Mining giant Glencore Xstrata has reported a sharp improvement in first-half performance, marking a big switch back into profit.

The group, which came into being with a mega-merger last year, said it had made a net profit of $US1.72 billion ($A1.86 billion) during the first half of 2014, up from a $US9.39-billion loss a year earlier. The deep loss during the first half of 2013 was largely due to…