Two shareholders in Xstrata are planning to vote against a planned takeover by commodities trader Glencore.
Earlier this week Xstrata formally announced plans to merge with Glencore to create a $90bn major natural resources group to be named Glencore Xstrata International.
But, Standard Life Investments and Schroders, which together own 3.6% of Xstrata, said the deal undervalued their shares.
According to Reuters only 16% of Xstrata's register have to vote against the deal to block it.
The deal, which is a merger of equals, will create a group which will focus on the commodities value chain, from mining and processing, storage, freight and logistics, to marketing and sales.
Xstrata CEO, Mick Davis, commented: "A merger between Glencore and Xstrata offers a unique opportunity to create a new business model in our industry to respond to a changing environment. It is the logical next step for two complementary businesses, each with an outstanding track record of shareholder value creation, entrepreneurial management and a proven ability to spot valuable opportunities and capitalise on them."
The group is expected to have a significant and expanded operational footprint, including positions in the next major regions for mining investment, including African copper-belt, Kazakhstan and South America.
Davis will be appointed as CEO of the combined group while Ivan Glasenberg, current Glencore CEO, will be the Deputy CEO and president of the new company.