Anglo American posted an annual loss of $3.1 billion on Thursday after taking an impairment of $3.8 billion, mostly due to its ailing diamond unit, as it races to restructure into a major copper producer following a bruising takeover battle with BHP last year.

Anglo is considering either selling or listing De Beers, the carrying value of which is now about $4bn. That includes about $2bn worth of stock, a similar amount to last year.

The miner wrote down the value of its embattled diamond business again as it seeks to ready the division for disposal.