An Australian regulator raised antitrust concerns over a planned $6.5 billion takeover by Canada’s Brookfield Asset Management (BAMa.TO) of freight firm Asciano Ltd (AIO.AX), potentially jeopardizing the country’s biggest inbound deal in four years. The proposed deal, which would be the largest-ever purchase of an Australian firm by a Canadian company, would give Brookfield Asciano’s rail network and train operations in two of the country’s eight states, the Australian Competition and Consumer Commission (ACCC) said in a statement on Thursday.