Emerging-market economies had a brutal week. For years, during the crash and its aftermath, they did well as the advanced economies slumped. Recently, not so much. Many developing countries are seeing their currencies drop and their bonds and equities hammered. Just as the global recovery appeared to be strengthening, a fresh source of instability has presented itself.
The issue now is how to keep the turmoil from derailing the global expansion. In a way, this was not an unexpected development: The recession in the advanced economies caused central banks to push short-term interest rates to zero and buy assets to drive long-term rates down as well. Capital flowed to the developing world in search of better returns. As investors prepare for a resumption of normal monetary policy, demand for emerging-market assets is bound to fall. The question has always been whether this adjustment would be smooth or abrupt.