Teck Resources Ltd., Canada’s largest diversified miner, warned that fourth-quarter earnings will be “significantly” below consensus estimates following “disappointing” results at its energy unit and trail operations, as well as on inventory valuations.

Earnings will be reduced by 30 cents  per share and earnings before interest, taxes, depreciation and amortization by $195 million, it said in a statement. The company expects to report a loss of $92 million before depreciation and amortization and inventory writedowns in its energy business unit, resulting in an after-tax loss of $86 million.

Teck said that “dramatic” widening of heavy oil differentials hurt results, while a decline in commodity prices in the quarter led to pretax inventory write-downs of $80 million. The company expects to report an after-tax loss of $31 million in its trail operations, citing factors including a maintenance shutdown and a fire in a silver refinery. In the third quarter, the miner reported results that trailed estimates amid rising costs in its coal business.