Mining firm Xstrata has formally announced plans to merge with Glencore, the world's biggest commodity trader.
The deal values the combined new business at $US90 billion, of which Xstrata would comprise $US39 billion.
The new group will be the world's biggest exporter of coal for power plants, and the largest producer of zinc.
The announcement came as Xstrata revealed a 20% increase in profits for 2011 to $US5.9 billion.
But the BBC reports it has been given a mixed reception, with two major Xstrata shareholders saying they will vote against the deal because it undervalues their shares.
Between them, Standard Life Investments and Schroders own 3.6% of Xstrata.
Xstrata shares fall almost 5% by Tuesday afternoon.
Glencore was floated on the stock exchange in May last year in London.
