The ruble headed for the biggest weekly drop in emerging markets after oil producing nations in OPEC were said to agree on an expansion of output, pushing the price of Russia’s main export lower. The currency fell 1 percent against the dollar to 68.0920 by 5:50 p.m. in Moscow, taking its decline this week to 2.6 percent. The price of Brent, the benchmark for Russia’s main export blend, neared a six-year low Friday after OPEC set a new oil-output ceiling of 31.5 million barrels a day, according to a delegate with knowledge of the decision. Russia, which derives almost 50 percent of its budget revenue from oil and natural-gas exports, is pumping crude at near-record levels as it weathers its first recession since 2009 exacerbated by sanctions over the country’s role in the conflict in Ukraine. The price of crude in rubles sank to its lowest since 2011 last […]