The Fair Trade Commission searched 10 producers and sellers of glass wool Tuesday that are suspected of forming a cartel in violation of the Antimonopoly Law, officials of the antimonopoly watchdog said.
The FTC alleges the companies raised prices of the insulation material several times through negotiations with construction companies in accordance with agreements made over the size of price hikes and their timing.
Glass wool products are low margin products for manufacturers because they are made of recycled glass waste and less affected by outside factors, including crude oil prices.
The FTC suspects the manufacturers, including Asahi Fiber Glass Co. and Mag Co., both based in Tokyo, tried to avoid excessive competition to help secure profits. Sales agents were also included in the raided companies.
The size of the domestic glass wool market was estimated at about 51 billion yen in fiscal 2003. Asahi Fiber and Mag together held more than 70 percent of the market share, according to industry data.