Traders in international financial markets are increasingly on edge, as wild swings in commodity prices – ranging from oil, to palladium and platinum – stoke fears that some major players in these markets are being hit with hefty margin calls.

Some of these margin calls have already been revealed. Peabody Energy, the world’s biggest privately owned coal producer, has revealed that it has been forced to post an extra $US534 million ($720 million) in cash security since the end of December to satisfy margin calls on its coal hedges.