Investment returns from the world’s 40 biggest mining companies declined to the lowest since at least 2003 amid a slump in commodity prices, according to PricewaterhouseCoopers LLP.

The average return on capital employed fell to 9 percent in 2014 from 9.5 percent the previous year, PwC said in its 12th annual Mine report. Only six companies, including Coal India Ltd., OAO GMK Norilsk Nickel and Randgold Resources Ltd., beat the hurdle investment rate of 15 percent to 20 percent, Michal Kotze, a partner at PwC in Johannesburg, told reporters on Thursday.

“Companies are not producing the returns — that’s why you see investors leaving the sector,” Kotze said in an interview. “They are essentially the same companies but with lower returns.”

The world’s biggest mining companies from Glencore Plc to Anglo American Plc are closing operations or selling assets after commodity prices from coal to platinum slumped. The total market capitalization of the top 40 dropped 16 percent to $791 billion in 2014 from the previous year, Kotze said.

The average dividend yield for the world’s 40 largest mining companies has reached an unprecedented five per cent.

A five-per-cent yield would be perfectly normal in the telecom or utility sectors. But it is highly irregular in mining, where companies need to plow significant capital into their projects to add new production and sustain existing production. We have already seen dividend reductions in the industry this year, and more would not be a shock.

The PwC report also had some positive news for the mining business.

It found that operating costs among the top 40 companies decreased five per cent last year, and free cash flow reached US$24 billion.

• [Editor:Juan]