The miner expects surplus to be about 100,000 metric tons this year, down from a previous estimate of 190,000 tons.

The value of deals in the industry declined 12.5% to $74.2 billion this year.

BHP has until 5 p.m. London on Wednesday to commit to an offer.

Sibanye issued the convertible bonds in November last year, partly to fund the $156 million acquisition of a US-based recycling business.

Such an outflow, if a deal goes ahead, could weaken the rand.

Anglo American was encouraged by key shareholders to continue engaging in talks with BHP over its proposed $49.18 billion mining merger.

Nornickel is the world's largest producer of palladium and a major producer of platinum.

Of the investors that Bloomberg spoke to this week, some suggested that BHP should provide a commitment to cover any lost value suffered by the subsidiaries’ new owners.