• Rusal shares plunged on Monday, losing 50 percent in Hong Kong
  • Kremlin is considering ways to support sanctioned companies

At Davos this year, Oleg Deripaska hurled a party with champagne, Russian folk dancers and a performance by Enrique Iglesias. Now the Russian billionaire is on an international blacklist usually reserved for terrorists and warlords.

On Friday, the U.S. aimed its toughest sanctions at Deripaska's metals empire, banning Americans from dealing with companies including United Co. Rusal. As the drastic nature of Washington's move became clear on Monday, the biggest aluminum producer outside China lost half its value in one day.

“This is economic assassination of the company, ” according to a senior executive at a trading home, who asked not to be identified talking about a customer.

Aluminum Giant

Share of world ex-China aluminum consumption

Source: CRU