The divestment of PM2 was a condition set by the European Commission upon its approval of the merger of Billerud and Korsnäs in late-November 2012.
The machine produces kraft and sack paper.
Following the sale of PM2, BillerudKorsnäs will supply input items such as pulp, steam and water to SwedPaper. In addition, BillerudKorsnäs will sell a maximum of 66,000 tons per year of pulp to SwedPaper.
Other operations at Gävle will not be affected by the sale and will remain unchanged in BillerudKorsnäs' ownership, the company said.