The German competition authority, the BundesKartellamt, has fined Microsoft €9m for colluding with retailers to set the price of "Office Home and Student 2007".
Suppliers are allowed to talk to retailers about prices but need to be careful not to break competition rules.
But in this case, Microsoft staff and a leading German stationer met at least twice to set prices. The two worked together on an advertising campaign in autumn 2008, which Microsoft funded.
BundesKartellamt rules state that discussions between suppliers and retailers must not lead to coordination to the extent that the supplier influences future actions by the retailer.
But the regulator ruled: "In the present case, this boundary has been crossed."
Microsoft has accepted the fine. ®