Mining company Rio Tinto has announced the sudden departure of its chief executive Tom Albanese.
The company says Mr Albanese is stepping down after Rio made a $13.3 billion writedown on its coal division in Mozambique and a writedown of $10.5 billion on its aluminium assets.
Rio Tinto chairman Jan du Plessis has described the results as unacceptable.
"I would like to pay tribute to Tom for his considerable contribution to Rio Tinto over more than 30 years of service and for his integrity and dedication to the company," he said in a statement.
Mr Albanese says his resignation is effective immediately.
"While I leave the business in good shape in many respects, I fully recognise that accountability for all aspects of the business rests with the CEO," he said in a statement.
Mr du Plessis says the head of Rio's iron ore division, Sam Walsh, will step into the role.
"He is ideally placed to cast a fresh eye over how we address the challenges and opportunities in the business and derive greater value from it," he said.
Doug Ritchie, who led the acquisition and integration of the Mozambique coal assets, has also stepped aside.