Nigeria’s foreign exchange reserves fell 3 percent in two weeks to $37.59 billion by Nov. 13, as the central bank stepped up support for the ailing naira currency. Data published by the central bank on Monday showed the reserves were at $38.76 billion on October 29. The bank has spent billions of dollars defending the naira, hit by falling global oil prices, in the past month. But despite repeated interventions, the naira closed at a new low of 173.20 on Monday.