Egypt’s foreign-exchange reserves have overtaken Nigeria’s for the first time since 2011. The North African country, which floated the pound and secured international monetary funding in November, has seen overseas holdings of local-currency bonds soar to $7.5 billion from just $100 million earlier. In Nigeria, where the central bank has tried to manage the naira instead of freeing it, reserves fell 2.3 percent last month. The lesson? Sometimes it’s better to let the market tell you what the rate should be, than the other way around.