Untethering the ruble helped Russia ride out the biggest oil downturn in a generation. But it’s left the world’s biggest energy exporter vulnerable to greater volatility in crude prices as OPEC pushes output cuts . To address that, the Bank of Russia is preparing to wade back into the currency market after an 18-month absence and soak up foreign revenue earned in excess of the $40 oil price assumed in the budget. First Deputy Prime Minister Igor Shuvalov said in an interview last week that currency purchases are possible already at current oil prices. The exchange rate needs to be more “predictable,” Finance Minister Anton Siluanov said on Saturday. “At this stage of economic recovery, Russia would benefit from a stable ruble rather than further potentially excessive appreciation, which could undermine the competitiveness of Russian exporters at the time when the global trade pie seems to be shrinking ,” […]