Billionaire Vladimir Potanin has declined a $19.2 billion for a 30 percent stake in Russia’s Norilsk Nickel metals producer from Viktor Vekselberg and Leonard Blavatnik, Vedomosti business daily quoted sources as saying on Friday. Norilsk Nickel has been the center of a conflict between Potanin and RusAl aluminum company owner Oleg Deripaska, which started last […]