The key index of Russia’s main stock exchange tumbled 20 percent after a delayed opening as investors feared the effects of Western sanctions following Moscow’s decision to attack Ukraine.
The RTS index was down 20.16 percent on February 24 after reopening following a suspension implemented by authorities.
The ruble crashed more than 9 percent on currency markets, prompting the Russian central bank to intervene to “stabilize” markets.
"To stabilize the situation on the financial market, the Bank of Russia has decided to start interventions in the foreign exchange market," the central bank said in a statement.
"The Bank of Russia will ensure the maintenance of financial stability and continuity of the operation of financial institutions, using all necessary tools," it said.
It added that other financial institutions "have clear action plans for any scenario."
Stock markets around the world also fell sharply early on February 24 as fears of economic disruptions hit the markets.
Oil prices rose above $100 a barrel, their highest levels since September 2014, on concerns of a disruption in supplies should Western sanctions affect Russian oil exports.
Gold prices and the Japanese yen -- traditional safe havens in the midst of global uncertainties -- also jumped higher.
"Russia/Ukraine tensions bring both a possible demand shock [for Europe], and more importantly a much larger supply shock for the rest of the world given the importance of Russia and Ukraine to energy, hard commodities, and soft commodities," National Australia Bank's Tapas Strickland was quoted by AFP as saying.
BNY Mellon Investment Management's Lale Akoner was quoted as saying: "Expect volatility to really persist in the next few months" amid global uncertainties.