Russia's ruble experienced its biggest one-day fall for over two years on Monday and stocks in major Russian companies also slid, as investors reacted to a new round of U.S. sanctions targeting some of Russia's biggest tycoons.

The sanctions, announced on Friday, target officials and businesspeople around President Vladimir Putin in an aggressive response to alleged Russian meddling in the 2016 U.S. election.

The impact of the new sanctions could threaten Russia's fragile economic recovery, which was only just beginning to take hold after the first major wave of sanctions against Russia, introduced in response to Moscow's annexation of Crimea in 2014.