Shares in firms controlled by Oleg Deripaska have plunged after the US imposed sanctions on seven Russian oligarchs and their companies on Friday.
Shares in the Russian aluminium giant Rusal nearly halved on the Hong Kong stock exchange on Monday.
EN+, the aluminium to hydropower firm controlled by Mr Deripaska, dived by 25% in London.
Russia’s main share index plunged 11% on Monday in the wake of the sanctions.
They follow a diplomatic crisis sparked by the poisoning of former spy Sergei Skripal in Salisbury.
The measures affect the seven oligarchs, 12 companies they own or control, as well as 17 senior Russian government officials.
The Kremlin slammed the sanctions. “This is an outrageous business from the point of view of illegality, from the point of view of flouting all the norms, and of course careful analysis is needed here,” said spokesman Dmitry Peskov.
The Russian government was “doing everything possible to minimise negative consequences” of the US measures, he added.
According to Washington, the individuals and companies were targeted for profiting from a Russian state engaged in “malign activities” around the world.
Other magnates hit by sanctions include Alexei Miller, director of state-owned energy giant Gazprom.