Brazil’s mining giant Vale (NYSE:VALE) reported Thursday its deepest quarterly net loss ever, becoming at the same time the first of the three largest iron ore producers to put some of its core assets up for sale.

The Rio de Janeiro-based company posted a fourth-quarter net loss of $8.57 billion, its fifth drop in the past six quarters, driven by a dramatic and sustained rout of its main profit driver, iron ore.

Vale also blamed its poor results on impairment charges and a 47% depreciation of the Brazilian real against the dollar last year, situation that increased the value of the company’s dollar-denominated debt.

Iron ore prices were particularly hit last year, averaging $55.5 a tonne, 42% than in 2014. The steel-making ingredient dropped as low as $37 a tonne by the end of last year.

Vale posted a fourth-quarter net loss of $8.57 billion, its fifth drop in the past six quarters.

Over the full year, the company slid to a net loss of $12.13 billion from a net profit of $657 million in the previous 12 months.

Vale had to take a few impairment charges, mostly on its coal and nickel assets, totalling $9.37 billion.

The Samarco dam collapse in Nov. last year, which killed at least 17 people and became Brazil’s worst environmental disaster, also forced Vale to book a write-down of $132 million in unpaid dividends and royalties.

Chief executive Murilo Ferreira said in a conference call that Vale wanted to reduce its net debt to $15 billion within 18 months, from $25.23 billion at the end of the fourth quarter. But given the uncertain outlook for prices of iron ore and other commodities, the firm has begun “actively exploring more aggressive actions for this deleveraging, including the sale of core assets,” he said.

Murillo’s comments mark a substantial change of strategy from his prior plan of offering assets only in peripheral assets, such as energy and logistics.

Despite the negative market conditions, Vale said it remains competitive, with iron ore production costs of $11.9 per tonne excluding royalties.

The world’s largest iron ore and nickel producer also announced that the chairman of the board has been replaced. Gueitiro Matsuo Genso will assume Vale’s top board post effective immediately. He replaces Dan Conrado, who will continue to be a member of the company’s board.

• [Editor:Juan]