Commodities trader Glencore is set to pay a larger premium than expected to finalise its proposed $88bn merger with global miner Xstrata.
The move is designed to defuse concerns among Xstrata investors about an easy deal between the chief executives of the two companies.
Xstrata shareholders are set to receive 2.8 shares in Glencore for each share held, according to the Financial Times.
The ratio, which represents an 8% premium, was higher than had been expected.
However, the terms of the deal could still change and each Xstrata share was valued at 2.66 times a Glencore share based on Friday's close.
Glencore already has a 34% stake in Xstrata and the two companies have held on-off talks over the years.
Last week Glencore approached Xstrata and opened discussions over an all-share merger of equals.
The two groups, which restarted dialogue in December 2011, have reached a preliminary understanding on the structure of the combined group's top management.
Xstrata is expected to take a majority of seats on the board while Glencore Chief Executive Ivan Glasenberg is expected to hold a deputy position.
Ivan Glasenberg and Mick Davis, the chief executives of Xstrata, will make-up the combined company's board and senior management.
Xstrata is now focused on organic or self-generated growth to boost production by 50% to 2014. It has a project pipeline budget of $19.5bn over the two years.