The European Union has fined Microsoft a record $1.35 billion for failing to comply with an anti-trust order.
The EU also said the company charged unreasonably high royalties to competing software developers who were trying to make their products compatible with Microsoft's.
The EU said the company had failed to abide by a 2004 ruling that required the company to share some of its software secrets with independent developers.
The fine is the biggest ever imposed on a single company and comes on top of a more than $600 million fine the EU imposed on Microsoft in 2004.
This is the first time the EU has penalized a company for failing to comply with an antitrust order.
Microsoft said the fines concerned "past issues" and that the company is now looking to the future. Company representatives did not say whether they would appeal the decision.
Some information for this report was provided by AFP and AP.