictions are typically imposed for a duration of 6-12 months following the last detection."
The company said bird flu has not been detected among any of its own suppliers.
After reviewing its planned sales from Denmark and Sweden, Scandi said that forecast a hit to operating profits of SEK4m-8m a month.
"The impact may however be larger during the initial stages as new markets/channels needs to be identified and logistics adapted," Scandi said.
In markets which are not closed for exports from the affected countries, the company forecast prices under pressure due to competition.
Scandi Standard shares in Sweden were down some 5.9% in afternoon deals at SEK52.00, the lowest level since January.
The latest outbreak of bird flu has been widespread.
The H5N8 strain is particularly virulent, as it has been carried by migrating waterfowl, which are usually immune such viruses.
This week cases have been reported in Iran, South Korea, Japan, and across a swathe of northern and eastern Europe.
In Germany, more than 100,000 turkeys have been culled on the order of the Lower Saxony regional government, while in West Pomerania an emu in Ueckermünde Zoo succumbed to the disease.
Swedish authorities on Thursday announced that at least 37,000 poultry would need to be culled, and the figure could rise.
The World Health Organisation has also flagged a potential risk to human health, although no humans have so far been detected with the H5NA strain.
By William Clarke