The European Court of Justice has reduced a €9m fine against the Quinn Group of companies, which were implicated in a cartel which illegally fixed the price of acrylic glass.
The company, which manufactures plastics used in household appliances, appealed the €9m fine which was imposed in 2006.
The European Commission had taken the case against a number of European companies which it accused of operating a cartel in the 1990s.
The companies were accused of discussing prices, agreeing, implementing and monitoring price agreements and the exchange of commercially important and confidential information.
The case dates back to the 1990s when executives were accused of meeting in a Dublin hotel to exchange sensitive data and fix prices. Following today's judgment the fine was reduced to €8.25m.
Earlier this year, IBRC, the former Anglo Irish Bank, appointed a share receiver to take control of the Quinn family's stake in Quinn Group, which includes the glass business.
Quinn Insurance jobs safe, says new owners
Quinn Insurance, now owned by US group Liberty Mutual, says the future of the 1,500 jobs at the company will be secure under its new owners.
The company plans to rebrand under the Liberty name in the first three months of next year.
During the last 18 months, when the company was under administration, its business shrank by up to 40% and it made 900 staff redundant. However, its new owners say they have no plans for cost cutting.
The company's chief executive in Ireland, Patrick O'Brien, said the group planned to expand in household insurance in the coming years where it has had market share of about 4%.