MOSCOW (Reuters) - Shares in some Russian companies targeted by new U.S. sanctions plummeted on Friday, but the broader market showed little reaction to the new round of geopolitical tensions.

FILE PHOTO: A wall sign with the logo of aluminium and power producer En+ Group is seen on the facade of a building in central Moscow, Russia February 13, 2018. REUTERS/Sergei Karpukhin/File Photo

The United States imposed sanctions against Russian businessmen, companies and government officials, striking at associates of President Vladimir Putin in one of Washington’s most aggressive moves to punish Moscow for a range of activities, including alleged meddling in the 2016 U.S. election.

Shares in EN+ Group, which is on the sanctions list and manages tycoon Oleg Deripaska’s aluminum and hydropower assets, were down 20.9 percent on the London stock exchange as of 1535 GMT.

Shares in Rusal, a Russian aluminum giant also included on the list, fell 16 percent on the Moscow Exchange. Deripaska stepped down as president of Rusal in February.

A trader at a U.S. bank in Moscow, who asked not to be named, said the main reason for such steep drops was that the sanctions require investors subject to U.S. jurisdiction to ditch the stocks within a month.

“Investors have to cancel positions before share prices hit the ground. European investors are likely to sell these shares only because of the negative mood. Very bad news,” the trader said.

A General License document published by the U.S. Treasury alongside the new sanctions list said investors had until May 7 to “to divest or transfer debt, equity, or other holdings” in EN+, Rusal and Russian vehicle maker GAZ.

Shares in GAZ, in which Deripaska also controls a majority stake, were up 1.95 percent in Moscow.

BCS brokerage said in a note that the new U.S. measures dashed Rusal’s hopes of inclusion in the global MSCI index.

“The stock will not enter MSCI indexes due to sanctions, despite all other criteria having been met,” BCS said.

Rusal said it regretted its inclusion on the new U.S. list, adding that its advisers were studying the situation.

The benchmark MOEX index fell briefly after the sanctions were announced but soon returned to its levels earlier in the day. At 1450 GMT, the rouble-denominated index was 0.5 percent lower at 2,283.6 points.

Market-watchers said the scale of new sanctions, which hit Deripaska and Andrei Kostin, the head of Russia’s number two lender VTB, came as a surprise. But the negative market impact will not be long-term, they said.

“There will be no particular impact on the economy and the markets,” said Andrey Movchan, director of the Economic Policy Program at the Carnegie Moscow Centre.

“The effect is rather psychological, as for the first time sanctions hit people who are informally connected to the authorities. This could be a stronger signal for Russian oligarchs that they are not immune.”

The rouble weakened against the dollar to its lowest level since Feb. 12 after the new sanctions were announced, but was also hit by falling oil prices.

The currency was 0.6 percent weaker at 58.07 versus the dollar at 1535 GMT, and Brent crude futures were 1.6 percent lower on the day, at $67.26 per barrel.

“Such publications do not weaken the rouble and the stock market, but they hamper their growth. The only thing that limits growth (on the Russian market) is geopolitics,” said Vladimir Miklashevsky, senior economist and trading desk strategist at Danske Bank in Helsinki.