Russia's aluminium and nickel sectors set to merge
The deal is likely to mark the first stage in creation of Russia's first diversified global metals and mining firm.
Another agreement by RusAl to purchase a 25% plus one share interest in Norilsk Nickel from Prokhorov's Onexim Group came into effect on December 21.
The board of KM Invest decided to sell 2% of its stake in Norilsk Nickel on December 19.
Norilsk, based in northern Russia, is the world's biggest nickel mining company. It is believed to be worth about $US 40 billion.