Osmose was fined in the High Court at Auckland for taking part in the cartel to lift prices in the wood preservatives industry.
The Commerce Commission, which led the investigation, said their actions had led to higher prices for treated timber such as fence posts and decking.
Four companies and three individuals involved in the case were fined more than NZ$5m, in both civil and criminal actions. Commission general manager Geoff Thorn said cartels damaged the economy.
“Cartels raise prices above competitive levels and harm companies who buy the cartel’s products as inputs for their own businesses,” said Mr Thorn.
Another seven companies and individuals are still going through the courts.
