The Micex falls have been blamed on panic selling by nervy investors
One of Russia's leading stock exchanges has suspended trading until Friday after share prices fell too sharply.
Shares on Moscow's Micex index dropped by 14% in the first half hour of Wednesday trading, prompting the halt.
The country's other key index, the RTS exchange, has also been suspended after falls of 11%, though no time frame has been set for it to reopen.
Both indexes saw record losses on Monday, and measures to boost banking system liquidity got a tepid reception.
Many observers had not expected the markets to open on Wednesday after recent losses.
"From a market point of view, they [the Micex exchange] had to get a sense of the [trading] situation," a trader at a major Russia bank told Reuters.
"Closing it was justified, although it was probably not justified to open it in the first place."
The falls in Russia and elsewhere have been blamed on panic selling by global investors fearful of a deep worldwide recession.
Russian shares were also hit in August amid concerns about the conflict between Russia and Georgia.