Three Russian tycoons targeted by a new list of US sanctions may have lost a combined $7.5 billion since the list was announced.

This is according to Reuters calculations, which are based on price moves in the listed companies the three co-own. 

The US Treasury on April 6 announced sanctions on seven Russian oligarchs and 12 companies they own or control, saying they were profiting from a Russian state engaged in "malign activities" around the world. 

The news hit Russian markets, denting the rouble and sending shares in four publicly listed companies with links to those sanctioned plummeting both in Russia and elsewhere - Rusal, EN+ Group, GAZ group and Polyus. 

Of the seven oligarchs, three have links to publicly listed companies - Oleg Deripaska, Viktor Vekselberg and Suleiman Kerimov. 

In US dollar terms, Deripaska may have lost $4.56 billion in four trading days, Vekselberg could have lost $1.32 billion, and Kerimov appeared to have lost $1.58 billion, Reuters' calculations showed.

Reuters calculated the change in capitalisation of the four publicly traded companies they are linked to from just before the sanctions announcement up to the close of trade yesterday. 

It then adjusted the figures based on the stakes the three own in the firms and used the central bank's exchange rate set for April 11. 

The numbers do not include possible losses related to companies sanctioned by Washington but which have no market listings. 

Rusal and En+, controlled by Deripaska, declined to comment. 

Polyus's majority shareholder PGIL, through which the Kerimov family controls the company, also declined to comment. Vekselberg's Renova has not replied to a request for comment.

The latest sanctions have increased overall risk-aversion towards Russian assets, while hitting the companies named on the list especially hard. 

The main reason for steep drops in the companies' prices is that the sanctions require investors subject to US jurisdiction to ditch the stocks by May 7.

Shares in Hong Kong-listed aluminium giant Rusal had plunged 55.6% by yesterday's close in Hong Kong compared with Friday's close in Hong Kong before the US sanctions were announced. 

The company owns the Aughinish Alumina plant near Limerick. 

A Government spokeswoman was unable to say earlier this week what the sanctions mean for Rusal and its employees here. 

"The Department of Business, Enterprise and Innovation is assessing the potential implications that new US sanctions, targeting certain Russian individuals and firms, may have for both Irish and overseas companies operating in Ireland. The Department is also in close and regular contact with its enterprise agencies, IDA Ireland and Enterprise Ireland, who are monitoring this evolving situation," she said.

Shares in EN+ Group, Deripaska's company listed in London late last year, had fallen 50.8% by the close last night compared with late last week on the eve of the sanctions.

Deripaska owns a 76.6% stake in EN+, while EN+ owns a 48% stake in Rusal. 

Russian billionaire Vekselberg and his partners also own a 26.5% stake in Rusal, the world's second-largest aluminium producer. 

Shares in Russia's GAZ group, a manufacturer of light commercial vehicles in which Deripaska owns a 65% stake, had shed 9% by last night from last Thursday's close on the Moscow Exchange. 

Meanwhile, Shares in Polyus PLZL.MM, Russia's largest gold producer, in which the family of sanctioned tycoon Kerimov owns an 82% stake, dropped over 20.3% by Wednesday's close on the Moscow Exchange compared with Thursday's close a week ago. 

Polyus itself was not included in the sanctions list.