Gold mining giant Gold Fields reported strong third-quarter results that shot the stock price up 20 percent – the biggest one-day gain since September 1999.

Its net cash flow also increased to $75 million, from $63 million a year ago, despite gold prices falling 13% over the same period.

Gold Fields’ South Deep saw costs and production improve significantly; suggesting the large-scale gold mine could achieve cash breakeven by the end of 2016.

In a statement from the company said: “Gold Fields is one of the very few gold miners producing profits and free cash flow at today's gold price.”

Gold Fields (NYSE:GFI) is a South African gold producer with eight operating mines in Ghana, Australia, Peru and South Africa.

In a statement, Gold Fields said: “The key catalyst that drove the stock price was more so the big production and cost improvement at the large-scale South Deep gold mine in South Africa.”

“It seems that the company could achieve cash breakeven prior to the end of 2016, and this is great news for shareholders,” it added.

It said: “Gold Fields has a strong balance sheet that we think could withstand lower gold prices. We think an uptick in U.S. interest rates could cause gold prices to drop to $1,000/oz and force gold miners to rethink their business models.”