In a surprise announcement just before 1 a.m. in Moscow, the Russian central bank said it would raise its key interest rate to 17 percent from 10.5 percent, effective today. The move was the largest single increase since 1998, when Russian rates soared past 100 percent and the government defaulted on debt.

The news prompted an immediate gain in the ruble, with one-month ruble forwards up 1.6 percent in Asian trading.

via Russia Defends Ruble With Biggest Rate Rise Since 1998 – Bloomberg.