The ruble tumbled Wednesday to its weakest level in six months against the euro and to a more than two-month low versus the dollar on speculation that other countries will try to stem currency gains after Japan sold the yen for the first time since 2004.
A drop in oil prices also helped push Russia's currency lower, with the ruble weakening as much as 1.6 percent to 40.20 per euro, the lowest intraday price since March 17, and the first time the currency has broken 40 for six months, according to data compiled by Bloomberg. It lost as much as 0.7 percent to 30.97 per dollar, the weakest since July 8.
The Bank of Japan sold yen Wednesday to cap currency appreciation that erodes export competitiveness, Finance Minister Yoshihiko Noda said in Tokyo. Most Asian currencies fell after the move threatened to cut overseas sales. The yen slid from a 15-year high versus the dollar and slumped 1.8 percent to 36.1739 against the ruble.
Crude retreated for a second day in New York, sliding as much as 2.8 percent.
"The Japanese move has led to weakness in developing-market currencies across Asia as investors fear that other central banks will have to replicate Tokyo's move," Chris Weafer, chief strategist at UralSib, said in an e-mail interview. "Contagion to other global emerging-market currencies is also likely to weaken the ruble basket."